THERMO ELECTRON CORP
S-4, 2000-05-01
MEASURING & CONTROLLING DEVICES, NEC
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<PAGE>   1

      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 1, 2000

                                                      REGISTRATION NO. 333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                            ------------------------

                                    FORM S-4
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933

                            ------------------------

                          THERMO ELECTRON CORPORATION
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

<TABLE>
<S>                                    <C>                                    <C>
               DELAWARE                                 3569                                04-2209186
     (STATE OR OTHER JURISDICTION           (PRIMARY STANDARD INDUSTRIAL                 (I.R.S. EMPLOYER
  OF INCORPORATION OR ORGANIZATION)         CLASSIFICATION CODE NUMBER)               IDENTIFICATION NUMBER)
</TABLE>

                                81 WYMAN STREET
                       WALTHAM, MASSACHUSETTS 02454-9046
                                 (781) 622-1000
              (ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER,
       INCLUDING AREA CODE, OF REGISTRANT'S PRINCIPAL EXECUTIVE OFFICES)

                            ------------------------

                          SANDRA L. LAMBERT, SECRETARY
                          THERMO ELECTRON CORPORATION
                                81 WYMAN STREET
                       WALTHAM, MASSACHUSETTS 02454-9046
                                 (781) 622-1000
           (NAME, ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER,
                   INCLUDING AREA CODE, OF AGENT FOR SERVICE)

                            ------------------------

                                   COPIES TO:

<TABLE>
<S>                                                      <C>
                SETH H. HOOGASIAN, ESQ.                                   DAVID E. REDLICK, ESQ.
                    GENERAL COUNSEL                                         HALE AND DORR LLP
              THERMO ELECTRON CORPORATION                                    60 STATE STREET
                    81 WYMAN STREET                                    BOSTON, MASSACHUSETTS 02109
           WALTHAM, MASSACHUSETTS 02454-9046                                  (617) 526-6000
                     (781) 622-1000
</TABLE>

                            ------------------------

    APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:  As
promptly as practicable after this Registration Statement becomes effective and
the other conditions to the exchange offer are met or waived.

    If the securities being registered on this form are being offered in
connection with the formation of a holding company and there is compliance with
General Instruction G, check the following box. [ ]

    If this form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, check the following box and
list the Securities Act registration statement number of the earlier effective
registration statement for the same offering. [ ]

    If this form is a post-effective amendment filed pursuant to Rule 462(d)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [ ]

                            ------------------------

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
=================================================================================================================================
                                                      AMOUNT            PROPOSED MAXIMUM     PROPOSED MAXIMUM
           TITLE OF EACH CLASS OF                      TO BE           OFFERING PRICE PER   AGGREGATE OFFERING      AMOUNT OF
       SECURITIES TO BE REGISTERED(1)              REGISTERED(2)             SHARE               PRICE(3)       REGISTRATION FEE
- ---------------------------------------------------------------------------------------------------------------------------------
<S>                                           <C>                     <C>                  <C>                  <C>
Common Stock, par value $1.00 per share
  (including preferred stock purchase rights
  attached thereto)(4).......................    5,397,453 shares             N/A             $97,079,181.28         $25,629
=================================================================================================================================
</TABLE>

(1) This registration statement relates to securities of the registrant
    exchangeable for shares of common stock of Thermedics Inc., a Massachusetts
    corporation, par value $.10 per share, in the exchange offer by the
    registrant for all the outstanding shares of Thermedics common stock and in
    the proposed merger of Thermedics with and into the registrant.

(2) Based on the maximum number of shares expected to be issued in connection
    with the exchange offer and the merger, calculated as the product of (a)
    11,994,339, representing the aggregate number of shares of Thermedics common
    stock outstanding on March 31, 2000 (other than shares owned by the
    registrant) plus the number of such shares for which options were
    outstanding on March 31, 2000, and (b) the exchange ratio of 0.45 shares of
    the registrant's common stock for each share of Thermedics common stock.

(3) Estimated solely for the purpose of calculating the registration fee in
    accordance with Rules 457(c) and 457(f) under the Securities Act of 1933,
    based upon (a) $8.09375, the average of the high and low prices per share of
    Thermedics common stock on April 27, 2000 as reported in the consolidated
    transaction reporting system, multiplied by (b) 11,994,339, representing the
    aggregate number of shares of Thermedics common stock outstanding on March
    31, 2000 (other than shares owned by the registrant) plus the number of such
    shares for which options were outstanding on March 31, 2000.

(4) Shares of Thermo Electron common stock being registered hereby are
    accompanied by Thermo Electron's preferred stock purchase rights. Until the
    occurrence of certain prescribed events, such rights are not exercisable,
    are evidenced by the certificate for the Thermo Electron common stock and
    will be transferred along with and only with the Thermo Electron common
    stock.

                            ------------------------

    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING
PURSUANT TO SECTION 8(a), MAY DETERMINE.
================================================================================
<PAGE>   2
THE INFORMATION CONTAINED IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED.
WE MAY NOT SELL THESE SECURITIES UNTIL THE RELATED REGISTRATION STATEMENT FILED
WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT
AN OFFER TO SELL THESE SECURITIES AND WE ARE NOT SOLICITING AN OFFER TO BUY
THESE SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

                    Subject to Completion, dated May 1, 2000

                          THERMO ELECTRON CORPORATION

                               OFFER TO EXCHANGE
                          0.45 SHARES OF COMMON STOCK
                                       OF
                          THERMO ELECTRON CORPORATION
                                      FOR
                     EACH OUTSTANDING SHARE OF COMMON STOCK
                                       OF
                                THERMEDICS INC.

                            ------------------------

                                     MERGER
                                       OF
                                THERMEDICS INC.
                                      INTO
                          THERMO ELECTRON CORPORATION

                            ------------------------

                        THE OFFER AND WITHDRAWAL RIGHTS
               WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY TIME,
             ON FRIDAY, MAY 26, 2000, UNLESS THE OFFER IS EXTENDED.

    We are offering to exchange 0.45 shares of common stock of Thermo Electron
Corporation for each outstanding share of common stock of Thermedics Inc. that
stockholders of Thermedics validly tender, and do not properly withdraw, before
the exchange offer expires. You may withdraw shares of Thermedics common stock
that you tender pursuant to this exchange offer at any time prior to the
expiration of the exchange offer.
    If we complete the exchange offer, we intend to cause Thermedics to merge
into Thermo Electron. In the merger, we will issue 0.45 shares of our common
stock for each outstanding share of Thermedics common stock, subject to any
applicable appraisal rights. This prospectus also relates to the shares of our
common stock that we would issue in the merger.
    You should read this prospectus carefully. It sets forth the terms and
conditions of the exchange offer and the merger. It also describes our and
Thermedics' businesses and finances. We have prepared this prospectus so that
you will have the information necessary to make a decision about the exchange
offer and whether to pursue your appraisal rights in connection with the merger.
    OUR OBLIGATION TO EXCHANGE OUR COMMON STOCK FOR THERMEDICS COMMON STOCK IS
SUBJECT TO THE IMPORTANT CONDITIONS LISTED BELOW UNDER "THE EXCHANGE
OFFER -- CONDITIONS OF THE EXCHANGE OFFER." THESE INCLUDE THE CONDITION THAT
STOCKHOLDERS OF THERMEDICS VALIDLY TENDER, AND DO NOT WITHDRAW, A SUFFICIENT
NUMBER OF SHARES OF THERMEDICS COMMON STOCK WHICH, TOGETHER WITH SHARES OF
THERMEDICS COMMON STOCK OWNED BY US, CONSTITUTE AT LEAST 90% OF THE OUTSTANDING
SHARES OF THERMEDICS COMMON STOCK UPON THE EXPIRATION OF THE EXCHANGE OFFER. AS
OF MARCH 31, 2000, WE OWNED 31,759,424 SHARES OF THERMEDICS COMMON STOCK,
REPRESENTING APPROXIMATELY 75.5% OF THE OUTSTANDING SHARES OF THERMEDICS COMMON
STOCK ON THAT DATE.
    Our common stock trades on the New York Stock Exchange under the symbol
"TMO." On April 27, 2000, the last reported sale price for our common stock was
$19.50. Thermedics common stock trades on the American Stock Exchange under the
symbol "TMD." On April 27, 2000, the last reported sale price for Thermedics
common stock was $8.00.
    An investment in our common stock involves a high degree of risk. You should
carefully review the "Risk Factors" beginning on page 15 for a discussion of
important factors that you should consider in connection with our offer, the
merger and an investment in our common stock.

                            ------------------------

    We incorporate by reference into this prospectus important business and
financial information about Thermedics and about us. This information is not
included in, or delivered with, this prospectus.
    We will provide you with a copy of any and all of the information that we
incorporate by reference in this prospectus, without charge, upon written or
oral request. If we do not specifically incorporate by reference in this
prospectus exhibits to the documents that we incorporate in this prospectus,
then we will not provide copies of those exhibits. TO OBTAIN TIMELY DELIVERY,
YOU MUST REQUEST THE INFORMATION NO LATER THAN MAY 19, 2000.
    You should direct any requests for documents relating to Thermedics or to us
to: Sandra L. Lambert, Corporate Secretary, Thermo Electron Corporation, 81
Wyman Street, Waltham, Massachusetts 02454 (telephone: 781-622-1000; facsimile:
781-768-6620).

                            ------------------------

    NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE
ADEQUACY OR ACCURACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIME.

                            ------------------------

               The date of this prospectus is             , 2000
<PAGE>   3

                               TABLE OF CONTENTS

<TABLE>
<S>                                                           <C>
QUESTIONS AND ANSWERS ABOUT THE EXCHANGE OFFER AND THE
  MERGER....................................................    1
SUMMARY.....................................................    4
RISK FACTORS................................................   15
FORWARD-LOOKING STATEMENTS..................................   21
INFORMATION ABOUT THERMO ELECTRON AND THERMEDICS............   22
BACKGROUND TO THE EXCHANGE OFFER AND THE MERGER.............   23
THE EXCHANGE OFFER..........................................   32
MARKET PRICES AND DIVIDENDS.................................   46
THE MERGER; APPRAISAL RIGHTS................................   47
FEDERAL INCOME TAX CONSEQUENCES.............................   49
COMPARISON OF THE RIGHTS OF HOLDERS OF OUR COMMON STOCK AND
  THE RIGHTS OF HOLDERS OF THERMEDICS COMMON STOCK..........   50
TRANSACTIONS WITH RELATED PARTIES...........................   61
LEGAL MATTERS...............................................   62
EXPERTS.....................................................   62
WHERE YOU CAN FIND MORE INFORMATION.........................   63
THERMO ELECTRON CORPORATION PRO FORMA CONSOLIDATED CONDENSED
  FINANCIAL STATEMENTS (UNAUDITED)..........................  F-1
ANNEX A.....................................................  A-1
ANNEX B.....................................................  B-1
ANNEX C.....................................................  C-1
</TABLE>

     THIS PROSPECTUS INCORPORATES IMPORTANT BUSINESS AND FINANCIAL INFORMATION
ABOUT THERMO ELECTRON AND THERMEDICS THAT IS NOT INCLUDED OR DELIVERED WITH THE
PROSPECTUS. YOU MAY OBTAIN THIS INFORMATION WITHOUT CHARGE TO YOU UPON WRITTEN
OR ORAL REQUEST. YOU MUST ADDRESS YOUR REQUEST TO SANDRA L. LAMBERT, CORPORATE
SECRETARY, THERMO ELECTRON CORPORATION, 81 WYMAN STREET, WALTHAM, MASSACHUSETTS
02454-9046, TELEPHONE (781) 622-1000. TO OBTAIN TIMELY DELIVERY, YOU MUST
REQUEST THE INFORMATION NO LATER THAN MAY 19, 2000.
<PAGE>   4

         QUESTIONS AND ANSWERS ABOUT THE EXCHANGE OFFER AND THE MERGER

Q: What is the exchange offer?

A: We are offering to exchange shares of our common stock for all of the
outstanding shares of Thermedics common stock that we do not already own.

Q: What is the exchange ratio?

A: We are offering to exchange 0.45 shares of our common stock for each share of
Thermedics common stock that stockholders of Thermedics validly tender in the
exchange offer. This exchange ratio represents a valuation of the Thermedics
common stock at a premium of 19.2% over its last reported sale price on March 7,
2000, the day before we announced the exchange ratio, based on the last reported
sale price of our common stock on that date.

Q: What happens to any fractional shares?

A: We will not issue fractional shares of our common stock in the exchange offer
or the merger in which we will cause Thermedics to merge into Thermo Electron.
Instead, we will pay you cash in an amount equal to $19.50 per whole share of
our common stock for your fractional shares.

Q: How do I participate in the exchange offer?

A: To tender your shares, you should:

     - If you hold your shares in your own name, complete and sign the enclosed
       letter of transmittal. Once completed, you should return it with your
       share certificates to EquiServe, L.P., the depositary for the exchange
       offer, at one of its addresses on the back cover of this prospectus.

     - If you hold your shares in "street name" through a broker, ask your
       broker to tender your shares.

Q: Will I have to pay any fees or commissions?

A: If you are the record owner of your shares and you tender your shares in the
exchange offer, you will not have to pay brokerage fees or incur similar
expenses. If you own your shares through a broker or other nominee and your
broker tenders the shares on your behalf, your broker may charge you a fee for
doing so. You should consult your broker or nominee to determine whether any
charges will apply.

Q: Can I withdraw shares that I have tendered?

A: You may withdraw shares that you have tendered at any time on or before May
26, 2000, or, if we extend the exchange offer, before the exchange offer
expires. Unless we have accepted your shares for exchange on or before June 29,
2000, you may also withdraw shares you have tendered which we have not accepted
for exchange at any time after that date.

Q: What are the conditions to the exchange offer?

A: Our obligation to complete the exchange offer is subject to a number of
conditions. Thermedics stockholders must tender, and not withdraw, a sufficient
number of shares of Thermedics common stock so

                                        1
<PAGE>   5

that when the exchange offer expires we own at least 90% of Thermedics'
outstanding shares. As of March 31, 2000:

<TABLE>
<S>                                                                             <C>
Our ownership of Thermedics common stock as a percentage of
  outstanding shares was:...................................                        75.5%
Based on that percentage, the number of shares of Thermedics
  common stock that Thermedics stockholders must tender for
  us to meet the 90% condition is:..........................                    6,085,222
Our ownership of Thermedics common stock as a percentage of
  the shares of Thermedics common stock then outstanding,
  assuming that optionholders had exercised all outstanding
  Thermedics options issued by Thermedics or us and
  debenture holders did not convert any of the two issues of
  Thermedics' outstanding $47.4 million total principal
  amount of convertible debentures into Thermedics common
  stock at their conversion prices of $32.68 and $14.928 per
  share, would have been:...................................                        72.5%
Based on that percentage, the number of shares of Thermedics
  common stock that Thermedics stockholders must tender for
  us to meet the 90% condition is:..........................                    7,625,284
</TABLE>

Our obligation to complete the exchange offer is also subject to the other
conditions described below under "The Exchange Offer -- Conditions Of The
Exchange Offer."

Q: How long will it take to complete the exchange offer and the merger?

A: The exchange offer will expire at 12:00 midnight on May 26, 2000. We can
elect at any time to extend the exchange offer. We will need to extend the
exchange offer if the registration statement of which this prospectus is a part
is not effective by May 26, 2000. If we complete the exchange offer, we expect
to close the merger as promptly as practicable after we have completed the
exchange offer.

Q: What will happen after you complete the exchange offer?

A: We plan to take Thermedics private by acquiring all of the outstanding shares
of Thermedics common stock that we do not currently own. The exchange offer is
the first step in this plan. If we complete the exchange offer, we will own at
least 90% of Thermedics' outstanding shares. We would then cause Thermedics to
merge with and into Thermo Electron in a so-called "short-form" merger. A
short-form merger would not require approval of Thermedics' board of directors
or the stockholders of Thermedics other than Thermo Electron.

Q. What will happen to my shares if you complete the exchange offer and I have
not tendered my shares?

A: If you do not tender your shares of Thermedics common stock and we complete
the exchange offer, your shares will remain outstanding until the closing of the
merger of Thermedics and Thermo Electron. After the merger, each of your shares
will be converted, subject to appraisal rights, into the right to receive 0.45
shares of our common stock.

Q: What are the federal income tax consequences to me of the exchange offer and
the merger?

A: For federal income tax purposes, your receipt of shares of our common stock
in the exchange offer or the merger would be tax-free. However, your receipt of
cash in lieu of fractional shares of our common stock in the exchange offer or
the merger would be taxable to you.

                                        2
<PAGE>   6

Q: Is Thermo Electron's financial condition relevant to my decision to tender my
   shares in the exchange offer or to pursue my appraisal rights in connection
   with the merger?

A: Yes. If you tender your shares of Thermedics common stock and we close the
exchange offer, you will receive shares of our common stock in exchange for your
Thermedics common stock. Similarly, if you do not tender your shares of
Thermedics common stock, you will receive shares of our common stock in the
merger unless you pursue your appraisal rights. You should consider our
financial condition before you decide to become one of our stockholders through
the exchange offer or the merger. In considering our financial condition, you
should review this prospectus and the documents that we incorporate by reference
in this prospectus, because they contain detailed business, financial and other
information about us.

Q: Where can I find more information about Thermo Electron and Thermedics?

A: You can find more information about Thermo Electron and Thermedics from
various documents that we file and that Thermedics files with the SEC. You can
obtain copies of these documents in the manner described under "Where You Can
Find More Information" on page 63.

Q: What should I do if I have questions?

A: If you have any questions about the exchange offer, you should call our
information agent, D.F. King & Co., Inc. If you are a banker or broker, call
collect at (212) 269-5550. All others should call toll-free at (800) 290-6433.

                                        3
<PAGE>   7

- --------------------------------------------------------------------------------

                                    SUMMARY

     Before you make any decision with respect to the exchange offer or the
merger, you should read the following summary together with the more detailed
information included elsewhere, or that we incorporate by reference, in this
prospectus.

- - THE COMPANIES

     - Thermo Electron Corporation (page 22).  Thermo Electron Corporation, a
       Delaware corporation, develops, manufactures and sells measurement and
       detection instruments that our customers use to collect, monitor and
       analyze data. As discussed below, we are in the process of spinning off
       our business that serves the healthcare industry with a range of medical
       products for diagnosis and monitoring and our paper recycling and
       papermaking equipment business. We are also in the process of selling
       various non-core businesses. We plan to take Thermo Ecotek Corporation,
       our electric power generation business, private. Although we no longer
       consider it a core business under our new strategy, we expect to retain
       Thermo Ecotek after we take it private while we continue to evaluate how
       to best exit that business and create maximum value for our stockholders.

      Our common stock is listed on the New York Stock Exchange under the symbol
      "TMO." Our principal executive offices are located at 81 Wyman Street,
      P.O. Box 9046, Waltham, Massachusetts 02454-9046, and our telephone number
      is (781) 622-1000.

     - Thermedics Inc. (page 22).  Thermedics Inc., a Massachusetts corporation,
       develops, manufactures and markets diverse product lines, including
       biomedical products, security instruments and equipment that assures the
       quality of a wide variety of consumer products and bulk materials.
       Thermedics is seeking a buyer for its Thermo Cardiosystems Inc.
       subsidiary, which manufactures implantable heart assist devices.
       Thermedics' common stock is listed on the American Stock Exchange under
       the symbol "TMD." Thermedics' principal executive offices are located at
       470 Wildwood Street, P.O. Box 2999, Woburn, Massachusetts 01888-1799 and
       its telephone number is (781) 622-1000.

     - Affiliation of Thermedics and Thermo Electron (pages 26 and 28).  We own
       a majority of Thermedics' common stock. Several officers and directors of
       Thermedics are also officers or directors of Thermo Electron. See
       "Background To The Exchange Offer And The Merger."

     - The Thermo Electron reorganization (page 23).  On January 31, 2000, we
       announced that our board of directors had authorized our management to
       proceed with a major reorganization of our operations. As part of this
       reorganization, we plan to:

        - acquire the public minority interest in most of our subsidiaries that
          have minority investors;

        - spin off our business that serves the healthcare industry with a range
          of medical products for diagnosis and monitoring and our paper
          recycling and papermaking equipment business; and

        - divest a variety of non-core businesses.

      The primary goal of the reorganization is to allow us to focus on our core
      business and each of our spun-off subsidiaries to focus on its core
      business. The purpose of the exchange offer and merger described in this
      prospectus is to allow us to acquire the minority public interest in
      Thermedics as part of our overall reorganization. The exchange offer and
      merger also would provide the public stockholders of Thermedics with a
      continuing equity interest in the restructured company.

     - The Thermedics reorganization.  On January 31, 2000, Thermedics announced
       its intention to acquire, through cash tender offers and mergers, the
       minority public interests in two of its public subsidiaries. Thermedics
       completed these acquisitions in April 2000. Thermedics spent
       approximately $40.0 million to acquire the public minority interests in
       these subsidiaries. We loaned Thermedics $12.0 million to finance a
       portion of these acquisitions and related expenses. Thermedics has
       entered into letters of intent for the sale of its remaining Thermo
       Voltek businesses

- --------------------------------------------------------------------------------


                                        4
<PAGE>   8

- --------------------------------------------------------------------------------

       and is seeking a buyer for Thermo Cardiosystems, its only remaining
       subsidiary with publicly-held minority interests.

- - PRINCIPAL TERMS OF THE EXCHANGE OFFER

     - Exchange offer for all outstanding Thermedics shares (page 32).  We are
       offering to acquire all of the outstanding shares of common stock of
       Thermedics that we do not currently own in exchange for shares of our
       common stock.

     - Exchange ratio (page 32).  We are offering to exchange 0.45 shares of our
       common stock for each share of Thermedics common stock that Thermedics
       stockholders validly tender in the exchange offer. We sometimes refer to
       this ratio of 0.45 to 1 as the "exchange ratio." The following table
       shows the last reported sale price of Thermedics common stock on the
       American Stock Exchange and our common stock on the New York Stock
       Exchange on March 7, 2000, the last trading date before we announced the
       exchange ratio, and on April 27, 2000.

<TABLE>
<CAPTION>
      DATE                                                          THERMEDICS    THERMO ELECTRON
      ----                                                          ----------    ---------------
      <S>                                                           <C>           <C>
      March 7, 2000...............................................   $9.0625          $24.00
      April 27, 2000..............................................   $  8.00          $19.50
</TABLE>

      The exchange ratio represents a valuation of the Thermedics common stock
      at a premium of 19.2% over its last reported sale price on March 7, 2000,
      based on the last reported sale price of our common stock on that date.
      For more information regarding the trading ranges of our common stock and
      Thermedics common stock, see "-- Comparative Per Share Market
      Information."

     - Cash in lieu of fractional shares (page 32).  We will not issue
       fractional shares of our common stock in the exchange offer or the
       merger. Instead, we will pay an amount in cash equal to $19.50 per whole
       share of our common stock for fractional shares.

     - Expiration of the exchange offer (page 32).  The exchange offer will
       expire at 12:00 midnight on Friday, May 26, 2000. We can elect at any
       time to extend the exchange offer. If we extend the exchange offer, we
       will issue a press release announcing the extension. See "The Exchange
       Offer -- Terms Of The Exchange Offer; Expiration Date."

     - Procedures for accepting the exchange offer and tendering shares (page
       35).  To exchange your shares of Thermedics common stock for shares of
       our common stock in the exchange offer, you must follow the procedures
       described below under "The Exchange Offer -- Procedures For Accepting The
       Exchange Offer And Tendering Shares" and in the accompanying letter of
       transmittal before the exchange offer expires.

     - Issuance of Thermo Electron shares for tendered shares (page 34).  If we
       satisfy or waive all of the conditions of the exchange offer and we
       accept for exchange shares of Thermedics common stock that you tendered,
       we will issue you shares of our common stock in exchange for your shares
       of Thermedics common stock promptly after the exchange offer expires. See
       "The Exchange Offer -- Acceptance For Exchange And Exchange Of Shares."

     - Withdrawal rights (pages 32 and 38).  You may withdraw shares of
       Thermedics common stock that you have tendered at any time on or before
       May 26, 2000, or, if we extend the exchange offer, before the exchange
       offer expires. Unless accepted for exchange on or before June 29, 2000,
       you may also withdraw shares that you have tendered and which we have not
       accepted for exchange at any time after June 29, 2000. For your
       withdrawal to be effective, EquiServe, the depositary for the exchange
       offer, must receive your notice of withdrawal at one of the addresses on
       the back cover of this prospectus before the exchange offer expires. For
       more information on your withdrawal rights, see "The Exchange
       Offer -- Withdrawal Rights."

- --------------------------------------------------------------------------------


                                        5
<PAGE>   9

- --------------------------------------------------------------------------------

     - Conditions of the exchange offer (page 39).  Our obligation to complete
       the exchange offer is subject to a number of conditions. In particular,
       Thermedics stockholders must tender, and not withdraw, enough shares of
       Thermedics common stock so that at the time the exchange offer expires we
       own at least 90% of Thermedics' outstanding shares of common stock. In
       addition, our obligation to complete the exchange offer is subject to the
       condition that the SEC declare effective the registration statement of
       which this prospectus is a part. You can tender your shares of Thermedics
       common stock before the registration statement is effective but we cannot
       accept these shares for exchange before the registration statement is
       effective or before the exchange offer expires. If the SEC has not
       declared the registration statement effective by the expiration date, we
       will extend or withdraw the exchange offer. For more information
       regarding the conditions to our obligation to complete the exchange
       offer, see "The Exchange Offer -- Conditions Of The Exchange Offer." We
       are not aware of any other material filing, approval or other action by
       any federal or state governmental or administrative authority that we
       must obtain in connection with our acquisition of shares of Thermedics
       common stock as contemplated by this prospectus.

- - THE MERGER

     - Subsequent merger (pages 28 and 47).  We plan to take Thermedics private
       by acquiring all of the outstanding shares of Thermedics common stock
       that we do not currently own. The exchange offer is the first step in
       this plan. If we complete the exchange offer, we will own at least 90% of
       Thermedics' outstanding shares of common stock. We would then cause
       Thermedics to merge with and into Thermo Electron in a so-called
       "short-form" merger. A short-form merger would not require approval of
       Thermedics' board of directors or the stockholders of Thermedics other
       than Thermo Electron.

     - No public stockholder action for merger; appraisal rights (page 47).  We
       do not intend to enter into a merger agreement with Thermedics or to seek
       the approval of the directors of Thermedics for the merger. Even if you
       do not tender your shares of Thermedics common stock in the exchange
       offer, you would not be entitled to vote your shares with respect to the
       merger. If you do not tender your shares and we complete the merger, you
       would have a right to demand a judicial appraisal of the fair value of
       your shares of Thermedics common stock. You could lose your right to an
       appraisal, however, if you fail to follow the statutory procedure. See
       "The Merger; Appraisal Rights."

     - Merger consideration (page 47).  In the merger, we would issue 0.45
       shares of our common stock for each share of Thermedics common stock that
       we do not already own. This is the same consideration for each share of
       Thermedics common stock that we are offering in this exchange offer. See
       "Background To The Exchange Offer And The Merger -- The Merger."

- - SHARE OWNERSHIP INFORMATION

     - Thermedics shares outstanding.  As of March 31, 2000, Thermedics had
       outstanding:

        - 42,049,606 shares of common stock;

        - options to purchase 1,640,945 shares of common stock;

        - approximately $31.6 million principal amount of non-interest bearing
          convertible subordinated debentures due June 1, 2003 convertible into
          a total of 965,881 shares of common stock; and

        - approximately $15.9 million principal amount of 2 7/8% convertible
          subordinated debentures due June 1, 2003 convertible into a total of
          1,061,830 shares of common stock.

- --------------------------------------------------------------------------------


                                        6
<PAGE>   10

- --------------------------------------------------------------------------------

     - Ownership of Thermedics common stock by Thermo Electron and officers and
       directors of Thermo Electron and Thermedics.  On March 31, 2000, we owned
       31,759,424 shares of Thermedics common stock, or approximately 75.5% of
       the outstanding shares of Thermedics common stock. Assuming that
       optionholders exercised all outstanding options to purchase Thermedics
       common stock and debenture holders did not convert any of Thermedics'
       outstanding non-interest bearing convertible subordinated debentures into
       Thermedics common stock at the current conversion price of $32.68 per
       share or 2 7/8% convertible subordinated debentures into Thermedics
       common stock at the current conversion price of $14.928 per share, we
       would have owned approximately 72.5% of the outstanding shares of
       Thermedics common stock on that date. On January 31, 2000, our directors
       and executive officers owned less than 1% of the outstanding shares of
       our common stock and less than 1% of the outstanding shares of Thermedics
       common stock. On January 31, 2000, the directors and executive officers
       of Thermedics who are not also our directors or executive officers owned
       less than 1% of the outstanding shares of Thermedics common stock and
       less than 1% of the outstanding shares of our common stock. On that date,
       our executive officers and directors also owned options to purchase
       2,660,715 shares of our common stock and 199,650 shares of Thermedics
       common stock.

     - Ownership of Thermo Electron after the exchange offer and the merger.  If
       we acquire all of the outstanding shares of Thermedics common stock
       pursuant to the exchange offer and the merger, former stockholders of
       Thermedics would acquire through the exchange offer and the merger
       approximately 3% of the then outstanding shares of our common stock,
       based upon the number of shares of Thermedics common stock and of our
       common stock outstanding on March 31, 2000 and the assumption that no
       Thermedics optionholders exercise their options and that no Thermedics
       debenture holders convert their debentures. In our reorganization, we are
       also offering shares of our common stock in connection with acquiring the
       minority interests in five of our other public subsidiaries. We would
       issue approximately 17.7 million additional shares of our common stock in
       these other transactions, assuming that optionholders do not exercise any
       options to purchase shares of common stock of the subject companies and
       debenture holders do not convert any convertible debt securities of the
       subject companies.

- - RISK FACTORS (PAGE 15)

     Before you make any decision about the exchange offer or the merger, you
should read carefully this prospectus and the documents that we incorporate by
reference in this prospectus. You should also carefully consider the risks of
the exchange offer and the merger, our reorganization and our business that we
identify in this prospectus and in the documents that we incorporate by
reference in this prospectus. These risks include the following:

     - we may not complete our reorganization as proposed, including the two
       proposed spin-offs, the acquisition of the minority interests in most of
       our subsidiaries and the dispositions of our non-core businesses;

     - we may not realize the anticipated benefits of our reorganization;

     - the fixed exchange ratio in this exchange offer and the merger may work
       to your disadvantage if Thermedics common stock increases in value or our
       common stock decreases in value;

     - the trading price for our common stock has been and may continue to be
       volatile; and

     - our business is subject to a number of risks, including intense
       competition, rapid technological changes, significant governmental
       regulation and difficulties of international operations.

     You should carefully review "Risk Factors" beginning on page 15 for a more
complete discussion of these and other risk factors relating to the exchange
offer, the merger, our reorganization and our business.

- --------------------------------------------------------------------------------


                                        7
<PAGE>   11

- --------------------------------------------------------------------------------

- - FEDERAL INCOME TAX CONSEQUENCES (PAGE 49)

     For federal income tax purposes, your receipt of shares of our common stock
pursuant to the exchange offer or the merger would be tax-free. However, you
would recognize taxable income upon the receipt of cash in lieu of fractional
shares of our common stock in the exchange offer or the merger.

     For a more detailed discussion of the tax consequences of the exchange
offer and the merger, you should carefully review "Federal Income Tax
Consequences." We urge you to consult with your own tax advisor.

- - CONSEQUENCES OF THE EXCHANGE OFFER AND THE MERGER (PAGE 28)

     Completion of the exchange offer and the merger would have the following
consequences:

     - The shares of Thermedics would no longer be listed on the American Stock
       Exchange; and

     - Thermedics would no longer be subject to the requirements of the
       Securities Exchange Act of 1934, including requirements to file annual
       and other periodic reports.

     If you do not tender your shares of Thermedics common stock and we complete
the exchange offer, your shares will remain outstanding until the merger of
Thermedics and Thermo Electron. After the merger, each of your shares will
convert, subject to appraisal rights, into the right to receive 0.45 shares of
our common stock.

- - EFFECT OF THE MERGER ON THERMEDICS STOCK OPTIONS AND DEBENTURES (PAGES 30 AND
31)

     - Stock options.  In connection with the exchange offer and the merger, we
       will assume Thermedics' stock option plans and any outstanding options to
       purchase shares of Thermedics common stock under those plans. After we
       have assumed these options, they will be exercisable for shares of our
       common stock. The number of shares of our common stock underlying each
       assumed option will equal the number of shares of Thermedics common stock
       underlying the option before the merger multiplied by the exchange ratio.
       The exercise price for each assumed option will be calculated by dividing
       the exercise price of the Thermedics stock option before the merger by
       the exchange ratio, rounded up to the nearest whole cent.

     - Debentures.  In connection with the merger, we will assume Thermedics'
       non-interest bearing convertible subordinated debentures due June 1, 2003
       and its 2 7/8% convertible subordinated debentures due June 1, 2003.
       After we assume these debentures, they will be convertible into shares of
       our common stock, instead of shares of Thermedics common stock. As of
       March 31, 2000, approximately $31.6 million principal amount of
       Thermedics' non-interest bearing debentures was outstanding and
       approximately $15.9 million principal amount of Thermedics' 2 7/8%
       debentures was outstanding. As of that date, the non-interest bearing
       debentures were convertible into a total of 965,881 shares of Thermedics
       common stock at a conversion price of $32.68 per share and the 2 7/8%
       debentures were convertible into a total of 1,061,830 shares of
       Thermedics common stock at a conversion price of $14.928 per share. After
       the merger, the non-interest bearing debentures would be convertible into
       a total of 434,647 shares of our common stock at a conversion price of
       $72.62 per share and the 2 7/8% debentures would be convertible into a
       total of 477,824 shares of our common stock at a conversion price of
       $33.17 per share. Holders of these debentures will not have the right to
       require Thermedics to redeem their debentures as a result of the merger.

- - POTENTIAL CONFLICTS OF INTEREST (PAGE 26)

     In setting the exchange ratio, our financial interest was adverse to the
financial interest of the public stockholders of Thermedics. We set the exchange
ratio on our own and without any negotiations with Thermedics.

- --------------------------------------------------------------------------------


                                        8
<PAGE>   12

- --------------------------------------------------------------------------------

- - APPRAISAL RIGHTS (PAGE 47)

     If you tender your shares of Thermedics common stock in the exchange offer,
you will not be entitled to exercise appraisal rights under the Massachusetts
Business Corporation Law. If you do not tender your shares in the exchange
offer, upon the merger of Thermedics into Thermo Electron, you will have a right
to object and demand payment of the judicially appraised fair value of your
Thermedics shares under the Massachusetts Business Corporation Law. This value
may be more or less than the market value of the 0.45 shares of our common stock
issuable for each share of Thermedics common stock in the exchange offer and the
merger. See "The Merger; Appraisal Rights."

- - COMPARISON OF STOCKHOLDERS' RIGHTS (PAGE 50)

     If you tender your shares of Thermedics common stock in the exchange offer
or do not exercise appraisal rights in the merger, you will become a stockholder
of Thermo Electron. Your rights as a stockholder of Thermo Electron will be
governed by Delaware corporate law and by our certificate of incorporation and
bylaws. Unlike Thermedics, we have a classified board of directors and we have
adopted a stockholders rights plan. The classified board, the rights plan and
other provisions of our certificate of incorporation and bylaws may make it more
difficult for a third party to acquire us, even if an acquisition is favored by
many of our stockholders. See "Comparison Of The Rights Of Holders Of Our Common
Stock And The Rights Of Holders Of Thermedics Common Stock."

- - SUMMARY HISTORICAL AND UNAUDITED PRO FORMA COMBINED SELECTED FINANCIAL
  INFORMATION

     We will exchange shares of our common stock for shares of Thermedics common
stock that we accept in the exchange offer or we acquire in the merger. You
should consider our financial condition before you decide to become one of our
stockholders through the exchange offer or the merger. In considering our
financial condition, you should review the documents that we incorporate by
reference in this prospectus because they contain detailed business, financial
and other information about us and about Thermedics.



- --------------------------------------------------------------------------------


                                        9
<PAGE>   13

- --------------------------------------------------------------------------------

               SELECTED FINANCIAL INFORMATION -- THERMO ELECTRON

     We have derived the selected financial information presented below as of
and for the fiscal years ended January 1, 2000, and January 2, 1999, and for the
fiscal year ended January 3, 1998, from our consolidated financial statements,
which Arthur Andersen LLP, independent public accountants, audited, as indicated
in their report. We incorporate these financial statements by reference into
this prospectus from our Annual Report on Form 10-K for the fiscal year ended
January 1, 2000. We have derived the selected financial information presented
below as of January 3, 1998, and as of and for the fiscal years ended December
28, 1996 and December 30, 1995, from our consolidated financial statements,
which Arthur Andersen LLP audited, but which we have not included or
incorporated by reference in this prospectus. You should read this information
in conjunction with our consolidated financial statements and the related notes
that we incorporate by reference into this prospectus.

<TABLE>
<CAPTION>
                                                                FISCAL YEAR(1)
                                        --------------------------------------------------------------
                                         1999(2)      1998(3)        1997       1996(4)        1995
                                        ----------   ----------   ----------   ----------   ----------
                                                   (IN THOUSANDS EXCEPT PER SHARE AMOUNTS)
<S>                                     <C>          <C>          <C>          <C>          <C>
STATEMENT OF OPERATIONS DATA:
Revenues..............................  $2,471,193   $2,055,805   $1,979,602   $1,573,005   $1,059,064
Income (Loss) from Continuing
  Operations Before Extraordinary
  Items...............................     (14,580)     114,676      174,665      164,172       76,167
Net Income (Loss).....................    (174,573)     181,901      239,328      190,816      139,582
Earnings (Loss) per Share from
  Continuing Operations Before
  Extraordinary Items:
  Basic...............................        (.09)         .71         1.15         1.16          .60
  Diluted.............................        (.11)         .67         1.05         1.03          .55
Earnings (Loss) per Share:
  Basic...............................       (1.10)        1.12         1.57         1.35         1.10
  Diluted.............................       (1.13)        1.08         1.41         1.17          .95
BALANCE SHEET DATA (AT END OF PERIOD):
Working Capital.......................  $1,450,858   $2,163,010   $2,001,963   $2,218,617   $1,317,146
Total Assets..........................   5,181,842    5,421,060    4,961,046    4,546,942    3,247,952
Long Term Obligations.................   1,565,974    1,808,582    1,518,687    1,531,668    1,079,761
Minority Interest.....................     364,278      399,512      464,191      364,163      200,868
Common Stock of Subsidiaries Subject
  to Redemption.......................       7,692       40,500       40,500        2,613           --
Shareholders' Investment..............   2,014,486    2,254,802    2,007,862    1,755,576    1,311,311
OTHER DATA (UNAUDITED):
Book Value per Share..................  $    12.87   $    14.23   $    12.62   $    11.71   $     9.82
Cash Dividends Declared per Share.....          --           --           --           --           --
Ratio of Earnings to Fixed
  Charges(5)..........................        1.32x        3.35x
</TABLE>

- ---------------

(1) Our 1999, 1998, 1997, 1996 and 1995 fiscal years ended January 1, 2000,
    January 2, 1999, January 3, 1998, December 28, 1996 and December 30, 1995,
    respectively.

(2) Reflects a $182.4 million pretax charge for restructuring and related costs.

(3) Reflects a $32.5 million pretax charge for restructuring and related costs,
    the issuance of $150.0 million principal amount of our notes and our public
    offering of common stock for net proceeds of $290.1 million.

(4) Reflects the issuance of $585.0 million principal amount of our convertible
    debentures.

(5) For purposes of computing the ratios of earnings to fixed charges,
    "earnings" represent income from continuing operations before taxes,
    minority interest and extraordinary items, plus fixed charges. "Fixed
    charges" consist of interest on indebtedness and amortization of debt
    expense and one-third of rental expense, which we treat as the interest
    component of rental expense.

- --------------------------------------------------------------------------------


                                       10
<PAGE>   14

- --------------------------------------------------------------------------------

                  SELECTED FINANCIAL INFORMATION -- THERMEDICS

     We have derived the selected financial information presented below as of
and for the fiscal years ended January 1, 2000, and January 2, 1999, and for the
fiscal year ended January 3, 1998, from Thermedics' consolidated financial
statements, which Arthur Andersen LLP, independent public accountants, audited,
as indicated in their report. We incorporate these financial statements by
reference into this prospectus from Thermedics' Annual Report on Form 10-K for
the fiscal year ended January 1, 2000. We have derived the selected financial
information presented below as of January 3, 1998, and as of and for the fiscal
years ended December 28, 1996 and December 30, 1995, from Thermedics'
consolidated financial statements, which Arthur Andersen LLP audited, but which
we have not included or incorporated by reference in this prospectus. You should
read this information in conjunction with Thermedics' consolidated financial
statements and the related notes that we incorporate by reference into this
prospectus.

<TABLE>
<CAPTION>
                                                                 FISCAL YEAR(1)
                                              ----------------------------------------------------
                                              1999(2)    1998(3)    1997(4)    1996(5)      1995
                                              --------   --------   --------   --------   --------
                                                    (IN THOUSANDS EXCEPT PER SHARE AMOUNTS)
<S>                                           <C>        <C>        <C>        <C>        <C>
STATEMENT OF OPERATIONS DATA:
Revenues....................................  $223,503   $208,644   $200,184   $179,608   $118,835
Income from Continuing Operations Before
  Extraordinary Item........................    10,578     14,939     36,861     21,808      6,644
Net Income (Loss)...........................   (13,221)    23,610     41,492     29,138     17,174
Earnings per Share from Continuing
  Operations Before Extraordinary Item:
  Basic.....................................       .25        .36       1.00        .60        .20
  Diluted...................................       .25        .35        .95        .57        .20
Earnings (Loss) per Share:
  Basic.....................................      (.32)       .57       1.13        .80        .51
  Diluted...................................      (.31)       .55       1.07        .75        .49
BALANCE SHEET DATA (AT END OF PERIOD):
Working Capital.............................  $153,419   $183,832   $213,866   $184,051   $ 71,833
Total Assets................................   441,809    408,483    380,179    349,086    267,445
Long Term Obligations.......................    47,599     47,552     65,021     65,014      8,319
Minority Interest...........................    44,273     42,007     38,632     25,325         --
Shareholders' Investment....................   223,402    248,127    227,851    211,643    171,799
OTHER DATA (UNAUDITED):
Book Value per Share........................  $   5.33   $   5.95   $   6.21   $   5.77   $   5.06
Cash Dividends Declared per Share...........        --         --         --         --         --
Ratio of Earnings to Fixed Charges(6).......      6.09x      9.55x
</TABLE>

- ---------------
(1) Thermedics' 1999, 1998, 1997, 1996 and 1995 fiscal years ended January 1,
    2000, January 2, 1999, January 3, 1998, December 28, 1996 and December 30,
    1995, respectively.

(2) Reflects a $2.7 million pretax charge for restructuring and related costs
    consisting of $0.8 million of unusual costs and $1.9 million of inventory
    provisions. Also reflects Thermedics' July 1999 acquisition of Eric Jaeger,
    GmbH.

(3) Reflects a $4.6 million extraordinary gain, net of taxes, and Thermedics'
    June 1998 acquisition of its product-monitoring business.

(4) Reflects a $17.1 million nontaxable gain from the issuance of stock by a
    subsidiary.

(5) Reflects $23.7 million of nontaxable gains from the issuance of stock by
    subsidiaries, a $12.7 million pretax charge for restructuring and unusual
    costs, Thermedics' January 1996 acquisition of Moisture Systems Corporation
    and certain affiliated companies and Rutter & Co. B.V. and Thermedics' May
    1996 issuance of $65.0 million principal amount of non-interest bearing
    subordinated convertible debentures.

(6) For purposes of computing the ratios of earnings to fixed charges,
    "earnings" represent income from continuing operations before taxes,
    minority interest and extraordinary items, plus fixed charges. "Fixed
    charges" consist of interest on indebtedness and amortization of debt
    expense and one-third of rental expense, which we treat as the interest
    component of rental expense.

- --------------------------------------------------------------------------------


                                       11
<PAGE>   15

- --------------------------------------------------------------------------------

          UNAUDITED PRO FORMA COMBINED SELECTED FINANCIAL INFORMATION
                         AND COMPARATIVE PER SHARE DATA

     The following table presents unaudited pro forma combined selected
financial information for us and for Thermedics, historical selected financial
information for us and for Thermedics, and unaudited pro forma combined per
share data for us and for Thermedics. We derived the historical financial
information from our financial statements and those of Thermedics, which we
incorporate by reference into this prospectus. We derived the pro forma
information from the pro forma consolidated condensed financial information
included elsewhere in this prospectus. The unaudited pro forma consolidated
condensed statement of operations data sets forth our results of operations for
the fiscal year ended January 1, 2000, assuming that we had successfully
completed the exchange offer and the merger as of the beginning of fiscal 1999.
The unaudited pro forma consolidated condensed balance sheet data sets forth our
financial position as of January 1, 2000, assuming that we had successfully
completed the exchange offer and the merger on January 1, 2000.

     This data is not necessarily indicative of the results of the future
operations of the combined entity or the actual results that would have occurred
had we completed the exchange offer and the merger prior to the periods
indicated.

<TABLE>
<CAPTION>
                                                              FISCAL YEAR ENDED
                                                               JANUARY 1, 2000
                                                              -----------------
                                                                (IN THOUSANDS
                                                              EXCEPT PER SHARE
                                                                  AMOUNTS)
<S>                                                           <C>
PRO FORMA COMBINED:
STATEMENT OF OPERATIONS DATA:
  Revenues..................................................     $2,471,193
  Loss from Continuing Operations Before Extraordinary
     Items..................................................        (15,870)
BALANCE SHEET DATA (AT END OF PERIOD):
  Working Capital...........................................     $1,462,011
  Total Assets..............................................      5,244,582
  Long-term Obligations.....................................      1,565,974
  Minority Interest.........................................        318,958
  Common Stock of Subsidiaries Subject to Redemption........          7,692
  Shareholders' Investment..................................      2,122,546
PER SHARE DATA:
THERMO ELECTRON (HISTORICAL):
  Book Value per Common Share...............................     $    12.87
  Cash Dividends Declared per Share.........................             --
  Loss per Share from Continuing Operations Before
     Extraordinary Items:
     Basic..................................................     $     (.09)
     Diluted................................................     $     (.11)
  Ratio of Earnings to Fixed Charges(2).....................           1.32x
PRO FORMA:
COMBINED PER SHARE OF THERMO ELECTRON STOCK:
  Book Value per Common Share...............................     $    13.17
  Cash Dividends Declared per Share.........................             --
  Loss per Share from Continuing Operations Before
     Extraordinary Items:
     Basic..................................................     $     (.10)
     Diluted................................................     $     (.12)
  Ratio of Earnings to Fixed Charges(2).....................           1.31x
</TABLE>

- --------------------------------------------------------------------------------


                                       12
<PAGE>   16

- --------------------------------------------------------------------------------

<TABLE>
<CAPTION>
                                                              FISCAL YEAR ENDED
                                                               JANUARY 1, 2000
                                                              -----------------
                                                                (IN THOUSANDS
                                                              EXCEPT PER SHARE
                                                                  AMOUNTS)
<S>                                                           <C>
COMBINED PER THERMO ELECTRON SHARE EQUIVALENT(1):
  Book Value per Common Share...............................     $     5.93
  Cash Dividends Declared per Share.........................             --
  Loss per Share from Continuing Operations Before
     Extraordinary Items:
     Basic..................................................     $     (.05)
     Diluted................................................     $     (.05)
  Ratio of Earnings to Fixed Charges(2).....................            .59x
THERMEDICS (HISTORICAL):
  Book Value per Common Share...............................     $     5.33
  Cash Dividends Declared per Share.........................             --
  Earnings per Share from Continuing Operations:
     Basic..................................................     $      .25
     Diluted................................................     $      .25
  Ratio of Earnings to Fixed Charges(2).....................           6.09x
</TABLE>

- ---------------
(1) Pro forma combined per Thermo Electron share equivalent data has been
    calculated based on the pro forma combined data for Thermo Electron common
    stock, multiplied by an exchange ratio of 0.45. See "The Exchange
    Offer -- Terms Of The Exchange Offer; Expiration Of The Exchange Offer --
    Exchange Ratio" for a description of the exchange ratio. The exchange ratio
    is the 0.45 shares of our common stock which you would have received for
    each share of Thermedics common stock in the exchange offer or the merger.

(2) For purposes of computing the ratios of earnings to fixed charges,
    "earnings" represent income from continuing operations before taxes,
    minority interest and extraordinary items, plus fixed charges. "Fixed
    charges" consist of interest on indebtedness and amortization of debt
    expense and one-third of rental expense, which we treat as the interest
    component of rental expense.



- --------------------------------------------------------------------------------


                                       13
<PAGE>   17

- --------------------------------------------------------------------------------

- - COMPARATIVE PER SHARE MARKET INFORMATION (PAGE 46)

     Our common stock is traded on the New York Stock Exchange under the symbol
"TMO." Thermedics' common stock is traded on the American Stock Exchange under
the symbol "TMD."

     The following table presents the closing prices per share of Thermedics
common stock and the closing prices per share of our common stock on:

     - March 7, 2000, the last trading day before our public announcement of the
       terms, including the exchange ratio, of the exchange offer and the
       merger; and

     - April 27, 2000.

     The table also presents, in the line entitled "Equivalent Per Share Price,"
the price per share of Thermedics common stock based upon the exchange ratio of
0.45 shares of our common stock for each share of Thermedics common stock.

<TABLE>
<CAPTION>
                                                            MARCH 7, 2000    APRIL 27, 2000
                                                            -------------    --------------
<S>                                                         <C>              <C>
Thermedics................................................    $ 9.0625           $ 8.00
Thermo Electron...........................................    $  24.00           $19.50
Equivalent Per Share Price................................    $  10.80           $8.775
</TABLE>

     You should obtain current stock price quotations for our common stock and
the Thermedics common stock.

- - FOR MORE INFORMATION (PAGE 63)

     You can obtain more information about Thermedics and about us from our
respective public filings with the SEC. See "Where You Can Find More
Information."

     If you have any questions about the exchange offer, you should call the
information agent, D.F. King & Co., Inc. If you are a banker or broker, call
collect at (212) 269-5550. All others should call toll-free at (800) 290-6433.


- --------------------------------------------------------------------------------


                                       14
<PAGE>   18

                                  RISK FACTORS

     The exchange offer, the merger and an investment in our common stock
involve a high degree of risk. If any of the following events occurs, our
business, financial condition and results of operations would likely suffer,
possibly materially.

RISK RELATED TO THE EXCHANGE OFFER AND THE MERGER

BECAUSE WE WILL NOT ADJUST THE EXCHANGE RATIO TO REFLECT CHANGES IN OUR OR
THERMEDICS' STOCK PRICE, THE FIXED EXCHANGE RATIO USED IN THE EXCHANGE OFFER MAY
PROVE UNFAVORABLE TO YOU.

     We have fixed the exchange ratio at 0.45 shares of our common stock for
each share of Thermedics common stock. We will not adjust the exchange ratio to
reflect fluctuations in the market value of shares of our common stock or
Thermedics common stock. We will use the same exchange ratio in the exchange
offer and the merger. If you tender your shares of Thermedics common stock and
we complete the exchange offer or if you do not tender your shares of Thermedics
common stock and do not properly exercise your appraisal rights in connection
with the merger, you will be locked into the exchange ratio and you will not be
able to capture gains from possible increases in the value of Thermedics common
stock. You may incur losses from possible decreases in the value of our common
stock.

RISKS RELATED TO OUR REORGANIZATION

BECAUSE OUR REORGANIZATION IS VERY COMPLEX AND WILL REQUIRE GOVERNMENTAL AND
THIRD PARTY CONSENTS AND APPROVALS, WE MAY NOT BE ABLE TO SUCCESSFULLY COMPLETE
THIS REORGANIZATION OR TO DO SO ON THE TIME SCHEDULE WE CONTEMPLATE.

     Our reorganization consists of:

     - the acquisition of the public minority interest in most of our
       subsidiaries that have minority investors;

     - the spin off of two of our businesses; and

     - the sale of a variety of non-core businesses.

To accomplish these objectives, we will need to obtain a variety of governmental
and third party consents and approvals. In particular, in addition to the
Internal Revenue Service ruling that we discuss below, we will need to obtain:

     - approval of the spin-offs and some of the other transactions by our board
       of directors;

     - when we are making a tender or exchange offer, the tender by minority
       stockholders of enough shares to allow us to own at least 90% of the
       target subsidiary's outstanding shares;

     - the satisfactory resolution of any comments that the SEC raises on
       various registration statements, tender offer documents and other
       filings; and

     - the receipt of any necessary third party contractual consents.

     If we do not receive these consents and approvals, we may not be able to
effect some aspects of our reorganization. If we are not able to effect all
aspects of the reorganization, we may not achieve some or all of the anticipated
benefits of our reorganization. Until we have completed the entire
reorganization, we will continue to own and operate a diverse group of
businesses, some of which may continue to have minority stockholders.

     Our reorganization is time-consuming and expensive, and consumes management
resources. The failure of our management to complete the proposed reorganization
in a timely manner could negatively affect the public market's confidence in our
management, which in turn may adversely affect the market price of our common
stock.

                                       15
<PAGE>   19

WE DO NOT EXPECT TO PROCEED WITH OUR TWO PLANNED SPIN-OFFS UNTIL WE RECEIVE A
FAVORABLE RULING FROM THE INTERNAL REVENUE SERVICE, WHICH THE INTERNAL REVENUE
SERVICE MAY NOT ISSUE OR WHICH MAY TAKE A SUBSTANTIAL PERIOD OF TIME FOR US TO
OBTAIN.

     We do not expect to spin-off our business that serves the healthcare
industry with a range of medical products for diagnosis and monitoring or our
paper recycling and papermaking equipment business unless we obtain a favorable
ruling from the Internal Revenue Service. The Internal Revenue Service may not
grant the necessary ruling or may seek to impose conditions to the granting of
the ruling that are not acceptable to us. We do not expect the Internal Revenue
Service to issue a tax ruling before the end of 2000, and additional delays are
possible.

AS PART OF OUR REORGANIZATION, WE ARE SEEKING TO DIVEST A SIGNIFICANT NUMBER OF
BUSINESSES; WE MAY NOT SUCCEED IN SELLING ALL OF THESE BUSINESSES IN A TIMELY
MANNER OR AT PRICES WE CONSIDER ACCEPTABLE.

     We plan to sell a significant number of businesses as part of our
reorganization. This process will entail a number of risks:

     - We may not find buyers for all of these businesses.

     - The timing of these dispositions is uncertain.

     - We cannot be certain that the terms, including price, for the sale of
       these businesses will be acceptable to us.

     - Each of these sales will be subject to various conditions, including
       conditions in the agreements governing the transaction and the receipt of
       necessary governmental approvals.

EVEN IF WE SUCCEED IN COMPLETING OUR REORGANIZATION, WE WILL FACE A NUMBER OF
CHALLENGES IN INTEGRATING OUR INSTRUMENT BUSINESS.

     Currently we operate our instrument business directly and through a number
of majority-owned subsidiaries, including Thermo Instrument Systems Inc. and
Thermedics. We have conducted these operations largely as autonomous,
unaffiliated businesses. As part of our reorganization, we plan to manage these
operations in a more coordinated manner. The following factors may make it
difficult for us to successfully integrate and consolidate our instrument
operations:

     - Our success in integrating these businesses will depend on our ability to
       coordinate geographically separate organizations and integrate personnel
       with different business backgrounds and corporate cultures.

     - Our ability to combine these businesses will require coordination of
       administrative, sales and marketing, distribution and accounting and
       finance functions and expansion of information and management systems.

     - The integration process could disrupt our instrument business.

     - Retaining key employees of these businesses may be difficult.

OUR REORGANIZATION CONTEMPLATES THE ISSUANCE OF A SIGNIFICANT NUMBER OF
ADDITIONAL SHARES OF OUR COMMON STOCK, WHICH MAY DEPRESS THE MARKET PRICE OF OUR
SHARES.

     We expect to issue a substantial number of shares of our common stock or
securities exercisable for shares of our common stock in connection with the
exchange offer, the merger and our reorganization. At March 31, 2000,
156,904,025 shares of our common stock were outstanding. The number of shares of
our

                                       16
<PAGE>   20

common stock outstanding may increase by as many as 58.1 million shares because,
as part of our reorganization:

     - We plan to exchange shares of our common stock for the common stock held
       by minority stockholders in a number of our public subsidiaries,
       including Thermedics. We expect to issue a total of approximately 22.3
       million shares of our common stock in these transactions.

     - We plan to assume employee stock options in these transactions, including
       the merger with Thermedics, that would be exercisable for approximately
       17.9 million shares of our common stock. In addition, we may be required
       to issue additional stock options to retain our key employees.

     - The debentures issued by some of our subsidiaries, including Thermedics,
       will become convertible into shares of our common stock. Based on the
       total principal amounts outstanding of these debentures and the
       conversion prices at March 31, 2000, these debentures would be
       convertible into approximately 17.9 million shares of our common stock.

     The increase in the number of outstanding shares of our common stock, as
well as the potential future issuance of shares of our common stock upon
conversion of debentures or exercise of employee stock options, may depress the
market price of our common stock.

WE ARE UNABLE TO PREDICT THE LIQUIDITY OR PROSPECTIVE PERFORMANCE OF THE COMMON
STOCK OF THE COMPANIES THAT WE INTEND TO SPIN OFF.

     We are unable to predict the liquidity or market performance of the shares
of the businesses we plan to spin off. Although Thermo Fibertek Inc., the
company that conducts our paper recycling and papermaking equipment business,
has publicly traded shares, the historic prices of these shares may not be
representative of the trading price of Thermo Fibertek's common stock after the
number of shares held by its stockholders other than us increases as a result of
the spin-off. We currently conduct our business that serves the healthcare
industry with a range of medical products for diagnosis and monitoring both
directly and through some of our subsidiaries. There is currently no public
trading market for the shares of the company that will conduct this business
following the proposed spin-off. The businesses that we are spinning off may not
have the financial resources and management skills necessary to succeed as
independent entities.

AS A RESULT OF THE SPIN-OFF OF THERMO FIBERTEK AND ITS SUBSIDIARIES, WE WILL
REMAIN AS THE GUARANTOR OF INDEBTEDNESS AND STOCK REDEMPTION RIGHTS OF THESE
COMPANIES EVEN THOUGH WE WILL NO LONGER CONTROL THEIR BUSINESS OR OPERATIONS.

     We have guaranteed the payment of principal and interest on $153 million
principal amount of debentures issued by Thermo Fibertek. These debentures
mature in July 2004. We have also guaranteed the financial obligations of Thermo
Fibergen Inc., a subsidiary of Thermo Fibertek, under stock redemption rights
granted by Thermo Fibergen. We are contingently liable for $60.1 million under
these stock redemption rights, some of which terminate in September 2000 and the
remainder of which terminate in September 2001. We will remain liable as a
guarantor for these obligations following the spin-offs, although we will no
longer control the business or operations of Thermo Fibertek or of its
subsidiaries.

RISKS RELATED TO OUR BUSINESS AND FINANCIAL CONDITION

OUR STOCK PRICE MAY BE VOLATILE, WHICH COULD CAUSE YOU TO LOSE PART OR ALL OF
YOUR INVESTMENT.

     The market price for our common stock can be very volatile. The market
price for our common stock may be affected by a number of factors, including:

     - the risks described in this prospectus;

     - our financial results; and

     - general market conditions.

                                       17
<PAGE>   21

In addition, the stock market has experienced extreme price and volume
fluctuations. This volatility has significantly affected the market prices of
securities for reasons frequently unrelated to or disproportionate to the
operating performance of the specific companies. These broad market fluctuations
may adversely affect the market price of our common stock.

WE MAY NOT BE ABLE TO COMPLETE PENDING OR FUTURE ACQUISITIONS, AND WE MAY NOT BE
ABLE TO INTEGRATE ANY ACQUIRED BUSINESSES INTO OUR EXISTING BUSINESS OR MAKE THE
ACQUIRED BUSINESSES PROFITABLE.

     One of our strategies is to supplement our internal growth by acquiring
businesses and technologies that complement or augment our existing product
lines. Some of the businesses we have acquired have had low levels of
profitability. In addition, businesses we may seek to acquire may be marginally
profitable or unprofitable. For these acquired businesses to achieve acceptable
levels of profitability, we must change their operations and improve their
market penetration. We may not be successful in this regard.

     We may be unable to identify or complete promising acquisitions for many
reasons, including:

     - competition among buyers;

     - the need for regulatory approvals, including antitrust approvals; and

     - the high valuations of businesses resulting from historically high stock
       prices.

     We may have to pay, and have paid, substantial premiums over the fair value
of the net assets of the companies we acquire. We have acquired significant
intangible assets, including approximately $1.2 billion of cost in excess of net
assets of acquired companies, or goodwill, recorded on our balance sheet as of
January 1, 2000. We expect to record additional goodwill in 2000 as a result of
our plans to acquire the minority interests in most of our publicly-traded
subsidiaries. Our ability to realize the value of this asset will depend on
future cash flows of the acquired businesses. These cash flows in turn depend on
how well we have identified these acquired businesses as desirable acquisition
candidates and how well we can integrate these acquired businesses.

     To finance our acquisitions, we may have to raise additional funds, either
through public or private financings. We may be unable to obtain such funds or
may be able to do so only on unfavorable terms.

IT MAY BE DIFFICULT FOR US TO EXPAND BECAUSE SOME OF THE MARKETS FOR OUR
PRODUCTS ARE NOT GROWING.

     Some of the markets in which we compete have been flat or declining over
the past several years. To address this issue, we have pursued a number of
potential growth strategies, including:

     - acquiring complementary businesses;

     - developing new applications for our technologies; and

     - strengthening our presence in selected geographic markets.

These strategies may not result in growth of our business, and we may not be
able to successfully implement these strategies.

WE HAVE SIGNIFICANT INTERNATIONAL OPERATIONS WHICH CAN ENTAIL ADDITIONAL RISKS.

     We are a global company with substantial operations outside of the United
States. We intend to continue to expand our international operations. In 1999,
our international revenues from continuing operations, including export revenues
from the U.S., accounted for approximately 63% of our total revenues. Our
international revenues are subject to many risks, including the following:

     - changes in exchange rates may adversely affect demand for our products
       and the profitability in U.S. dollars of products and services we provide
       in foreign markets, where payment for our products and services is made
       in the local currency;

                                       18
<PAGE>   22

     - we may find it hard to enforce agreements and collect receivables using a
       foreign country's legal system;

     - our foreign customers may have longer payment cycles;

     - foreign countries may impose additional withholding taxes or otherwise
       tax our foreign income, impose tariffs, or adopt other restrictions on
       foreign trade;

     - U.S. export licenses may be difficult to obtain;

     - intellectual property rights may be harder to enforce in foreign
       countries;

     - foreign countries may have unexpected changes in regulatory requirements;

     - we may have difficulty managing and staffing our foreign operations
       because of, among other factors, language and cultural differences;

     - foreign countries in which we operate may be characterized by
       unpredictable political instability; and

     - our revenues could be affected by seasonal reductions in business
       activity in some foreign countries.

     Of these factors, exchange rate fluctuations, in particular, have had an
adverse impact upon our business and results of operations.

     A portion of our revenues come from exports to Asia. Some countries in Asia
experienced a severe economic crisis in the late 1990's, involving sharply
reduced economic activity and liquidity, highly volatile
foreign-currency-exchange and interest rates, and unstable stock markets.
Unstable conditions in Asia depressed our export sales to Asia in 1998 and early
1999. Unstable economic conditions in this region and other parts of the world
may adversely affect our future export sales.

WE MUST DEVELOP NEW PRODUCTS, ADAPT TO RAPID AND SIGNIFICANT TECHNOLOGICAL
CHANGE AND RESPOND TO INTRODUCTIONS OF NEW PRODUCTS TO REMAIN COMPETITIVE.

     Our growth strategy includes significant investment in product development.
We intend to increase our investment in research and development. We sell our
products in several industries that are characterized by rapid and significant
technological changes, frequent new product and service introductions and
enhancements and evolving industry standards. Without the timely introduction of
new products, services and enhancements, our products and services will likely
become technologically obsolete over time, in which case our revenue and
operating results would suffer.

     Our customers use many of our products to develop, test and manufacture
their new products. As a result, we must anticipate industry trends and develop
products in advance of the commercialization of our customers' products. If we
fail to adequately predict our customers' needs and future activities, we may
invest heavily in research and development of products and services that do not
lead to significant revenue.

     Many of our products and products under development are technologically
innovative and require significant planning, design, development and testing at
the technological, product and manufacturing-process levels. These activities
require us to make significant investments.

     Products in our markets undergo rapid and significant technological change
because of quickly changing industry standards and the introduction of new
products and technologies that make existing products and technologies
uncompetitive or obsolete. Our competition may adapt more quickly to new
technologies and changes in our customers' requirements than we can. The
products we are currently developing, or those we will develop in the future,
may not be technologically feasible or accepted by the marketplace, and our
products or technologies could become uncompetitive or obsolete.

                                       19
<PAGE>   23

CHANGES IN GOVERNMENTAL REGULATIONS MAY REDUCE DEMAND FOR OUR PRODUCTS OR
INCREASE OUR EXPENSES.

     We compete in many markets in which we or our customers must comply with
federal, state, local and foreign regulations, such as environmental, health and
safety and food and drug regulations. We develop, configure and market our
products to meet customer needs created by these regulations. Any significant
change in these regulations could reduce demand for our products. For example,
demand for electromagnetic compatibility test instruments made by one of our
subsidiaries decreased because of the declining importance of IEC 801, the
European Union directive on electromagnetic compatibility.

DEMAND FOR SOME OF OUR PRODUCTS DEPENDS ON CAPITAL SPENDING POLICIES OF OUR
CUSTOMERS AND ON GOVERNMENT FUNDING POLICIES.

     Our customers include manufacturers of semiconductors and products
incorporating semiconductors, pharmaceutical and chemical companies,
laboratories, universities, healthcare providers, government agencies and public
and private research institutions. Many factors, including public policy
spending provisions, available resources and economic cycles have a significant
effect on the capital spending policies of these entities. These policies in
turn can have a significant effect on the demand for our products. For example,
a reduction in discretionary capital spending by petrochemical, oil and gas, and
mining companies, due to difficult market conditions, has adversely affected our
businesses operating in the process control industry. Similarly, softness in the
semiconductor industry has resulted in lower revenues at some of our businesses.
Also, our Thermedics Detection Inc. subsidiary has experienced lower demand for
its detection instruments as a result of a shift in the process of recycling
plastic containers in Europe, from sanitizing and reusing recyclables, to
melting and re-forming plastic containers.

OBTAINING AND ENFORCING PATENT PROTECTION FOR OUR PROPRIETARY PRODUCTS,
PROCESSES AND TECHNOLOGIES MAY BE DIFFICULT AND EXPENSIVE.

     Patent and trade secret protection is crucial to us, because developing and
marketing new technologies and products is time-consuming and expensive. We own
many U.S. and foreign patents, and intend to apply for additional patents as
appropriate to cover our products. We may not obtain issued patents from any
pending or future patent applications owned by or licensed to us. The claims
allowed under any issued patents may not be broad enough to protect our
technology.

     We may incur significant expense in any legal proceedings to protect our
proprietary rights. In addition, third parties may seek to challenge, invalidate
or circumvent any issued patents owned by or licensed to us, and the rights
granted under those patents may not provide competitive advantages to us.
Defending infringement and/or invalidity claims would be expensive and divert
management's attention. In addition, those claims could result in awards of
substantial damages, which could have a significant adverse effect on our
results of operations, or court orders that could effectively prevent us from
making, using or selling our products and services in the United States or
abroad.

                                       20
<PAGE>   24

                           FORWARD-LOOKING STATEMENTS

     This prospectus and the information that we incorporate by reference into
this prospectus include statements that are subject to risks and uncertainties
and are based on the beliefs and assumptions of our and Thermedics' management,
based on information currently available to each company's management. When we
use words such as "believes," "expects," "anticipates," "intends," "plans,"
"estimates," "should," "likely" or similar expressions, we are making
forward-looking statements. Forward-looking statements include the information
concerning possible or assumed future results of our and Thermedics' operations
set forth:

     - under "Summary," "Risk Factors," "Information About Thermo Electron And
       Thermedics," "Background To The Exchange Offer And The Merger,"
       "Transactions With Related Parties" and "Thermo Electron Corporation Pro
       Forma Consolidated Condensed Financial Statements (Unaudited)" in this
       prospectus; and

     - under "Business" and "Management's Discussion and Analysis of Financial
       Condition and Results of Operations" in our and Thermedics' Annual
       Reports on Form 10-K that we incorporate by reference into this
       prospectus.

     Forward-looking statements are not guarantees of performance. They involve
risks, uncertainties and assumptions. The future results and stockholder values
of Thermo Electron and Thermedics may differ materially from those expressed in
the forward-looking statements. Many of the important factors that will
determine these results and values are beyond our ability to control or predict.
You should not put undue reliance on any forward-looking statements. For a
discussion of important factors that may cause actual results to differ
materially from those suggested by the forward-looking statements, you should
read carefully the section of this prospectus captioned "Risk Factors" that
starts on page 15.

                                       21
<PAGE>   25

                INFORMATION ABOUT THERMO ELECTRON AND THERMEDICS

THERMO ELECTRON

     Thermo Electron Corporation, a Delaware corporation, develops, manufactures
and sells measurement and detection instruments that our customers use to
collect, monitor and analyze data. We are in the process of spinning off our
business that serves the healthcare industry with a range of medical products
for diagnosis and monitoring, and our paper recycling and papermaking equipment
business. We are also in the process of selling various non-core businesses. We
plan to take Thermo Ecotek, our electric power generation business, private.
Although we no longer consider it a core business under our new strategy, we
expect to retain Thermo Ecotek after it is taken private while we continue to
evaluate how to best exit that business and create maximum value for our
stockholders.

     Our common stock is listed on the New York Stock Exchange under the symbol
"TMO." Our principal executive offices are located at 81 Wyman Street, P.O. Box
9046, Waltham, Massachusetts 02454-9046, and our telephone number is (781)
622-1000.

     The name, business address, principal occupation, five-year employment
history and citizenship of each of our directors and executive officers is
included in Annex A to this prospectus. None of our executive officers or
directors purchased or sold any shares of Thermedics common stock during the 60-
day period ended on April 27, 2000.

     During the past five years, we have not been convicted in a criminal
proceeding, excluding traffic violations or similar misdemeanors, or been a
party to any judicial or administrative proceeding, except for any matters that
were dismissed without sanction or settlement, that resulted in a judgment,
decree or final order enjoining us from future violations of, or prohibiting
activities subject to, federal or state securities laws, or a finding of any
violation of federal or state securities laws.

     We are subject to the disclosure requirements of the Exchange Act and are
required to file reports, proxy statements and other information with the SEC
relating to our business, financial condition and other matters. You can inspect
and copy, at prescribed rates, these reports, proxy statements and other
information at the offices of the SEC and the New York Stock Exchange. See
"Where You Can Find More Information."

THERMEDICS

     Thermedics Inc., a Massachusetts corporation, develops, manufactures and
markets diverse product lines, including biomedical products, security
instruments and equipment that assures the quality of a wide variety of consumer
products and bulk materials. Thermedics is seeking a buyer for its Thermo
Cardiosystems subsidiary, which manufactures implantable heart assist devices.

     Thermedics common stock is listed on the American Stock Exchange under the
symbol "TMD." Thermedics' principal executive offices are located at 470
Wildwood Street, P.O. Box 2999, Woburn, Massachusetts 01888-1799, and its
telephone number is (781) 622-1000.

     The name, business address, principal occupation, five-year employment
history and citizenship of each of Thermedics' directors and executive officers
is included in Annex A to this prospectus. Except as set forth in Annex B to
this prospectus, none of Thermedics' executive officers or directors purchased
or sold any shares of Thermedics common stock during the 60-day period ended on
April 27, 2000.

     Thermedics is subject to the disclosure requirements of the Exchange Act
and is required to file reports, proxy statements and other information with the
SEC relating to its business, financial condition and other matters. You can
inspect and copy, at prescribed rates, these reports, proxy statements and other
information at the offices of the SEC and the American Stock Exchange. See
"Where You Can Find More Information."

                                       22
<PAGE>   26

                BACKGROUND TO THE EXCHANGE OFFER AND THE MERGER

OUR REORGANIZATION; PURPOSE AND REASONS FOR THE EXCHANGE OFFER AND THE MERGER

     Our Reorganization.  On January 31, 2000, we announced that our board of
directors had authorized our management to proceed with a major reorganization
of our operations. The reorganization reflects a significant change in strategic
direction for us, both in terms of our business focus and operating structure.

     - Until we adopted the reorganization plan, we had historically been
       engaged in a diversified group of businesses. If we complete all aspects
       of the reorganization, we will focus primarily on our instruments
       business. Thermedics' Thermo Sentron Inc. and Thermedics Detection Inc.
       businesses would remain a part of our core instruments business. We
       expect to spin off some of the remaining Thermedics businesses as part of
       our business that serves the healthcare industry with a range of medical
       products for diagnosis and monitoring and to sell the balance of those
       businesses. Thermedics has signed letters of intent to sell its remaining
       Thermo Voltek Corp. businesses for a total of approximately $10.6 million
       and is seeking a buyer for its Thermo Cardiosystems subsidiary, which
       manufactures implantable heart assist devices.

     - We have historically pursued a strategy of publicly offering minority
       interests in some of our subsidiaries. These subsidiaries, in turn,
       pursued the same strategy. Our management has reevaluated the benefits
       and detriments of this corporate structure and concluded that we would
       benefit if we reorganized our instrument businesses under a single parent
       company without minority interests. To acquire the minority interests in
       our subsidiaries, this new strategy includes exchanging shares of our
       common stock for publicly held shares of the common stock of a number of
       our subsidiaries, and tender offers and mergers by Thermedics and Thermo
       Instrument involving publicly held shares of common stock of their
       subsidiaries.

     As part of our reorganization, we intend to spin-off or dispose of all of
our businesses other than our instrument business and our electric power
generation business. We do not expect to complete the spin-offs until the end of
2000 or early 2001. If you receive shares of our common stock in the exchange
offer or the merger and hold them at the time we complete the spin-offs, you
will receive shares of common stock of the companies that conduct our business
that serves the healthcare industry with a range of medical products for
diagnosis and monitoring and our paper recycling and papermaking equipment
business. See "Risk Factors -- Risks Related to Our Reorganization -- We are
unable to predict the liquidity or prospective performance of the common stock
of the companies that we intend to spin off." In addition, we will continue to
hold non-core assets until we sell them, which may not occur until after we
complete the proposed spin-offs. During the fiscal year ended January 1, 2000,
revenue from these non-core businesses and the businesses we are spinning off
was approximately $1.83 billion and net loss from the non-core businesses and
the businesses we are spinning off was approximately $111.5 million.

     We plan to take Thermo Ecotek, our electric power generation business,
private. Although we no longer consider it a core business under our new
strategy, we expect to retain Thermo Ecotek after we take it private while we
continue to evaluate how to best exit that business and create maximum value for
our stockholders.

     Our August 1998 Proposal.  In August 1998, we determined that we would
benefit from a corporate restructuring that would simplify our corporate
structure, consolidate and strategically realign some of our businesses and
increase the liquidity in the public stock of some of our publicly-traded
subsidiaries. We subsequently refined and expanded this proposal and, on January
31, 2000, announced our proposed reorganization described above under "-- Our
Reorganization; Purpose And Reasons For The Exchange Offer And The Merger -- Our
Reorganization."

     As part of the August 1998 announcement, we proposed transferring our
wholly-owned biomedical group of companies to Thermedics in exchange for the
stock held by Thermedics in its instruments subsidiaries, Thermo Sentron,
Thermedics Detection and Thermo Voltek, along with additional shares of

                                       23
<PAGE>   27

Thermedics common stock. We also proposed that, as part of this process, we or
Thermedics would take Thermo Sentron and Thermedics Detection private.

     In September 1998, the board of directors of Thermedics formed a special
committee consisting of Messrs. T. Anthony Brooks and Nicholas T. Zervas,
directors of Thermedics who are not employees of ours or any of our affiliates.
The special committee was authorized to negotiate the terms of the transaction
outlined in our August 1998 announcement and to retain its own legal and
financial advisors. Subsequently, the special committee engaged legal and
financial advisors in connection with the proposed transaction.

     In 1999, we had several discussions with the special committee of the
Thermedics board of directors regarding terms for the proposed transaction.
However, in January 2000, we determined not to proceed with the proposed
transaction with Thermedics as described above, but instead decided to proceed
with the exchange offer and the merger described in this prospectus.

     Purpose of the Exchange Offer and the Merger.  The purpose of this exchange
offer and the merger is to acquire the minority public interest in Thermedics as
part of our overall reorganization. We are seeking through the reorganization
to:

     - eliminate the complexity of our corporate structure; and

     - focus on and integrate our instruments business.

     We anticipate that our stockholders may realize the following benefits from
the exchange offer and the merger:

     - By conducting our operations in a more coordinated manner with our
       instruments subsidiaries, we would achieve greater marketing, operating
       and administrative efficiency.

     - We would eliminate additional burdens on management associated with
       public reporting and other tasks resulting from Thermedics' public
       company status. For example, Thermedics' management would no longer need
       to dedicate time and resources to stockholder and analyst inquiries and
       investor and public relations.

     - We would lower costs, particularly those associated with being a public
       company. For example, as a privately-held entity, Thermedics would no
       longer be required to file quarterly, annual or other periodic reports
       with the SEC or publish and distribute to its stockholders annual reports
       and proxy statements. We anticipate that eliminating these costs,
       including fees for an audit by an independent accounting firm and legal
       fees, will result in savings of approximately $450,000 per year.

CERTAIN PROJECTED FINANCIAL DATA

     Thermedics does not, as a matter of course, make public forecasts or
projections as to future sales, earnings or other income statement data, cash
flows or balance sheet and financial position information. However, in
connection with the exchange offer and the merger, we had access to Thermedics'
projections for the fourth quarter of fiscal 1999 and for fiscal 1999 and 2000.
These projections were prepared by management of Thermedics in the course of its
regular business planning.

     We have included a summary of these Thermedics projections below. These
projections do not reflect any of the effects of the exchange offer or the
merger or other changes that may in the future be appropriate concerning
Thermedics and its assets, business, operations, properties, policies, corporate
structure, capitalization and management in light of the circumstances then
existing. Further, these projections include results from Thermedics' Thermo
Cardiosystems subsidiary and Thermo Voltek business. We treat Thermo
Cardiosystems and Thermo Voltek as discontinued operations in Thermedics'
financial statements that we incorporate by reference in this prospectus because
of Thermedics' plan to sell those businesses. We and Thermedics believe that the
assumptions were reasonable at the time Thermedics prepared the projections,
given the information known by our and Thermedics' management.

                                       24
<PAGE>   28

     Thermedics did not prepare its projections for the fourth quarter of fiscal
1999 and for fiscal 1999 and 2000 with a view toward public disclosure or
compliance with published guidelines of the SEC or the American Institute of
Certified Public Accountants regarding forward-looking information or generally
accepted accounting principles. Neither Thermedics' independent auditors, nor
any other independent accountants, have compiled, examined or performed any
procedures with respect to the prospective financial information contained in
these projections nor have they expressed any opinion or given any form of
assurance on this information or its achievability. They assume no
responsibility for, and disclaim any association with, this prospective
financial information.

     In preparing its projections for the fourth quarter of fiscal 1999 and for
fiscal 1999 and 2000, Thermedics necessarily made numerous assumptions, many of
which are beyond our or Thermedics' control and may prove not to have been, or
may no longer be, accurate. Except as otherwise indicated, this information does
not reflect revised prospects for Thermedics' business, changes in general
business and economic conditions or any other transaction or event that has
occurred or that may occur and that Thermedics did not anticipate at the time it
prepared this information, including the proposed sale of Thermo Cardiosystems.
Accordingly, this information is not necessarily indicative of current values or
future performance, which may be significantly more favorable or less favorable
than as set forth below. You should not regard our inclusion of these
projections as a representation that they will be achieved.

     THE THERMEDICS PROJECTIONS FOR THE FOURTH QUARTER OF FISCAL 1999 AND FOR
FISCAL 1999 AND 2000 ARE NOT GUARANTEES OF PERFORMANCE. THEY INVOLVE RISKS,
UNCERTAINTIES AND ASSUMPTIONS. THE FUTURE FINANCIAL RESULTS AND STOCKHOLDER
VALUE OF THERMEDICS MAY DIFFER MATERIALLY FROM THOSE EXPRESSED IN THESE
PROJECTIONS. MANY OF THE FACTORS THAT WILL DETERMINE THESE RESULTS AND VALUES
ARE BEYOND THERMEDICS' ABILITY TO CONTROL OR PREDICT. YOU SHOULD NOT PLACE UNDUE
RELIANCE ON THESE PROJECTIONS. THESE PROJECTIONS MAY NOT BE REALIZED, AND
THERMEDICS' FUTURE FINANCIAL RESULTS MAY VARY MATERIALLY FROM THESE PROJECTIONS.
NEITHER THERMEDICS NOR WE INTEND TO UPDATE OR REVISE THESE PROJECTIONS.

                                       25
<PAGE>   29

                             THERMEDICS PROJECTIONS
                                 (IN THOUSANDS)

<TABLE>
<CAPTION>
                                                               FOURTH        FISCAL      FISCAL
                                                               QUARTER        YEAR        YEAR
                                                             FISCAL 1999      1999        2000
                                                             -----------    --------    --------
<S>                                                          <C>            <C>         <C>
SELECTED STATEMENT OF OPERATIONS DATA:
Revenues...................................................   $ 88,901      $327,529    $377,276
                                                              --------      --------    --------
Costs and Operating Expenses
  Cost of Revenues.........................................     45,372       172,469     190,556
  Operating Expenses.......................................     36,442       130,145     148,408
  Restructuring Costs, Net.................................        400        32,438          --
                                                              --------      --------    --------
                                                                82,214       335,052     338,964
                                                              --------      --------    --------
Operating Income (Loss)....................................      6,687        (7,523)     38,312
Interest Income............................................      2,663        10,911      10,575
Interest Expense...........................................     (1,928)       (6,596)     (6,883)
                                                              --------      --------    --------
Income (Loss) Before Provision for Income Taxes and
  Minority
  Interest.................................................      7,422        (3,208)     42,004
Provision for Income Taxes.................................      2,789         8,762      16,810
Minority Interest Expense..................................      1,365         4,863       5,911
                                                              --------      --------    --------
Net Income (Loss)..........................................   $  3,268      $(16,833)   $ 19,283
                                                              ========      ========    ========
SELECTED BALANCE SHEET DATA:
Accounts Receivable, Net...................................   $ 72,941      $ 72,941    $ 76,335
Inventories................................................     65,836        65,836      66,835
Prepaid Income Taxes and Other Current Assets..............     16,071        16,071      15,852
                                                              --------      --------    --------
Total Current Assets Excluding Cash and Investments........    154,848       154,848     159,022
Property, Plant and Equipment:
  Balance, Beginning of Period.............................     22,623        21,907      23,076
  Additions................................................      2,781         7,865       9,444
  Depreciation Expense.....................................     (2,126)       (7,931)     (9,175)
  Sales....................................................       (202)        1,235          --
                                                              --------      --------    --------
  Balance, End of Period...................................     23,076        23,076      23,345
Cost in Excess of Net Assets of Acquired Companies.........    154,132       154,132     149,934
</TABLE>

CONFLICTS OF INTEREST

     Thermo Electron.  In setting the exchange ratio, our financial interest was
adverse to the financial interest of the public stockholders of Thermedics. We
set the exchange ratio on our own and without any negotiations with Thermedics.

     Our Directors.  The members of our board of directors own, or hold options
to purchase, shares of our common stock and/or shares of common stock of
Thermedics. These positions and equity interests presented these directors with
actual or potential conflicts of interest in determining the exchange ratio and
the other terms of the exchange offer and the merger.

     Officers and Directors of Thermedics.  We set the exchange ratio on our own
and without negotiation with Thermedics. The board of directors of Thermedics
has formed a special committee to evaluate the exchange offer and to make a
recommendation to Thermedics' stockholders as to whether to accept or reject the
exchange offer. Messrs. T. Anthony Brooks and Nicholas T. Zervas, directors of
Thermedics who are not employees of Thermo Electron or of our affiliates, are
the members of this special committee.

                                       26
<PAGE>   30

     The special committee of the board of directors of Thermedics has not yet
made a recommendation with respect to the exchange offer. Thermedics must file a
Schedule 14D-9 with the SEC, which will include Thermedics' recommendation with
respect to the exchange offer, no later than May 12, 2000. Thermedics also must
publish or send you its recommendation. YOU SHOULD CAREFULLY CONSIDER
THERMEDICS' RECOMMENDATION BEFORE DETERMINING WHETHER TO TENDER YOUR SHARES IN
THE EXCHANGE OFFER OR TO PURSUE YOUR APPRAISAL RIGHTS IN CONNECTION WITH THE
MERGER.

     In considering any position that Thermedics may take with respect to the
exchange offer and the merger, you should be aware that the officers and several
directors of Thermedics have interests in connection with the exchange offer and
the merger that present them with actual or potential conflicts of interest, as
summarized below.

     Several members of the board of directors and executive officers of
Thermedics are directors or officers of ours and of our other affiliates, as set
forth below:

     - Mr. John T. Keiser, the chief executive officer, president and a director
       of Thermedics, is our chief operating officer, biomedical, and a director
       of our affiliates Metrika Systems Corporation, Thermo Cardiosystems Inc.,
       ThermoLase Corporation, ThermoTrex Corporation and Trex Medical
       Corporation;

     - Mr. Theo Melas-Kyriazi, the chief financial officer of Thermedics, is
       also our chief financial officer; and

     - Mr. Peter O. Crisp is one of our directors and one of Thermedics'
       directors.

Consequently, these directors and officers receive or have received compensation
not only from Thermedics but also from us and/or our other affiliates.

     Officers and directors of Thermedics who own shares of Thermedics common
stock will receive shares of our common stock in the exchange offer or the
merger at the same exchange ratio and on the same terms as the Thermedics public
stockholders. As of January 31, 2000, the members of the board of directors and
executive officers of Thermedics owned a total of 178,766 shares of Thermedics
common stock. These individuals would receive in exchange for their shares of
Thermedics common stock a total of 80,441 shares of our common stock, assuming
that they tender all of their shares of Thermedics common stock in the exchange
offer.

     In addition, as of January 31, 2000, the members of the board of directors
and executive officers of Thermedics held options to acquire a total of 406,000
shares of Thermedics common stock, with exercise prices ranging from $7.14 to
$17.11. We would assume these options and convert them into options to acquire
shares of our common stock on the same terms as we assume and convert all of the
other outstanding Thermedics options in connection with the exchange offer and
the merger. See "-- Effects Of The Exchange Offer And The Merger -- Treatment of
Thermedics Options."

     As of January 31, 2000, Mr. Brooks, Mr. Crisp and Dr. Zervas, directors of
Thermedics, had accumulated deferred units representing shares of Thermedics
common stock under Thermedics' deferred compensation plan for directors. These
units would be converted into shares of our common stock in the merger. See
"-- Effects Of The Exchange Offer And The Merger -- Treatment of Thermedics
Deferred Compensation Plan for Directors." The following table sets forth the
number of shares of Thermedics common stock each director's units represent and
the number of shares of our common stock into which those units would be
converted in the merger:

<TABLE>
<CAPTION>
                                                                                      SHARES OF OUR
                                                              SHARES OF THERMEDICS       COMMON
                                                                  COMMON STOCK            STOCK
                                                              --------------------    -------------
<S>                                                           <C>                     <C>
Mr. Brooks..................................................          1,367                 615
Mr. Crisp...................................................          9,971               4,486
Dr. Zervas..................................................         10,364               4,663
</TABLE>

                                       27
<PAGE>   31

     Indemnification Agreements.  We have entered into separate indemnification
agreements with each of Thermedics' executive officers and directors. These
agreements require us to indemnify and advance expenses to the indemnified
director or officer if he or she, by reason of his or her status as a director
or officer of Thermedics, or service as a director, officer or fiduciary of
another enterprise at our request, is made or threatened to be made a party to
any threatened, pending or completed action, suit or other proceeding, whether
civil, criminal, administrative or investigative. We are only required to
provide these benefits if the director or officer seeking indemnification acted
in good faith and in a manner he or she reasonably believed to be in or not
opposed to our best interests, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe his or her conduct was unlawful.
We are required to provide indemnification to the maximum extent permitted by
Delaware law in the case of any threatened, pending or completed action, suit or
proceeding by or in our right.

THE MERGER

     If we successfully complete the exchange offer, we plan to cause Thermedics
to merge into us in a so-called "short-form" merger. This merger would occur as
promptly as practicable after completion of the exchange offer. Under the
Massachusetts Business Corporation Law and the Delaware General Corporation Law,
if we own at least 90% of the outstanding shares of Thermedics common stock, we
would have the power to approve, adopt and complete the merger without a vote of
Thermedics' stockholders or board of directors. Our stockholders would own all
of the outstanding shares of the surviving corporation after the merger.

     On the effective date of the merger, each outstanding share of Thermedics
common stock, other than shares of Thermedics common stock held by us or
Thermedics and shares of Thermedics common stock held by stockholders, if any,
who are entitled to and perfect their appraisal rights under Section 82(e) and
Sections 86 through 98 of the Massachusetts Business Corporation Law, would be
cancelled and converted into the right to receive 0.45 shares of our common
stock.

EFFECTS OF THE EXCHANGE OFFER AND THE MERGER

     General.  Upon completion of the exchange offer and the merger, we would
have complete control over the conduct of Thermedics' business and would have a
100% interest in the net book value and net earnings of Thermedics. In addition,
we would receive the benefit of complete control over any future increases in
the value of Thermedics and would bear the complete risk of any losses incurred
in the operation of Thermedics and any decrease in the value of Thermedics. Our
ownership of Thermedics, before the transactions contemplated by the exchange
offer and the merger, totaled approximately 75.5%.

     Possible Effect of the Exchange Offer on the Market for Thermedics Common
Stock.  After the completion of the exchange offer and before the effective date
of the merger, our exchange of shares of our common stock for shares of
Thermedics common stock pursuant to the exchange offer would reduce the number
of shares of Thermedics common stock that might otherwise trade publicly and may
reduce the number of holders of shares of Thermedics common stock. These
exchanges could adversely affect the liquidity and market value of the remaining
shares of Thermedics common stock held by the public.

     American Stock Exchange Listing.  If we complete the exchange offer and the
merger, the shares of Thermedics common stock would not meet the requirements
for continued listing on the American Stock Exchange and would be delisted.
Assuming that the merger occurs shortly after the completion of the exchange
offer, we do not expect the American Stock Exchange to delist the shares of
Thermedics common stock until after the effective date of the merger. However,
as discussed below, it is possible that the American Stock Exchange could take
this action.

     The shares of Thermedics common stock may not meet the quantitative
requirements for continued listing on the American Stock Exchange following the
closing of the exchange offer and prior to the

                                       28
<PAGE>   32

effective date of the merger. Whether the shares of Thermedics common stock
meets those requirements will depend upon:

     - the aggregate market value and the number of shares of Thermedics common
       stock that we do not exchange for shares of our common stock pursuant to
       the exchange offer; and

     - the number of Thermedics public stockholders who are not affiliated with
       us.

     To be listed on the American Stock Exchange, an issuer must have at least
200,000 publicly held shares, held by at least 300 stockholders, with a market
value of at least $1,000,000 and have stockholders' equity of at least
$2,000,000 or $4,000,000, depending on profitability levels during the issuer's
four most recent fiscal years.

     If the shares of Thermedics common stock no longer meet the requirements
for listing on the American Stock Exchange, it is possible that the shares would
continue to trade in the over-the-counter market before the effective date of
the merger and that price or other quotations might still be available from
other sources. The extent of the public market for the shares of Thermedics
common stock and the availability of such quotations would, however, depend upon
such factors as:

     - the number of holders and/or the aggregate market value of such shares of
       Thermedics common stock remaining at the time;

     - the interest in maintaining a market in those shares of Thermedics common
       stock on the part of securities firms; and

     - the possible termination of registration of shares of Thermedics common
       stock under the Exchange Act, as described below.

     We cannot predict whether a reduction in the number of shares of Thermedics
common stock that might otherwise trade publicly would have an adverse or
beneficial effect on the market price for or marketability of the shares of
Thermedics common stock or whether it would cause future market prices to be
greater or less than the price paid in the exchange offer and the merger.

     Exchange Act Registration.  The shares of Thermedics common stock are
currently registered under the Exchange Act. If we complete the exchange offer
and the merger, Thermedics' reporting obligations under the Exchange Act would
terminate.

     Before the effective date of the merger, the exchange of shares of
Thermedics common stock for shares of our common stock pursuant to the exchange
offer may result in the shares of Thermedics common stock becoming eligible for
deregistration under the Exchange Act. Thermedics may apply to the SEC for
termination of the registration of its common stock if the common stock is not
listed on a national securities exchange and there are fewer than 300 record
holders of the shares of Thermedics common stock. See "-- American Stock
Exchange Listing."

     If Thermedics terminates the registration of its common stock under the
Exchange Act:

     - Thermedics would no longer be required to provide its stockholders with
       annual, quarterly and other reports under the Exchange Act;

     - Thermedics would no longer be required to comply with other provisions of
       the Exchange Act, such as the short-swing profit recovery provisions of
       Section 16(b), the requirement of furnishing a proxy statement in
       connection with stockholders' meetings pursuant to Section 14(a) and the
       requirements of Rule 13e-3 under the Exchange Act with respect to "going
       private" transactions;

     - "affiliates" of Thermedics and persons holding "restricted securities" of
       Thermedics may be deprived of the ability to dispose of their securities
       pursuant to Rule 144 under the Securities Act; and

     - the shares of Thermedics common stock would no longer be "margin
       securities" or eligible for listing on the American Stock Exchange.

                                       29
<PAGE>   33

     We presently intend to cause Thermedics to terminate the registration of
the shares of Thermedics common stock under the Exchange Act as soon after the
completion of the exchange offer or the merger as the requirements for
termination of registration are met.

     Margin Regulations.  The shares of Thermedics common stock are currently
"margin securities" under the rules of the Board of Governors of the Federal
Reserve System. As a result, brokers are allowed to extend credit, known as
purpose loans, on the collateral of shares of Thermedics common stock for the
purpose of buying, carrying or trading in securities. If we complete the
exchange offer and the merger, shares of Thermedics common stock would no longer
be "margin securities." Following the exchange of shares of Thermedics common
stock pursuant to the exchange offer and before the effective date of the
merger, depending upon factors such as the number of record holders of the
shares of Thermedics common stock and the number and market value of publicly
held shares of Thermedics common stock, the shares of Thermedics common stock
might no longer constitute "margin securities" for purposes of the Federal
Reserve Board's margin regulations and you could not then use your shares of
Thermedics common stock as collateral for purpose loans made by brokers. In
addition, if Thermedics terminated the registration of shares of its common
stock under the Exchange Act, the shares of its common stock would no longer
constitute "margin securities."

     Treatment of Thermedics Options.  Thermedics has issued options to acquire
shares of its common stock pursuant to Thermedics' Equity Incentive Plan,
Directors Stock Option Plan and Employees Equity Incentive Plan. In connection
with the exchange offer and the merger, we would assume Thermedics' plans and
each outstanding option under these plans. Each option that we assume would
continue to have, and be subject to, the same terms and conditions applicable to
the option immediately before the effective date of the merger, except that:

     - each option would be exercisable, or would become exercisable in
       accordance with its terms, for that number of whole shares of our common
       stock equal to the product of the number of shares of Thermedics common
       stock that were issuable upon exercise of the option immediately before
       the effective date of the merger multiplied by the exchange ratio,
       rounded down to the nearest whole number of shares of our common stock;
       and

     - the per share exercise price for the shares of our common stock issuable
       upon exercise of such assumed option would be equal to the quotient
       determined by dividing the exercise price per share at which the option
       was exercisable immediately before the effective date of the merger by
       the exchange ratio, rounded up to the nearest whole cent.

     Treatment of Thermedics Employees' Stock Purchase Plan.  In connection with
the exchange offer and the merger, we would assume each outstanding option to
purchase shares of Thermedics common stock under Thermedics' Employees' Stock
Purchase Plan. Each stock option under the plan that we assume would continue to
have, and be subject to, the same terms and conditions as set forth in the plan
immediately before the effective date of the merger, except that:

     - the assumed stock option would be exercisable, or would become
       exercisable in accordance with its terms, for that number of whole shares
       of our common stock equal to the product of the number of shares of
       Thermedics common stock that were issuable upon exercise of the assumed
       stock option immediately before the effective date of the merger
       multiplied by the exchange ratio, rounded down to the nearest whole
       number of shares of our common stock;

     - the purchase price per share of our common stock would be the lower of:

        -- 85% of the per share market value of the shares of Thermedics common
           stock on the grant date of the assumed stock option divided by the
           exchange ratio, with the resulting price rounded up to the nearest
           whole cent; and

        -- 85% of the per share market value of our common stock as of the
           exercise date of the assumed stock option; and

                                       30
<PAGE>   34

     - the $25,000 limit under Section 9.2(i) of the plan would be applied by
       taking into account our assumption of the stock options in accordance
       with Section 423(b)(8) of the Internal Revenue Code of 1986 and
       regulations under that section.

     Treatment of Thermedics Deferred Compensation Plan for Directors.  In
connection with the exchange offer and the merger, we would assume Thermedics'
deferred compensation plan for directors and the units for Thermedics common
stock outstanding under the plan would be converted into shares of our common
stock at the exchange ratio. Based on the units accumulated on January 1, 2000:

     - Mr. Brooks would receive 615 shares of our common stock;

     - Mr. Crisp would receive 4,486 shares of our common stock; and

     - Dr. Zervas would receive 4,663 shares of our common stock.

     Treatment of Thermedics Debentures.  From and after the effective date of
the merger, we would assume Thermedics' non-interest bearing convertible
subordinated debentures due June 1, 2003 and its 2 7/8% convertible subordinated
debentures due June 1, 2003. After we assume these debentures, they would be
convertible into shares of our common stock, instead of Thermedics common stock.
As of March 31, 2000, approximately $31.6 million principal amount of
Thermedics' non-interest bearing debentures was outstanding and approximately
$15.9 million principal amount of Thermedics' 2 7/8% debentures was outstanding.
As of that date, the non-interest bearing debentures were convertible into a
total of 965,881 shares of Thermedics common stock at a conversion price of
$32.68 per share and the 2 7/8% debentures were convertible into a total of
1,061,830 shares of Thermedics common stock at a conversion price of $14.928 per
share. After the merger, the non-interest bearing debentures would be
convertible into a total of 434,647 shares of our common stock at a conversion
price of $72.62 per share and the 2 7/8% convertible subordinated debentures
would be convertible into a total of 477,824 shares of our common stock at a
conversion price of $33.17 per share. Holders of these debentures would not have
the right to require Thermedics to redeem their debentures as a result of the
merger.

     Accounting Treatment.  The exchange offer and the merger would be accounted
for as the acquisition of a minority interest by us using the purchase method of
accounting.

     Tax Consequences.  For federal income tax purposes, your receipt of shares
of our common stock pursuant to the exchange offer or the merger would be
tax-free. However, you would be taxed upon your receipt of cash in lieu of
fractional shares of our common stock in the exchange offer or the merger. See
"Federal Income Tax Consequences."

CONDUCT OF THERMEDICS' BUSINESS AFTER THE EXCHANGE OFFER AND THE MERGER

     Following our reorganization, we plan to retain Thermedics' Thermo Sentron
and Thermedics Detection businesses as part of our core measurement and
detection instruments business. We expect to spin off some of the remaining
Thermedics businesses as part of our business that serves the healthcare
industry with a range of medical products for diagnosis and monitoring and to
sell the balance of those businesses. Thermedics has signed letters of intent to
sell its remaining Thermo Voltek businesses for a total of approximately $10.6
million and is seeking a buyer for its Thermo Cardiosystems subsidiary, which
manufactures implantable heart assist devices.

CONDUCT OF THERMEDICS' BUSINESS IF THE EXCHANGE OFFER IS NOT COMPLETED

     If we do not complete the exchange offer because, on the date the exchange
offer expires, we do not own at least 90% of Thermedics' outstanding shares or
because another condition to the exchange offer is not satisfied or waived, we
expect that Thermedics' current management will continue to operate Thermedics'
business substantially as presently operated. In that event, we may consider:

     - engaging in open market or privately negotiated purchases of shares of
       Thermedics common stock to increase our ownership of shares of Thermedics
       common stock to at least 90% of the outstanding shares of Thermedics
       common stock; or
                                       31
<PAGE>   35

     - proposing that we and Thermedics enter into a long-form merger agreement,
       which would require the approval of Thermedics' board of directors, and
       vote all of our shares of Thermedics common stock in favor of such
       merger.

     If we were to pursue either of these alternatives, it may take considerably
longer for you to receive any consideration for your shares of Thermedics common
stock, other than through sales in the open market, than if you had tendered
your shares in the exchange offer. Any such transaction may result in proceeds
per share to you that are more or less than the value of the shares of our
common stock that we propose to issue in exchange for shares of Thermedics
common stock in the exchange offer and the merger.

                               THE EXCHANGE OFFER

TERMS OF THE EXCHANGE OFFER; EXPIRATION OF THE EXCHANGE OFFER

     Offer For All Outstanding Shares.  We are offering to acquire all the
shares of Thermedics common stock, par value $.10 per share, outstanding on the
expiration date that we do not currently own.

     Exchange Ratio.  We are offering to exchange 0.45 shares of our common
stock for each outstanding share of common stock of Thermedics that Thermedics
stockholders validly tender and do not properly withdraw.

     Fractional Shares.  We will not issue fractional shares of our common stock
in the exchange offer or the merger. Instead, we will pay an amount in cash
equal to $19.50 for each whole share of our common stock in lieu of any
fractional share that we would otherwise issue to you.

     Withdrawal Rights.  You may withdraw shares that you have tendered at any
time on or before May 26, 2000. If we extend the exchange offer, all shares of
Thermedics common stock that you have previously tendered and not properly
withdrawn would remain subject to the exchange offer, although you would have
the right to withdraw your shares of Thermedics common stock. Unless we accept
your shares for exchange on or before June 29, 2000, you may also withdraw
shares that you have tendered at any time after that date. See "-- Withdrawal
Rights."

     Expiration Date.  This exchange offer will expire at 12:00 midnight, New
York City time, on Friday, May 26, 2000, unless we, in our sole discretion,
extend the period during which the exchange offer is open.

     Extension of Expiration Date.  If allowed by the rules of the SEC, we may
extend the period during which the exchange offer is open. We may exercise this
right in our sole discretion at any time and for any reason, including the
failure to satisfy any of the conditions specified below under "-- Conditions Of
The Exchange Offer." We can extend the period during which the exchange offer is
open by providing oral or written notice to EquiServe, the depositary for the
exchange offer. If we extend the period during which the exchange offer is open,
we will make an announcement no later than 9:00 a.m., New York City time, on the
next business day after the previously scheduled expiration of the exchange
offer. Any extension would delay our acceptance for exchange and the actual
exchange of any shares of Thermedics common stock that you tender.

     Termination, Amendment and Waiver.  If allowed by the rules of the SEC, we
may also, in our sole discretion, at any time before the exchange offer expires:

     - terminate the exchange offer and not accept for exchange, or exchange,
       any shares of Thermedics common stock if any of the conditions described
       in "-- Conditions Of The Exchange Offer" has not been satisfied or upon
       the occurrence and during the continuance of any of the events specified
       in "-- Conditions Of The Exchange Offer;" or

     - waive any condition or amend the exchange offer in any respect,

in each case by giving oral or written notice of termination, waiver or
amendment to the depositary and by making a public announcement thereof. If we
terminate or withdraw the exchange offer, we will promptly


                                       32
<PAGE>   36

return any shares of Thermedics common stock that you have tendered. We may not
delay acceptance for exchange, or the exchange, of any shares of Thermedics
common stock upon the occurrence of any of the conditions specified in
"-- Conditions Of The Exchange Offer" without extending the period during which
the exchange offer is open.

     If the number of shares of Thermedics common stock tendered is insufficient
to satisfy the minimum tender condition or any other condition specified in
"-- Conditions Of The Exchange Offer" is not fulfilled by the expiration of the
exchange offer, we may:

     - decline to exchange shares of our common stock for any of the shares of
       Thermedics common stock tendered, return to you all shares of Thermedics
       common stock that you tendered and terminate the exchange offer;

     - extend the exchange offer and retain all tendered shares of Thermedics
       common stock until the expiration of the exchange offer, as extended,
       subject to the terms and conditions of the exchange offer, including your
       rights to withdraw your shares of Thermedics common stock; or

     - waive or amend the condition and, subject to complying with the rules of
       the SEC, accept for exchange and exchange shares of our common stock for
       all shares of Thermedics common stock validly tendered.

     We will publicly announce any extension, termination or amendment of the
exchange offer as promptly as practicable. Without limiting the manner in which
we may choose to make any public announcement, except as provided by applicable
law, including Rules 14d-4(c), 14d-6(d) and 14e-1 under the Exchange Act, which
require that material changes be promptly disseminated to holders of shares of
Thermedics common stock, we will have no obligation to publish, advertise or
otherwise communicate any public announcement other than by issuing a release to
the Dow Jones News Service.

     Material Change to Exchange Offer.  If we make a material change in the
terms of the exchange offer or the information concerning the exchange offer, or
waive a material condition of the exchange offer, we will disseminate additional
exchange offer materials, including by public announcement as described above,
and extend the exchange offer to the extent required by Rules 14d-4(d), 14d-6(d)
and 14e-1 under the Exchange Act. The minimum period during which we will keep
the exchange offer open following material changes in the terms of the exchange
offer or information concerning the exchange offer, other than a change in
price, a change in percentage of securities sought or a change in any dealer's
soliciting fee, will depend upon the facts and circumstances, including the
relative materiality of the changes.

     With respect to a change in price or, subject to limitations, a change in
the percentage of securities sought or a change in any dealer's soliciting fee,
we will keep the exchange offer open for a minimum ten business day period from
the date of the change to allow for adequate dissemination to stockholders.
Accordingly, if, before the exchange offer expires, we:

     - decrease the number of shares of Thermedics common stock sought in the
       exchange offer,

     - increase the consideration offered in the exchange offer, or

     - add a dealer's soliciting fee,

and if the exchange offer is scheduled to expire at any time earlier than the
period ending on the tenth business day from the date that we first publish,
send or give to stockholders notice of such increase, decrease or addition, we
will extend the exchange offer at least until the ten business day period
expires. For purposes of the exchange offer, a "business day" means any day
other than a Saturday, Sunday or federal holiday and consists of the time period
from 12:01 a.m. through 12:00 midnight, New York City time.

     Mailing of the Prospectus.  Thermedics has provided us with its stockholder
list and security position listings for the purpose of disseminating materials
relating to the exchange offer to holders of shares of Thermedics common stock.
We will mail this prospectus and a related letter of transmittal and, if
required, other relevant materials to record holders of shares of Thermedics
common stock. We will also


                                       33
<PAGE>   37

furnish those materials to brokers, dealers, commercial banks, trust companies
and similar persons whose names, or the names of whose nominees, appear on
Thermedics' stockholder list or who are listed as participants in a clearing
agency's security position listing for subsequent transmittal to beneficial
owners of shares of Thermedics common stock.

     Subsequent Offering Period.  Although we do not currently intend to, we may
elect to provide a subsequent offering period. Any subsequent offering period
would last between three and 20 business days after our acceptance of Thermedics
shares in the exchange offer. We will comply with the requirements under
Exchange Act Rule 14d-11 if we elect to provide a subsequent offering period.
You will not have the right to withdraw any Thermedics shares that you tender
during any subsequent offering period.

ACCEPTANCE FOR EXCHANGE AND EXCHANGE OF SHARES

     Timing of Exchange of Shares.  Upon the terms and subject to the conditions
of this exchange offer, including, if we extend or amend the exchange offer, the
terms and conditions of any such extension or amendment, we will accept for
exchange, and will exchange for shares of our common stock, all shares of
Thermedics common stock validly tendered before the exchange offer expires and
not properly withdrawn, including shares of Thermedics common stock validly
tendered and not withdrawn during any extension of the exchange offer, if we
extend the exchange offer, subject to the terms and conditions of the extension,
promptly after the expiration of the exchange offer. In addition, subject to
complying with Rule 14e-1 under the Exchange Act, we may, in our sole
discretion, delay the acceptance for exchange or exchange of shares of
Thermedics common stock to comply, in whole or in part, with any law.

     In all cases, we will exchange shares of our common stock for shares of
Thermedics common stock tendered and accepted for exchange pursuant to the
exchange offer only after timely receipt by the depositary of:

     - certificates evidencing shares of Thermedics common stock or timely
       confirmation, known as a book-entry confirmation, of a book-entry
       transfer of shares of Thermedics common stock into the depositary's
       account at The Depository Trust Company pursuant to the procedures set
       forth below under "-- Procedures For Accepting The Exchange Offer And
       Tendering Shares;"

     - a properly completed and duly executed letter of transmittal, or a
       facsimile of that document, with any required signature guarantees, or an
       agent's message in connection with a book-entry transfer; and

     - any other documents required by the letter of transmittal.

Accordingly, we may issue shares of our common stock to tendering stockholders
at different times if delivery of their shares of Thermedics common stock and
other required documents occurs at different times.

     Agent's Message.  The term "agent's message" means a message transmitted by
The Depository Trust Company to, and received by, the depositary and forming a
part of a book-entry confirmation, which states that The Depository Trust
Company has received an express acknowledgment from the participant in The
Depository Trust Company tendering the shares of Thermedics common stock which
are the subject of the book-entry confirmation, that the participant has
received and agrees to be bound by the terms of the letter of transmittal and
that we may enforce the agreement against such participant.

     Acceptance of Shares.  For purposes of the exchange offer, we will have
accepted for exchange, and thereby exchanged, shares of our common stock for
shares of Thermedics common stock validly tendered and not properly withdrawn
if, as and when we give oral or written notice to the depositary of our
acceptance for exchange of such shares of Thermedics common stock pursuant to
the exchange offer. Upon the terms and subject to the conditions of the exchange
offer, we will issue shares of our common stock in exchange for shares of
Thermedics common stock that we accept for exchange by depositing the total
number of shares of our common stock issuable in exchange for shares of
Thermedics common stock with the depositary.

                                       34
<PAGE>   38

     The depositary will act as agent for tendering stockholders for the purpose
of receiving shares of our common stock and transmitting these shares to
stockholders whose shares of Thermedics common stock we have accepted for
exchange. UNDER NO CIRCUMSTANCES WILL WE PAY INTEREST ON THE MARKET VALUE OF
SHARES OF OUR COMMON STOCK OR ON THE AMOUNT OF ANY CASH PAYABLE TO A TENDERING
STOCKHOLDER IN LIEU OF FRACTIONAL SHARES OF OUR COMMON STOCK, REGARDLESS OF ANY
EXTENSION OF THE EXCHANGE OFFER OR DELAY IN MAKING SUCH EXCHANGE. When we
deposit shares of our common stock with the depositary for the purpose of
issuing these shares to validly tendering stockholders, our obligation to make
such exchange will be satisfied and from then on tendering stockholders must
look solely to the depositary for the shares of our common stock owed to them by
reason of the acceptance for exchange of shares of Thermedics common stock
pursuant to the exchange offer.

     Shares Not Accepted For Exchange.  If for any reason we do not accept any
shares of Thermedics common stock that you tender pursuant to the terms and
conditions of the exchange offer, or if you submit share certificates
representing more shares of Thermedics common stock than you are tendering, we
will return share certificates representing shares of Thermedics common stock
that we do not accept for exchange or that you do not tender, without expense,
to you. In the case of shares of Thermedics common stock that you tender by
book-entry transfer, we will credit your account at The Depository Trust Company
for any shares that we do not accept for exchange as promptly as practicable
following expiration or termination of the exchange offer.

     Other Terms.  If we increase the exchange ratio or otherwise increase the
consideration in the exchange offer before the exchange offer expires, we will
apply the higher rate or increased consideration to all shares of Thermedics
common stock that you tender in the exchange offer, whether or not you tendered
or we exchanged such shares of Thermedics common stock before we increased the
exchange ratio or other consideration.

     We may transfer or assign to one or more of our affiliates our right to
exchange shares of our common stock for shares of Thermedics common stock
tendered pursuant to the exchange offer. We may exercise this right in whole or
in part from time to time. If we exercise this right, we will still be required
to comply with our obligations under the exchange offer. Your right to receive
shares of our common stock in exchange for your shares of Thermedics common
stock that you validly tender and that we accept for exchange pursuant to the
exchange offer will not be prejudiced by any such transfer or assignment by us.

PROCEDURES FOR ACCEPTING THE EXCHANGE OFFER AND TENDERING SHARES

     General.  Except as set forth below, for you to validly tender your shares
of Thermedics common stock pursuant to the exchange offer, the depositary must
receive either:

     - your letter of transmittal, or a facsimile of your letter of transmittal,
       properly completed and duly executed, together with any required
       signature guarantees, or

     - an agent's message in connection with a book-entry delivery of shares of
       Thermedics common stock,

together with any other documents required by the letter of transmittal. The
depositary must receive these documents at one of its addresses set forth on the
back cover of this prospectus before the exchange offer expires. In addition,
either

     - the depositary must receive share certificates evidencing your tendered
       shares of Thermedics common stock at one of the addresses set forth on
       the back cover of this prospectus or you must tender your shares of
       Thermedics common stock pursuant to the procedures for book-entry
       transfer set forth below, and the depositary must receive a book-entry
       confirmation, in each case before the exchange offer expires; or

     - you must comply with the guaranteed delivery procedures set forth below.

     We will not accept alternative, conditional or contingent tenders. We will
not accept for exchange fractional shares of Thermedics common stock. By
execution of the letter of transmittal included with this


                                       35
<PAGE>   39

prospectus, or a facsimile of the letter of transmittal, you will waive any
right to receive any notice of the acceptance for exchange of your shares of
Thermedics common stock.

     THE METHOD OF DELIVERY OF SHARE CERTIFICATES, THE LETTER OF TRANSMITTAL AND
ALL OTHER REQUIRED DOCUMENTS, INCLUDING DELIVERY THROUGH THE DEPOSITORY TRUST
COMPANY, IS AT YOUR SOLE OPTION AND RISK. EXCEPT AS OTHERWISE PROVIDED UNDER
THIS HEADING "PROCEDURES FOR ACCEPTING THE EXCHANGE OFFER AND TENDERING SHARES,"
WE WILL TREAT YOUR SHARE CERTIFICATES, LETTER OF TRANSMITTAL AND OTHER REQUIRED
DOCUMENTS AS DELIVERED ONLY WHEN THEY ARE ACTUALLY RECEIVED BY THE DEPOSITARY.
IF YOU USE THE MAIL FOR DELIVERY, WE RECOMMEND THAT YOU USE REGISTERED MAIL WITH
RETURN RECEIPT REQUESTED, PROPERLY INSURED. IN ALL CASES, YOU SHOULD ALLOW
SUFFICIENT TIME TO ENSURE TIMELY DELIVERY.

     Book-Entry Transfer.  Within two business days after the commencement date
of the exchange offer, the depositary will request that The Depository Trust
Company establish an account with respect to the shares of Thermedics common
stock for purposes of the exchange offer. Any financial institution that is a
participant in the system of The Depository Trust Company may make book-entry
delivery of your shares of Thermedics common stock by causing The Depository
Trust Company to transfer your shares into the depositary's account at The
Depository Trust Company in accordance with The Depository Trust Company's
procedures for such transfer. Although you may deliver your shares of Thermedics
common stock through book-entry transfer into the depositary's account at The
Depository Trust Company, the depositary must receive:

     - your letter of transmittal, or a facsimile of your letter of transmittal,
       properly completed and duly executed, together with any required
       signature guarantees, or an agent's message, and

     - any other documents required by the letter of transmittal,

at one of its addresses set forth on the back cover of this prospectus before
the exchange offer expires for you to validly tender your shares of Thermedics
common stock pursuant to the exchange offer, or you must comply with the
guaranteed delivery procedures described below.

     DELIVERY OF DOCUMENTS TO THE DEPOSITORY TRUST COMPANY IN ACCORDANCE WITH
THE DEPOSITORY TRUST COMPANY'S PROCEDURES DOES NOT CONSTITUTE DELIVERY TO THE
DEPOSITARY.

     Signature Guarantees.  Except as described below, a firm that is a bank,
broker, dealer, credit union, savings association or other entity which is a
member in good standing of:

     - the Securities Transfer Agents Medallion Program,

     - the Stock Exchanges' Medallion Program, or

     - the New York Stock Exchange, Inc. Medallion Signature Program

must guarantee signature on your letter of transmittal. Each firm that is a
member of these medallion programs is referred to in this prospectus as an
"eligible institution." We will not require a signature guarantee on your letter
of transmittal if:

     - you are the registered holder of shares of Thermedics common stock and do
       not complete either the box entitled "Special Delivery Instructions" or
       the box entitled "Special Issuance Instructions" on your letter of
       transmittal; or

     - you tender shares of Thermedics common stock for the account of an
       eligible institution.

For more information regarding these procedures, you should review Instruction 1
of the letter of transmittal.

     If your share certificates are registered in the name of a person other
than the person who signs the letter of transmittal, or if you direct us to make
payment or to return your share certificates for exchanged shares of Thermedics
common stock to a person other than the registered holders, then the tendered
share certificates must be endorsed or accompanied by appropriate stock powers
signed exactly as the names of the registered holders appear on the share
certificates, with the signatures on the share certificates or stock

                                       36
<PAGE>   40

powers guaranteed by an eligible institution as provided above and in the letter
of transmittal. See Instructions 1 and 5 of the letter of transmittal.

     Guaranteed Delivery.  If you wish to tender shares of Thermedics common
stock pursuant to the exchange offer and your share certificates are not
immediately available or you cannot deliver all of the required documents to the
depositary before the exchange offer expires or you cannot comply with the
procedures for book-entry transfer on a timely basis, you may still tender your
shares of Thermedics common stock, so long as all of the following conditions
are satisfied:

     - you make your tender by or through an eligible institution;

     - the depositary receives a properly completed and duly executed notice of
       guaranteed delivery, substantially in the form provided with this
       prospectus, as provided below before the exchange offer expires; and

     - the depositary receives within three American Stock Exchange trading days
       after the date of execution of the notice of guaranteed delivery the
       share certificates, or a book-entry confirmation, for your tendered
       shares of Thermedics common stock, in proper form for transfer, in each
       case together with a properly completed and duly executed letter of
       transmittal, or a facsimile of a properly completed and duly executed
       letter of transmittal, with any required signature guarantees or, in the
       case of a book-entry transfer, an agent's message and any other documents
       required by the letter of transmittal.

You may deliver the notice of guaranteed delivery by hand or transmit it by
telegram, facsimile transmission or mail to the depositary. You must include a
guarantee by an eligible institution in the form set forth in the notice of
guaranteed delivery.

     Timing for Exchange.  In all cases, we will exchange shares of Thermedics
common stock that you have tendered and we have accepted for exchange pursuant
to the exchange offer only after timely receipt by the depositary of:

     - share certificates for Thermedics shares, or book-entry confirmation of
       the transfer of the shares of Thermedics common stock into the
       depositary's account at The Depository Trust Company;

     - a properly completed and duly executed letter of transmittal, or a
       facsimile of a properly completed and duly executed letter of
       transmittal, together with any required signature guarantees or, in the
       case of a book-entry transfer, an agent's message; and

     - any other documents required by the letter of transmittal.

Accordingly, tendering stockholders of Thermedics may receive shares of our
common stock at different times depending upon when share certificates or
book-entry confirmations for their shares of Thermedics common stock are
received by the depositary.

     Backup Federal Income Tax Withholding.  Under U.S. federal income tax laws,
the depositary may be required to withhold 31% of the amount of any cash
payments made to you in lieu of fractional shares of our common stock. To
prevent backup federal income tax withholding with respect to any reportable
cash payments made to you in the exchange offer, you must provide the depositary
with your correct taxpayer identification number and certify that you are not
subject to backup federal income tax withholding by completing the Substitute
Form W-9 included in the letter of transmittal. See Instruction 9 of the letter
of transmittal.

     Appointment as Proxy.  By executing the letter of transmittal, you
irrevocably appoint our designees as your attorneys-in-fact and proxies in the
manner set forth in the letter of transmittal, each with full power of
substitution with respect to any shares of Thermedics common stock you tendered,
and with respect to any and all other shares of Thermedics common stock or other
securities issued or issuable in respect of such shares of Thermedics common
stock on or after May 1, 2000. This appointment will not be effective until we
accept your tendered shares of Thermedics common stock for exchange and deposit
shares of our common stock as the exchange consideration with the depositary.
All such proxies will be


                                       37
<PAGE>   41

irrevocable and coupled with an interest in your tendered shares of Thermedics
common stock. When this appointment becomes effective, all other powers of
attorney and proxies that you have given will be revoked, and you may not give
any subsequent powers of attorney or proxies or execute any subsequent written
consents and, if given or executed, we will treat them as ineffective.

     Upon our deposit of shares of our common stock as the exchange
consideration with the depositary, our designees will, with respect to your
shares of Thermedics common stock and other securities for which the appointment
is effective, be empowered to exercise all of your voting and other rights as
they in their sole discretion consider proper. We may exercise these rights at
any time Thermedics stockholders vote. We reserve the right to require that, for
us to treat your shares of Thermedics common stock as validly tendered, we be
able to exercise full voting and other rights of a record and beneficial holder
immediately upon our acceptance for exchange of your shares of Thermedics common
stock.

     Determination of Validity.  We will determine all questions as to the
validity, form, eligibility, including the time of receipt, and acceptance for
exchange of any tendered shares of Thermedics common stock pursuant to any of
the procedures described above. We will make these determinations in our sole
discretion, and our determinations will be final and binding. We reserve the
absolute right to reject any and all tenders of shares of Thermedics common
stock that we determine are not in proper form or for which the acceptance of,
or exchange for, may, in the opinion of our counsel, be unlawful.

     We also reserve the absolute right to waive any of the conditions of the
exchange offer or any defect or irregularities in the tender of any shares of
Thermedics common stock, whether or not we waived similar defects or
irregularities in the case of any other shares of Thermedics common stock. We
will not treat your tender of shares of Thermedics common stock as validly made
until all defects and irregularities have been cured or waived. Neither we nor
any of our affiliates or assigns, the information agent, the depositary or any
other person will be under any duty to give notification of any defects or
irregularities in tenders or incur any liability for failure to give any such
notification. Our interpretations of the terms and conditions of the exchange
offer, including the letter of transmittal and the instructions to the letter of
transmittal, will be final and binding.

     OUR ACCEPTANCE FOR EXCHANGE OF YOUR SHARES OF THERMEDICS COMMON STOCK
TENDERED PURSUANT TO THE PROCEDURES DESCRIBED ABOVE WILL BE A BINDING AGREEMENT
BETWEEN US AND YOU UPON THE TERMS AND CONDITIONS OF THIS EXCHANGE OFFER.

WITHDRAWAL RIGHTS

     General.  Your tender of shares of Thermedics common stock pursuant to the
exchange offer is irrevocable except as otherwise provided in this section. You
may withdraw shares of Thermedics common stock that you tender in the exchange
offer at any time before the exchange offer expires and, unless we have
previously accepted these shares for exchange as provided in this prospectus, at
any time after June 29, 2000. If we elect to provide a subsequent offering
period under Exchange Act Rule 14d-11, you will not have the right to withdraw
shares of Thermedics common stock that you tender in the subsequent offering
period.

     Extensions.  If we:

     - extend the exchange offer,

     - are delayed in, or delay, our acceptance for exchange or the actual
       exchange of shares of our common stock for shares of Thermedics common
       stock, or

     - are unable for any reason to accept for exchange or exchange shares of
       Thermedics common stock,

then, without prejudice to our other rights under the exchange offer, the
depositary, on our behalf, may nevertheless retain your tendered shares of
Thermedics common stock and you may not exercise withdrawal rights except to the
extent described in this section. We will extend the exchange offer to the
extent required by law in the event of any extension or delay.

                                       38
<PAGE>   42

     Effectiveness of Withdrawal.  For your withdrawal to be effective, the
depositary must receive from you a written, telegraphic or facsimile
transmission notice of withdrawal at one of its addresses set forth on the back
cover of this prospectus. Your notice of withdrawal must include:

     - your name;

     - the number of shares of Thermedics common stock that you wish to
       withdraw; and

     - the name of the registered holder of the shares of Thermedics common
       stock that you wish to withdraw, if different from that of the person who
       tendered the shares of Thermedics common stock.

If you have delivered or otherwise identified your share certificates to the
depositary, then, before the physical release of the share certificates, you
must also submit the serial numbers shown on the share certificates to the
depositary and you must have the signatures on the notice of withdrawal
guaranteed by an eligible institution, unless the shares of Thermedics common
stock have been tendered for the account of an eligible institution. If you
tendered shares of Thermedics common stock pursuant to the procedures for
book-entry transfer, as set forth above under "-- Procedures For Accepting The
Exchange Offer And Tendering Shares," any notice of withdrawal must specify the
name and number of the account at The Depository Trust Company to be credited
with the withdrawn shares of Thermedics common stock and must otherwise comply
with the procedures of The Depository Trust Company.

     Revocation of Withdrawal.  You may not revoke a withdrawal. We will treat
any shares of Thermedics common stock properly withdrawn as not validly tendered
for purposes of the exchange offer. However, you may re-tender withdrawn shares
of Thermedics common stock at any time before the exchange offer expires by
again following one of the procedures described above under "-- Procedures For
Accepting The Exchange Offer And Tendering Shares."

     Validity of Withdrawals.  We will determine all questions as to the form
and validity, including the time of receipt, of any notice of withdrawal in our
sole discretion, and our determination will be final and binding. Neither we nor
any of our affiliates or assigns, the information agent, the depositary or any
other person will be under any duty to notify you of any defects or
irregularities in any notice of withdrawal or incur any liability for failure to
give any such notification.

CONDITIONS OF THE EXCHANGE OFFER

     We have the right to extend or amend the exchange offer in our sole
discretion at any time before the exchange offer expires. In addition, we:

     - are not required to accept for exchange or, subject to any applicable
       rules and regulations of the SEC, including Rule 14e-1(c) under the
       Exchange Act, relating to our obligation to return tendered shares of
       Thermedics common stock promptly after termination or withdrawal of the
       exchange offer, exchange shares of our common stock for any tendered
       shares of Thermedics common stock; and

     - may delay the acceptance for exchange of or, subject to the restriction
       referred to above, the exchange of, any tendered shares of Thermedics
       common stock.

     Minimum Number of Shares.  We may amend or terminate the exchange offer if
we would not own at least 90% of the outstanding shares of Thermedics common
stock immediately following the closing of the exchange offer. As of March 31,
2000, we owned approximately 75.5% of the outstanding shares of Thermedics
common stock. Assuming that optionholders exercised all outstanding Thermedics
stock options and debenture holders did not convert any of Thermedics'
convertible subordinated debentures into Thermedics common stock, we would have
owned approximately 72.5% of the outstanding shares of Thermedics common stock
at that date.

                                       39
<PAGE>   43

     Other Conditions.  In addition, we may amend or terminate the exchange
offer at any time on or after May 1, 2000 and before the time of acceptance of
the shares of Thermedics common stock for exchange in the exchange offer if any
of the following events shall occur:

     - any change occurs in the business, properties, assets, liabilities,
       capitalization, stockholders' equity, financial condition, cash flows,
       operations, licenses, franchises or results of operations of Thermedics
       or its subsidiaries which has a material adverse effect on Thermedics and
       its subsidiaries taken as a whole;

     - any "governmental entity," including a government or governmental
       authority or agency, whether domestic, foreign or supranational,
       institutes or threatens any action, proceeding, application, claim or
       counterclaim, seeks or obtains any judgment, order or injunction, or
       takes any other action, which:

       -- challenges the acquisition by us or any of our affiliates of any
          shares of Thermedics common stock pursuant to the exchange offer or
          the merger, restrains, prohibits or materially delays the making or
          consummation of the exchange offer or the merger, prohibits the
          performance of any of the contracts or other arrangements entered into
          by us or any of our affiliates in connection with the acquisition of
          the shares of Thermedics common stock or Thermedics, seeks to obtain
          any material amount of damages, or otherwise directly or indirectly
          adversely affects the exchange offer or the merger;

       -- seeks to prohibit or limit materially the ownership or operation by
          us, any of our affiliates or Thermedics of all or any material portion
          of our business or assets or the businesses or assets of our
          affiliates or of Thermedics and its subsidiaries, or to compel us, any
          of our affiliates or Thermedics to dispose of or to hold separate all
          or any material portion of our, any of our affiliates' or Thermedics'
          or its subsidiaries' businesses or assets as a result of the
          transactions contemplated by the exchange offer or the merger;

       -- seeks to impose any material limitation on the ability of us, any of
          our affiliates or Thermedics to conduct Thermedics' or its
          subsidiaries' businesses or to own Thermedics' or its subsidiaries'
          assets;

       -- seeks to impose or confirm any material limitation on the ability of
          us or any of our affiliates to acquire or hold, or to exercise full
          rights of ownership of, any shares of Thermedics common stock,
          including the right to vote such shares of Thermedics common stock on
          all matters properly presented to the stockholders of Thermedics;

       -- seeks to require us or any of our affiliates to divest all or any of
          our shares of Thermedics common stock; or

       -- otherwise has resulted in or has a reasonable likelihood of resulting
          in a material adverse effect on our, any of our affiliates' or
          Thermedics' business, financial condition, results of operation or
          prospects;

     - any statute, rule or regulation is enacted, promulgated, entered,
       enforced or treated as applicable to the exchange offer or the merger, or
       any other action is taken by any governmental entity or court, that
       results in, directly or indirectly, any of the consequences referred to
       in the first four sub-bullets of the preceding bullet;

     - any preliminary or permanent judgment, order, decree, ruling or
       injunction is entered or issued, or any other action is taken by any
       governmental entity or court, whether on its own initiative or the
       initiative of any other person, which:

       -- restrains, prohibits or materially delays the making or completing of
          the exchange offer or the merger, prohibits the performance of any of
          the contracts or other arrangements entered into by us or any of our
          affiliates in connection with the acquisition of the shares of
          Thermedics

                                       40
<PAGE>   44

          common stock or Thermedics or otherwise directly or indirectly
          materially adversely affects the exchange offer or the merger;

       -- prohibits or limits materially the ownership or operation by us, any
          of our affiliates or Thermedics of all or any material portion of our
          business or assets or the businesses or assets of our affiliates or of
          Thermedics and its subsidiaries, or compels us, any of our affiliates
          or Thermedics to dispose of or to hold separate all or any material
          portion of our, any of our affiliates' or Thermedics' or its
          subsidiaries' businesses or assets as a result of the transactions
          contemplated by the exchange offer or the merger;

       -- imposes any material limitation on the ability of us or any of our
          affiliates to conduct Thermedics' or its subsidiaries' businesses or
          to own Thermedics' or its subsidiaries' assets;

       -- imposes or confirms any material limitation on the ability of us or
          any of our affiliates to acquire or hold, or to exercise full rights
          of ownership of, any shares of Thermedics common stock, including the
          right to vote such shares of Thermedics common stock on all matters
          properly presented to the stockholders of Thermedics;

       -- requires us or any of our affiliates to divest of all or any of our
          shares of Thermedics common stock; or

       -- otherwise has resulted in or has a reasonable likelihood of resulting
          in a material adverse effect on our, any of our affiliates' or
          Thermedics' business, financial condition, results of operation or
          prospects;

     - any action, proceeding, application, claim or counterclaim is instituted
       or pending before any governmental entity or court, or any judgment,
       order or injunction is sought or any other action is taken by any person
       or entity, other than a governmental entity, which:

       -- challenges the acquisition by us or any of our affiliates of any
          shares of Thermedics common stock pursuant to the exchange offer or
          the merger, restrains, prohibits or materially delays the making or
          consummation of the exchange offer or the merger, prohibits the
          performance of any of the contracts or other arrangements entered into
          by us or any of our affiliates in connection with the acquisition of
          the shares of Thermedics common stock, seeks to obtain any material
          amount of damages, or otherwise directly or indirectly adversely
          affects the exchange offer or the merger;

       -- seeks to prohibit or limit materially the ownership or operation by
          us, any of our affiliates or Thermedics of all or any material portion
          of our business or assets or the businesses or assets of our
          affiliates or of Thermedics and its subsidiaries, or to compel us, any
          of our affiliates or Thermedics to dispose of or to hold separate all
          or any material portion of our, any of our affiliates' or Thermedics'
          or its subsidiaries' businesses or assets as a result of the
          transactions contemplated by the exchange offer or the merger;

       -- seeks to impose any material limitation on the ability of us, any of
          our affiliates or Thermedics to conduct Thermedics' or its
          subsidiaries' businesses or to own Thermedics' and its subsidiaries'
          assets;

       -- seeks to impose or confirm any material limitation on the ability of
          us or any of our affiliates to acquire or hold, or to exercise full
          rights of ownership of, any shares of Thermedics common stock,
          including the right to vote such shares of Thermedics common stock on
          all matters properly presented to the stockholders of Thermedics;

       -- seeks to require us or any of our affiliates to divest of all or any
          of our shares of Thermedics common stock; or

       -- otherwise has resulted in or, in our reasonable discretion, has a
          reasonable likelihood of resulting in a material adverse effect on
          our, any of our affiliates' or Thermedics' business, financial
          condition, results of operation or prospects;


                                       41
<PAGE>   45

      and which in the case of the first five sub-bullets of this bullet is
      successful or we determine, in our reasonable discretion, has a reasonable
      likelihood of being successful;

     - the registration statement of which this prospectus is a part does not
       become effective under the Securities Act of 1933 or is the subject of
       any stop order or proceedings seeking a stop order;

     - the shares of our common stock issuable to Thermedics stockholders in the
       exchange offer and the merger and the shares issuable upon the exercise
       of options to purchase shares of our common stock or the conversion of
       debentures convertible into our common stock are not approved for listing
       on the New York Stock Exchange, subject to official notice of issuance;

     - any general suspension of trading in, or limitation on prices for,
       securities occurs on the New York Stock Exchange or the American Stock
       Exchange or in the over-the-counter market, other than any temporary
       suspension pursuant to a circuit breaker procedure then in effect and
       lasting for not more than three trading hours;

     - any declaration of a banking moratorium by federal or New York
       authorities or general suspension of payments in respect of lenders that
       regularly participate in the U.S. market in loans occurs;

     - any material limitation by any federal, state or local government or any
       court, administrative or regulatory agency or commission or other
       governmental authority or agency in the United States occurs that
       materially affects the extension of credit generally by lenders that
       regularly participate in the U.S. market in loans;

     - any commencement of a war involving the United States or any commencement
       of armed hostilities or other national or international circumstance
       involving the United States occurs that has a material adverse effect on
       bank syndication or financial markets in the United States; or

     - in the case of any occurrence described in the previous four bullets that
       existed on or at the time of the commencement of the exchange offer, a
       material acceleration or worsening of that occurrence; which in our
       reasonable judgment, in any case and regardless of the circumstances
       giving rise to the condition, makes it inadvisable to proceed with the
       exchange offer or with acceptance of shares of Thermedics common stock
       for exchange or exchanges of shares of our common stock for shares of
       Thermedics common stock.

     Conditions Solely for Our Benefit.  The foregoing conditions are for our
sole benefit and we may assert them regardless of any circumstances giving rise
to any condition. We may waive these conditions in whole or in part, at any time
and from time to time before the exchange offer expires, in our reasonable
discretion. Our failure, or the failure of any of our affiliates, at any time to
exercise any of the foregoing rights will not constitute a waiver of any right.
We will treat each right as an ongoing right which may be asserted at any time
and from time to time before the exchange offer expires.

LEGAL MATTERS; REGULATORY APPROVALS

     General.  Except as described below, we are not aware of any license or
regulatory permit that appears to be material to the business of Thermedics and
its subsidiaries and may be adversely affected by our acquisition of shares of
Thermedics common stock in the exchange offer or the merger.

     Except as described in this section, we are not aware of any other material
filing, approval or other action by any federal or state governmental or
administrative authority that we must obtain in connection with our acquisition
of shares of Thermedics common stock as contemplated in this prospectus. Should
any other similar approval or action be required, we currently contemplate
seeking that approval or action. We cannot assure you that we could obtain any
other approval or action, if needed, without substantial conditions or costs or
that adverse consequences would not result to our or Thermedics' business if we
do not obtain any other required approvals or actions. Our obligation under the
exchange offer to accept for exchange and exchange shares of Thermedics common
stock is subject to a number of conditions, including conditions relating to the
legal matters discussed in this section. See "-- Conditions Of The Exchange
Offer."


                                       42
<PAGE>   46

     Antitrust.  We believe that the exchange offer and the merger are exempt
from the reporting requirements contained in the Hart-Scott-Rodino Antitrust
Improvements Act of 1976. Nevertheless, we cannot assure that a challenge to the
exchange offer and the merger on antitrust grounds will not be made or, if such
challenge is made, what the result will be.

     Foreign Approvals.  Thermedics conducts business in a number of foreign
countries and jurisdictions. In connection with our acquisition of shares of
Thermedics common stock pursuant to the exchange offer or the merger, we and/or
Thermedics may be required to file information with, or obtain the approval or
consent of, governmental authorities in those foreign countries and
jurisdictions. The governments in those countries and jurisdictions might
attempt to impose additional conditions on Thermedics' operations conducted in
such countries and jurisdictions as a result of our acquisition of the shares of
Thermedics common stock pursuant to the exchange offer or the merger of
Thermedics into Thermo Electron.

     If foreign approvals or consents are required, we intend to make the
appropriate filings and applications. We do not know if or when we will obtain
any required foreign approvals or consents for which we file or apply. In
addition, we may be unable to cause Thermedics or its subsidiaries to satisfy or
comply with foreign laws. Noncompliance may have adverse consequences for
Thermedics or its subsidiaries after the exchange of shares of our common stock
for shares of Thermedics common stock pursuant to the exchange offer or the
merger.

     State Anti-Takeover Statutes.  Chapters 110C, 110D and 110F of the General
Laws of the Commonwealth of Massachusetts prohibit, restrict or impose
procedural and disclosure requirements with respect to the acquisition of more
than 5% of the outstanding shares of a Massachusetts corporation, such as
Thermedics, and with respect to take-over bids and business combinations
involving a Massachusetts corporation. Thermedics, through a provision in its
bylaws, has elected to "opt out" of the prohibitions and restrictions of Chapter
110D. We believe that neither the exchange offer nor the merger is adversely
affected by these statutes.

     A number of other states have adopted laws and regulations applicable to
attempts to acquire securities of corporations which are incorporated, or have
substantial assets, stockholders, principal executive offices or principal
places of business, or whose business operations otherwise have substantial
economic effects, in such states. In 1982, in Edgar v. MITE Corp., the Supreme
Court of the United States invalidated on constitutional grounds the Illinois
Business Takeover Statute, which, as a matter of state securities law, made
takeovers of corporations meeting the statute's requirements more difficult.
However, in 1987 in CTS Corp. v. Dynamics Corp. of America, the Supreme Court
held that the State of Indiana may, as a matter of corporate law, and, in
particular, with respect to those aspects of corporate law concerning corporate
governance, constitutionally disqualify a potential acquiror from voting on the
affairs of a target corporation without the prior approval of the remaining
stockholders. The state law before the Supreme Court was by its terms applicable
only to corporations that had a substantial number of stockholders in that state
and were incorporated there.

     Thermedics, directly or through its subsidiaries, conducts business in a
number of states throughout the United States, some of which have enacted
anti-takeover laws. We do not know whether any of these laws will, by their
terms, apply to the exchange offer or the merger, and we have not necessarily
complied with any such laws. Should any person seek to apply any state
anti-takeover law to the exchange offer or the merger, we will take such action
as then appears desirable, which may include challenging the validity or
applicability of any such statute in appropriate court proceedings. In the event
it is asserted that one or more state anti-takeover laws is applicable to the
exchange offer or the merger, and an appropriate court does not determine that
it is inapplicable or invalid as applied to the exchange offer or the merger, we
may be required to file information with, or receive approvals from, the
relevant state authorities. In addition, if enjoined, we may be unable to accept
for exchange any shares of Thermedics common stock tendered pursuant to the
exchange offer, or be delayed in continuing or consummating the exchange offer.
In any such case, we may not be obligated to accept for exchange any shares of
Thermedics common stock tendered. See "-- Conditions Of The Exchange Offer."

                                       43
<PAGE>   47

DIVIDENDS AND DISTRIBUTIONS

     If, on or after May 1, 2000, Thermedics should declare or pay any dividend
or other distribution, including without limitation the issuance of additional
shares of Thermedics common stock pursuant to any stock dividend or stock split
or the issuance of rights for the purchase of any securities, with respect to
the shares of Thermedics common stock, and the dividend or distribution is
payable or distributable to stockholders of record on a date occurring before
the transfer to our name or the name of our nominees or transferees on
Thermedics' stock transfer records of the shares of Thermedics common stock
acquired pursuant to the exchange offer, then, without prejudice to our rights
described in "-- Conditions Of The Exchange Offer":

     - in the event of a cash dividend or distribution, the exchange ratio per
       share will be reduced by multiplying the exchange ratio by a fraction the
       numerator of which is $8.9375, the closing market price of the Thermedics
       common stock on March 7, 2000, minus the amount of the cash dividend or
       distribution and the denominator is $8.9375; and

     - in the event of a non-cash dividend or distribution, you will be required
       to deliver promptly and transfer to the depositary for our account any
       non-cash dividend or distribution, including additional shares of
       Thermedics common stock, together with appropriate documentation of
       transfer. Pending your remittance or appropriate assurance of your
       remittance, we will be entitled to all rights and privileges as owner of
       any such non-cash dividend, distribution or right, and may withhold all
       of the shares of our common stock issuable to you in the exchange offer
       or reduce the exchange ratio by multiplying the exchange ratio by a
       fraction, the numerator of which is $8.9375, the closing price of the
       Thermedics common stock on March 7, 2000, minus the value of such
       non-cash dividend, distribution or right, as determined by us in our sole
       discretion, and the denominator of which is $8.9375.

     If, on or after May 1, 2000, Thermedics should split the shares of its
common stock or combine or otherwise change the shares of its common stock or
its capitalization, then, without prejudice to our rights described in
"-- Conditions Of The Exchange Offer," we may make appropriate adjustments to
reflect such split, combination or change in the exchange ratio and other terms
of the exchange offer, including without limitation the number or type of
securities we are offering in exchange for Thermedics common stock.

FEES AND EXPENSES

     J.P. Morgan Securities Inc. and The Beacon Group Capital Services, LLC are
acting as our financial advisors in connection with the exchange offer and the
merger involving Thermedics described in this prospectus.

     In October 1999, we engaged The Beacon Group as our financial advisor in
connection with our proposed acquisition of the outstanding shares held by
public stockholders in certain of our subsidiaries. We paid The Beacon Group
$500,000 in fees for services that The Beacon Group rendered pursuant to that
engagement in connection with our acquisition of the outstanding publicly-held
shares of common stock of ThermoTrex Corporation and ThermoLase Corporation.

     Pursuant to our letter agreement with J.P. Morgan and The Beacon Group,
dated January 17, 2000, we agreed to pay each of J.P. Morgan and The Beacon
Group a fee of $500,000 for its services in connection with the exchange offer
and the merger involving Thermedics described in this prospectus. In addition,
we will reimburse J.P. Morgan and The Beacon Group for expenses incurred in
connection with these transactions. The letter agreement also relates to our
overall reorganization and provides for separate fees for services with respect
to other elements of our reorganization. These other fees include a minimum
retainer for each of J.P. Morgan and The Beacon Group of $1.25 million. The
engagement letter provides for substantial additional compensation if we
complete some or all of the other elements of our reorganization. We have agreed
to indemnify J.P. Morgan and The Beacon Group and their affiliates

                                       44
<PAGE>   48

against certain liabilities, including liabilities under the federal securities
laws in connection with their engagement.

     We have retained D.F. King & Co. to act as the information agent and
EquiServe to act as the depositary in connection with the exchange offer. The
information agent may contact holders of shares of Thermedics common stock by
mail, telephone, telex, telecopy, telegraph and personal interview and may
request brokers, dealers, commercial banks, trust companies and other nominees
to forward the exchange offer material to beneficial owners. Each of the
information agent and the depositary will receive reasonable and customary
compensation for its services, will be reimbursed for reasonable out-of-pocket
expenses and will be indemnified against certain liabilities and expenses in
connection with the exchange offer, including certain liabilities under U.S.
federal securities laws.

     We will not pay any fees or commissions to any broker or dealer or any
other person for soliciting tenders of shares of Thermedics common stock in the
exchange offer, other than to the information agent. We will, upon request,
reimburse brokers, dealers, commercial banks and trust companies for customary
mailing and handling expenses incurred by them in forwarding materials to their
customers.

     The following is an estimate of the fees and expenses that we expect to
incur in connection with the exchange offer and the merger:

<TABLE>
<CAPTION>

<S>                                                           <C>
Financial Advisors..........................................  $1,000,000
Legal.......................................................     250,000
Printing....................................................     100,000
Listing Fee.................................................      25,650
Filing......................................................      25,629
Depositary..................................................      10,000
Information Agent, including mailing........................      15,000
Miscellaneous...............................................      23,721
                                                              ----------
                                                              $1,450,000
                                                              ==========
</TABLE>

     We will pay these fees and expenses, including any cash paid for fractional
shares, out of cash that we currently hold. Thermedics will not pay any of the
fees and expenses to be incurred by us in connection with the exchange offer.

STOCK EXCHANGE LISTING

     Our common stock is listed on the New York Stock Exchange. We will make an
application as necessary to list on the New York Stock Exchange the common stock
that we will issue pursuant to the exchange offer and the merger. We will not
accept for exchange, or exchange for shares of our common stock, any shares of
common stock of Thermedics or complete the merger unless the following shares of
our common stock are approved for listing on the New York Stock Exchange,
subject to official notice of issuance:

     - the shares issuable to Thermedics stockholders in the exchange offer and
       the merger;

     - the shares issuable upon the exercise of options to purchase shares of
       Thermedics common stock that we assume in connection with the exchange
       offer and the merger; and

     - the shares issuable upon the conversion of the Thermedics convertible
       debentures that we assume in connection with the exchange offer and the
       merger.

                                       45
<PAGE>   49

                          MARKET PRICES AND DIVIDENDS

PRICE RANGE OF SHARES OF OUR COMMON STOCK AND OF THERMEDICS COMMON STOCK

     Our common stock is listed on the New York Stock Exchange under the symbol
"TMO." Thermedics' common stock is listed on the American Stock Exchange under
the symbol "TMD." The following table sets forth the high and low sales prices
per share of our common stock and of Thermedics common stock, as reported in
publicly available sources for each of the periods indicated.

<TABLE>
<CAPTION>
                                                            THERMO ELECTRON         THERMEDICS
                                                            ----------------      --------------
                                                            HIGH        LOW       HIGH      LOW
                                                            -----      -----      ----      ----
<S>                                                         <C>        <C>        <C>       <C>
Fiscal Year Ended January 2, 1999:
  First Quarter.......................................       43 5/16    36 5/8     17 7/8    14 5/8
  Second Quarter......................................       41 15/16   30 3/4     17 15/16  12 5/16
  Third Quarter.......................................       35 3/16    14 3/16    13 9/16    7 1/4
  Fourth Quarter......................................       20 1/16    13 9/16    11 1/4     6 5/8
Fiscal Year Ended January 1, 2000:
  First Quarter.......................................       18 3/16    13 3/8     11 3/8     6 1/2
  Second Quarter......................................       20 1/4     12 1/2      9 5/16    6 1/8
  Third Quarter.......................................       19 11/16   13 1/8      9 5/8     5 5/8
  Fourth Quarter......................................       16 1/8     12 3/4      7         4 3/4
Fiscal Year Ending December 30, 2000:
  First Quarter.......................................       26 7/8     14         11 1/4     5 3/16
  Second Quarter, through April 27, 2000..............       21 7/16    17 3/4      8 3/4     7 3/8
</TABLE>

     As of April 27, 2000, there were 8,402 holders of record and in excess of
36,500 beneficial owners of the shares of our common stock. As of April 27,
2000, there were 2,330 holders of record and in excess of 6,100 beneficial
owners of shares of Thermedics common stock.

     On January 28, 2000, the last full trading day prior to the public
announcement of our intention to commence the exchange offer, the closing sale
price per share of Thermedics common stock, as reported on the American Stock
Exchange, was $6.125. On March 7, 2000, the day prior to our announcement of the
exchange ratio, the closing sale price per share of Thermedics common stock, as
reported on the American Stock Exchange, was $9.0625.

     YOU SHOULD OBTAIN CURRENT MARKET QUOTATIONS FOR THE SHARES OF OUR COMMON
STOCK AND THERMEDICS COMMON STOCK.

DIVIDENDS

     Neither we nor Thermedics has ever declared or paid any cash dividends in
respect of our common stock.

                                       46
<PAGE>   50

                          THE MERGER; APPRAISAL RIGHTS

THE MERGER

     If we complete the exchange offer, we will cause Thermedics to merge with
and into Thermo Electron in accordance with the Massachusetts Business
Corporation Law, Chapter 156B of the Massachusetts General Laws, and the
Delaware General Corporation Law. Upon the effective date of this merger, each
share of Thermedics common stock issued and outstanding immediately prior to the
effective date of the merger, other than shares owned by us and shares held by
Thermedics' public stockholders, if any, who are entitled to and who properly
exercise their dissenters' rights under the Massachusetts Business Corporation
Law, as described below under "-- Appraisal Rights," will be cancelled and
converted into a right to receive 0.45 shares of our common stock for each share
of Thermedics common stock. Thermedics stockholders will also be entitled to
receive cash in lieu of the issuance of fractional shares of our common stock in
an amount equal to $19.50 for each whole share of our common stock. As a result
of the merger, Thermedics will cease to exist as a separate legal entity, and we
will own all of Thermedics' assets.

     Under the Massachusetts Business Corporation Law and the Delaware General
Corporation Law, if we hold at least 90% of the outstanding shares of Thermedics
common stock, we may effect the merger without a vote of Thermedics' board of
directors or Thermedics' other stockholders. We intend to take all necessary and
appropriate action to cause the merger to become effective as promptly as
practicable after we complete the exchange offer, and without a meeting of the
Thermedics' stockholders.

APPRAISAL RIGHTS

     Under the Massachusetts Business Corporation Law, stockholders of
Thermedics who tender their shares of Thermedics common stock in the exchange
offer may not exercise appraisal rights. If we complete the merger, then
stockholders of Thermedics who do not tender their shares of Thermedics common
stock to us pursuant to the exchange offer would have the right to demand an
appraisal of the fair value of their shares of Thermedics common stock in
accordance with the provisions of Section 82(e) and Sections 86 through 98 of
the Massachusetts Business Corporation Law. These sections set forth the rights
and obligations of stockholders of Thermedics demanding an appraisal and the
procedures to be followed.

     The Appraisal Statute.  Under Massachusetts law, if you follow the
procedures of Section 82(e) and Sections 86 through 98, you will be entitled to
have a court appraise the fair value of your shares and to have us pay the fair
value of your shares together with interest. The following is a summary of
Section 82(e) and Sections 86 through 98 of the Massachusetts Business
Corporation Law. We qualify this summary in its entirety by reference to the
full text of Section 82(e) and Sections 86 through 98. Annex C sets forth the
full text of these sections of the Massachusetts Business Corporation Law. If
you fail to follow these procedures, you will lose your appraisal rights.
Consequently, you should carefully review Annex C and consult your legal advisor
if you would like to exercise your appraisal rights.

     You should execute any demand for appraisal in your name, as it appears on
your stock certificates. If you own shares in a fiduciary capacity, such as in a
capacity as a trustee, guardian or custodian, you should execute the demand in
that capacity. If more than one person owns the shares, as in a joint tenancy or
tenancy in common, all of the joint owners should execute the demand. An
authorized agent, including one or more joint owners, may execute the demand for
appraisal for a holder of record; however, the agent must identify the record
owner or owners and expressly disclose the fact that, in executing the demand,
the agent is acting for such owner or owners.

     A record holder such as a broker who holds shares of Thermedics common
stock as a nominee for beneficial owners, some of whom desire to demand
appraisal, is required to exercise appraisal rights on behalf of those
beneficial owners. In this case, the written demand for appraisal should set
forth the number of shares covered by it. Unless a demand for appraisal
specifies a number of shares, we will treat the demand as applying to all of the
shares held in the name of the record holder. If you beneficially own

                                       47
<PAGE>   51

shares through a nominee, you may also notify us of such beneficial ownership
and your intention to exercise appraisal rights before we mail the notice
discussed below.

     Required Notice and Demand.  Within ten days following the consummation of
the merger, we would notify the Thermedics stockholders of record of:

     - the effective date of the merger;

     - the terms and conditions of the merger; and

     - the availability of appraisal rights under Section 82(e) and Sections 86
       through 98.

If you are entitled to appraisal rights, you would have the right, within 20
days after the date of mailing of the required notice, to demand in writing from
us an appraisal of your shares of Thermedics common stock. Any demand that
reasonably informs us of your identity and your intent to demand an appraisal of
the fair value of your shares would be sufficient. Failure to make such a timely
demand would foreclose your right to appraisal.

     You can withdraw your demand for appraisal only with our approval. If you
withdraw your demand for appraisal, you would be entitled to receive 0.45 shares
of our common stock for each share of Thermedics common stock plus cash in lieu
of the issuance of fractional shares of our common stock in an amount equal to
$19.50 per whole share, without interest.

     If, following the merger, you perfect a demand for payment of your shares
of Thermedics common stock as provided above, and if we reach agreement with you
on the fair value of the shares, we will pay you the fair value of the shares
within 30 days after the expiration of the 20-day period during which the demand
for appraisal may be made.

     The Court's Determination.  If within that 30-day period we cannot reach
agreement with you on the fair value of your shares of Thermedics common stock,
either of us may elect to have the fair value of the shares of all dissenting
stockholders determined through judicial proceedings in the Massachusetts
Superior Court for Middlesex County within four months after the 30-day period
has expired. We are not under any obligation, and have no present intention, to
elect to have the fair value of the shares of all dissenting stockholders
determined through judicial proceedings.

     Although Massachusetts courts have broad discretion in determining the fair
value of stock of dissenting stockholders, Massachusetts courts have generally
used a weighted average of the market, earnings and asset values for the stock.
The Massachusetts Supreme Judicial Court has recently held that this method is
an appropriate, but not mandated, approach to determining the fair value of
stock of dissenting stockholders. The trial judge may determine the appropriate
valuation method to apply. The Massachusetts Business Corporation Law requires
us to pay a fair rate of interest on any award determined by the Court from the
date our board of directors votes to approve the merger.

     If:

     - you do not file a suit to determine the value of your shares of
       Thermedics common stock within four months of the expiration of the
       30-day period during which we and any dissenting stockholders would try
       to reach agreement on the value of the dissenters' shares,

     - any suit you file to determine the value of your shares of Thermedics
       common stock is dismissed, or

     - you withdraw your demand in writing with our written approval,

then you would only have the right to receive the consideration of 0.45 shares
of our common stock for each share of Thermedics common stock we offered in the
merger.

     Under Massachusetts statutory law, your right to receive payment for your
shares in the manner provided by Section 82(e) and Sections 86 through 98 of the
Massachusetts Business Corporation Law is your exclusive remedy if you object to
the merger, except if you object to the merger on the grounds that completing
the merger will be or is illegal or fraudulent. In addition, the Massachusetts
Supreme Judicial Court has held that dissenting stockholders are not limited to
the statutory remedy of judicial appraisal in cases involving breaches of
fiduciary duty.

                                       48
<PAGE>   52

     If you are considering seeking appraisal, you should bear in mind that the
fair value of your shares determined under Section 82(e) and Sections 86 through
98 of the Massachusetts Business Corporation Law could be more, the same or less
than the consideration you would have received in the merger.

     Consequences of a Demand for Appraisal.  After the effective date of the
merger, you would not be entitled to vote your shares for any purpose and would
not be entitled to receive payment of dividends or other distributions in
respect of your shares of Thermedics common stock.

     For federal income tax purposes, stockholders who receive cash for their
shares of Thermedics common stock upon exercise of dissenters' rights will
realize taxable gain or loss. See "Federal Income Tax Consequences."

     THE FOREGOING SUMMARY IS NOT A COMPLETE STATEMENT OF THE PROCEDURES THAT
YOU MUST FOLLOW TO EXERCISE YOUR DISSENTING APPRAISAL RIGHTS. THE FULL TEXT OF
THE MASSACHUSETTS APPRAISAL STATUTE IS ATTACHED TO THIS PROSPECTUS AS ANNEX C.
YOU SHOULD READ ANNEX C IN ITS ENTIRETY BECAUSE FAILING TO COMPLY WITH THE
PROCEDURES SET FORTH IN THE MASSACHUSETTS APPRAISAL STATUTE WILL RESULT IN THE
LOSS OF YOUR APPRAISAL RIGHTS.

                        FEDERAL INCOME TAX CONSEQUENCES

     This section summarizes the important federal income tax consequences of
the exchange offer and the merger to you. This summary is based on the current
Internal Revenue Code, Treasury regulations and administrative rulings and court
decisions, all of which can change. If there are any changes to the Internal
Revenue Code, those regulations or those rulings and decisions, the tax
consequences to you might change. Any changes could be retroactive.

     You should know that this summary does not deal with all federal income tax
considerations that may be relevant to you because of your particular
circumstances. Some examples of circumstances that would involve different
federal income tax consequences are if you:

     - were a dealer in securities;

     - were an insurance company or financial institution;

     - were a foreign person or entity;

     - do not hold your Thermedics common stock as a capital asset; or

     - acquired your shares in connection with stock option or stock purchase
       plans or in other compensatory transactions.

     In addition, the following discussion does not address the tax consequences
of the exchange offer and the merger under foreign, state or local tax laws. WE
RECOMMEND THAT YOU CONSULT YOUR OWN TAX ADVISOR AS TO THE SPECIFIC TAX
CONSEQUENCES TO YOU OF THE EXCHANGE OFFER AND THE MERGER, INCLUDING THE
APPLICATION OF STATE, LOCAL, FOREIGN AND OTHER TAX LAWS.

     In connection with the exchange offer and merger, Hale and Dorr LLP, our
legal counsel, has rendered a tax opinion to Thermedics that the exchange offer
and the merger of Thermedics into us should be treated as one integrated
transaction that will qualify as a "reorganization" within the meaning of
Section 368(a) of the Internal Revenue Code. We and Thermedics gave Hale and
Dorr information about the exchange offer and the merger. Hale and Dorr based
their tax opinion on that information. In addition, Hale and Dorr assumed some
facts in giving their tax opinion, and their opinion contains various
qualifications and limitations. We have filed Hale and Dorr's tax opinion as an
exhibit to the registration statement of which this prospectus is a part.
Subject to the assumptions, limitations and qualifications in the tax opinion,
Hale and Dorr is of the opinion that the exchange offer and the merger should
result in the following federal income tax consequences:

     - You will not recognize any gain or loss solely upon the exchange of your
       shares of Thermedics common stock for our common stock pursuant to the
       exchange offer or the merger, except for any cash you receive in lieu of
       fractional shares of our common stock.

                                       49
<PAGE>   53

     - Your aggregate tax basis in our common stock that you receive pursuant to
       the exchange offer or the merger will be the same as your aggregate tax
       basis in the Thermedics common stock that you tendered, reduced by the
       amount of any tax basis attributable to any fractional shares that you do
       not actually receive.

     - Your holding period for our common stock that you receive pursuant to the
       exchange offer or the merger will include the period for which you held
       the Thermedics common stock that you exchange for our common stock, if
       you held the Thermedics common stock as a capital asset at the time of
       the exchange.

     - Cash payments that you receive in lieu of a fractional share will be
       treated as if that fractional share of our common stock had been issued
       pursuant to the exchange offer or the merger and then redeemed by us. You
       generally will recognize gain or loss upon any cash you so receive
       measured by the difference, if any, between the amount of cash you
       receive and your basis in that fractional share.

     - Neither we nor Thermedics will recognize gain or loss directly as a
       result of the exchange offer or the merger.

     We will not, and Thermedics will not, request a ruling from the Internal
Revenue Service in connection with the exchange offer or the merger. You should
be aware that Hale and Dorr's tax opinion will not bind the Internal Revenue
Service. Hale and Dorr relied upon many factual representations by us in
rendering its tax opinion and, in particular, upon our representation that if
the exchange offer is successful, we will cause the merger of Thermedics with
and into us to occur.

     Hale and Dorr's tax opinion does not address or consider the tax effect on
you of our proposed spin-offs of our business that serves the healthcare
industry with a range of medical products for diagnosis and monitoring and our
paper recycling and papermaking equipment business. In that regard, we have
requested a ruling from the Internal Revenue Service regarding the tax
consequences of the spin-offs. We expect to proceed with the spin-offs only if
we receive a ruling that the spin-offs will qualify under Section 355 of the
Internal Revenue Code. Accordingly, if the spin-offs occur, we anticipate that
the ruling we receive from the Internal Revenue Service will address the tax
consequences of the spin-offs to our stockholders, including those stockholders
who received their shares pursuant to the exchange offer or the merger. Any
ruling that we receive from the Internal Revenue Service may provide that the
spin-offs could be taxable to some or all of our stockholders, including the
prior stockholders of Thermedics who received our common stock pursuant to the
exchange offer or the merger.

     A successful challenge by the Internal Revenue Service to the
reorganization status of the exchange offer and the merger would result in your
recognizing taxable gain or loss on each share of Thermedics common stock that
you exchange in the exchange offer or receive in the merger. The amount of gain
or loss would be equal to the difference between your basis in that share and
the fair market value, as of the effective time of the exchange, of our common
stock that you received in exchange for that share. In such event, a
stockholder's aggregate basis in our common stock so received would equal its
fair market value as of the effective time of the exchange, and the
stockholder's holding period for such stock would begin the day after the
exchange.

          COMPARISON OF THE RIGHTS OF HOLDERS OF OUR COMMON STOCK AND
                THE RIGHTS OF HOLDERS OF THERMEDICS COMMON STOCK

     Upon completion of the exchange offer and the merger, stockholders of
Thermedics will become stockholders of Thermo Electron, rather than stockholders
of Thermedics. Thermo Electron's charter and bylaws will govern your rights as a
stockholder of Thermo Electron. Our charter and bylaws differ in some important
respects from Thermedics' charter and bylaws. In addition, Thermedics is
incorporated under the laws of the Commonwealth of Massachusetts, and the rights
of Thermedics stockholders are currently governed by Chapter 156B of the
Massachusetts General Laws, which is referred to in this prospectus as the
Massachusetts Business Corporation Law. We are incorporated under the laws of
the State of

                                       50
<PAGE>   54

Delaware. As Thermo Electron stockholders, the Delaware General Corporation Law
will govern the rights of former Thermedics stockholders.

     The following is a comparison of:

     - the current rights of Thermedics stockholders under Thermedics' charter
       and bylaws and the Massachusetts Business Corporation Law, and

     - the rights Thermedics stockholders would have as Thermo Electron
       stockholders under Thermo Electron's charter and bylaws and the Delaware
       General Corporation Law after the completion of the offer and the merger.

The comparison summarizes the material differences but does not list all
differences between the rights of Thermo Electron stockholders and Thermedics
stockholders.

<TABLE>
<CAPTION>
                                      THERMO ELECTRON                                THERMEDICS
                          ---------------------------------------      ---------------------------------------
<S>                       <C>                                          <C>
BOARD OF DIRECTORS

Classified Board          Divided into three classes, as nearly        Consists of single class serving a
                          equal in number as possible, with each       one-year term.
                          class serving a staggered three-year
                          term.

Removal of Directors      Directors may be removed for cause           Directors may be removed, with or
                          only, at any special or annual meeting,      without cause, by the holders of a
                          by the affirmative vote of a majority        majority of the shares then entitled to
                          of shares present in person or by proxy      vote at an election of directors.
                          at such meeting entitled to vote for         Directors may also be removed with
                          the election of such director.               cause by a majority of the directors
                                                                       then in office. A director may only be
                                                                       removed with cause after reasonable
                                                                       notice and an opportunity to be heard.

Filling of Board          Vacancies on the board of directors may      Same.
Vacancies                 be filled by the vote of a majority of
                          the directors then in office.

Size of Board             The number of directors shall be fixed       The number of directors shall be fixed
                          by resolution of the board, but may not      by resolution of the board or a vote of
                          be less than 3. The current number of        the holders of Thermedics common stock
                          directors is 9.                              but may not be less than 3 nor more
                                                                       than 8. The current number of directors
                                                                       is 6.

ANNUAL MEETING OF         Held on date fixed by the board.             Same.
  STOCKHOLDERS
</TABLE>

                                       51
<PAGE>   55

<TABLE>
<CAPTION>
                                      THERMO ELECTRON                                THERMEDICS
                          ---------------------------------------      ---------------------------------------

<S>                       <C>                                          <C>
CALLING A SPECIAL         Special meetings may be called by the        Special meetings may be called by the
MEETING OF STOCKHOLDERS   board of directors, the chairman of the      board of directors, the chairman of the
                          board of directors or the chief              board of directors or the president and
                          executive officer.                           shall be called by the clerk or another
                                                                       officer upon written application of
                                                                       stockholders holding at least 10% of
                                                                       the Thermedics common stock entitled to
                                                                       vote at a special meeting.

QUORUM REQUIREMENTS       The presence in person or by proxy of        The presence in person or by proxy of
                          the holders of a majority of the votes       the holders of a majority of the shares
                          represented by the shares entitled to        entitled to vote at the meeting
                          vote at the meeting constitute a quorum      constitute a quorum for that meeting.
                          for that meeting, except as otherwise
                          provided by the Delaware General
                          Corporation Law.

VOTING RIGHTS             Each holder of our common stock is           Each holder of Thermedics common stock
                          entitled to one vote per share and may       is entitled to one vote per share and
                          not cumulate votes for the election of       may not cumulate votes for the election
                          directors. Each holder of our Series B       of directors.
                          junior participating stock is entitled
                          to 10,000 votes per share and may not
                          cumulate votes for the election of
                          directors.

STOCKHOLDER ACTION BY     In general, if a quorum is present at a      In general, if a quorum is present at a
VOTE AT A MEETING         meeting of stockholders, the                 meeting of stockholders, the
                          affirmative vote of a majority of the        affirmative vote of a majority of the
                          votes represented by the shares present      shares present and entitled to vote at
                          and entitled to vote at the meeting is       the meeting is required to take action.
                          required to take action, except that         Most mergers and consolidations would
                          the election of directors is by vote of      require the approval of a majority of
                          a plurality of the votes represented by      the shares of Thermedics common stock
                          the shares present and entitled to vote      outstanding and entitled to vote.
                          at the meeting. Most mergers,                Sales, leases or exchanges of all or
                          consolidations and sales, leases or          substantially all of Thermedics' assets
                          exchanges of all or substantially all        would require the approval of
                          of our assets would require the              two-thirds of the shares of Thermedics
                          approval of our board of directors and       common stock outstanding and entitled
                          of a majority of the votes represented       to vote. The voting requirements
                          by all outstanding shares of our common      necessary to approve amendments to
                          stock entitled to vote. The voting           Thermedics' charter and bylaws are set
                          requirements necessary to approve            forth below under "Amendments to
                          amendments to the charter and bylaws         Organizational Documents."
                          are set forth below under "Amendments
                          to Organizational Documents."
</TABLE>

                                       52
<PAGE>   56

<TABLE>
<CAPTION>
                                      THERMO ELECTRON                                THERMEDICS
                          ---------------------------------------      ---------------------------------------

<S>                       <C>                                          <C>
STOCKHOLDER ACTION BY     May take action by written consent of        May take action by written consent of
WRITTEN CONSENT           stockholders having no less than the         all stockholders entitled to vote on
                          minimum number of votes that would be        the action if a meeting were held.
                          necessary to take such action at a
                          meeting at which all shares entitled to
                          vote on the matter were present and
                          voted.

ADVANCE NOTICE FOR        A stockholder must deliver notice of         No advance notice provisions.
STOCKHOLDER NOMINATIONS   stockholder nominations or proposals to
AND OTHER BUSINESS        be made at an annual stockholders
                          meeting to the secretary not less than
                          60 days nor more than 75 days before
                          the first anniversary of the date on
                          which proxy materials for the preceding
                          year's annual stockholders meeting were
                          first mailed. However, if the date of
                          the annual meeting is moved ahead more
                          than 30 days before or delayed by more
                          than 30 days after the anniversary of
                          the preceding year's annual stockholder
                          meeting, a stockholder must deliver
                          notice not later than the close of
                          business on the later of:
                          - the 90th day prior to such annual
                            meeting; or
                          - the 10th day following the day on
                            which public announcement of the date
                            of such meeting is made.

AMENDMENTS TO
ORGANIZATIONAL DOCUMENTS

Certificate of            The approval of both our board of            The approval of the holders of a
Incorporation or          directors and the holders of a majority      majority of the outstanding Thermedics
Articles of Organization  of the votes represented by our              shares entitled to vote for the
                          outstanding shares entitled to vote for      amendment is required for an amendment
                          the amendment is required for an             to Thermedics' articles of
                          amendment to our certificate of              organization.
                          incorporation. Any amendment to our
                          certificate of incorporation which
                          would materially alter or change the
                          powers, preferences or special rights
                          of our Series B junior participating
                          preferred stock so as to affect them
                          adversely also requires the approval of
                          at least two-thirds of the outstanding
                          shares of Series B junior participating
                          preferred stock entitled to vote.
</TABLE>

                                       53
<PAGE>   57

<TABLE>
<CAPTION>
                                      THERMO ELECTRON                                THERMEDICS
                          ---------------------------------------      ---------------------------------------

<S>                       <C>                                          <C>
Bylaws                    The board of directors may amend and         The board of directors may amend and
                          repeal bylaws. The holders of a              repeal bylaws, except for amendments
                          majority of the votes represented by         relating to meetings of stockholders,
                          the shares of capital stock issued and       the removal of directors, the
                          outstanding and entitled to vote,            requirements for amendments to bylaws
                          voting together as a single class, may       and other matters reserved to the
                          also amend or repeal any bylaw or may        stockholders by the Massachusetts
                          adopt a new bylaw, except that the           Business Corporation Law or Thermedics'
                          affirmative vote of the holders of at        charter. The holders of a majority of
                          least two-thirds of the votes                the shares of capital stock issued and
                          represented by the shares of our             outstanding and entitled to vote,
                          capital stock issued and outstanding         voting together as a single class, may
                          and entitled to vote is required to          also amend or repeal any bylaw or may
                          amend or repeal, or adopt new bylaws         adopt a new bylaw.
                          inconsistent with, those which relate
                          to directors or amending the bylaws.

INSPECTION RIGHTS         Delaware law entitles any stockholder        Under Massachusetts law, a
                          of record of a corporation, in person        corporation's stockholders are entitled
                          or by agent, upon written demand under       to inspect and copy its charter,
                          oath stating the inspection's purpose,       bylaws, records of stockholders
                          to inspect during usual business hours,      meetings, and stock and transfer
                          for any proper purpose, the                  records. These documents must be kept
                          corporation's stock ledger, a list of        either at the corporation's principal
                          its stockholders and its other books         office, the transfer agent's office or
                          and records, and to make copies or           at the office of the corporation's
                          extracts therefrom. A proper purpose         clerk or resident agent. If access to
                          means a purpose reasonably related to        these documents is refused, the
                          the person's interest as a stockholder.      corporation will be liable to the
                                                                       requesting stockholder for any actual
                                                                       damages which result from the refusal.
                                                                       However, the corporation is not
                                                                       obligated to produce the documents if
                                                                       the inspection is being sought to
                                                                       secure a list of stockholders or other
                                                                       information to be sold or used for a
                                                                       purpose unrelated to the requesting
                                                                       person's interest as a stockholder.

CAPITALIZATION

Authorized Common Stock   350 million shares.                          100 million shares.
</TABLE>

                                       54
<PAGE>   58

<TABLE>
<CAPTION>
                                      THERMO ELECTRON                                THERMEDICS
                          ---------------------------------------      ---------------------------------------

<S>                       <C>                                          <C>
Authorized Preferred      50,000 shares of preferred stock;            None.
Stock                     40,000 shares of the preferred stock
                          designated as Series B junior
                          participating preferred stock, used in
                          the stockholder rights plan described
                          below. The board of directors may fix
                          the rights and preferences of any class
                          or series of the remaining 10,000
                          shares of preferred stock. The rights
                          of the holders of our common stock will
                          be subject to, and may be adversely
                          affected by, the rights of holders of
                          any preferred stock that may be issued
                          in the future.

RIGHTS PLAN               We have a rights agreement dated as of       None.
                          January 19, 1996, which is described
                          below. The rights agreement is
                          triggered by, among other things, the
                          acquisition by a third party of 15% or
                          more of our total outstanding common
                          stock without the approval of our board
                          of directors. The board of directors
                          may redeem rights at any time until ten
                          days after a triggering acquisition.
</TABLE>

                                       55
<PAGE>   59

<TABLE>
<CAPTION>
                                      THERMO ELECTRON                                THERMEDICS
                          ---------------------------------------      ---------------------------------------

<S>                       <C>                                          <C>
EXCULPATION AND           Our certificate of incorporation             Thermedics' bylaws provide
INDEMNIFICATION OF        provides indemnification to persons          indemnification to persons that are or
DIRECTORS, OFFICERS AND   that are or were directors or officers       were directors, officers, employees or
EMPLOYEES                 of ours, or are or were serving at our       agents of Thermedics, or are or were
                          request as directors or officers of          serving at the request of Thermedics as
                          another corporation, partnership, joint      directors, officers, employees or
                          venture, trust or other enterprise, to       agents of another corporation,
                          the fullest extent permitted by              partnership, joint venture, business
                          Delaware law.                                trust or other enterprise, to the
                                                                       fullest extent permitted by
                          In the case of any action or suit by us      Massachusetts law.
                          to procure a judgment in our favor, we
                          will indemnify those directors and           In the case of any action or suit by
                          officers only for expenses, including        Thermedics to procure a judgment in its
                          attorneys' fees, relating to any claim,      favor, Thermedics will indemnify those
                          issue or matter as to which the              directors, officers, employees and
                          director or officer has been judged to       agents only for liabilities, expenses,
                          be liable to us, if and only to the          including attorneys' fees, relating to
                          extent that the court determines that,       any claim, issue or matter as to which
                          despite the adjudication of liability        the director or officer has been judged
                          but in view of all of the circumstances      to be liable to Thermedics, if and only
                          of the case, the director or officer is      to the extent that the court determines
                          entitled to indemnity for such expenses      that, despite the adjudication of
                          which the court finds proper.                liability but in view of all of the
                                                                       circumstances of the case, the director
                          Our certificate of incorporation also        or officer is entitled to indemnity for
                          provides that, to the extent permitted       such expenses which the court finds
                          by Delaware law, no director would be        proper.
                          personally liable to Thermo Electron or
                          its stockholders for monetary damages        Thermedics' articles of organization
                          for any breach of fiduciary duty as a        also provide that no director shall be
                          director.                                    personally liable to Thermedics or its
                                                                       stockholders for monetary damages for
                                                                       any breach of fiduciary duty as a
                                                                       director except in the case of:
                                                                       - a breach of a director's duty of
                                                                         loyalty;
                                                                       - acts or omissions not in good faith
                                                                         or which involve intentional
                                                                         misconduct or a knowing violation of
                                                                         law;
                                                                       - unauthorized distributions or loans
                                                                         of corporate assets under
                                                                         Massachusetts law; or
                                                                       - any transaction in which the director
                                                                         derived an improper personal benefit.
</TABLE>

                                       56
<PAGE>   60

<TABLE>
<CAPTION>
                                      THERMO ELECTRON                                THERMEDICS
                          ---------------------------------------      ---------------------------------------

<S>                       <C>                                          <C>
DISSENTER'S RIGHTS        Under Delaware law, dissenting               Under Massachusetts law, dissenting
                          stockholders who follow prescribed           stockholders who follow prescribed
                          statutory procedures would be entitled       statutory procedures would be entitled
                          to have us pay them the fair value of        to have Thermedics pay them the fair
                          their shares of our capital stock in         value of their shares of Thermedics
                          connection with a merger or                  capital stock when the stockholders
                          consolidation, except where:                 approve:
                          - we would be the surviving corporation
                            and no vote of our stockholders is         - the sale, lease or exchange of all or
                            required to approve the merger; or           substantially all of Thermedics'
                          - the consideration that our                   property or assets;
                            stockholders would receive in the          - an amendment to Thermedics' articles
                            merger or consolidation consists             of organization which adversely
                            solely of:                                   affects the rights of the dissenting
                          -- shares of stock of the surviving            stockholders; or
                             corporation;                              - a merger or consolidation with
                          -- shares of stock of another                   another corporation unless
                             corporation which are listed on a            Thermedics is the surviving
                             national securities exchange or              corporation and a vote of the
                             designated as a national market              stockholders of Thermedics was not
                             system security on an interdealer            required to approve such merger or
                             quotation system by the National             consolidation.
                             Association of Security Dealers,
                             Inc. or are held of record by more
                             than 2,000 stockholders;
                          -- cash in lieu of fractional shares;
                             or
                          -- any combination of the foregoing.
</TABLE>

                                       57
<PAGE>   61

<TABLE>
<CAPTION>
                                      THERMO ELECTRON                                THERMEDICS
                          ---------------------------------------      ---------------------------------------

<S>                       <C>                                          <C>
INTERESTED DIRECTOR       Delaware law provides that no                Thermedics' bylaws provide that, absent
TRANSACTIONS              transaction between a corporation and a      fraud, no contract or other transaction
                          director or officer or any entity in         between Thermedics and any other person
                          which any of them have an interest is        or entity will be affected or
                          void or voidable solely for this reason      invalidated, and no director or officer
                          or solely because the director or            shall be liable to Thermedics or its
                          officer is present at or participates        creditors or stockholders, due to the
                          in the meeting of the board or               fact that a director or officer of
                          committee which authorized the contract      Thermedics is directly or indirectly
                          or transaction. A transaction is also        pecuniarily or otherwise interested in
                          not void or voidable solely because a        or connected to, or is a party to, the
                          director's votes are counted for such        contract or transaction, as long as the
                          purpose if:                                  director's or officer's interest in or
                                                                       connection to the transaction or
                          - after full disclosure the transaction      contract is disclosed to or known by
                            is approved by the disinterested           the Thermedics board at the time it
                            directors or by the stockholders; or       approves the transaction or contract.
                          - the transaction is fair to the             Any such transaction or contract must
                            corporation at the time it is              be:
                            approved.                                  - approved by a majority of directors
                                                                         of Thermedics who are not interested
                                                                         in or connected to the contract or
                                                                         transaction; or
                                                                       - approved or ratified by a majority of
                                                                         the shares of Thermedics capital
                                                                         stock entitled to vote on such matter
                                                                         at a meeting of stockholders.
</TABLE>

THERMO ELECTRON STOCKHOLDER RIGHTS PLAN

     Under Delaware law, every corporation may create and issue rights entitling
the holders of the rights to purchase from the corporation shares of its capital
stock of any class or classes, subject to any provisions of its certificate of
incorporation. The price and terms of the shares must be stated in the company's
certificate of incorporation or in a resolution adopted by the board of
directors for the creation or issuance of such rights.

     We entered into a rights agreement dated as of January 19, 1996 with
BankBoston, N.A. as rights agent. On January 19, 1996, our board declared a
dividend distribution of one right for each outstanding share of our common
stock to our stockholders. Each right entitles the registered holder to purchase
from us a unit consisting of one ten-thousandth of a share of Series B junior
participating preferred stock at a purchase price of $250 in cash per unit,
subject to adjustment.

     The following description is a summary of all the material terms of our
stockholder rights plan. It does not restate these terms in their entirety. We
urge you to read our stockholder rights plan because it, and not this
description, defines the terms and provisions of our plan. We have filed a copy
of the rights agreement that established our rights plan as an exhibit to our
Registration Statement on Form 8-A, which we filed with the SEC on January 26,
1996 and which we incorporate by reference into the registration statement which
includes this prospectus. You may obtain a copy of the rights agreement at no
charge by writing to us at the address listed below under the caption "Where You
Can Find More Information."

                                       58
<PAGE>   62

     Distribution of rights.  Initially, the rights are attached to our
outstanding common stock certificates and we are not distributing separate
rights certificates. Rights will be attached to the shares of our common stock
that we issue in the exchange offer and in the merger. The rights will separate
from our common stock, and a distribution date for purposes of the rights plan
will occur, upon the earlier of the following events:

     - 10 days after a public announcement that a person or group of affiliated
       or associated persons has acquired, or obtained the right to acquire,
       beneficial ownership of 15% or more of the outstanding shares of our
       common stock; and

     - 10 business days following the start of a tender offer or exchange offer
       that would result in a person or group beneficially owning 15% or more of
       the outstanding shares of our common stock.

Until the distribution date:

     - the rights are evidenced by our common stock certificates and will be
       transferred only with our common stock certificates;

     - new common stock certificates of ours will incorporate the rights
       agreement by reference; and

     - the surrender for transfer of any certificates of our common stock will
       also transfer the rights associated with our common stock represented by
       the certificate.

     The rights are not exercisable until the distribution date and will expire
at the close of business on January 29, 2006, unless we redeem or exchange them
earlier as described below.

     Flip in event.  If a person becomes the beneficial owner of 15% or more of
the shares of our common stock, each holder of a right will then have the right
to receive, upon exercise, a number of shares of our common stock, or, in some
circumstances, cash, property or other securities of ours, which equals the
exercise price of the right divided by one-half of the current market price of
our common stock on the date the acquisition occurs. However, following the
acquisition:

     - rights are not exercisable until the rights are no longer redeemable by
       us as set forth below; and

     - all rights that are, or were, under circumstances specified in the rights
       agreement, beneficially owned by any acquiring person will be null and
       void.

The event set forth in this paragraph is referred to as a "section 11(a)(ii)
event." A section 11(a)(ii) event does not occur in the case of an offer for all
of our outstanding shares of common stock that our board of directors determines
is fair to our stockholders and in their best interests.

     For example, at an exercise price of $250 per right, each right not owned
by an acquiring person, or by some related parties, following a section
11(a)(ii) event would entitle the holder to purchase for $250 the number of
shares of our common stock, or other consideration, as noted above, as equals
$250 divided by one-half of the current market price of our common stock.
Assuming that our common stock had a per share value of $50 at that time, the
holder of each valid right would be entitled to purchase ten shares of our
common stock for $250.

     Flip over event.  If at any time after a person has become the beneficial
owner of 15% or more of the shares of our common stock:

     - we are acquired in a merger or other business combination transaction in
       which we are not the surviving corporation, or our common stock is
       changed or exchanged, or

     - 50% or more of our assets or earning power is sold or transferred,

each holder of a right, except rights which previously have been voided as set
forth above, shall then have the right to receive, upon exercise, that number of
shares of common stock of the acquiring company which equals the exercise price
of the right divided by one-half of the current market price of that company's
common stock at the date of the occurrence of the event. This exercise right
does not arise if

                                       59
<PAGE>   63

the merger or other transaction follows an offer for all of our outstanding
shares of common stock that our board of directors determines is fair to our
stockholders and in their best interests.

     For example, at an exercise price of $250 per right, each right following
an event described in the preceding paragraph would entitle the holder to
purchase for $250 the number of shares of common stock of the acquiring company
as equals $250 divided by one-half of the current market price of that company's
common stock. Assuming that the common stock had a per share value of $100 at
that time, the holder of each valid right would be entitled to purchase five
shares of common stock of the acquiring company for $250.

     Exchange of rights.  At any time after a section 11(a)(ii) event, our board
of directors may exchange the rights, other than rights owned by the acquiring
person that have become void, in whole or in part, at an exchange ratio of one
share of our common stock, or one ten-thousandth of a share of preferred stock,
or of a share of a class or series of our preferred stock having equivalent
rights, preferences and privileges, per right.

     Series B junior participating preferred stock.  Preferred stock purchasable
upon exercise of the rights will not be redeemable. Each share of preferred
stock will be entitled to a minimum preferential quarterly dividend payment of
$100 per share and will be entitled to an aggregate dividend of 10,000 times the
dividend declared per share of our common stock. In the event of liquidation,
the holders of the preferred stock will be entitled to a minimum preferential
liquidating payment of $100 per share and will be entitled to an aggregate
payment of 10,000 times the payment made per share of our common stock. Each
share of preferred stock will have 10,000 votes, voting together with our common
stock. Finally, in the event of any merger, consolidation or other transaction
in which our common stock is changed or exchanged, each share of preferred stock
will be entitled to receive 10,000 times the amount received per share of our
common stock.

     These rights are protected by customary antidilution provisions and, in
light of our stock dividend in 1996, currently provide for the following:

     - an aggregate dividend per share of preferred stock of 15,000 times the
       dividend declared per share of our common stock;

     - an aggregate payment per share of preferred stock, in the event of
       liquidation, of 15,000 times the payment made per share of our common
       stock; and

     - 15,000 votes per share of preferred stock, voting together with our
       common stock.

     Because of the nature of the preferred stock's dividend, liquidation and
voting rights, the value of one ten-thousandth of a share of preferred stock
purchasable upon exercise of each right should approximate the value of one
share of our common stock.

     Redemption of rights.  At any time until ten days following the date a
person becomes the beneficial owner of 15% or more of the shares of our common
stock, we may redeem the rights in whole, but not in part, at a price of $.01
per right, payable in cash or stock. Immediately upon an action of our board of
directors ordering redemption of the rights, the rights will terminate and the
only right of the holders of rights will be to receive the $.01 redemption
price.

     Status of rights holder and tax effects.  Until a right is exercised, the
holder of the right, as such, will have no rights as a stockholder of ours,
including the right to vote or to receive dividends. Stockholders may, depending
upon the circumstances, recognize taxable income in the event that the rights
become exercisable for our common stock, or other consideration, or for common
stock of the acquiring company as described above.

     Effects of the rights.  The rights are intended to have anti-takeover
effects. The rights will cause substantial dilution to a person or group that
attempts to acquire us without conditioning the offer on a substantial number of
rights being acquired. The rights, however, should not affect any prospective
offeror willing to make an offer at a fair price and otherwise in the best
interests of us and our stockholders, as

                                       60
<PAGE>   64

determined by a majority of our board of directors. The rights should not
interfere with any merger or other business combination approved by our board of
directors because the board of directors may, at its option, at any time prior
to the close of business on the earlier of:

     - the tenth day following the date a person becomes the beneficial owner of
       15% or more of the shares of our common stock; or

     - January 29, 2006,

and in other specified circumstances, redeem all of the then outstanding rights
at the redemption price.

STATE ANTI-TAKEOVER STATUTES

     We are subject to Section 203 of the Delaware General Corporation Law
which, under some circumstances, may make it more difficult for a person who
would be an "interested stockholder," as defined in Section 203, in us to effect
various business combinations with us for a three-year period after becoming an
interested stockholder. Under Delaware law, a corporation's certificate of
incorporation or bylaws may exclude a corporation from the restrictions imposed
by Section 203. Our certificate of incorporation and bylaws do not exclude us
from the restrictions imposed by Section 203.

     Chapters 110C, 110D and 110F of the General Laws of the Commonwealth of
Massachusetts prohibit, restrict or impose procedural and disclosure
requirements with respect to the acquisition of more than 5% of the outstanding
shares of a Massachusetts corporation, such as Thermedics, and with respect to
take-over bids and business combinations involving a Massachusetts corporation.
Thermedics, through a provision in its bylaws, has elected to "opt out" of the
prohibitions and restrictions of Chapter 110D.

                       TRANSACTIONS WITH RELATED PARTIES

PRIOR CONTACTS

     Except as set forth in, or incorporated by reference in, this prospectus,
since January 1, 1998, there have been no contacts, negotiations or transactions
between us, on the one hand, and Thermedics or any of its officers, directors or
affiliates, on the other hand, concerning a merger, consolidation or
acquisition, a tender offer or other acquisition of securities, an election of
directors or a sale or other transfer of a material amount of assets.

PRIOR BUSINESS RELATIONSHIPS

     Except as set forth in, or incorporated by reference in, this prospectus,
we have not, since January 1, 1998, had any business relationships or
transactions with Thermedics or any of its executive officers, directors or
affiliates that would require disclosure in this prospectus under the SEC's
rules.

     On February 5, 1998, the Thermedics board of directors voted to issue
4,880,533 shares of common stock to us in exchange for 100% of the stock of our
subsidiary TMO TCA Holdings, Inc., which beneficially owns 3,355,705 shares of
Thermo Cardiosystems' common stock. We acquired these shares of Thermo
Cardiosystems common stock as consideration for the acquisition by Thermo
Cardiosystems of International Technidyne Corporation from us in May 1997. The
value of these Thermo Cardiosystems shares was $75,000,000 at the time Thermo
Cardiosystems acquired International Technidyne. Thermo Cardiosystems' issuance
of the 3,355,705 shares of its common stock was subject to its stockholders
approving the listing of the shares for trading on the American Stock Exchange.
Its stockholders approved the listing at a special meeting on April 13, 1998.
Thermedics' issuance of the 4,880,533 shares of its common stock to us was
subject to its stockholders approving the listing of the shares for trading on
the American Stock Exchange. Its stockholders approved the listing at a special
meeting on March 31, 1999. The fair market values of the 4,880,553 shares of
Thermedics' common stock and of the 3,355,705 shares of Thermo Cardiosystems'
common stock as of February 5, 1998 were each $75,587,000.

                                       61
<PAGE>   65

     In June 1998, we loaned Thermo Sentron, a subsidiary of Thermedics,
$21,000,000 pursuant to a promissory note due December 1998. That promissory
note bore interest at the 90-day Commercial Paper Composite Rate plus 25 basis
points, set at the beginning of each quarter. Thermo Sentron borrowed this money
to partially finance its acquisition of the three businesses that constituted
the product-monitoring group of Graseby Limited, a subsidiary of Smiths
Industries plc, for $44,000,000 in cash, net of cash acquired, and the
assumption of some of Graseby's liabilities. Thermo Sentron repaid the principal
amount of the loan as follows:

<TABLE>
<S>                            <C>
- - Fourth quarter 1998          $2,000,000;
- - Second quarter 1999          $6,000,000;
- - Third quarter 1999           $1,000,000; and
- - Fourth quarter 1999          $1,000,000.
</TABLE>

As each payment was made, we canceled the existing promissory note and Thermo
Sentron issued us a new promissory note for the balance. In March 2000, we
refinanced Thermo Sentron's remaining balance under our cash management
arrangement. The outstanding amount under this cash management arrangement bears
interest at a rate equal to the 30-day Dealers Commercial Paper Rate plus 150
basis points. We reset this rate at the beginning of each month. The rate was
7.99% as of April 1, 2000.

     We have entered into a fifteen-year lease arrangement with Thermo Sentron,
effective as of January 1, 2000, with respect to Thermo Sentron's principal
executive offices in Minneapolis, Minnesota. We purchased the building in
December 1999 from Baker Hughes Corporation for $5.5 million. Thermo Sentron
pays us rent under this lease as follows:

     - $50,000 per month for the first five years of the lease term;

     - $55,000 per month for the second five years of the lease term; and

     - $60,000 per month for the third five years of the lease term.

     Our Tecoment division provides metal fabrication services to Thermo
Cardiosystems in connection with its manufacture of heart assist devices. Thermo
Cardiosystems paid Tecoment $3,651,000 in 1999 and $1,717,000 in 1998 for these
services.

                                 LEGAL MATTERS

     Seth H. Hoogasian, Esq., our General Counsel, will pass on the validity of
the shares of our common stock offered by this prospectus. Mr. Hoogasian is a
full-time employee and officer of Thermo Electron, is an officer of Thermedics
and, as of April 27, 2000, owned or had the right to acquire 386,647 shares of
our common stock and 132,700 shares of the common stock of our subsidiaries.

                                    EXPERTS

     Our financial statements and those of Thermedics that we incorporate by
reference in this prospectus and the financial statement schedules that we
incorporated by reference in the registration statement of which this prospectus
is a part have been audited by Arthur Andersen LLP, independent public
accountants, to the extent and for the periods as indicated in their reports
with respect thereto, and are incorporated by reference in reliance upon the
authority of said firm as experts in giving said reports.

                                       62
<PAGE>   66

                      WHERE YOU CAN FIND MORE INFORMATION

     THIS PROSPECTUS INCORPORATES DOCUMENTS BY REFERENCE, INCLUDING IMPORTANT
BUSINESS AND FINANCIAL INFORMATION, WHICH ARE NOT PRESENTED IN OR DELIVERED WITH
THIS PROSPECTUS.

     YOU SHOULD RELY ONLY ON THE INFORMATION CONTAINED IN THIS DOCUMENT OR IN
DOCUMENTS TO WHICH WE HAVE REFERRED YOU. WE HAVE NOT AUTHORIZED ANYONE TO
PROVIDE YOU WITH ANY INFORMATION THAT IS DIFFERENT.

THERMEDICS

     We incorporate by reference into this prospectus the following documents,
filed by Thermedics (File No. 1-9567) with the SEC:

     - Thermedics' Annual Report on Form 10-K for the fiscal year ended January
       1, 2000; and

     - Thermedics' Current Reports on Forms 8-K dated February 1, 2000, March
       31, 2000 and April 7, 2000.

THERMO ELECTRON

     We incorporate by reference into this prospectus the following documents,
which we have filed (File No. 1-8002) with the SEC:

     - Our Annual Report on Form 10-K for the fiscal year ended January 1, 2000;

     - Our Current Report on Form 8-K dated February 1, 2000;

     - Our Proxy Statement dated April 19, 2000;

     - The description of our common stock which is contained in our
       registration statement on Form 8-A and the amendment to that registration
       statement, filed under the Exchange Act; and

     - The description of our preferred stock purchase rights which is contained
       in our registration statement on Form 8-A and the amendments to that
       registration statement, filed under the Exchange Act.

     All documents that we file or that Thermedics files pursuant to Sections
13(a), 13(c), 14 or 15(d) of the Exchange Act from the date of this prospectus
to the date that shares are accepted for exchange pursuant to our offer, the
date that our offer is terminated or the date that the merger is closed will
also be deemed to be incorporated in this prospectus by reference.

     The information incorporated by reference in this prospectus is deemed to
be a part of this prospectus, except for any information superseded by
information in this prospectus or in any subsequently filed document that we
incorporate by reference in this prospectus.

     We will provide a copy of any and all of the information that we
incorporate by reference in this prospectus to any person, without charge, upon
written or oral request. If we do not specifically incorporate by reference
exhibits to the documents that we incorporate by reference in this prospectus,
then we will not provide copies of those exhibits. TO OBTAIN TIMELY DELIVERY,
YOU MUST REQUEST THE INFORMATION NO LATER THAN MAY 19, 2000.

     You should direct requests for documents relating to Thermedics or to us
to: Sandra L. Lambert, Corporate Secretary, Thermo Electron Corporation, 81
Wyman Street, Waltham, Massachusetts 02454 (telephone: 781-622-1000; facsimile:
781-768-6620).

                                       63
<PAGE>   67

     We file reports, proxy statements and other information with the SEC. You
may inspect and copy our reports, proxy statements and other information at the
public reference facilities maintained by the SEC at:

<TABLE>
<S>                     <C>                      <C>
Judiciary Plaza         Citicorp Center          Seven World Trade Center
Room 1024               500 West Madison Street  13th Floor
450 Fifth Street, N.W.  Suite 1400               New York, New York 10048
Washington, D.C. 20549  Chicago, Illinois 60661
</TABLE>

     You can also inspect reports, proxy statements and other information
concerning Thermedics at:

     The American Stock Exchange
     86 Trinity Place
     New York, New York 10006-1881

     You can also inspect reports, proxy statements and other information
concerning us at:

     The New York Stock Exchange
     20 Broad Street
     New York, New York 10005

     You can also obtain copies of these materials by mail at prescribed rates
from the Public Reference Room at the SEC, 450 Fifth Street, N.W., Washington,
D.C. 20549. You may obtain information on the operation of the Public Reference
Room by calling the SEC toll-free at l-800-SEC-0330. The SEC maintains an
Internet site that contains reports, proxy statements and other information
regarding Thermo Electron and Thermedics. The address of the SEC website is
http://www.sec.gov.

     We have filed a registration statement on Form S-4 under the Securities Act
with the SEC with respect to our common stock we would issue to Thermedics
stockholders in the exchange offer and the merger. This prospectus constitutes
our prospectus filed as part of the registration statement. This prospectus does
not contain all of the information set forth in the registration statement
because we have omitted some parts of the registration statement in accordance
with the SEC's rules. The registration statement and its exhibits are available
for inspection and copying as set forth above.

     We have also filed with the SEC a statement on Schedule TO pursuant to Rule
14d-3 under the Exchange Act furnishing certain information about the exchange
offer. You may read and copy the Schedule TO and any amendments thereto at the
SEC's public reference room in Washington, D.C. referred to above.

     If you have any questions about the exchange offer, you should call the
information agent, D.F. King & Co., Inc. If you are a banker or broker, call
collect at (212) 269-5550. All others should call toll-free at (800) 290-6433.

     THIS PROSPECTUS DOES NOT CONSTITUTE AN OFFER TO SELL, OR A SOLICITATION OF
AN OFFER TO PURCHASE, THE SECURITIES OFFERED BY THIS PROSPECTUS, IN ANY
JURISDICTION OR FROM ANY PERSON TO WHOM OR FROM WHOM IT IS UNLAWFUL TO MAKE SUCH
OFFER OR SOLICITATION OF AN OFFER IN SUCH JURISDICTION. NEITHER THE DELIVERY OF
THIS PROSPECTUS NOR ANY DISTRIBUTION OF SECURITIES PURSUANT TO THIS PROSPECTUS
SHALL, UNDER ANY CIRCUMSTANCES, CREATE ANY IMPLICATION THAT THERE HAS BEEN NO
CHANGE IN THE INFORMATION SET FORTH OR INCORPORATED INTO THIS PROSPECTUS BY
REFERENCE OR IN OUR AFFAIRS SINCE THE DATE OF THIS PROSPECTUS.

                                       64
<PAGE>   68

                          THERMO ELECTRON CORPORATION

         INDEX TO PRO FORMA CONSOLIDATED CONDENSED FINANCIAL STATEMENTS
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                              PAGE
<S>                                                           <C>
Pro Forma Consolidated Condensed Financial Information of
  Thermo Electron Corporation (Unaudited)...................  F-2
Pro Forma Consolidated Condensed Statement of Continuing
  Operations for the fiscal year ended January 1, 2000......  F-3
Pro Forma Consolidated Condensed Balance Sheet as of January
  1, 2000...................................................  F-4
Notes to Pro Forma Consolidated Condensed Financial
  Statements................................................  F-5
</TABLE>

                                       F-1
<PAGE>   69

                          THERMO ELECTRON CORPORATION

             PRO FORMA CONSOLIDATED CONDENSED FINANCIAL STATEMENTS
                                  (UNAUDITED)

     The following unaudited pro forma consolidated condensed statement of
operations sets forth our results of continuing operations for the fiscal year
ended January 1, 2000, as if we had completed the exchange offer and the merger
at the beginning of fiscal 1999. The following unaudited pro forma consolidated
condensed balance sheet sets forth our financial position as of January 1, 2000,
as if we had completed the exchange offer and the merger on January 1, 2000. For
purposes of determining the number of shares of our common stock that we will
issue in the exchange offer and the merger, we have used the exchange ratio of
0.45 shares of our common stock for each share of Thermedics common stock not
already owned by us. The pro forma results of operations are not necessarily
indicative of future operations or the actual results that would have occurred
if we had completed the exchange offer and the merger at the beginning of fiscal
1999.

                                       F-2
<PAGE>   70

                          THERMO ELECTRON CORPORATION

      PRO FORMA CONSOLIDATED CONDENSED STATEMENT OF CONTINUING OPERATIONS
                       FISCAL YEAR ENDED JANUARY 1, 2000
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                                        PRO FORMA
                                                         HISTORICAL    ADJUSTMENTS    PRO FORMA
                                                         ----------    -----------    ----------
                                                         (IN THOUSANDS EXCEPT PER SHARE AMOUNTS)
<S>                                                      <C>           <C>            <C>
Revenues                                                 $2,471,193      $    --      $2,471,193
                                                         ----------      -------      ----------
Costs and Operating Expenses:
  Cost of revenues.....................................   1,378,494           --       1,378,494
  Selling, general and administrative expenses.........     673,004        1,290         674,294
  Research and development expenses....................     171,100           --         171,100
  Restructuring and other unusual costs, net...........     149,589           --         149,589
                                                         ----------      -------      ----------
                                                          2,372,187        1,290       2,373,477
                                                         ----------      -------      ----------
Operating Income.......................................      99,006       (1,290)         97,716
Other Expense, Net.....................................     (61,520)          --         (61,520)
                                                         ----------      -------      ----------
Income from Continuing Operations Before Income Taxes,
  Minority Interest and Extraordinary Items............      37,486       (1,290)         36,196
Income Tax Provision...................................      33,073           --          33,073
Minority Interest Expense..............................      18,993           --          18,993
                                                         ----------      -------      ----------
Loss from Continuing Operations Before Extraordinary
  Items................................................  $  (14,580)     $(1,290)     $  (15,870)
                                                         ==========      =======      ==========
Loss per Share from Continuing Operations Before
  Extraordinary Items:
  Basic................................................  $     (.09)                  $     (.10)
                                                         ==========                   ==========
  Diluted..............................................  $     (.11)                  $     (.12)
                                                         ==========                   ==========
Basic and Diluted Weighted Average Shares..............     157,987        4,631         162,618
                                                         ==========      =======      ==========
</TABLE>

                                       F-3
<PAGE>   71

                          THERMO ELECTRON CORPORATION

                 PRO FORMA CONSOLIDATED CONDENSED BALANCE SHEET
                                JANUARY 1, 2000
                                  (UNAUDITED)

<TABLE>
<CAPTION>
                                                                        PRO FORMA
                                                         HISTORICAL    ADJUSTMENTS    PRO FORMA
                                                         ----------    -----------    ----------
                                                                     (IN THOUSANDS)
<S>                                                      <C>           <C>            <C>
                        ASSETS
Current Assets:
  Cash and cash equivalents............................  $  281,760     $     --      $  281,760
  Short-term available-for-sale investments, at quoted
     market value......................................     555,501           --         555,501
  Accounts receivable, net.............................     574,126           --         574,126
  Other current assets.................................     588,470           --         588,470
  Net assets of discontinued operations................     517,350       11,153         528,503
                                                         ----------     --------      ----------
                                                          2,517,207       11,153       2,528,360
                                                         ----------     --------      ----------
Property, Plant and Equipment, at Cost, Net............     510,647           --         510,647
                                                         ----------     --------      ----------
Other Assets...........................................     247,897           --         247,897
                                                         ----------     --------      ----------
Cost in Excess of Net Assets of Acquired Companies.....   1,227,335       51,587       1,278,922
                                                         ----------     --------      ----------
Long-term Net Assets of Discontinued Operations........     678,756           --         678,756
                                                         ----------     --------      ----------
                                                         $5,181,842     $ 62,740      $5,244,582
                                                         ==========     ========      ==========

       LIABILITIES AND SHAREHOLDERS' INVESTMENT
Current Liabilities....................................  $1,066,349     $     --      $1,066,349
                                                         ----------     --------      ----------
Deferred Income Taxes and Other Deferred Items.........     163,063           --         163,063
                                                         ----------     --------      ----------
Long-term Obligations:
  Subordinated convertible obligations.................   1,209,305           --       1,209,305
  Other................................................     356,669           --         356,669
                                                         ----------     --------      ----------
                                                          1,565,974           --       1,565,974
                                                         ----------     --------      ----------
Minority Interest......................................     364,278      (45,320)        318,958
                                                         ----------     --------      ----------
Common Stock of Subsidiary Subject to Redemption.......       7,692           --           7,692
                                                         ----------     --------      ----------
Shareholders' Investment:
  Common stock.........................................     167,433        4,631         172,064
  Capital in excess of par value.......................   1,052,837      103,429       1,156,266
  Retained earnings....................................   1,041,968           --       1,041,968
  Treasury stock at cost...............................    (189,646)          --        (189,646)
  Deferred compensation................................      (3,190)          --          (3,190)
  Accumulated other comprehensive items................     (54,916)          --         (54,916)
                                                         ----------     --------      ----------
                                                          2,014,486      108,060       2,122,546
                                                         ----------     --------      ----------
                                                         $5,181,842     $ 62,740      $5,244,582
                                                         ==========     ========      ==========
</TABLE>

                                       F-4
<PAGE>   72

                          THERMO ELECTRON CORPORATION

         NOTES TO PRO FORMA CONSOLIDATED CONDENSED FINANCIAL STATEMENTS
                                  (UNAUDITED)

<TABLE>
NOTE 1 -- PRO FORMA ADJUSTMENTS TO PRO FORMA CONSOLIDATED
          CONDENSED STATEMENT OF CONTINUING OPERATIONS (IN
          THOUSANDS EXCEPT IN TEXT)
                                                               YEAR ENDED
                                                              JANUARY 1, 2000
                                                              ---------------
                                                              DEBIT (CREDIT)
<S>                                                           <C>
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES
Amortization of cost in excess of net assets of acquired
  companies created by the acquisition of additional shares
  of Thermedics.............................................     $   1,290
                                                                 ---------
WEIGHTED AVERAGE SHARES
Increase in weighted average shares outstanding due to the
  assumed issuance of 4,630,582 shares of our common stock
  for the acquisition of additional shares of Thermedics as
  of the beginning of 1999..................................         4,631
                                                                 ---------
NOTE 2 -- PRO FORMA ADJUSTMENTS TO PRO FORMA CONSOLIDATED
          CONDENSED BALANCE SHEET (IN THOUSANDS EXCEPT IN
          TEXT)
                                                              JANUARY 1, 2000
                                                              ---------------
                                                              DEBIT (CREDIT)
NET ASSETS OF DISCONTINUED OPERATIONS -- CURRENT
Increase in current net assets of discontinued operations as
  a result of our increased ownership of Thermedics.........     $  11,153
                                                                 ---------
COST IN EXCESS OF NET ASSETS OF ACQUIRED COMPANIES
Increase in cost in excess of net assets of acquired
  companies as a result of our increased ownership of
  Thermedics................................................        51,587
                                                                 ---------
MINORITY INTEREST
Decrease in minority interest as a result of our increased
  ownership of Thermedics...................................        45,320
                                                                 ---------
COMMON STOCK
Increase in common stock due to the assumed issuance of
  4,630,582 shares of our common stock for the acquisition
  of additional shares of Thermedics........................       (4,631)
                                                                 ---------
CAPITAL IN EXCESS OF PAR VALUE
Increase in capital in excess of par value as a result of
  our increased ownership of Thermedics and the conversion
  of outstanding stock options of Thermedics into our stock
  options...................................................     (103,429)
                                                                 ---------
</TABLE>

                                       F-5
<PAGE>   73

                      [THIS PAGE INTENTIONALLY LEFT BLANK]
<PAGE>   74

                                    ANNEX A

              DIRECTORS AND EXECUTIVE OFFICERS OF THERMO ELECTRON
                                 AND THERMEDICS

THERMO ELECTRON

     We have set forth in the following table:

     - the name, business address, position with Thermo Electron, present
       principal occupation or employment and five-year employment history of
       each of our directors and executive officers; and

     - the names, principal businesses and addresses of any corporations or
       other organizations in which those principal occupations are conducted.

     Unless otherwise indicated:

     - each occupation listed in the table refers to Thermo Electron;

     - each individual is a United States citizen; and

     - each individual's business address is 81 Wyman Street, Waltham,
       Massachusetts 02454.

     Unless otherwise indicated, to our knowledge, none of our directors or
executive officers:

     - beneficially owns any shares of our common stock or Thermedics common
       stock or rights to acquire shares of our common stock or Thermedics
       common stock;

     - has been convicted in a criminal proceeding during the last five years,
       excluding traffic violations or similar misdemeanors; or

     - was a party to any judicial or administrative proceeding during the last
       five years that resulted in a judgement, decree or final order enjoining
       the person from future violations of, or prohibiting activities subject
       to, federal or state securities laws, or a finding of any violation of
       federal or state securities laws.

     Mr. John N. Hatsopoulos retired from our board of directors effective
February 21, 2000. Dr. George N. Hatsopoulos retired from our board of directors
effective March 31, 2000.

SAMUEL W. BODMAN...................    Dr. Bodman, 61, has been a director of
                                       Thermo Electron since May 1999. Since
                                       1988, Mr. Bodman has served as the
                                       chairman and chief executive officer of
                                       Cabot Corporation, a manufacturer of
                                       specialty chemicals and materials located
                                       at 75 State Street, Boston, MA 02109. Dr.
                                       Bodman is also a director of Cabot
                                       Corporation, John Hancock Financial
                                       Services, Inc., Security Capital Group
                                       Incorporated and Westvaco Corporation.

PETER O. CRISP.....................    Mr. Crisp, 67, has been a director of
                                       Thermo Electron since 1974. Mr. Crisp was
                                       a general partner of Venrock Associates,
                                       a venture capital investment firm located
                                       at 30 Rockefeller Plaza, New York, NY
                                       10112, for more than five years until his
                                       retirement in September 1997. He has been
                                       the vice chairman of Rockefeller
                                       Financial Services, Inc. since December
                                       1997. Mr. Crisp is also a director of
                                       American Superconductor Corporation,
                                       Evans & Sutherland Computer Corporation,
                                       Thermedics Inc., ThermoTrex Corporation
                                       and United States Trust Corporation.

                                       A-1
<PAGE>   75

ELIAS P. GYFTOPOULOS...............    Dr. Gyftopoulos, 72, has been a director
                                       of Thermo Electron since 1976. Dr.
                                       Gyftopoulos is Professor Emeritus of the
                                       Massachusetts Institute of Technology,
                                       where he was the Ford Professor of
                                       Mechanical Engineering and of Nuclear
                                       Engineering for more than 20 years until
                                       his retirement in 1996. Dr. Gyftopoulos
                                       is also a director of Thermo
                                       Cardiosystems Inc., ThermoLase
                                       Corporation, ThermoRetec Corporation and
                                       Trex Medical Corporation.

FRANK JUNGERS......................    Mr. Jungers, 73, has been a director of
                                       Thermo Electron since 1978. Mr. Jungers
                                       has been a consultant on business and
                                       energy matters since 1977. His business
                                       address is 822 N.W. Murray Boulevard,
                                       Suite 242, Portland, OR 97229. Mr.
                                       Jungers is also a director of The AES
                                       Corporation, Donaldson, Lufkin &
                                       Jenrette, Inc., Statia Terminals Group
                                       N.V., Thermo Ecotek Corporation and
                                       ThermoQuest Corporation.

ROBERT A. MCCABE...................    Mr. McCabe, 65, has been a director of
                                       Thermo Electron since 1962. He has been
                                       the chairman of Pilot Capital Corporation
                                       located at 444 Madison Avenue, Suite
                                       2103, New York, NY 10022, which is
                                       engaged in private investments, since
                                       1998. Mr. McCabe was the president of
                                       Pilot Capital Corporation from 1987 to
                                       1998. Mr. McCabe is also a director of
                                       Atlantic Bank & Trust Company, Burns
                                       International Services Corporation,
                                       Church & Dwight Company and Thermo Optek
                                       Corporation.

HUTHAM S. OLAYAN...................    Ms. Olayan, 46, has been a director of
                                       Thermo Electron since 1987. She has
                                       served since 1995 as president and a
                                       director of Olayan America Corporation, a
                                       member of the Olayan Group, and as
                                       president and a director of Competrol
                                       Real Estate Limited, another member of
                                       the Olayan Group, from 1986 until its
                                       merger into Olayan America Corporation in
                                       1997. The surviving company which is
                                       located at 505 Park Avenue, Suite 1100,
                                       New York, NY 10022, is engaged in private
                                       investments, including real estate, and
                                       advisory services. Ms. Olayan is also a
                                       director of Trex Medical Corporation. Ms.
                                       Olayan is a citizen of Saudi Arabia.

ROBERT W. O'LEARY..................    Mr. O'Leary, 56, has been a director of
                                       Thermo Electron since June 1998. He has
                                       been the chairman of Premier, Inc., a
                                       strategic alliance of not-for-profit
                                       health care and hospital systems located
                                       at 12225 El Camino Real, San Diego, CA
                                       92130, since 1995, and he was the chief
                                       executive officer from 1995 to 1999.

RICHARD F. SYRON...................    Dr. Syron, 56, has been a director of
                                       Thermo Electron since September 1997, its
                                       president and chief executive officer
                                       since June 1999 and chairman of the board
                                       since January 2000. From April 1994 until
                                       May 1999, Dr. Syron was the chairman and
                                       chief executive officer

                                       A-2
<PAGE>   76

                                       of the American Stock Exchange Inc.
                                       located at 86 Trinity Place, New York, NY
                                       10006-1881. Dr. Syron is also a director
                                       of Dreyfus Corporation, John Hancock
                                       Financial Services, Inc., and Thermo
                                       Fibertek Inc.

ROGER D. WELLINGTON................    Mr. Wellington, 73, has been a director
                                       of Thermo Electron since 1986. Mr.
                                       Wellington serves as the president and
                                       chief executive officer of Wellington
                                       Consultants, Inc. and Wellington
                                       Associates Inc., international business
                                       consulting firms he founded in 1994 and
                                       1989, respectively, each of which is
                                       located at P.O. Box 8186, 5555 Gulf of
                                       Mexico Drive, Unit 302, Longboat Key, FL
                                       34228. Mr. Wellington is also a director
                                       of Photoelectron Corporation and Thermo
                                       Fibergen Inc.

BRIAN D. HOLT......................    Mr. Holt, 51, became the chief operating
                                       officer, energy and environment, of
                                       Thermo Electron in September 1998. Mr.
                                       Holt has been the president and chief
                                       executive officer of Thermo Ecotek
                                       Corporation, a majority-owned subsidiary
                                       of Thermo Electron located at 245 Winter
                                       Street, Waltham, MA 02451, that is
                                       involved in electric power generation
                                       since February 1994. From March 1996 to
                                       September 1998, he was a vice president
                                       of Thermo Electron. Mr. Holt is also a
                                       director of The Randers Killam Group
                                       Inc., Thermo Ecotek Corporation,
                                       ThermoRetec Corporation and Thermo
                                       TerraTech Inc.

JOHN T. KEISER.....................    Mr. Keiser, 64, became chief operating
                                       officer, biomedical, of Thermo Electron
                                       in September 1998 and was a vice
                                       president from April 1997 until his
                                       promotion. Mr. Keiser has been the
                                       president and chief executive officer of
                                       Thermedics Inc., a manufacturer of
                                       biomedical products, product
                                       quality-assurance systems and security
                                       devices, since March 1998 and December
                                       1998, respectively, and served as a
                                       senior vice president of Thermedics Inc.
                                       from 1994 until his promotion to
                                       president. He has also been the president
                                       of Thermo Electron's wholly owned
                                       biomedical group, a manufacturer of
                                       medical equipment and instruments, since
                                       1994. Mr. Keiser is a director of Metrika
                                       Systems Corporation, Thermedics Inc.,
                                       Thermo Cardiosystems Inc., ThermoLase
                                       Corporation, ThermoTrex Corporation and
                                       Trex Medical Corporation.

EARL R. LEWIS......................    Mr. Lewis, 56, became chief operating
                                       officer, measurement and detection, of
                                       Thermo Electron in September 1998, and
                                       served as senior vice president of Thermo
                                       Electron from June 1998 to September 1998
                                       and vice president from September 1996 to
                                       June 1998. Mr. Lewis has been president
                                       and chief executive officer of Thermo
                                       Instrument Systems Inc. since March 1997
                                       and January 1998, respectively, and was
                                       chief operating officer from January 1996
                                       to January 1998. Prior to that time,

                                       A-3
<PAGE>   77

                                       he was executive vice president of Thermo
                                       Instrument Systems Inc. from January 1996
                                       to March 1997 and senior vice president
                                       from January 1994 to January 1996. Mr.
                                       Lewis served as chief executive officer
                                       of Thermo Optek Corporation, a
                                       majority-owned subsidiary of Thermedics
                                       and a manufacturer of analytical
                                       instruments that measure energy and light
                                       for purposes of materials analysis,
                                       characterization and preparation, from
                                       its inception in August 1995 to January
                                       1998. Mr. Lewis is a director of FLIR
                                       Systems Inc., Metrika Systems
                                       Corporation, SpectRx Inc.,
                                       Spectra-Physics Lasers, Inc., Thermo
                                       Optek Corporation and ThermoQuest
                                       Corporation.

THEO MELAS-KYRIAZI.................    Mr. Melas-Kyriazi, 40, has been a vice
                                       president, of Thermo Electron since March
                                       1998 and its chief financial officer
                                       since January 1999. Prior to his
                                       appointment as a vice president of Thermo
                                       Electron, Mr. Melas-Kyriazi served as
                                       president and chief executive officer of
                                       ThermoSpectra Corporation, which
                                       develops, manufactures, and markets
                                       precision imaging, inspection,
                                       measurement, and temperature-control
                                       instrumentation, from its inception in
                                       August 1994 until March 1998. Mr. Melas-
                                       Kyriazi is a director of ThermoRetec
                                       Corporation. Mr. Melas-Kyriazi is a
                                       citizen of Greece.

WILLIAM A. RAINVILLE...............    Mr. Rainville, 58, became chief operating
                                       officer, recycling and resource recovery,
                                       of Thermo Electron in September 1998. Mr.
                                       Rainville was a senior vice president of
                                       Thermo Electron from March 1993 to
                                       September 1998, and a vice president of
                                       Thermo Electron from 1986 to 1993. He has
                                       been president and chief executive
                                       officer of Thermo Fibertek Inc., a
                                       majority-owned subsidiary of Thermo
                                       Electron located at 245 Winter Street,
                                       Waltham, MA 02451 that develops and
                                       manufactures equipment and products for
                                       the papermaking and paper-recycling
                                       industries, since its inception in 1991.
                                       Mr. Rainville is also a director of
                                       Thermo Ecotek Corporation, Thermo
                                       Fibergen Inc., Thermo Fibertek Inc.,
                                       ThermoRetec Corporation and Thermo
                                       TerraTech Inc.

     Stock Ownership.  The following table sets forth the beneficial ownership
of common stock of Thermedics and Thermo Electron, as of January 31, 2000, with
respect to each of our directors and executive officers. Our directors and
executive officers disclaim beneficial ownership of the shares of Thermedics
common stock beneficially owned by us.

<TABLE>
<CAPTION>
                                                                 THERMO
                                                                ELECTRON
NAME(1)                                                       CORPORATION(2)   THERMEDICS INC.(3)
- -------                                                       --------------   ------------------
<S>                                                           <C>              <C>
Samuel W. Bodman............................................       27,599                  0
Peter O. Crisp..............................................      121,767             37,076
Elias P. Gyftopoulos........................................       91,399              8,298
Brian D. Holt...............................................      322,941                  0
</TABLE>

                                       A-4
<PAGE>   78

<TABLE>
<CAPTION>
                                                                  THERMO
                                                                 ELECTRON
NAME(1)                                                       CORPORATION(2)   THERMEDICS INC.(3)
- -------                                                       --------------   ------------------
<S>                                                           <C>              <C>
Frank Jungers...............................................      171,021              3,000
John T. Keiser..............................................      331,636            194,693
Earl R. Lewis...............................................      215,477                  3
Robert A. McCabe............................................       66,326              2,498
Theo Melas-Kyriazi..........................................      458,532             11,861
Hutham S. Olayan............................................       49,568                  0
Robert W. O'Leary...........................................       43,830                  0
William A. Rainville........................................      361,499                  0
Richard F. Syron............................................    1,074,006                  0
Roger D. Wellington.........................................       55,795                  0
All directors and current executive officers as a group (14
  persons)..................................................    3,391,396            257,429
</TABLE>

- ---------------
(1) Except as reflected in the footnotes to this table, shares beneficially
    owned consist of shares owned by the indicated person or by that person for
    the benefit of minor children, and all share ownership includes sole voting
    and investment power.

(2) Shares of the Common Stock of Thermo Electron beneficially owned by Dr.
    Bodman, Mr. Crisp, Dr. Gyftopoulos, Mr. Holt, Mr. Jungers, Mr. Keiser, Mr.
    Lewis, Mr. McCabe, Mr. Melas-Kyriazi, Ms. Olayan, Mr. O'Leary, Mr.
    Rainville, Dr. Syron, Mr. Wellington and all directors and current executive
    officers as a group include 26,000, 25,596, 27,442, 284,948, 24,673,
    263,230, 212,278, 27,442, 384,361, 27,442, 27,000, 294,630, 1,011,000,
    24,673 and 2,660,715 shares, respectively, that such person or members of
    the group have the right to acquire within 60 days of January 31, 2000
    through the exercise of stock options. Shares beneficially owned by Mr.
    Melas-Kyriazi and all directors and current executive officers as a group
    include 1,071 shares allocated to Mr. Melas-Kyriazi's account maintained
    pursuant to the Thermo Electron's employee stock ownership plan, or ESOP.
    Shares beneficially owned by Dr. Bodman, Mr. Crisp, Dr. Gyftopoulos, Mr.
    Jungers, Mr. McCabe, Ms. Olayan, Mr. O'Leary, Dr. Syron, Mr. Wellington and
    all directors and current executive officers as a group include 1,599,
    49,277, 1,378, 80,427, 34,725, 19,876, 3,830, 2,506, 26,342 and 219,960
    shares, respectively, allocated to accounts maintained pursuant to Thermo
    Electron's deferred compensation plan for directors. Shares beneficially
    owned by Ms. Olayan do not include 6,150,000 shares owned by Crescent
    Holding GmbH, a member of the Olayan Group. Crescent Holding GmbH is
    indirectly controlled by Suliman S. Olayan, Ms. Olayan's father. Ms. Olayan
    disclaims beneficial ownership of the shares owned by Crescent Holding GmbH.
    No director or current executive officer beneficially owned more than 1% of
    the Thermo Electron common stock outstanding as of such date; all directors
    and current executive officers as a group beneficially owned 2.13% of the
    Thermo Electron common stock outstanding as of January 31, 2000.

(3) Shares of the common stock of Thermedics beneficially owned by Mr. Crisp,
    Dr. Gyftopoulos, Mr. Keiser and all directors and current executive officers
    as a group include 9,000, 2,750, 187,900, and 199,650 shares, respectively,
    that such person or members of the group have the right to acquire within 60
    days of January 31, 2000 through the exercise of stock options. Shares
    beneficially owned by Mr. Melas-Kyriazi and all directors and current
    executive officers as a group include 1,119 shares allocated to Mr.
    Melas-Kyriazi's account maintained pursuant to Thermo Electron's ESOP.
    Shares beneficially owned by Mr. Crisp and all directors and current
    executive officers as a group include 9,971 shares allocated to Mr. Crisp's
    account maintained pursuant to Thermedics' deferred compensation plan for
    directors. No director or current executive officer beneficially owned more
    than 1% of the Thermedics common stock outstanding as of January 31, 2000;
    all directors and current executive officers as a group beneficially owned
    less than 1% of the Thermedics common stock outstanding as of January 31,
    2000.

                                       A-5
<PAGE>   79

THERMEDICS

     We have set forth in the following table:

     - The name, business address, position with Thermedics, present principal
       occupation or employment and five-year employment history of each of the
       directors and executive officers of Thermedics; and

     - the names, principal businesses and addresses of any corporations or
       other organizations in which those principal occupations are conducted.

     Unless otherwise indicated:

     - each occupation listed in the table refers to Thermedics;

     - each individual is a United States citizen; and

     - each individual's business address is 470 Wildwood Street, Woburn,
       Massachusetts 01888-1799.

     Unless otherwise indicated, to our knowledge, no director or executive
officer of Thermedics:

     - beneficially owns any shares of our common stock or of Thermedics common
       stock or rights to acquire shares of our common stock or Thermedics
       common stock;

     - has been convicted in a criminal proceeding during the last five years,
       excluding traffic violations or similar misdemeanors; or

     - was a party to any judicial or administrative proceeding during the last
       five years that resulted in a judgement, decree or final order enjoining
       the person from future violations of, or prohibiting activities subject
       to, federal or state securities laws, or a finding of any violation of
       federal or state securities laws.

     George N. Hatsopoulos retired from the board of directors of Thermedics
effective March 31, 2000.

T. ANTHONY BROOKS...................     Mr. Brooks, 60, has been a director of
                                         Thermedics since September 1998. Mr.
                                         Brooks was a managing director and
                                         member of the operating committee of
                                         Lehman Brothers Inc., a financial
                                         services firm located at 3 World
                                         Financial Center, New York, NY 10285
                                         from 1991 until his retirement in 1997.
                                         While at Lehman Brothers Inc., Mr.
                                         Brooks was the head of the European
                                         equity division from 1995 to 1996.

PETER O. CRISP......................     Mr. Crisp, 67, has been a director of
                                         Thermedics since 1983. Mr. Crisp was a
                                         general partner of Venrock Associates,
                                         a venture capital investment firm
                                         located at 30 Rockefeller Plaza, New
                                         York, NY 10112, for more than five
                                         years until his retirement in September
                                         1997. He has been the vice chairman of
                                         Rockefeller Financial Services, Inc.
                                         since December 1997. Mr. Crisp is also
                                         a director of American Superconductor
                                         Corporation, Evans & Sutherland
                                         Computer Corporation, Thermo Electron,
                                         ThermoTrex Corporation and United
                                         States Trust Corporation.

PAUL F. FERRARI.....................     Mr. Ferrari, 69, has been a director of
                                         Thermedics since 1991. Mr. Ferrari was
                                         a vice president of Thermo Electron
                                         from 1988 until his retirement at the
                                         end of 1990. Mr. Ferrari is also a
                                         director of General Scanning Inc. and
                                         ThermoTrex Corporation.

                                       A-6
<PAGE>   80

JOHN T. KEISER......................     Mr. Keiser, 64, has been a director of
                                         Thermedics since April 1997. He has
                                         been the president and chief executive
                                         officer of Thermedics since March 1998
                                         and December 1998, respectively. From
                                         1994 until March 1998, Mr. Keiser
                                         served as a senior vice president of
                                         Thermedics. Mr. Keiser has been the
                                         chief operating officer, biomedical, of
                                         Thermo Electron since September 1998,
                                         and a vice president from April 1997
                                         until his promotion. He has also been
                                         the president of Thermo Electron's
                                         wholly owned biomedical group, a
                                         manufacturer of medical equipment and
                                         instruments, since 1994. Mr. Keiser is
                                         a director of Metrika Systems
                                         Corporation, Thermo Cardiosystems Inc.,
                                         ThermoLase Corporation, ThermoTrex
                                         Corporation and Trex Medical
                                         Corporation.

JOHN W. WOOD JR. ...................     Mr. Wood, 56, has been a director of
                                         Thermedics since 1984 and chairman of
                                         the board since March 1998. Mr. Wood
                                         was president and chief executive
                                         officer of Thermedics from 1984 to
                                         March 1998. Mr. Wood has been a senior
                                         vice president of Thermo Electron since
                                         December 1995, and, prior to that
                                         promotion, was a vice president of
                                         Thermo Electron from September 1994 to
                                         December 1995.

NICHOLAS T. ZERVAS..................     Dr. Zervas, 70, has been a director of
                                         Thermedics since 1987. Dr. Zervas has
                                         been Chief of Neurosurgical Service,
                                         Massachusetts General Hospital, located
                                         at 55 Fruit Street, Boston, MA 02114,
                                         since 1977. Dr. Zervas is also a
                                         director of Thermo Cardiosystems Inc.,
                                         ThermoLase Corporation and ThermoTrex
                                         Corporation.

THEO MELAS-KYRIAZI..................     Mr. Melas-Kyriazi, 40, has been the
                                         chief financial officer of Thermedics
                                         since January 1999. Mr. Melas-Kyriazi
                                         also has served as a vice president of
                                         Thermo Electron since March 1998 and
                                         its chief financial officer since
                                         January 1999. Prior to his appointment
                                         as a vice president of Thermo Electron,
                                         Mr. Melas-Kyriazi served as president
                                         and chief executive officer of
                                         ThermoSpectra Corporation, which
                                         develops, manufactures and markets
                                         precision imaging, inspection,
                                         measurement and temperature-control
                                         instrumentation, from its inception in
                                         August 1994 until March 1998. He is a
                                         director of ThermoRetec Corporation.
                                         Mr. Melas-Kyriazi is a citizen of
                                         Greece.

VICTOR L. POIRIER...................     Mr. Poirier, 58, has been a senior vice
                                         president of Thermedics since 1985. He
                                         has also been president and chief
                                         technical officer of Thermo
                                         Cardiosystems Inc., a majority-owned
                                         subsidiary of Thermedics located at 470
                                         Wildwood Street, Woburn, Massachusetts
                                         01888-2697 since 1990 and 1999,
                                         respectively, and was its chief
                                         executive officer from 1991 to November
                                         1998.

                                       A-7
<PAGE>   81

     Stock Ownership.  The following table sets forth the beneficial ownership
of common stock of Thermedics and Thermo Electron, as of January 31, 2000, with
respect to each director and executive officer of Thermedics. While some
directors and executive officers of Thermedics are also directors and executive
officers of Thermo Electron or its subsidiaries, all such persons disclaim
beneficial ownership of the shares of common stock beneficially owned by us.

<TABLE>
<CAPTION>
                                                                                        THERMO
                                                                                       ELECTRON
NAME(1)                                                       THERMEDICS INC.(2)    CORPORATION(3)
- -------                                                       ------------------    --------------
<S>                                                           <C>                   <C>
T. Anthony Brooks...........................................           5,367                   0
Peter O. Crisp..............................................          37,076             121,767
Paul F. Ferrari.............................................          11,050              16,482
John T. Keiser..............................................         194,693             331,636
Theo Melas-Kyriazi..........................................          11,861             458,532
Victor L. Poirier...........................................          69,455              53,880
John W. Wood Jr. ...........................................         233,200             293,550
Nicholas T. Zervas..........................................          22,064                   0
All directors and current executive officers as a group (8
  persons)..................................................         584,766           1,275,847
</TABLE>

- ---------------
(1) Except as reflected in the footnotes to this table, shares beneficially
    owned consist of shares owned by the indicated person or by that person for
    the benefit of minor children, and all share ownership includes sole voting
    and investment power.

(2) Shares of the Thermedics common stock beneficially owned by Mr. Brooks, Mr.
    Crisp, Mr. Ferrari, Mr. Keiser, Mr. Poirier, Mr. Wood, and all directors and
    current executive officers as a group include 1,000, 9,000, 8,950, 187,900,
    25,000, 174,150 and 406,000 shares, respectively, that such person or group
    had the right to acquire within 60 days of January 31, 2000 through the
    exercise of stock options. Shares beneficially owned by Mr. Melas-Kyriazi
    and all directors and current executive officers as a group include 1,119
    shares allocated through January 31, 2000 to Mr. Melas-Kyriazi's account
    maintained pursuant to Thermo Electron's ESOP. Shares beneficially owned by
    Mr. Brooks, Mr. Crisp, Dr. Zervas and all directors and current executive
    officers as a group include 1,367, 9,971, 10,364 and 21,702 shares,
    respectively, that had been allocated through January 1, 2000 to their
    respective accounts maintained under Thermedics' deferred compensation plan.
    Shares beneficially owned by Mr. Wood include 2,600 shares held in custodial
    accounts for the benefit of two minor children. No director or current
    executive officer beneficially owned more than 1% of the Thermedics common
    stock outstanding as of January 31, 2000; all directors and current
    executive officers as a group beneficially owned approximately 4.4% of the
    Thermedics common stock outstanding as of such date.

(3) Shares of the common stock of Thermo Electron beneficially owned by Mr.
    Crisp, Mr. Keiser, Mr. Melas-Kyriazi, Mr. Poirier, Mr. Wood and all
    directors and current executive officers as a group include 25,596, 263,230,
    384,361, 46,123, 249,298 and 968,608 shares, respectively, that such person
    or group has the right to acquire within 60 days of January 31, 2000 through
    the exercise of stock options. Shares beneficially owned by Mr.
    Melas-Kyriazi and all directors and current executive officers as a group
    include 1,071 shares allocated to Mr. Melas-Kyriazi's account maintained
    pursuant to Thermo Electron's ESOP. Shares beneficially owned by Mr. Crisp
    and all directors and current executive officers as a group include 49,277
    shares allocated through January 1, 2000 to Mr. Crisp's account maintained
    pursuant to Thermo Electron's deferred compensation plan for directors. No
    director or current executive officer beneficially owned more than 1% of the
    Thermo Electron common stock outstanding as of January 31, 2000; all
    directors and current executive officers as a group beneficially owned less
    than 1% of the Thermo Electron common stock outstanding as of such date.

                                       A-8
<PAGE>   82

                                    ANNEX B

                   INFORMATION CONCERNING TRANSACTIONS IN THE
                           COMMON STOCK OF THERMEDICS

     Neither we nor, to our knowledge, any of our directors or executive
officers engaged in any transactions in Thermedics common stock during the
60-day period ended April 27, 2000, except for the option exercise described
below.

<TABLE>
<CAPTION>
                                                                              NUMBER OF
                                                                           SHARES RECEIVED    EXERCISE PRICE
NAME                                 RELATIONSHIP        EXERCISE DATE      UPON EXERCISE       PER SHARE
- ----                             --------------------    --------------    ---------------    --------------
<S>                              <C>                     <C>               <C>                <C>
John W. Wood Jr.                 Director, Thermedics    March 10, 2000         2,100             $10.28
</TABLE>

                                       B-1
<PAGE>   83

                      [THIS PAGE INTENTIONALLY LEFT BLANK]
<PAGE>   84

                                    ANNEX C

SEC. 82. MERGER OF SUBSIDIARY INTO PARENT CORPORATION

     (e) If all the stock of a subsidiary Massachusetts corporation party to a
merger effected under this section is not owned by the parent corporation
immediately prior to the merger, any stockholder in such subsidiary
Massachusetts corporation (but no stockholder in a parent Massachusetts
corporation) who objects to such merger may demand payment for his stock from
the parent corporation and an appraisal thereof. Within ten days after the
effective date of the merger the parent corporation shall send written notice by
registered or certified mail to each stockholder of such subsidiary
Massachusetts corporation at his last known address as it appears in the records
of such subsidiary corporation, stating:

     1.  The date upon which such articles were filed and the effective date of
the merger.

     2.  The terms and conditions of the merger.

     3.  The right of any stockholder of such subsidiary Massachusetts
corporation who objects to the merger to demand in writing from the parent
corporation within twenty days after the mailing of such notice payment for his
stock and an appraisal thereof.

     If any such stockholder shall demand in writing from the parent corporation
within twenty days after the mailing of such notice payment for his stock and an
appraisal thereof, such stockholder and the parent corporation shall thereafter
have the rights and duties and follow the procedures set forth in sections
eighty-nine to ninety-eight, inclusive.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1965, c. 685, sec.sec. 37, 38;
St. 1980, c. 365, sec. 3.

SEC. 86. SECTIONS APPLICABLE TO APPRAISAL; PREREQUISITES

     If a corporation proposes to take a corporate action as to which any
section of this chapter provides that a stockholder who objects to such action
shall have the right to demand payment for his shares and an appraisal thereof,
sections eighty-seven to ninety-eight, inclusive, shall apply except as
otherwise specifically provided in any section of this chapter. Except as
provided in sections eighty-two and eighty-three, no stockholder shall have such
right unless (1) he files with the corporation before the taking of the vote of
the shareholders on such corporate action, written objection to the proposed
action stating that he intends to demand payment for his shares if the action is
taken and (2) his shares are not voted in favor of the proposed action.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1965, c. 685, sec. 40; St.
1973, c. 749, sec. 1.

SEC. 87. STATEMENT OF RIGHTS OF OBJECTING STOCKHOLDERS IN NOTICE OF MEETING;
FORM

     The notice of the meeting of stockholders at which the approval of such
proposed action is to be considered shall contain a statement of the rights of
objecting stockholders. The giving of such notice shall not be deemed to create
any rights in any stockholder receiving the same to demand payment for his
stock, and the directors may authorize the inclusion in any such notice of a
statement of opinion by the management as to the existence or non-existence of
the right of the stockholders to demand payment for their stock on account of
the proposed corporate action. The notice may be in such form as the directors
or officers calling the meeting deem advisable, but the following form of notice
shall be sufficient to comply with this section:

          "If the action proposed is approved by the stockholders at the meeting
     and effected by the corporation, any stockholder (1) who files with the
     corporation before the taking of the vote on the approval of such action,
     written objection to the proposed action stating that he intends to demand
     payment for his shares if the action is taken and (2) whose shares are not
     voted in favor of such action has or may have the right to demand in
     writing from the corporation (or, in the case of a consolidation or merger,
     the name of the resulting or surviving corporation shall be inserted),
     within twenty days after the date of mailing to him of notice in writing
     that the corporate action has become effective, payment for his shares and
     an appraisal of the value thereof. Such corporation and any such

                                       C-1
<PAGE>   85

     stockholder shall in such cases have the rights and duties and shall follow
     the procedure set forth in sections 88 to 98, inclusive, of chapter 156B of
     the General Laws of Massachusetts."
Added by St. 1964, c. 723, sec. 1. Amended by St. 1973, c. 749, sec. 2.

SEC. 88. NOTICE OF EFFECTIVENESS OF ACTION OBJECTED TO

     The corporation taking such action, or in the case of a merger or
consolidation the surviving or resulting corporation, shall, within ten days
after the date on which such corporate action became effective, notify each
stockholder who filed a written objection meeting the requirements of section
eighty-six and whose shares were not voted in favor of the approval of such
action, that the action approved at the meeting of the corporation of which he
is a stockholder has become effective. The giving of such notice shall not be
deemed to create any rights in any stockholder receiving the same to demand
payment for his stock. The notice shall be sent by registered or certified mail,
addressed to the stockholder at his last known address as it appears in the
records of the corporation.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1973, c. 749, sec. 3.

SEC. 89. DEMAND FOR PAYMENT; TIME FOR PAYMENT

     If within twenty days after the date of mailing of a notice under
subsection (e) of section eighty-two, subsection (f) of section eighty-three, or
section eighty-eight, any stockholder to whom the corporation was required to
give such notice shall demand in writing from the corporation taking such
action, or in the case of a consolidation or merger from the resulting or
surviving corporation, payment for his stock, the corporation upon which such
demand is made shall pay to him the fair value of his stock within thirty days
after the expiration of the period during which such demand may be made.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1973, c. 749, sec. 4.

SEC. 90. DEMAND FOR DETERMINATION OF VALUE; BILL IN EQUITY; VENUE

     If during the period of thirty days provided for in section eighty-nine the
corporation upon which such demand is made and any such objecting stockholder
fail to agree as to the value of such stock, such corporation or any such
stockholder may within four months after the expiration of such thirty-day
period demand a determination of the value of the stock of all such objecting
stockholders by a bill in equity filed in the superior court in the county where
the corporation in which such objecting stockholder held stock had or has its
principal office in the commonwealth.
Added by St. 1964, c. 723, sec. 1.

SEC. 91. PARTIES TO SUIT TO DETERMINE VALUE; SERVICE

     If the bill is filed by the corporation, it shall name as parties
respondent all stockholders who have demanded payment for their shares and with
whom the corporation has not reached agreement as to the value thereof. If the
bill is filed by a stockholder, he shall bring the bill in his own behalf and in
behalf of all other stockholders who have demanded payment for their shares and
with whom the corporation has not reached agreement as to the value thereof, and
service of the bill shall be made upon the corporation by subpoena with a copy
of the bill annexed. The corporation shall file with its answer a duly verified
list of all such other stockholders, and such stockholders shall thereupon be
deemed to have been added as parties to the bill. The corporation shall give
notice in such form and returnable on such date as the court shall order to each
stockholder party to the bill by registered or certified mail, addressed to the
last known address of such stockholder as shown in the records of the
corporation, and the court may order such additional notice by publication or
otherwise as it deems advisable. Each stockholder who makes demand as provided
in section eighty-nine shall be deemed to have consented to the provisions of
this section relating to notice, and the giving of notice by the corporation to
any such stockholder in compliance with the order of the court shall be a
sufficient service of process on him. Failure to give notice to any stockholder
making demand shall not invalidate the proceedings as to other stockholders to
whom notice was properly given, and the court may at any time before the entry
of a final decree make supplementary orders of notice.
Added by St. 1964, c. 723, sec. 1.


                                       C-2
<PAGE>   86

SEC. 92. DECREE DETERMINING VALUE AND ORDERING PAYMENT; VALUATION DATE

     After hearing the court shall enter a decree determining the fair value of
the stock of those stockholders who have become entitled to the valuation of and
payment for their shares, and shall order the corporation to make payment of
such value, together with interest, if any, as hereinafter provided, to the
stockholders entitled thereto upon the transfer by them to the corporation of
the certificates representing such stock if certificated or, if uncertificated,
upon receipt of an instruction transferring such stock to the corporation. For
this purpose, the value of the shares shall be determined as of the day
preceding the date of the vote approving the proposed corporate action and shall
be exclusive of any element of value arising from the expectation or
accomplishment of the proposed corporate action.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1983, c. 522, sec. 22.

SEC. 93. REFERENCE TO SPECIAL MASTER

     The court in its discretion may refer the bill or any question arising
thereunder to a special master to hear the parties, make findings and report the
same to the court, all in accordance with the usual practice in suits in equity
in the superior court.
Added by St. 1964, c. 723, sec. 1.

SEC. 94. NOTATION ON STOCK CERTIFICATES OF PENDENCY OF BILL

     On motion the court may order stockholder parties to the bill to submit
their certificates of stock to the corporation for the notation thereon of the
pendency of the bill and may order the corporation to note such pendency in its
records with respect to any uncertificated shares held by such stockholder
parties, and may on motion dismiss the bill as to any stockholder who fails to
comply with such order.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1983, c. 522, sec. 23.

SEC. 95. COSTS; INTEREST

     The costs of the bill, including the reasonable compensation and expenses
of any master appointed by the court, but exclusive of fees of counsel or of
experts retained by any party, shall be determined by the court and taxed upon
the parties to the bill, or any of them, in such manner as appears to be
equitable, except that all costs of giving notice to stockholders as provided in
this chapter shall be paid by the corporation. Interest shall be paid upon any
award from the date of the vote approving the proposed corporate action, and the
court may on application of any interested party determine the amount of
interest to be paid in the case of any stockholder.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1965, c. 685, sec. 41.

SEC. 96. DIVIDENDS AND VOTING RIGHTS AFTER DEMAND FOR PAYMENT

     Any stockholder who has demanded payment for his stock as provided in this
chapter shall not thereafter be entitled to notice of any meeting of
stockholders or to vote such stock for any purpose and shall not be entitled to
the payment of dividends or other distribution on the stock (except dividends or
other distributions payable to stockholders of record at a date which is prior
to the date of the vote approving the proposed corporate action) unless:

     (1) A bill shall not be filed within the time provided in section ninety;

     (2) A bill, if filed, shall be dismissed as to such stockholder; or

     (3) Such stockholder shall with the written approval of the corporation, or
         in the case of a consolidation or merger, the resulting or surviving
         corporation, deliver to it a written withdrawal of his objections to
         and an acceptance of such corporate action.

     Notwithstanding the provisions of clauses (1) to (3), inclusive, said
stockholder shall have only the rights of a stockholder who did not so demand
payment for his stock as provided in this chapter.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1982, c. 149.

                                       C-3
<PAGE>   87

     The shares of the corporation paid for by the corporation pursuant to the
provisions of this chapter shall have the status of treasury stock, or in the
case of consolidation or merger the shares or the securities of the resulting or
surviving corporation into which the shares of such objecting stockholder would
have been converted had he not objected to such consolidation or merger shall
have the status of treasury stock or securities.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1965, c. 685, sec. 42.

SEC. 98. EXCLUSIVE REMEDY; EXCEPTION

     The enforcement by a stockholder of his right to receive payment for his
shares in the manner provided in this chapter shall be an exclusive remedy
except that this chapter shall not exclude the right of such stockholder to
bring or maintain an appropriate proceeding to obtain relief on the ground that
such corporate action will be or is illegal or fraudulent as to him.
Added by St. 1964, c. 723, sec. 1. Amended by St. 1965, c. 685, sec. 43.

                                       C-4
<PAGE>   88

                      [THIS PAGE INTENTIONALLY LEFT BLANK]
<PAGE>   89

     You or your broker, dealer, commercial bank, trust company or other nominee
should deliver your letter of transmittal, certificates for Thermedics shares
and any other required documents to the depositary at one of its address set
forth below.

                   The Depositary for the exchange offer is:

                                EQUISERVE, L.P.

<TABLE>
<S>                             <C>                                    <C>
     By First Class Mail:                     By Hand:                  By Overnight, Certified or Express
                                                                                       Mail:
       EquiServe, L.P.             Securities Transfer & Reporting
Attn: Corporate Reorganization             Services, Inc.                         EquiServe, L.P.
        P.O. Box 8029                    c/o EquiServe, L.P.              Attn: Corporate Reorganization
    Boston, MA 02266-8029           100 Williams Street/Galleria                 150 Royall Street
                                         New York, NY 10038                      Canton, MA 02021

    For Information Call:            By Facsimile Transmission:               For Confirmation Call:
        (781) 575-3120
                                         (781) 575-2233/2232                      (781) 575-3417
                                        (Valid for Book Entry
                                           Accounts Only)
</TABLE>

     You should direct any questions or requests for assistance or additional
copies of the prospectus, the letter of transmittal and the notice of guaranteed
delivery to the Information Agent at its telephone numbers and location listed
below. You may also contact your local broker, commercial bank, trust company or
nominee for assistance concerning the exchange offer.

                The Information Agent for the exchange offer is:

                             D.F. KING & CO., INC.
                          77 Water Street, 20th Floor
                               New York, NY 10005
                Bankers and Brokers Call Collect (212) 269-5550
                    All Others Call Toll-Free (800) 290-6433
<PAGE>   90

                                    PART II

                     INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 20.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

     The Delaware General Corporation Law and Thermo Electron's Certificate of
Incorporation and Bylaws limit the monetary liability of directors to Thermo
Electron and to its stockholders and provide for indemnification of Thermo
Electron's officers and directors for liabilities and expenses that they may
incur in such capacities. In general, officers and directors are indemnified
with respect to actions taken in good faith in a manner reasonably believed to
be in, or not opposed to, the best interests of Thermo Electron and, with
respect to any criminal action or proceeding, actions that the indemnitee had no
reasonable cause to believe were unlawful. Thermo Electron also has
indemnification agreements with its directors and officers that provide for the
maximum indemnification allowed by law.

     Thermo Electron has an insurance policy which insures its directors and
officers against those liabilities set forth in the insurance policy which might
be incurred in connection with the performance of their duties.

ITEM 21.  EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.

     (a) The following exhibits are filed herewith or incorporated herein by
         reference:

<TABLE>
<CAPTION>
EXHIBIT
NUMBER                      DESCRIPTION OF DOCUMENT
- -------                     -----------------------
<C>       <S>
  3.1     Amended and Restated Certificate of Incorporation of the
          Registrant (incorporated by reference to Exhibit 1 to the
          Registrant's Amendment No. 3 to Registration Statement on
          Form 8-A/A filed on September 9, 1999 (SEC File No.
          1-8002)).
  3.2     Bylaws of the Registrant (incorporated by reference to
          Exhibit 3 to the Registrant's Quarterly Report on Form 10-Q
          for the quarter ended July 3, 1999 (SEC File No. 1-8002)).
  4.1     Reference is made to Exhibits 3.1 and 3.2 above.
  4.2     Fiscal Agency Agreement dated as of January 3, 1996, between
          the Registrant and Chemical Bank pertaining to the
          Registrant's 4 1/4% Subordinated Convertible Debentures due
          2003 (incorporated by reference to Exhibit 4.1 to
          Registrant's Annual Report on Form 10-K for the fiscal year
          ended December 30, 1995 (SEC File No. 1-8002)). The
          Registrant agrees, pursuant to Item 601(b)(4)(iii)(A) of
          Regulation S-K, to furnish to the Commission upon request, a
          copy of each instrument with respect to other long-term debt
          of the Registrant or its consolidated subsidiaries.
  4.3     Rights Agreement, dated as of January 19, 1996, between the
          Registrant and The First National Bank of Boston, as Rights
          Agent, which includes as Exhibit A the Form of Certificate
          of Designations, as Exhibit B the Form of Rights Certificate
          and as Exhibit C the Summary of Rights to Purchase Preferred
          Stock (incorporated by reference to Exhibit 1 to the
          Registrant's Registration Statement on Form 8-A filed on
          January 26, 1996, as amended by Amendment No. 1 to
          Registration Statement on Form 8-A/A filed on May 30, 1997
          (SEC File No. 1-8002)).
  4.4     Amendment No. 1 to Rights Agreement, dated as of June 11,
          1999, between the Registrant and BankBoston, N.A. (formerly,
          The First National Bank of Boston), as Rights Agent, which
          includes as Exhibit B the amended and restated Form of
          Rights Certificate and as Exhibit C the amended and restated
          Summary of Rights to Purchase Preferred Stock (incorporated
          by reference to Exhibit 2 to the Registrant's Amendment No.
          2 to Registration Statement on Form 8-A/A filed on June 21,
          1999 (SEC File No. 1-8002)).
</TABLE>

                                      II-1
<PAGE>   91

<TABLE>
<CAPTION>
EXHIBIT
NUMBER                      DESCRIPTION OF DOCUMENT
- -------                     -----------------------
<C>       <S>
  4.5     Indenture dated as of October 29, 1998, by and between the
          Registrant and Bankers Trust Company, as Trustee, relating
          to the issuance of senior debt securities by the Registrant
          (incorporated by reference to Exhibit 4.1 to the
          Registrant's Current Report on Form 8-K dated October 29,
          1998, filed with the SEC on October 30, 1998 (SEC File No.
          1-8002)).
  4.6     First Supplemental Indenture dated as of October 29, 1998,
          by and between the Registrant and Bankers Trust Company, as
          Trustee, relating to the issuance by the Registrant of
          $150,000,000 aggregate principal amount of its 7.625% Notes
          due 2008 (incorporated by reference to Exhibit 4.2 to the
          Registrant's Current Report on Form 8-K dated October 29,
          1998, filed with the SEC on October 30, 1998 (SEC File No.
          1-8002)).
  5.1     Opinion and consent of Seth H. Hoogasian, Esq. as to the
          validity of the securities being issued.
  8.1     Opinion and consent of Hale and Dorr LLP as to the material
          United States federal income tax consequences of the
          exchange offer and the merger.
 10.1     Form of Indemnification Agreement between the Registrant and
          the directors and officers of its majority-owned
          subsidiaries (filed as Exhibit 10.1 to the Registrant's
          Registration Statement on Form S-4 (Reg. No. 333-90661) and
          incorporated herein by reference).
 10.2     Form of Amended and Restated Indemnification Agreement
          between the Registrant and its officers and directors (filed
          as Exhibit 10.2 to the Registrant's Registration Statement
          on Form S-4 (Reg. No. 333-90661) and incorporated herein by
          reference).
 12.1     Computation of Registrant's ratio of earnings to fixed
          charges.
 12.2     Computation of Thermedics' ratio of earnings to fixed
          charges.
 21.1     Subsidiaries of the Registrant (incorporated by reference to
          Exhibit 21.1 to the Registrant's Annual Report on Form 10-K
          for the fiscal year ended January 1, 2000 (SEC File No.
          1-8002)).
 23.1     Consent of Arthur Andersen LLP, independent accountants to
          the Registrant.
 23.2     Consent of Arthur Andersen LLP, independent accountants to
          Thermedics Inc.
 23.3     Consent of Seth H. Hoogasian, Esq. (included in Exhibit 5.1
          of this Registration Statement)
 23.4     Consent of Hale and Dorr LLP (included in Exhibit 8.1 of
          this Registration Statement).
 24.1     Powers of Attorney (included in the signature pages of this
          Registration Statement).
 99.1     Form of Letter of Transmittal
 99.2     Form of Notice of Guaranteed Delivery
 99.3     Form of Broker Dealer Letter
 99.4     Form of Letter to Clients
 99.5     Form of Guidelines for Certification of Taxpayer
          Identification Number on Substitute Form W-9
</TABLE>

ITEM 22.  UNDERTAKINGS.

     The undersigned registrant hereby undertakes:

          (1) that, for purposes of determining any liability under the
     Securities Act of 1933, each filing of the registrant's annual report
     pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act
     of 1934 (and, where applicable, each filing of an employee benefit plan's
     annual report pursuant to Section 15(d) of the Securities Exchange Act of
     1934) that is incorporated by reference in this registration statement
     shall be deemed to be a new registration statement relating to the
     securities offered therein, and the offering of such securities at that
     time shall be deemed to be the initial bona fide offering thereof;

          (2) that before any public reoffering of the securities registered
     hereunder through use of a prospectus which is a part of this registration
     statement, by any person or party who is deemed to be an underwriter within
     the meaning of Rule 145(c), the issuer undertakes that such reoffering

                                      II-2
<PAGE>   92

     prospectus will contain the information called for by the applicable
     registration form with respect to reofferings by persons who may be deemed
     underwriters, in addition to the information called for by the other items
     of the applicable form;

          (3) that every prospectus (i) that is filed pursuant to paragraph (2)
     immediately preceding, or (ii) that purports to meet the requirements of
     Section 10(a)(3) of the Act and is used in connection with an offering of
     securities subject to Rule 415, will be filed as a part of an amendment to
     the registration statement and will not be used until such amendment is
     effective, and that, for purposes of determining any liability under the
     Securities Act of 1933, each such post-effective amendment shall be deemed
     to be a new registration statement relating to the securities offered
     therein, and the offering of such securities at that time shall be deemed
     to be the initial bona fide offering thereof;

          (4) to respond to requests for information that is incorporated by
     reference into the prospectus pursuant to Items 4, 10(b), 11, or 13 of this
     Form, within one business day of receipt of such request, and to send the
     incorporated documents by first class mail or other equally prompt means,
     including information contained in documents filed after the effective date
     of this registration statement through the date of responding to such
     request; and

          (5) to supply by means of a post-effective amendment all information
     concerning a transaction, and the company being acquired involved therein,
     that was not the subject of and included in this registration statement
     when it became effective.

     Insofar as indemnification for liabilities under the Securities Act of 1933
may be permitted to directors, officers and controlling persons of the
registrant pursuant to the provisions described in Item 20 above, or otherwise,
the registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Securities Act and is therefore unenforceable. If a claim for
indemnification against such liabilities (other than the payment by the
registrant of expenses incurred or paid by a director, officer or controlling
person of the registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer, or controlling person in
connection with the securities being registered, the registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the Securities
Act and will be governed by the final adjudication of such issue.

                                      II-3
<PAGE>   93

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the registrant
has duly caused this registration statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of Waltham, Commonwealth of
Massachusetts, on this first day of May, 2000.

                                          THERMO ELECTRON CORPORATION

                                          By:          /s/ RICHARD F. SYRON
                                              ----------------------------------
                                                       Richard F. Syron
                                                       President, Chief
                                                       Executive Officer and
                                                       Chairman of the Board

                        POWER OF ATTORNEY AND SIGNATURES

     Each of the undersigned Directors and Officers of Thermo Electron
Corporation hereby appoints Theo Melas-Kyriazi, Seth H. Hoogasian and Sandra L.
Lambert, and each of them, his true and lawful attorneys-in-fact and agents,
with full power of substitution, for him and in his name, place and stead, in
any and all capacities, to sign any and all amendments (including post-effective
amendments) to this Registration Statement, and to file the same, with all
exhibits thereto, and all documents in connection therewith, with the Securities
and Exchange Commission, granting unto said attorneys-in-fact and agents, and
each of them, full power and authority to do and perform each and every act and
thing requisite and necessary to be done in and about the premises, as fully to
all intents and purposes as he might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents or any of them, or their
or his substitute or substitutes, may lawfully do or cause to be done by virtue
thereof.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated:

<TABLE>
<CAPTION>
  SIGNATURE                                                         TITLE                      DATE
  ---------                                                         -----                      ----
  <S>                                                  <C>                                <C>
           /s/ RICHARD F. SYRON                        President, Chief Executive         May 1, 2000
  ---------------------------------------------------    Officer and Chairman of the
           Richard F. Syron                              Board (Principal Executive
                                                         Officer)

           /s/ THEO MELAS-KYRIAZI                      Vice President and Chief           May 1, 2000
  ---------------------------------------------------    Financial Officer (Principal
           Theo Melas-Kyriazi                            Financial Officer and
                                                         Principal Accounting Officer)

           /s/ SAMUEL W. BODMAN                        Director                           May 1, 2000
  ---------------------------------------------------
           Samuel W. Bodman

           /s/ PETER O. CRISP                          Director                           May 1, 2000
  ---------------------------------------------------
           Peter O. Crisp

           /s/ ELIAS P. GYFTOPOULOS                    Director                           May 1, 2000
  ---------------------------------------------------
           Elias P. Gyftopoulos

           /s/ FRANK JUNGERS                           Director                           May 1, 2000
  ---------------------------------------------------
           Frank Jungers
</TABLE>

                                      II-4
<PAGE>   94

<TABLE>
<CAPTION>
  SIGNATURE                                                         TITLE                      DATE
  ---------                                                         -----                      ----
  <S>                                                  <C>                                <C>
           /s/ ROBERT A. MCCABE                        Director                           May 1, 2000
  ---------------------------------------------------
           Robert A. McCabe

           /s/ HUTHAM S. OLAYAN                        Director                           May 1, 2000
  ---------------------------------------------------
           Hutham S. Olayan

           /s/ ROBERT W. O'LEARY                       Director                           May 1, 2000
  ---------------------------------------------------
           Robert W. O'Leary

           /s/ ROGER D. WELLINGTON                     Director                           May 1, 2000
  ---------------------------------------------------
           Roger D. Wellington
</TABLE>

                                      II-5

<PAGE>   1

                                                                    EXHIBIT 5.1


                           Thermo Electron Corporation
                                 81 Wyman Street
                        Waltham, Massachusetts 02454



                                                           May 1, 2000

Thermo Electron Corporation
81 Wyman Street
Waltham, Massachusetts 02454-9046

Re: Registration Statement on Form S-4
    Relating to Common Stock, $1.00 par value, of Thermo Electron Corporation
    -------------------------------------------------------------------------

Dear Sirs:

     I am General Counsel to Thermo Electron Corporation, a Delaware corporation
(the "Company"), and have acted as its counsel in connection with the exchange
offer by the Company for all issued and outstanding shares of Thermedics Inc., a
majority-owned subsidiary of the Company ("Thermedics"), and the filing of a
Registration Statement on Form S-4 (the "Registration Statement") in order to
register, under the Securities Act of 1933, as amended, the shares of the
Company's Common Stock, $1.00 par value per share (the "Shares"), to be issued
in exchange for the issued and outstanding shares of Thermedics.

     I or a member of my legal staff have reviewed the corporate proceedings
taken by the Company with respect to the authorization of the issuance of the
Shares. I or a member of my legal staff have also examined and relied upon
originals or copies, certified or otherwise authenticated to my satisfaction, of
all corporate records, documents, agreements or other instruments of the Company
and have made all investigations of law and have discussed with the Company's
representatives all questions of fact that I have deemed necessary or
appropriate.

     Based upon and subject to the foregoing, I am of the opinion that:

     1. The Company is a corporation validly existing and in corporate good
standing under the laws of the State of Delaware.

     2. The issuance of the Shares as contemplated in the Registration Statement
has been duly authorized by the Company.
<PAGE>   2


     3. The Shares, when issued in accordance with the provisions of the Merger
Agreement, will be validly issued, fully paid and nonassessable.

     This opinion is limited to the applicable provisions of the Delaware
Constitution, the General Corporation Law of the State of Delaware ("Delaware
Law") and reported judicial decisions interpreting Delaware Law.

     I hereby consent to the filing of this opinion as Exhibit 5 to the
Registration Statement and to being named in the Registration Statement under
the caption "LEGAL MATTERS".

                                          Very truly yours,



                                          /s/ Seth H. Hoogasian
                                          ----------------------------
                                          Seth H. Hoogasian
                                          General Counsel



<PAGE>   1


                                                                    EXHIBIT 8.1


                           [Hale and Dorr Letterhead]





                                                          May 1, 2000


Thermedics Inc.
470 Wildwood Street
P.O. Box 2999
Woburn, Massachusetts 01888-1799

             Re:  Merger of Thermedics Inc. into Thermo Electron Corporation
                  Following Completion of Thermo Electron Corporation's Offer to
                  Exchange Shares of Thermo Electron Corporation Common Stock
                  for Outstanding Shares of Thermedics Inc. Common Stock

Ladies and Gentlemen:

     This opinion is being delivered to you in connection with the filing of a
registration statement (the "Registration Statement") on Form S-4, which
includes the Prospectus relating to the merger of Thermedics Inc. ("Target")
with and into Thermo Electron Corporation ("Acquiror") in accordance with the
Massachusetts Business Corporation Law and the Delaware General Corporation Law
(the "Merger") following consummation of Acquiror's offer to exchange 0.45
shares of common stock of Acquiror for each outstanding share of common stock of
Target (the "Exchange Offer"). Except as otherwise provided, capitalized terms
not defined herein have the meanings set forth in the letters delivered to Hale
and Dorr LLP by Acquiror and Target containing certain representations of
Acquiror and Target relevant to this opinion (the "Representation Letters"). All
section references, unless otherwise indicated, are to the United States
Internal Revenue Code of 1986, as amended (the "Code").

     In our capacity as counsel to Acquiror and Target in the Merger, and for
purposes of rendering this opinion, we have examined and relied upon the
Registration Statement and the exhibits thereto, the Representation Letters, and
such other documents as we considered relevant to our analysis. In our
examination of documents, we have assumed the authenticity of original
documents, the accuracy of copies, the genuineness of signatures, and the legal
capacity of signatories.

     We have assumed that all parties to all documents examined by us have
acted, and will act, in accordance with the terms of such documents and that the
Exchange Offer and the Merger will be consummated pursuant to the terms and
conditions set forth in the Registration Statement without the waiver or
modification of any such terms and conditions. Furthermore, we have assumed that
all representations contained in the Representation Letters, are, and at the
Effective Time will be, true and complete in all material respects, and that any
representation made in any of the documents referred to herein "to the best of
the knowledge and belief" or "to the best of the belief" (or similar
qualification) of any person or party is, and at the Effective Time will be,
correct without such qualification. We have also assumed that as to all matters
for which a person or entity has represented that such person or entity is not a
party to, does not have, or is not aware of, any plan, intention, understanding,
or agreement, there is no such plan,

<PAGE>   2

Thermedics Inc.
May 1, 2000
Page 2

intention, understanding, or agreement. We have not attempted to verify
independently such representations, but in the course of our representation,
nothing has come to our attention that would cause us to question the accuracy
thereof.

     The conclusions expressed herein represent our judgment as to the proper
treatment of certain aspects of the Exchange Offer and the Merger under the
income tax laws of the United States based upon the Code, Treasury Regulations,
case law, and rulings and other pronouncements of the Internal Revenue Service
(the "IRS") as in effect on the date of this opinion. No assurances can be given
that such laws will not be amended or otherwise changed prior to the Effective
Time, or at any other time, or that such changes will not affect the conclusions
expressed herein. Nevertheless, we undertake no responsibility to advise you or
your shareholders of any developments after the Effective Time in the
application or interpretation of the income tax laws of the United States.

     Our opinion represents our best judgment of how a court would decide if
presented with the issues addressed herein and is not binding upon either the
IRS or any court. Thus, no assurances can be given that a position taken in
reliance on our opinion will not be challenged by the IRS or rejected by a
court.

     This opinion addresses only the specific United States federal income tax
consequences of the Exchange Offer and the Merger set forth below, and does not
address any other federal, state, local, or foreign income, estate, gift,
transfer, sales, use, or other tax consequences that may result from the
Exchange Offer or the Merger or any other transaction (including any transaction
undertaken in connection with the Exchange Offer or the Merger). We express no
opinion regarding the tax consequences of the Exchange Offer or the Merger to
shareholders of Target that are subject to special tax rules, and we express no
opinion regarding the tax consequences of the Exchange Offer or the Merger
arising in connection with the ownership of options or warrants for Target
stock.

     On the basis of, and subject to, the foregoing, and in reliance upon the
representations and assumptions described above, we are of the opinion that the
Exchange Offer and the Merger should be treated as one integrated transaction
that will qualify as a reorganization within the meaning of Section 368(a).
Subject to the additional qualifications set forth immediately following the
numbered paragraphs below, the Exchange Offer and the Merger should result in
the following federal income tax consequences:

1.   A Target shareholder will not recognize any gain or loss solely upon the
     exchange of his or her shares of Target stock for Acquiror stock pursuant
     to the Exchange Offer or the Merger, except with respect to any cash the
     shareholder receives in lieu of fractional shares of Acquiror stock;

2.   A Target shareholder's aggregate tax basis in the Acquiror stock that the
     shareholder receives pursuant to the Exchange Offer or the Merger will be
     the same as the shareholder's aggregate tax basis in the Target stock
     tendered, reduced by the amount of any tax basis attributable to any
     fractional shares not actually received;

3.   A Target shareholder's holding period for the Acquiror stock that the
     shareholder receives pursuant to the Exchange Offer or the Merger will
     include the period for

<PAGE>   3

Thermedics Inc.
May 1, 2000
Page 3


     which the shareholder held the Target stock that he or she exchanged for
     the Acquiror stock, provided that the shareholder held the Target stock as
     a capital asset at the time of the exchange pursuant to the Exchange Offer
     or at the Effective Time, as the case may be;

4.   Cash payments that a Target shareholder receives in lieu of a fractional
     share will be treated as if that fractional share of Acquiror stock had
     been issued pursuant to the Exchange Offer or the Merger and then redeemed
     by Acquiror; and

5.   Neither Acquiror nor Target will recognize gain or loss directly as a
     result of the Exchange Offer or the Merger.

     No opinion is expressed as to any federal income tax consequence of the
Exchange Offer or the Merger except as specifically set forth herein, and this
opinion may not be relied upon except with respect to the consequences
specifically discussed herein. In particular, and without limiting the foregoing
sentence, no opinion is expressed as to any aspect or effect of Acquiror's
proposed spin-offs of its medical products business and paper recycling and
papermaking equipment business, and any associated transactions, as described in
Acquiror's Request for Ruling under Section 355 initially filed with the IRS on
April 7, 2000 (the "Spin-Offs"); and no opinion is expressed as to the tax
treatment of the shareholders of Target on their receipt of stock or other
property pursuant to the Spin-Offs.

     This opinion is intended solely for the purpose of inclusion as an exhibit
to the Registration Statement. It may not be relied upon for any other purpose
or by any other person or entity, and may not be made available to any other
person or entity without our prior written consent. We hereby consent to the
filing of this opinion as an exhibit to the Registration Statement and further
consent to the use of our name in the Registration Statement in connection with
references to this opinion and the tax consequences of the Exchange Offer and
the Merger. In giving this consent, however, we do not hereby admit that we are
in the category of persons whose consent is required under Section 7 of the
Securities Act of 1933, as amended.


                                      Very truly yours,


                                      /s/ Hale and Dorr LLP
                                      ----------------------------
                                      HALE AND DORR LLP





<PAGE>   1
                                                                    EXHIBIT 12.1



                           THERMO ELECTRON CORPORATION

                       RATIO OF EARNINGS TO FIXED CHARGES
                             (DOLLARS IN THOUSANDS)

<TABLE>
<CAPTION>
                                                                                        Pro Forma              Year Ended
                                                                                           1999           1999            1998
                                                                                       -----------     ----------     -----------
<S>                                                                                    <C>             <C>            <C>
Income from continuing operations before provision for income taxes, minority
 interest and extraordinary item                                                       $    36,196     $   37,486     $   254,493
Less:
 Minority interest in earnings of consolidated subsidiaries                                (18,993)       (18,993)        (35,246)
Add:
 Minority interest in consolidated subsidiaries with fixed charges                          18,993         18,993          35,246
 Interest on indebtedness and amortization of debt expense                                  96,992         96,992          90,329
 Portion of rents representative of the interest factor (1)                                 19,365         19,365          17,765
                                                                                       -----------     ----------     -----------

      Income as adjusted                                                               $   152,553     $  153,843     $   362,587
                                                                                       ===========     ==========     ===========

Fixed Charges:
 Interest on indebtedness and amortization of debt expense                             $    96,992     $   96,992     $    90,329
 Portion of rents representative of the interest factor (1)                                 19,365         19,365          17,765
                                                                                       -----------     ----------     -----------

      Fixed Charges                                                                    $   116,357     $  116,357     $   108,094
                                                                                       ===========     ==========     ===========

Ratio of Earnings to Fixed Charges                                                            1.31           1.32            3.35
                                                                                       ===========     ==========     ===========
</TABLE>

(1) Portion of rents representative of the interest factor is 1/3 of total
    rents.

<PAGE>   1
                                                                    EXHIBIT 12.2

                                THERMEDICS INC.

                       RATIO OF EARNINGS TO FIXED CHARGES
                             (DOLLARS IN THOUSANDS)

<TABLE>
<CAPTION>
                                                                                            Year Ended
                                                                                    ---------------------------
                                                                                      1999             1998
                                                                                      ----             ----

Income from continuing operations before provision for income taxes, minority
<S>                                                                                 <C>              <C>
 interest, and extraordinary item                                                     $20,396          $28,292
Less:
 Minority interest in earnings of consolidated subsidiaries                            (2,475)          (2,665)
Add:
 Minority interest in consolidated subsidiaries with fixed charges                      2,475            2,665
 Interest on indebtedness and amortization of debt expense                              2,581            1,777
 Portion of rents representative of the interest factor (1)                             1,423            1,531
                                                                                    ---------        ---------

      Income as adjusted                                                              $24,400          $31,600
                                                                                    =========        =========

Fixed Charges:
 Interest on indebtedness and amortization of debt expense                            $ 2,581          $ 1,777
 Portion of rents representative of the interest factor (1)                             1,423            1,531
                                                                                    ---------        ---------

      Fixed Charges                                                                   $ 4,004          $ 3,308
                                                                                    =========        =========

Ratio of Earnings to Fixed Charges                                                       6.09             9.55
                                                                                    =========        =========
</TABLE>

(1) Portion of rents representative of the interest factor is 1/3 of total
    rents.



<PAGE>   1
                                                                    EXHIBIT 23.1



                    Consent of Independent Public Accountants

To Thermo Electron Corporation:

         As independent public accountants, we hereby consent to the
incorporation by reference in this Registration Statement and related Prospectus
of Thermo Electron Corporation on Form S-4 of our reports dated February 17,
2000 (except with respect to the matters discussed in Note 17, as to which the
date is March 7, 2000) included or incorporated by reference in Thermo Electron
Corporation's Annual Report on Form 10-K for the year ended January 1, 2000, and
to all references to our Firm included in this Registration Statement and
related Prospectus.




                                            Arthur Andersen LLP



Boston, Massachusetts
April 27, 2000

<PAGE>   1
                                                                    EXHIBIT 23.2



                    Consent of Independent Public Accountants

To Thermedics Inc.:

         As independent public accountants, we hereby consent to the
incorporation by reference in this Registration Statement and related Prospectus
of Thermo Electron Corporation on Form S-4 of our reports dated February 10,
2000 (except with respect to the matters discussed in Note 16, as to which the
date is March 8, 2000) included or incorporated by reference in Thermedics
Inc.'s Annual Report on Form 10-K for the year ended January 1, 2000, and to all
references to our Firm included in this Registration Statement and related
Prospectus.




                                            Arthur Andersen LLP



Boston, Massachusetts
April 27, 2000

<PAGE>   1

                             LETTER OF TRANSMITTAL
                    TO EXCHANGE 0.45 SHARES OF COMMON STOCK

                                       OF

                          THERMO ELECTRON CORPORATION
                                      FOR

                     EACH OUTSTANDING SHARE OF COMMON STOCK

                                       OF

                                THERMEDICS INC.
                     AND CASH IN LIEU OF FRACTIONAL SHARES
                  PURSUANT TO THE PROSPECTUS DATED MAY 1, 2000

- --------------------------------------------------------------------------------

  THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY
          TIME, ON FRIDAY, MAY 26, 2000, UNLESS THE OFFER IS EXTENDED.

- --------------------------------------------------------------------------------

                        The Depositary for the Offer is:
                                EQUISERVE, L.P.

<TABLE>
<S>                                    <C>                                      <C>
        By First Class Mail:                          By Hand:                   By Overnight, Certified or Express
                                                                                                Mail:
           EquiServe, L.P.                 Securities Transfer & Reporting
   Attn: Corporate Reorganization                  Services, Inc.                          EquiServe, L.P.
            P.O. Box 8029                        c/o EquiServe, L.P.               Attn: Corporate Reorganization
        Boston, MA 02266-8029               100 Williams Street/Galleria                  150 Royall Street
                                                 New York, NY 10038                       Canton, MA 02021
</TABLE>

<TABLE>
<S>                                    <C>                                            <C>
        For Information Call:                   By Facsimile Transmission:                   For Confirmation Call:
           (781) 575-3120                           (781) 575-2233/2232                          (781) 575-3417
                                           (Valid For Book Entry Accounts Only)
</TABLE>

     DELIVERY OF THIS LETTER OF TRANSMITTAL TO AN ADDRESS OTHER THAN AS SET
FORTH ABOVE, OR TRANSMISSIONS OF INSTRUCTIONS VIA A FACSIMILE NUMBER (VALID FOR
BOOK ENTRY ACCOUNTS ONLY) OTHER THAN AS SET FORTH ABOVE, WILL NOT CONSTITUTE A
VALID DELIVERY. YOU MUST SIGN THIS LETTER OF TRANSMITTAL IN THE APPROPRIATE
SPACE PROVIDED THEREFOR AND COMPLETE THE SUBSTITUTE FORM W-9 SET FORTH BELOW.

     THE INSTRUCTIONS ACCOMPANYING THIS LETTER OF TRANSMITTAL SHOULD BE READ
CAREFULLY BEFORE THIS LETTER OF TRANSMITTAL IS COMPLETED.

     This Letter of Transmittal is to be completed by holders of shares of
common stock, par value $0.10 per share, of Thermedics Inc. (the "Shares")
either if certificates evidencing Shares ("Share Certificates") are to be
forwarded herewith or, unless an Agent's Message (as such term is used in the
Prospectus) is utilized, if delivery of Shares is to be made by book-entry
transfer into the account of EquiServe, L.P., as Depositary (the "Depositary"),
at The Depository Trust Company ("DTC") pursuant to the procedures set forth in
the section captioned "The Exchange Offer -- Procedures For Accepting The
Exchange Offer And Tendering Shares" of the Prospectus dated May 1, 2000 (the
"Prospectus"). Stockholders who tender Shares by book-entry transfer are
referred to herein as "Book-Entry Stockholders."

     Stockholders whose Share Certificates are not immediately available or who
cannot deliver their Share Certificates and all other documents required hereby
to the Depositary prior to the Expiration Date (as such term is used in the
section of the Prospectus captioned "The Exchange Offer -- Terms Of The Exchange
Offer; Expiration Of The Exchange Offer"), or who cannot complete the procedures
for delivery by book-entry transfer on a timely basis, may tender their Shares
according to the guaranteed delivery procedures set forth in the section of the
Prospectus captioned "The Exchange Offer -- Procedures For Accepting The
Exchange Offer And Tendering Shares." See Instruction 2. DELIVERY OF DOCUMENTS
TO DTC IN ACCORDANCE WITH DTC'S PROCEDURES DOES NOT CONSTITUTE DELIVERY TO THE
DEPOSITARY.
<PAGE>   2
<TABLE>
<CAPTION>
- --------------------------------------------------------------------------------  --------------------------------------------------
                         DESCRIPTION OF SHARES TENDERED                                         DESCRIPTION OF SHARES TENDERED
- --------------------------------------------------------------------------------  --------------------------------------------------
                                                                                        SHARE CERTIFICATE(S) AND SHARE(S) TENDERED
                NAME(S) AND ADDRESS(ES) OF REGISTERED HOLDER(S)                       (ATTACH ADDITIONAL SIGNED LIST, IF NECESSARY).
(PLEASE FILL IN, IF BLANK, EXACTLY AS NAME(S) APPEAR(S) ON SHARE CERTIFICATE(S))                    SEE INSTRUCTION 3.
- --------------------------------------------------------------------------------  --------------------------------------------------
                                                                                                      TOTAL NUMBER
                                                                                                       OF SHARES
                                                                                     SHARE            REPRESENTED           NUMBER
                                                                                  CERTIFICATE          BY SHARE            OF SHARES
                                                                                  NUMBER(S)*        CERTIFICATE(S)*       TENDERED**
<S>                                                                               <C>                 <C>                 <C>
                                                                                  --------------------------------------------------

                                                                                  --------------------------------------------------

                                                                                  --------------------------------------------------

                                                                                  --------------------------------------------------

                                                                                  --------------------------------------------------

                                                                                     TOTAL SHARES
- ------------------------------------------------------------------------------------------------------------------------------------
 *  Need not be completed by Book-Entry Stockholders.
 ** Unless otherwise indicated, all Shares represented by Share Certificates
    delivered to the Depositary will be deemed to have been tendered. See
    Instruction 4.
 IF ANY SHARE CERTIFICATES HAVE BEEN LOST OR DESTROYED, SEE INSTRUCTION 11.
- ------------------------------------------------------------------------------------------------------------------------------------
</TABLE>

[ ] CHECK HERE IF SHARES ARE BEING DELIVERED BY BOOK-ENTRY TRANSFER MADE TO AN
    ACCOUNT MAINTAINED BY THE DEPOSITARY WITH DTC AND COMPLETE THE FOLLOWING
    (ONLY PARTICIPANTS IN DTC MAY DELIVER SHARES BY BOOK-ENTRY TRANSFER):

   Name of Tendering Institution:_______________________________________________

   DTC Account Number:__________________________________________________________

   DTC Transaction Code Number:_________________________________________________

[ ] CHECK HERE IF SHARES ARE BEING DELIVERED PURSUANT TO A NOTICE OF GUARANTEED
    DELIVERY PREVIOUSLY SENT TO THE DEPOSITARY AND COMPLETE THE FOLLOWING
    (PLEASE ENCLOSE A PHOTOCOPY OF SUCH NOTICE OF GUARANTEED DELIVERY):

   Name(s) of Registered Holder(s):_____________________________________________

   Window Ticket Number (if any):_______________________________________________

   Date of Execution of Notice of Guaranteed Delivery:__________________________

   Name of Institution that Guaranteed Delivery:________________________________

   If delivered by Book-Entry Transfer:_________________________________________

   DTC Account Number:__________________________________________________________

   DTC Transaction Code Number:_________________________________________________

                    NOTE: SIGNATURES MUST BE PROVIDED BELOW.
              PLEASE READ THE ACCOMPANYING INSTRUCTIONS CAREFULLY.

Ladies and Gentlemen:

     The undersigned hereby tenders to Thermo Electron Corporation, a Delaware
corporation (the "Acquiror"), the above-described shares of common stock, par
value $0.10 per share (the "Shares"), of Thermedics Inc., a Massachusetts
corporation (the "Company"), pursuant to the Acquiror's offer to exchange shares
of Acquiror's common stock, par value $1.00 per share ("Thermo Electron
Shares"), for Shares at an exchange ratio of 0.45 Thermo Electron Shares for
each Share and cash in lieu of fractional Thermo Electron Shares, upon the terms
and subject to the conditions set forth in the Acquiror's Prospectus dated May
1, 2000 (the "Prospectus") relating to its offer to exchange Thermo Electron
Shares for Shares and in this Letter of Transmittal (which, together with any
amendments or supplements thereto or hereto, collectively constitute the
"Offer"), receipt of each of which is hereby acknowledged.

     Subject to, and effective upon, acceptance for exchange of the Shares
tendered herewith in accordance with the terms and subject to the conditions of
the Offer, including, if the Offer is extended or amended, the terms and
conditions of any such extension or amendment, the undersigned hereby sells,
assigns and transfers to, or upon the order of, the Acquiror all right, title
and interest in and to all of the Shares that are being tendered hereby and any
and all dividends and distributions, including, without limitation,
distributions of additional Shares or rights declared, paid or issued with
<PAGE>   3

respect to the tendered Shares on or after May 1, 2000 (collectively,
"Distributions"), and irrevocably constitutes and appoints the Depositary the
true and lawful agent and attorney-in-fact of the undersigned with respect to
such Shares and any Distributions with full power of substitution (such power of
attorney being deemed to be an irrevocable power coupled with an interest) to
(a) deliver such Share Certificates and any Distributions, or transfer ownership
of such Shares and any Distributions on the account books maintained by DTC,
together in either case with appropriate evidences of transfer and authenticity,
to, or upon the order of, the Acquiror, upon receipt by the Depositary, as the
undersigned's agent, of the Thermo Electron Shares to be issued in exchange for
the Shares evidenced by such Share Certificates, (b) present such Shares and any
Distributions for transfer on the books of the Company, and (c) receive all
benefits and otherwise exercise all rights of record and beneficial ownership of
such Shares and any Distributions, all in accordance with the terms and subject
to the conditions of the Offer.

     The undersigned hereby irrevocably appoints Theo Melas-Kyriazi, Sandra L.
Lambert and Seth H. Hoogasian in their respective capacities as officers of the
Acquiror or one of its affiliates, and any individuals who shall hereafter
succeed to any such office of the Acquiror or one of its affiliates, and each of
them or any other designees of the Acquiror, as attorneys-in-fact and proxies of
the undersigned, each with full power of substitution, to the full extent of the
undersigned's rights with respect to any Distributions and the Shares tendered
by the undersigned and accepted for exchange and as to which the Acquiror issues
Thermo Electron Shares in exchange therefor. This power of attorney and proxy
shall be considered irrevocable and coupled with an interest in the tendered
Shares. Such appointment will be effective when, and only to the extent that,
the Acquiror accepts such Shares for exchange and deposits the Thermo Electron
Shares to be issued in respect thereof with the Depositary. Upon such deposit,
all prior powers of attorney and proxies given by the undersigned at any time
with respect to such Shares and any Distributions will, without further action,
be revoked, and no subsequent powers of attorney or proxies may be given nor any
subsequent written consents executed by the undersigned (and, if given or
executed, will not be deemed effective). Upon such deposit by the Acquiror, the
designees of the Acquiror will, with respect to such Shares and any
Distributions, be empowered to exercise all voting and other rights of the
undersigned as they in their sole discretion may deem proper at any annual or
special meeting of the Company's stockholders, or any adjournment or
postponement thereof, by written consent in lieu of any such meeting or
otherwise. The Acquiror reserves the right to require that, in order for Shares
to be deemed validly tendered, immediately upon the Acquiror's issuance of
Thermo Electron Shares in exchange for such Shares, the Acquiror must be able to
exercise full voting rights and other rights of a record and beneficial owner
with respect to such Shares and any Distributions, including, without
limitation, voting at any meeting of stockholders or by written consent in lieu
of any such meeting.

     The undersigned hereby represents and warrants that (a) the undersigned has
full power and authority to tender, sell, assign and transfer the Shares
tendered hereby and any Distributions and (b) when the Shares are accepted for
exchange by the Acquiror, the Acquiror will acquire good, marketable and
unencumbered title to the Shares and any Distributions, free and clear of all
liens, restrictions, charges and encumbrances, and the same will not be subject
to any adverse claim. The undersigned, upon request, shall execute and deliver
any additional documents deemed by the Depositary or the Acquiror to be
necessary or desirable to complete the sale, assignment and transfer of the
Shares tendered hereby and any Distributions. In addition, the undersigned shall
promptly remit and transfer to the Depositary for the account of the Acquiror
any Distribution in respect of the Shares tendered hereby, accompanied by
appropriate documentation of transfer, and, pending such remittance or
appropriate assurance thereof, the Acquiror shall be, subject to applicable law,
entitled to all rights and privileges as record and beneficial owner of any such
Distribution and may withhold shares of Thermo Electron Shares or reduce the
number of Thermo Electron Shares to be issued to the undersigned pursuant to the
Offer as provided in the Prospectus.

     No authority herein conferred or agreed to be conferred shall be affected
by, and all authority herein conferred or agreed to be conferred shall survive,
the death or incapacity of the undersigned and any obligation of the undersigned
hereunder shall be binding upon the heirs, personal representatives, successors
and assigns of the undersigned.

     Except as otherwise provided in the Prospectus, tenders of Shares made
pursuant to the Offer are irrevocable. Shares tendered pursuant to the Offer may
be withdrawn at any time prior to the Expiration Date (as such term is used in
the Prospectus) and, unless theretofore accepted for payment by the Acquiror
pursuant to the Offer, may also be withdrawn at any time after June 29, 2000.
See the section of the Prospectus captioned "The Exchange Offer -- Withdrawal
Rights."

     The undersigned understands that tenders of Shares pursuant to any of the
procedures described in the section of the Prospectus captioned "The Exchange
Offer -- Procedures For Accepting The Exchange Offer And Tendering Shares" and
in the Instructions hereto will constitute the undersigned's acceptance of the
terms and conditions of the Offer. The Acquiror's acceptance of such Shares for
exchange will constitute a binding agreement between the undersigned and the
Acquiror upon the terms and subject to the conditions set forth in the Offer.

     The undersigned understands that the Offer is conditioned upon, among other
things set forth in the Prospectus, there being validly tendered and not
withdrawn prior to the expiration of the Offer that number of Shares which,
together
<PAGE>   4

with the Shares held by the Acquiror, constitutes at least ninety percent (90%)
of the Shares outstanding on the Expiration Date.

     The undersigned understands that, under certain circumstances set forth in
the Prospectus, the Acquiror may terminate or amend the Offer or may not be
required to accept for payment any of the Shares tendered herewith.

     Unless otherwise indicated herein under "Special Issuance Instructions,"
please issue the Thermo Electron Shares and check for any cash in lieu of
fractional shares and issue or return any Share Certificate(s) for Shares not
tendered or not exchanged in the name(s) of the registered holder(s) appearing
under "Description Of Shares Tendered." Similarly, unless otherwise indicated
herein under "Special Delivery Instructions," please mail the Thermo Electron
Shares and check for any cash in lieu of fractional shares and return any Share
Certificate(s) for Shares not tendered or not exchanged (and accompanying
documents, as appropriate) to the address of the registered holder(s) appearing
under "Description Of Shares Tendered." In the event that both the "Special
Delivery Instructions" and the "Special Issuance Instructions" boxes are
completed, please issue the Thermo Electron Shares and check for any cash in
lieu of fractional shares and return any Share Certificate(s) for Shares not
tendered or not exchanged in the name(s) of, and deliver such Thermo Electron
Shares and check for any cash in lieu of fractional shares and return such Share
Certificate(s) to, the person(s) so indicated. Please credit any Shares tendered
herewith by book-entry transfer that are not exchanged by crediting the DTC
account designated above. The undersigned recognizes that the Acquiror has no
obligation pursuant to the "Special Issuance Instructions" to transfer any
Shares from the name(s) of the registered holder(s) thereof if the Acquiror does
not accept for exchange any of the Shares tendered hereby.

- --------------------------------------------------------------------------------

                         SPECIAL ISSUANCE INSTRUCTIONS
                        (SEE INSTRUCTIONS 1, 5, 6 AND 7)

     To be completed ONLY if Share Certificate(s) evidencing Shares not tendered
or not exchanged, Thermo Electron Shares issued pursuant to the Offer or the
check for any cash in lieu of fractional shares accepted for exchange are to be
issued in the name of someone other than the undersigned.

   Issue:  [ ] check     [ ] certificates to:

   Name:__________________________________________________________
                                    (PLEASE PRINT)

   Address:_______________________________________________________

   _______________________________________________________________
                               (INCLUDE ZIP CODE)
   _______________________________________________________________
                  (TAX IDENTIFICATION OR SOCIAL SECURITY NO.)
                 (SEE SUBSTITUTE FORM W-9 ON THE REVERSE SIDE)
- --------------------------------------------------------------------------------


- --------------------------------------------------------------------------------

                         SPECIAL DELIVERY INSTRUCTIONS
                        (SEE INSTRUCTIONS 1, 5, 6 AND 7)

     To be completed ONLY if Share Certificate(s) evidencing Shares not tendered
or not exchanged, Thermo Electron Shares issued pursuant to the Offer or the
check for any cash in lieu of fractional shares accepted for exchange are to be
sent to someone other than the undersigned or to the undersigned at an address
other than that shown above.

   Mail:  [ ] check     [ ] certificates to:

   Name:__________________________________________________________
                                    (PLEASE PRINT)

   Address:_______________________________________________________

   _______________________________________________________________
                               (INCLUDE ZIP CODE)



- --------------------------------------------------------------------------------
<PAGE>   5

             -------------------------------------------------------------------
SIGN                                      IMPORTANT
HERE           SIGN HERE AND COMPLETE SUBSTITUTE FORM W-9 ON THE REVERSE SIDE
- -->          X _________________________________________________________________

- -->          X _________________________________________________________________
                                  SIGNATURE(S) OF HOLDER(S)

             Dated: __________________________________________, 2000

             (Must be signed by the registered holder(s) exactly as name(s)
             appear(s) on Share Certificate(s) or on a security position listing
             or by person(s) authorized to become registered holder(s) by
             certificates and documents transmitted herewith. If signature is by
             a trustee, executor, administrator, guardian, attorney-in-fact,
             officer of a corporation or other acting in a fiduciary or
             representative capacity, please provide the following information.
             See Instruction 5.)

             Name(s): __________________________________________________________
             ___________________________________________________________________
             ___________________________________________________________________
                                       (PLEASE PRINT)

             Capacity (Full Title): ____________________________________________
             ___________________________________________________________________
             ___________________________________________________________________

             Address: __________________________________________________________
             ___________________________________________________________________
             ___________________________________________________________________
                                     (INCLUDE ZIP CODE)

             Area Code and Telephone Number: ___________________________________

             Tax Identification or Social Security No.: ________________________

             Dated: ____________________________, 2000

                                  GUARANTEE OF SIGNATURE(S)
                                 (SEE INSTRUCTIONS 1 AND 5)

             Authorized Signature: _____________________________________________

             Name: _____________________________________________________________
                                       (PLEASE PRINT)

             Title: ____________________________________________________________

             Name of Firm: _____________________________________________________
                                       (PLEASE PRINT)

             Address: __________________________________________________________
                                     (INCLUDE ZIP CODE)

             Area Code and Telephone Number: ___________________________________

             Dated: ____________________________, 2000
<PAGE>   6

                                  INSTRUCTIONS

             FORMING PART OF THE TERMS AND CONDITIONS OF THE OFFER

     1.  Guarantee of Signatures.  No signature guarantee is required on this
Letter of Transmittal (a) if this Letter of Transmittal is signed by the
registered holder(s) of Shares (which term, for purposes of this document, shall
include any DTC participant whose name appears on a security position listing as
the owner of Share(s)) tendered herewith, unless such holder(s) has (have)
completed either the box entitled "Special Issuance Instructions" or the box
entitled "Special Delivery Instructions," or (b) if such Share(s) are tendered
for the account of a firm which is a commercial bank, broker, dealer, credit
union, savings association or other entity which is a member in good standing of
the Securities Transfer Agents Medallion Program, the Stock Exchanges' Medallion
Program or the New York Stock Exchange, Inc. Medallion Signature Program (each
of the foregoing being referred to as an "Eligible Institution"). In all other
cases, all signatures on this Letter of Transmittal must be guaranteed by an
Eligible Institution. See Instruction 5.

     2.  Delivery of Letter of Transmittal and Certificates.  This Letter of
Transmittal is to be completed by stockholders either if Share Certificates are
to be forwarded herewith or, unless an Agent's Message is utilized, if delivery
of Shares is to be made by book-entry transfer pursuant to the procedures set
forth in the section of the Prospectus captioned "The Exchange
Offer -- Procedures For Accepting The Exchange Offer And Tendering Shares." In
order for Shares to be validly tendered pursuant to the Offer, this Letter of
Transmittal (or a facsimile hereof), properly completed and duly executed,
together with any required signature guarantees, or an Agent's Message in
connection with a book-entry delivery of Shares, and any other documents
required by this Letter of Transmittal, must be received by the Depositary at
one of its addresses set forth on the front cover hereof prior to the Expiration
Date and either (i) Share Certificates evidencing tendered Shares must be
received by the Depositary at such address or such Shares must be tendered by
book-entry transfer and a timely confirmation of such book-entry transfer (a
"Book-Entry Confirmation") must be received by the Depositary, in each case
prior to the Expiration Date or (ii) the guaranteed delivery procedures
described in the following sentence must be complied with. Stockholders whose
Share Certificates are not immediately available or who cannot deliver their
Share Certificates and all other required documents to the Depositary prior to
the Expiration Date or who cannot complete the procedure for delivery by
book-entry transfer on a timely basis may tender their Shares by properly
completing and duly executing a Notice of Guaranteed Delivery pursuant to the
guaranteed delivery procedures set forth in the section of the Prospectus
captioned "The Exchange Offer -- Procedures For Accepting The Exchange Offer And
Tendering Shares." Pursuant to such procedures: (i) such tender must be made by
or through an Eligible Institution; (ii) a properly completed and duly executed
Notice of Guaranteed Delivery, substantially in the form made available by the
Acquiror, must be received by the Depositary prior to the Expiration Date; and
(iii) the Share Certificates (or a Book-Entry Confirmation) evidencing all
tendered Shares, in proper form for transfer, together with this Letter of
Transmittal (or a facsimile hereof), properly completed and duly executed, with
any required signature guarantees (or, in the case of a book-entry delivery, an
Agent's Message) and any other documents required by this Letter of Transmittal,
must be received by the Depositary within three American Stock Exchange trading
days after the date of execution of such Notice of Guaranteed Delivery.

     THE METHOD OF DELIVERY OF THIS LETTER OF TRANSMITTAL, SHARE CERTIFICATES
AND ALL OTHER REQUIRED DOCUMENTS, INCLUDING DELIVERY THROUGH DTC, IS AT THE SOLE
OPTION AND RISK OF THE TENDERING STOCKHOLDER, AND THE DELIVERY WILL BE DEEMED
MADE ONLY WHEN ACTUALLY RECEIVED BY THE DEPOSITARY. IF DELIVERY IS BY MAIL,
REGISTERED MAIL WITH RETURN RECEIPT REQUESTED, PROPERLY INSURED, IS RECOMMENDED.
IN ALL CASES, SUFFICIENT TIME SHOULD BE ALLOWED TO ENSURE TIMELY DELIVERY.

     No alternative, conditional or contingent tenders will be accepted. All
tendering stockholders, by execution of this Letter of Transmittal (or a
facsimile hereof), waive any right to receive any notice of the acceptance of
their Shares for exchange.

     If Share Certificates are forwarded to the Depositary in multiple
deliveries, a properly completed and duly executed Letter of Transmittal must
accompany each such delivery.

     3.  Inadequate Space.  If the space provided herein is inadequate, the
Share Certificate numbers, the number of Shares and any other required
information should be listed on a separate signed schedule attached hereto and
referenced in the box entitled "Description Of Shares Tendered."

     4.  Partial Tenders.  (Not Applicable to Book-Entry Stockholders.)  If
fewer than all the Shares evidenced by any Share Certificate submitted to the
Depositary herewith are to be tendered, fill in the number of Shares which are
to be
<PAGE>   7

tendered in the box entitled "Number of Shares Tendered." In such cases, new
Share Certificate(s) evidencing the Shares that were evidenced by the Share
Certificate(s) delivered to the Depositary herewith, but which were not tendered
hereby, will be sent to the registered holder(s) shown above, unless otherwise
provided in the box entitled "Special Delivery Instructions," as soon as
practicable after the expiration or termination of the Offer. All Shares
represented by Share Certificates delivered to the Depositary will be deemed to
have been tendered unless otherwise indicated.

     5.  Signatures on Letter of Transmittal, Stock Powers and Endorsements.  If
this Letter of Transmittal is signed by the registered holder(s) of the Shares
tendered hereby, the signature(s) must correspond with the name(s) as written on
the face of the Share Certificate(s) without alteration, enlargement or any
change whatsoever.

     If any of the Shares tendered hereby are owned of record by two or more
persons, all such persons must sign this Letter of Transmittal.

     If any of the tendered Shares are registered in the names of different
holders, it will be necessary to complete, sign and submit as many separate
Letters of Transmittal as there are different registrations of Share
Certificates.

     If this Letter of Transmittal or any Share Certificate or stock power is
signed by a trustee, executor, administrator, guardian, attorney-in-fact,
officer of a corporation or other person acting in a fiduciary or representative
capacity, such person should so indicate when signing, and proper evidence
satisfactory to the Acquiror of such person's authority so to act must be
submitted.

     If this Letter of Transmittal is signed by the registered holder(s) of the
Shares listed and tendered hereby, no endorsements of Share Certificates or
separate stock powers are required, unless Thermo Electron Shares or Share
Certificates evidencing Shares not tendered or not exchanged are to be issued in
the name of, a person other than the registered holder(s), in which case the
Share Certificate(s) evidencing the Shares tendered hereby must be endorsed or
accompanied by appropriate stock powers signed exactly as the name(s) of the
registered holder(s) appear(s) on such Share Certificate(s). Signatures on such
Share Certificate(s) or stock powers must be guaranteed by an Eligible
Institution.

     If this Letter of Transmittal is signed by a person other than the
registered holder(s) of the Share Certificate(s) listed and tendered hereby, the
Share Certificate(s) must be endorsed or accompanied by appropriate stock
powers, in either case signed exactly as the name(s) of the registered holder(s)
appear on such Share Certificate(s). Signature(s) on such Share Certificate(s)
and stock powers must be guaranteed by an Eligible Institution.

     6.  Stock Transfer Taxes.  Except as set forth in this Instruction 6, the
Acquiror will pay or cause to be paid any stock transfer taxes with respect to
the transfer and sale of Shares to it or its order pursuant to the Offer. If,
however, delivery of Thermo Electron Shares in exchange for Shares accepted for
exchange is to be made to, or if Share Certificate(s) evidencing Shares not
tendered or not exchanged are to be issued in the name of, any person other than
the registered holder(s), or if tendered Share Certificates are registered in
the name of any person other than the person(s) signing this Letter of
Transmittal, then the tendering holder must provide satisfactory evidence of the
payment of any applicable transfer taxes, (whether imposed on the registered
holder or such person) payable on account of the transfer to such person prior
to the delivery of Thermo Electron Shares.

     EXCEPT AS SET FORTH IN THIS INSTRUCTION 6, IT WILL NOT BE NECESSARY FOR
TRANSFER TAX STAMPS TO BE AFFIXED TO THE SHARE CERTIFICATE(S) TENDERED HEREBY.

     7.  Special Payment and Delivery Instructions.  If delivery of Thermo
Electron Shares in exchange for Shares accepted for exchange is to be made to,
if a check for cash in lieu of fractional shares accepted for exchange is to be
issued in the name of, or Share Certificate(s) evidencing Shares not tendered or
not exchanged are to be issued or returned to, a person other than the signer of
this Letter of Transmittal or if a check or such Share Certificate(s) are to be
returned to a person other than the signer of this Letter of Transmittal or to
an address of the signer other than that shown in this Letter of Transmittal,
the appropriate boxes on this Letter of Transmittal must be completed.

     8.  Waiver of Conditions.  The conditions of the Offer may be waived by the
Acquiror, in whole or in part, at any time and from time to time prior to the
Expiration Date in its sole discretion.

     9.  Substitute Form W-9.  Under U.S. federal income tax law, a stockholder
whose tendered Shares are accepted for exchange is required to provide the
Depositary with such stockholder's correct taxpayer identification number
<PAGE>   8

("TIN") (e.g., social security number or employer identification number) on
Substitute Form W-9 below and to certify whether such stockholder is subject to
backup withholding of federal income tax. If a tendering stockholder has been
notified by the Internal Revenue Service (the "IRS") that such stockholder is
subject to backup withholding, such stockholder must cross out item 2 of the
Certification box (Part 2) of the Substitute Form W-9, unless such stockholder
has since been notified by the IRS that such stockholder is no longer subject to
backup withholding. Failure to provide the information on the Substitute Form
W-9 may subject the tendering stockholder to federal income tax withholding at
the rate of 31% on the payment of any cash in lieu of fractional shares. If the
Depositary is not provided with the correct TIN, the IRS may subject the
stockholder or other payee to a $50 penalty.

     Certain stockholders are not subject to these backup withholding and
reporting requirements. Exempt recipients, such as corporations, are also
requested to provide their TIN and check the "Exempt" box in Part 3. Foreign
individuals or entities must submit a Form W-8 or W-8BEN, signed under penalties
of perjury, attesting to their foreign status. A Form W-8 or W8-BEN can be
obtained from the Depositary. See the enclosed "Guidelines For Certification Of
Taxpayer Identification Number On Substitute Form W-9" for more instructions.

     IF BACKUP WITHHOLDING APPLIES, THE DEPOSITARY IS REQUIRED TO WITHHOLD 31%
OF ANY CASH PAYMENTS MADE TO THE STOCKHOLDER OR OTHER PAYEE. BACKUP WITHHOLDING
IS NOT AN ADDITIONAL TAX. RATHER, THE TAX LIABILITY OF PERSONS SUBJECT TO BACKUP
WITHHOLDING WILL BE REDUCED BY THE AMOUNT OF TAX WITHHELD. IF WITHHOLDING
RESULTS IN AN OVERPAYMENT OF TAXES, A REFUND MAY BE OBTAINED FROM THE IRS.

     The "Awaiting TIN" box in Part 3 of the Substitute Form W-9 may be checked
if the tendering stockholder has not been issued a TIN and has applied for a TIN
or intends to apply for a TIN in the near future. If the "Awaiting TIN" box in
Part 3 is checked, the stockholder or other payee must also complete the
"Certificate Of Awaiting Taxpayer Identification Number" below in order to avoid
backup withholding. If the "Awaiting TIN" box in Part 3 is checked and the
"Certificate Of Awaiting Taxpayer Identification Number" is completed, the
Depositary may withhold 31% of all reportable cash payments made unless a
properly certified TIN is provided to the Depositary within 60 days.

     The stockholder is required to give the Depositary the TIN of the record
owner of the Shares or of the last transferee appearing on the transfers
attached to, or endorsed on, the Shares. If the Shares are in more than one name
or are not in the name of the actual owner, consult the enclosed "Guidelines For
Certification Of Taxpayer Identification Number On Substitute Form W-9" for
additional guidance on which number to report.

     10.  Questions and Requests for Assistance or Additional Copies.  Questions
and requests for assistance may be directed to the Information Agent at its
address and telephone numbers set forth below. Additional copies of the
Prospectus, this Letter of Transmittal and all other tender offer materials may
be obtained from the Information Agent or from brokers, dealers, commercial
banks or trust companies at the Acquiror's expense.

     11.  Lost, Destroyed or Stolen Certificates.  If any Share Certificate has
been lost, destroyed or stolen, the stockholder should promptly notify the
Depositary at (781) 575-3120. The Depositary will forward additional
documentation which such stockholder must complete in order to effectively
surrender such lost or destroyed Share Certificate(s) (including affidavits of
loss and indemnity bonds in lieu thereof). There may be a fee in respect of lost
or destroyed Share Certificates, and surrenders hereunder regarding such lost
certificates will be processed only after such documentation has been submitted
to and approved by the Depositary.

     IMPORTANT: THIS LETTER OF TRANSMITTAL (OR A FACSIMILE HEREOF), PROPERLY
COMPLETED AND DULY EXECUTED, OR, IF APPROPRIATE, AN AGENT'S MESSAGE, TOGETHER
WITH SHARE CERTIFICATES OR CONFIRMATION OF BOOK-ENTRY TRANSFER AND ALL OTHER
REQUIRED DOCUMENTS, OR A PROPERLY COMPLETED AND DULY EXECUTED NOTICE OF
GUARANTEED DELIVERY, MUST BE RECEIVED BY THE DEPOSITARY PRIOR TO THE EXPIRATION
DATE.
<PAGE>   9

<TABLE>
<S>                                <C>                                                    <C>
- ----------------------------------------------------------------------------------------------------------------------------
                                                 PAYER'S NAME: EQUISERVE, L.P.
- ----------------------------------------------------------------------------------------------------------------------------
 SUBSTITUTE                         PART 1 -- PLEASE PROVIDE YOUR TIN IN THE BOX AT THE    _______________________________
 FORM W-9                           RIGHT AND CERTIFY BY SIGNING AND DATING BELOW:              Social security number
 DEPARTMENT OF THE TREASURY,
 INTERNAL REVENUE SERVICE                                                                                 or
 PAYER'S REQUEST FOR                                                                       _______________________________
 TAXPAYER IDENTIFICATION                                                                       Employer identification
 NUMBER ("TIN")                                                                                         number
                                                                                           (If awaiting TIN, write "Applied
                                                                                                         For")
                                   -----------------------------------------------------------------------------------------
                                    PART 2 -- CERTIFICATION -- Under penalties of                  PART 3 --
                                    perjury, I certify that:                                       [ ] Awaiting TIN
                                    (1) The number shown on this form is my correct                [ ] Exempt
                                        Taxpayer Identification Number (or I am waiting
                                        for a number to be issued to me), and
                                    (2) I am not subject to backup withholding because:
                                        (a) I am exempt from backup withholding, or
                                        (b) I have not been notified by the Internal
                                            Revenue Service (the "IRS") that I am subject
                                            to backup withholding as a result of a failure
                                            to report all interest or dividends, or
                                        (c) the IRS has notified me that I am no longer
                                            subject to backup withholding.
                                   -----------------------------------------------------------------------------------------
                                    CERTIFICATION INSTRUCTIONS -- You must cross out Item (2) above if you have been
                                    notified by the IRS that you are currently subject to backup withholding because of
                                    underreporting interest or dividends on your tax return. However, if after being
                                    notified by the IRS that you were subject to backup withholding you received another
                                    notification from the IRS that you are no longer subject to backup withholding, do not
                                    cross out such Item (2).
- ----------------------------------------------------------------------------------------------------------------------------

          SIGN HERE -->            SIGNATURE ______________________________________________  DATE __________, 2000
- ----------------------------------------------------------------------------------------------------------------------------
</TABLE>

NOTE: FAILURE TO COMPLETE AND RETURN THIS FORM MAY RESULT IN BACKUP WITHHOLDING
      OF 31% OF ANY REPORTABLE CASH PAYMENTS MADE TO YOU PURSUANT TO THE OFFER.
      PLEASE REVIEW THE ENCLOSED GUIDELINES FOR CERTIFICATION OF TAXPAYER
      IDENTIFICATION NUMBER ON SUBSTITUTE FORM W-9 FOR ADDITIONAL DETAILS.
<PAGE>   10

               YOU MUST COMPLETE THE FOLLOWING CERTIFICATE IF YOU
        CHECKED THE "AWAITING TIN" BOX IN PART 3 OF SUBSTITUTE FORM W-9.

- --------------------------------------------------------------------------------

             CERTIFICATE OF AWAITING TAXPAYER IDENTIFICATION NUMBER

     I certify under penalties of perjury that a Taxpayer Identification Number
has not been issued to me, and either (1) I have mailed or delivered an
application to receive a Taxpayer Identification Number to the appropriate
Internal Revenue Service Center or Social Security Administration Office, or (2)
I intend to mail or deliver an application in the near future. I understand that
if I do not provide a Taxpayer Identification Number, 31% of all reportable cash
payments made to me may be withheld until I provide a Taxpayer Identification
Number with required certifications, which should be provided within 60 days.

Signature: ________________________________________  Dated: ______________, 2000

- --------------------------------------------------------------------------------
<PAGE>   11

                    The Information Agent for the Offer is:

                             D.F. KING & CO., INC.
                          77 Water Street, 20th Floor
                               New York, NY 10005
                Bankers and Brokers Call Collect (212) 269-5550
                    All Others Call Toll-Free (800) 290-6433

<PAGE>   1

                         NOTICE OF GUARANTEED DELIVERY
                                      FOR
                        TENDER OF SHARES OF COMMON STOCK
                                       OF
                                THERMEDICS INC.
                                       TO
                          THERMO ELECTRON CORPORATION

     As set forth in the section captioned "The Exchange Offer -- Procedures For
Accepting The Exchange Offer And Tendering Shares" of the Prospectus dated May
1, 2000 (the "Prospectus"), this Notice of Guaranteed Delivery or one
substantially in the form hereof must be used to tender shares of common stock,
par value $0.10 per share (the "Shares"), of Thermedics Inc., a Massachusetts
corporation (the "Company"), pursuant to the Offer (as defined below) if
certificates evidencing Shares are not immediately available or the certificates
evidencing Shares and all other required documents cannot be delivered to
EquiServe, L.P. (the "Depositary") prior to the Expiration Date (as such term is
used in the Prospectus), or if the procedures for delivery by book-entry
transfer cannot be completed on a timely basis. This instrument may be delivered
by hand or transmitted by facsimile transmission, overnight courier or mail to
the Depositary.

                        The Depositary for the Offer is:

                                EQUISERVE, L.P.

<TABLE>
<S>                                    <C>                                         <C>
        By First Class Mail:                            By Hand:                    By Overnight, Certified or Express
                                                                                                   Mail:
           EquiServe, L.P.                  Securities Transfer & Reporting
   Attn: Corporate Reorganization                    Services, Inc.                           EquiServe, L.P.
            P.O. Box 8029                         c/o EquiServe, L.P.                 Attn: Corporate Reorganization
        Boston, MA 02266-8029                 100 Williams Street/Galleria                   150 Royall Street
                                                   New York, NY 10038                        Canton, MA 02021
</TABLE>

<TABLE>
<S>                                    <C>                                            <C>
        For Information Call:                   By Facsimile Transmission:                   For Confirmation Call:
           (781) 575-3120                           (781) 575-2233/2232                          (781) 575-3417
                                           (Valid For Book Entry Accounts Only)
</TABLE>

     DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY TO AN ADDRESS OTHER THAN AS
SET FORTH ABOVE, OR TRANSMISSIONS OF INSTRUCTIONS VIA A FACSIMILE NUMBER OTHER
THAN AS SET FORTH ABOVE, WILL NOT CONSTITUTE A VALID DELIVERY.

     This Notice of Guaranteed Delivery is not to be used to guarantee
signatures. If a signature on a Letter of Transmittal is required to be
guaranteed by an Eligible Institution (as such term is used in the Prospectus)
under the instructions thereto, such signature guarantee must appear in the
applicable space provided in the signature box in the Letter of Transmittal.

              THE GUARANTEE ON THE REVERSE SIDE MUST BE COMPLETED
<PAGE>   2

Ladies and Gentlemen:

     The undersigned hereby tenders to Thermo Electron Corporation, a Delaware
corporation, upon the terms and subject to the conditions set forth in the
Prospectus and in the related Letter of Transmittal (which, together with any
amendments or supplements thereto, collectively constitute the "Offer"), receipt
of each of which is hereby acknowledged, the number of Shares indicated below
pursuant to the guaranteed delivery procedures set forth in the section of the
Prospectus captioned "The Exchange Offer -- Procedures For Accepting The
Exchange Offer And Tendering Shares."

- --------------------------------------------------------------------------------

 Signature(s): ____________________________      Address: ______________________

 Name(s) of Record Holder(s): _____________      _______________________________
                                                                        Zip Code
 __________________________________________
                                                 Area Code and Tel. No(s):______
 __________________________________________
          Please Type or Print                   Check box if shares will be
                                                 tendered by book-entry
 Number of Shares: ________________________      transfer: [ ]

 Share Certificate No(s). (if available):        DTC Account Number: ___________

 __________________________________________

 __________________________________________

 Dated: _____________________________, 2000

                                   GUARANTEE
                   (Not to be used for signature guarantees)

      The undersigned, a firm which is a commercial bank, broker, dealer,
 credit union, savings association or other entity which is a member in good
 standing of the Securities Transfer Agents Medallion Program, the Stock
 Exchanges' Medallion Program or the New York Stock Exchange, Inc. Medallion
 Signature Program, hereby guarantees to either deliver to the Depositary
 certificates evidencing all the Shares tendered hereby, in proper form for
 transfer, or to deliver such Shares pursuant to the procedure for book-entry
 transfer into the Depositary's account at The Depository Trust Company, in
 either case together with the Letter of Transmittal (or a facsimile thereof),
 properly completed and duly executed, with any required signature guarantees
 or an Agent's Message (as such term is used in the Prospectus) in the case of
 a book-entry transfer, and any other required documents, all within three
 American Stock Exchange trading days after the date hereof.

 Name of Firm: _________________________________________________________________

 Address: ______________________________________________________________________

 _______________________________________________________________________________
                                                                        Zip Code

 Area Code and Tel. No.: _______________________________________________________

 Authorized Signature: _________________________________________________________

 Name: _________________________________________________________________________

 Title: ________________________________________________________________________

 Dated: __________________________________________________________________, 2000

     NOTE: DO NOT SEND CERTIFICATES WITH THIS NOTICE OF GUARANTEED DELIVERY.
         CERTIFICATES SHOULD BE SENT WITH YOUR LETTER OF TRANSMITTAL.

- --------------------------------------------------------------------------------

<PAGE>   1

                          THERMO ELECTRON CORPORATION

                               OFFER TO EXCHANGE
                          0.45 SHARES OF COMMON STOCK
                                       OF

                          THERMO ELECTRON CORPORATION
                                      FOR
                     EACH OUTSTANDING SHARE OF COMMON STOCK
                                       OF

                                THERMEDICS INC.

- --------------------------------------------------------------------------------
  THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY
          TIME, ON FRIDAY, MAY 26, 2000, UNLESS THE OFFER IS EXTENDED.
- --------------------------------------------------------------------------------

                                                                     May 1, 2000

To:  Brokers, Dealers, Commercial Banks,
     Trust Companies and Other Nominees:

     This letter relates to the offer by Thermo Electron Corporation, a Delaware
corporation (the "Acquiror"), to exchange shares of the Acquiror's common stock,
par value $1.00 per share (the "Thermo Electron Shares"), for shares of common
stock, value $0.10 per share (the "Shares"), of Thermedics Inc., a Massachusetts
corporation (the "Company"), at an exchange ratio of 0.45 Thermo Electron Shares
for each Share (along with cash in lieu of fractional Thermo Electron Shares),
upon the terms and subject to the conditions set forth in the Prospectus dated
May 1, 2000 (the "Prospectus") and in the related Letter of Transmittal (which,
together with any amendments or supplements thereto, collectively constitute the
"Offer") enclosed herewith.

     THE OFFER IS CONDITIONED UPON, AMONG OTHER THINGS DESCRIBED IN THE
PROSPECTUS, THERE BEING VALIDLY TENDERED AND NOT WITHDRAWN PRIOR TO THE
EXPIRATION OF THE OFFER THAT NUMBER OF SHARES WHICH, TOGETHER WITH SHARES OWNED
BY THERMO ELECTRON, CONSTITUTES AT LEAST NINETY PERCENT (90%) OF THE OUTSTANDING
SHARES ON THE EXPIRATION DATE (AS SUCH TERM IS USED IN THE SECTION OF THE
PROSPECTUS CAPTIONED "THE EXCHANGE OFFER -- TERMS OF THE EXCHANGE OFFER;
EXPIRATION OF THE EXCHANGE OFFER"). THE OFFER IS ALSO SUBJECT TO OTHER IMPORTANT
TERMS AND CONDITIONS CONTAINED IN THE PROSPECTUS.

     Enclosed for your information and for forwarding to your clients for whose
accounts you hold Shares registered in your name or in the name of your nominees
are copies of the following documents:

        1. The Prospectus dated May 1, 2000.

        2. The Letter of Transmittal to tender Shares (for your use and for the
           information of your clients), including Guidelines for Certification
           of Taxpayer Identification Number on Substitute Form W-9.

        3. The Notice of Guaranteed Delivery for Shares (to be used to accept
           the Offer if certificates evidencing Shares ("Share Certificates")
           are not immediately available or if such Share Certificates and all
           other required documents cannot be delivered to EquiServe, L.P. (the
           "Depositary") prior to the Expiration Date or if the procedures for
           book-entry transfer cannot be completed on a timely basis).

        4. A printed form of letter which may be sent to your clients for whose
           accounts you hold Shares registered in your name or in the name of
           your nominees, with space provided for obtaining such clients'
           instructions with regard to the Offer.

        5. A return envelope addressed to the Depositary.

     YOUR PROMPT ACTION IS REQUESTED. WE URGE YOU TO CONTACT YOUR CLIENTS AS
PROMPTLY AS POSSIBLE. PLEASE NOTE THAT THE OFFER AND WITHDRAWAL RIGHTS WILL
EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY TIME, ON FRIDAY, MAY 26, 2000, UNLESS
THE OFFER IS EXTENDED.

     In all cases, the delivery of Thermo Electron Shares for Shares tendered
and accepted for exchange pursuant to the Offer will be made only after timely
receipt by the Depositary of (i) Share Certificates or timely confirmation of a
book-entry transfer of such Shares into the Depositary's account at The
Depository Trust Company pursuant to the procedures set forth in the section of
the Prospectus captioned "The Exchange Offer -- Procedures For Accepting The
Exchange Offer And Tendering Shares," (ii) the Letter of Transmittal (or a
facsimile thereof), properly completed and duly executed, with any required
signature guarantees, or an Agent's Message (as such term is used in the section
of the Prospectus captioned "The Exchange Offer -- Acceptance For Exchange And
Exchange Of Shares") in connection with a book-entry transfer, and (iii) any
other documents required by the Letter of Transmittal.
<PAGE>   2

     If a stockholder desires to tender Shares pursuant to the Offer and such
stockholder's Share Certificates are not immediately available or such
stockholder cannot deliver the Share Certificates and all other required
documents to reach the Depositary prior to the Expiration Date, or such
stockholder cannot complete the procedure for delivery by book-entry transfer on
a timely basis, such Shares may nevertheless be tendered by following the
guaranteed delivery procedures specified in the section of the Prospectus
captioned "The Exchange Offer -- Procedures For Accepting The Exchange Offer And
Tendering Shares."

     No fees or commissions will be paid to brokers, dealers or any other
persons (other than to D.F. King & Co., Inc., the Information Agent, as
described in the Prospectus) for soliciting tenders of Shares pursuant to the
Offer. The Acquiror will, however, upon request, reimburse you for customary
mailing and handling expenses incurred by you in forwarding any of the enclosed
materials to your clients.

     The Acquiror will pay or cause to be paid any stock transfer taxes payable
on the transfer of Shares by the Acquiror pursuant to the Offer, except as
otherwise provided in Instruction 6 of the Letter of Transmittal.

     Questions and requests for assistance or for additional copies of the
enclosed materials may be directed to the Information Agent at its address and
telephone numbers set forth on the back cover of the Prospectus.

     NOTHING CONTAINED HEREIN OR IN THE ENCLOSED DOCUMENTS SHALL CONSTITUTE YOU
OR ANY OTHER PERSON THE AGENT OF THERMO ELECTRON CORPORATION OR ANY OF ITS
SUBSIDIARIES, THE COMPANY, THE DEPOSITARY OR THE INFORMATION AGENT, OR ANY
AFFILIATE OF ANY OF THEM, OR AUTHORIZE YOU OR ANY OTHER PERSON TO MAKE ANY
STATEMENT OR USE ANY DOCUMENT ON BEHALF OF ANY OF THEM IN CONNECTION WITH THE
OFFER OTHER THAN THE ENCLOSED DOCUMENTS AND THE STATEMENTS CONTAINED THEREIN.

<PAGE>   1

                          THERMO ELECTRON CORPORATION
                               OFFER TO EXCHANGE
                          0.45 SHARES OF COMMON STOCK

                                       OF

                          THERMO ELECTRON CORPORATION
                                      FOR

                     EACH OUTSTANDING SHARE OF COMMON STOCK

                                       OF

                                THERMEDICS INC.

- --------------------------------------------------------------------------------

  THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY
          TIME, ON FRIDAY, MAY 26, 2000, UNLESS THE OFFER IS EXTENDED.

- --------------------------------------------------------------------------------

To Our Clients:

     Enclosed for your consideration is a Prospectus dated May 1, 2000 (the
"Prospectus") and the related Letter of Transmittal (which, together with any
amendments or supplements thereto, collectively constitute the "Offer") relating
to an offer by Thermo Electron Corporation, a Delaware corporation (the
"Acquiror"), to exchange shares of common stock of the Acquiror, par value $1.00
per share (the "Thermo Electron Shares"), for shares of common stock, par value
$0.10 per share (the "Shares"), of Thermedics Inc., a Massachusetts corporation
(the "Company"), at an exchange ratio of 0.45 Thermo Electron Shares for each
Share (along with cash in lieu of fractional Thermo Electron Shares), upon the
terms and subject to the conditions set forth in the Offer.

     We are the holder of record of Shares held by us for your account. A TENDER
OF SUCH SHARES CAN BE MADE ONLY BY US AS THE HOLDER OF RECORD AND PURSUANT TO
YOUR INSTRUCTIONS. THE LETTER OF TRANSMITTAL IS FURNISHED TO YOU FOR YOUR
INFORMATION ONLY AND CANNOT BE USED BY YOU TO TENDER SHARES HELD BY US FOR YOUR
ACCOUNT.

     We request instructions as to whether you wish to have us tender on your
behalf any or all of the Shares held by us for your account, pursuant to the
terms and subject to the conditions set forth in the Offer.

     Your attention is directed to the following:

     - The exchange ratio of 0.45 Thermo Electron Shares for each Share (along
       with cash in lieu of fractional Thermo Electron Shares).

     - The Offer and withdrawal rights will expire at 12:00 midnight, New York
       City time, on Friday, May 26, 2000, unless the Offer is extended.

     - The Offer is made for all of the outstanding Shares not owned by Thermo
       Electron.

     - The Offer is conditioned upon, among other things described in the
       Prospectus, there being validly tendered and not withdrawn prior to the
       expiration of the Offer that number of Shares which, together with Shares
       owned by Thermo Electron, constitutes at least ninety percent (90%) of
       the outstanding Shares on the Expiration Date (as such term is used in
       the section of the Prospectus captioned "The Exchange Offer -- Terms Of
       The Exchange Offer; Expiration Of The Exchange Offer"). The Offer is also
       subject to other important terms and conditions contained in the
       Prospectus.
<PAGE>   2

     - Tendering stockholders will not be obligated to pay brokerage fees or
       commissions or, except as set forth in Instruction 6 of the Letter of
       Transmittal, stock transfer taxes on the transfer of Shares to the
       Acquiror pursuant to the Offer.

     - In all cases, the delivery of Thermo Electron Shares for Shares tendered
       and accepted for exchange pursuant to the Offer will be made only after
       timely receipt by EquiServe, L.P. (the "Depositary") of (i) certificates
       evidencing Shares or timely confirmation of a book-entry transfer of such
       Shares into the Depositary's account at The Depository Trust Company
       pursuant to the procedures set forth in the section of the Prospectus
       captioned "The Exchange Offer -- Procedures For Accepting The Exchange
       Offer And Tendering Shares," (ii) the Letter of Transmittal (or a
       facsimile thereof), properly completed and duly executed, with any
       required signature guarantees, or an Agent's Message (as such term is
       used in the section of the Prospectus captioned "The Exchange
       Offer -- Acceptance For Exchange And Exchange Of Shares") in connection
       with a book-entry transfer and (iii) any other documents required by the
       Letter of Transmittal.

     The Offer is being made solely by the Prospectus and the related Letter of
Transmittal and is being made to all holders of Shares. The Offer is not being
made to (nor will tenders be accepted from or on behalf of) holders of Shares in
any jurisdiction in which the making of the Offer or the acceptance thereof
would not be in compliance with the laws of such jurisdiction. However, Thermo
Electron may, in its sole discretion, take such action as it may deem necessary
to make the Offer in any such jurisdiction and extend the Offer to holders of
Shares in such jurisdiction.

     If you wish to have us tender any or all of the Shares held by us for your
account, please instruct us by completing, executing and returning to us the
instruction form contained in this letter. If you authorize a tender of your
Shares, all such Shares will be tendered unless otherwise specified in such
instruction form. YOUR INSTRUCTIONS SHOULD BE FORWARDED TO US IN AMPLE TIME TO
PERMIT US TO SUBMIT A TENDER ON YOUR BEHALF PRIOR TO THE EXPIRATION OF THE
OFFER.
<PAGE>   3

                        INSTRUCTIONS WITH RESPECT TO THE
                               OFFER TO EXCHANGE
                          0.45 SHARES OF COMMON STOCK
                                       OF

                          THERMO ELECTRON CORPORATION
                                      FOR
                     EACH OUTSTANDING SHARE OF COMMON STOCK
                                       OF

                                THERMEDICS INC.

     The undersigned acknowledge(s) receipt of your letter and the enclosed
Prospectus dated May 1, 2000 (the "Prospectus") and the related Letter of
Transmittal (which, together with any amendments or supplements thereto,
collectively constitute the "Offer") relating to an offer by Thermo Electron
Corporation, a Delaware corporation, to exchange shares of common stock of
Thermo Electron, par value $1.00 share (the "Thermo Electron Shares"), for
shares of common stock, par value $0.10 per share (the "Shares"), of Thermedics
Inc., a Massachusetts corporation, at an exchange ratio of 0.45 Thermo Electron
Shares for each Share (along with cash in lieu of fractional Thermo Electron
Shares), upon the terms and subject to the conditions of the Offer.

     This will instruct you to tender the number of Shares indicated below (or,
if no number is indicated below, all Shares) that are held by you for the
account of the undersigned, upon the terms and subject to the conditions set
forth in the Offer.

<TABLE>
<CAPTION>
<S>  <C>                                                 <C>
     ------------------------------------------------
     Number of Shares to be
     Tendered(1):
     ------------------------------------------------
     Dated: ------------------------------, 2000

     SIGN HERE                                           x
                                                         ------------------------------------------------
                                                         Signature(s):
                                                         ------------------------------------------------
                                                         Please type or print name(s):
                                                         ------------------------------------------------
                                                         Address:
                                                         ------------------------------------------------
                                                         Area Code and Telephone Number:
                                                         ------------------------------------------------
                                                         Tax Identification or Social Security No.:

  (1) Unless otherwise indicated, it will be assumed that all of the Shares held by us for your account
      are to be tendered.
</TABLE>

<PAGE>   1

            GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                         NUMBER ON SUBSTITUTE FORM W-9

GUIDELINES FOR DETERMINING THE PROPER IDENTIFICATION NUMBER TO GIVE THE PAYER.
Social Security numbers have nine digits separated by two hyphens: i.e.,
000-00-0000. Employer identification numbers have nine digits separated by only
one hyphen: i.e., 00-0000000. The table below will help determine the number to
give the Payer.

<TABLE>
<C>  <S>                                 <C>
- ------------------------------------------------------------
                                         GIVE THE
FOR THIS TYPE OF ACCOUNT:                SOCIAL SECURITY
                                         NUMBER OF:
- ------------------------------------------------------------

 1.  An individual's account             The individual
 2.  Two or more individuals (joint      The actual owner of
     account)                            the account or, if
                                         combined funds, the
                                         first individual on
                                         the account(1)
 3.  Husband and wife (joint account)    The actual owner of
                                         the account or, if
                                         joint funds, the
                                         first individual on
                                         the account(1)
 4.  Custodian account of a minor        The minor(2)
     (Uniform Gift to Minors Act)
 5.  Adult and minor (joint account)     The adult, or, if
                                         the minor is the
                                         only contributor,
                                         the minor(1)
 6.  Account in the name of guardian or  The ward, minor, or
     committee for a designated ward,    incompetent
     minor or incompetent person         person(3)
 7.  (a) The usual revocable savings     The grantor-
         trust account (grantor is also  trustee(1)
         trustee)
     (b) So-called trust account that    The actual owner(1)
         is not a legal or valid trust
         under State law
 8.  Sole proprietorship account         The owner(4)
- ------------------------------------------------------------
</TABLE>

<TABLE>
<C>  <S>                                 <C>
- ------------------------------------------------------------
                                         GIVE THE EMPLOYER
FOR THIS TYPE OF ACCOUNT:                IDENTIFICATION
                                         NUMBER OF:
- ------------------------------------------------------------

 9.  A valid trust, estate, or pension   The legal entity
     trust                               (Do not furnish the
                                         identifying number
                                         of the personal
                                         representative or
                                         trustee unless the
                                         legal entity itself
                                         is not designated
                                         in the account
                                         title.)(5)
10.  Corporate account                   The corporation
11.  Religious, charitable, or           The organization
     educational organization account
12.  Partnership account held in the     The partnership
     name of the business
13.  Association, club, or other tax-    The organization
     exempt organization
14.  A broker or registered nominee      The broker or
                                         nominee
15.  Account with the Department of      The public entity
     Agriculture in the name of a
     public entity (such as a State or
     local government, school district,
     or prison) that receives
     agricultural program payments
- ------------------------------------------------------------
</TABLE>

(1) List first and circle the name of the person whose number you furnish.
(2) Circle the minor's name and furnish the minor's social security number.
(3) Circle the ward's, minor's or incompetent person's name and furnish such
    person's social security number.
(4) Show the name of the owner.
(5) List first and circle the name of the legal trust, estate, or pension trust.

NOTE: If no name is circled when there is more than one name, the number will be
      considered to be that of the first name listed.
<PAGE>   2

               GUIDELINES FOR CERTIFICATION OF TAXPAYER IDENTIFICATION
                            NUMBER ON SUBSTITUTE FORM W-9

                                        PAGE 2

OBTAINING A NUMBER
If you don't have a taxpayer identification number or you don't know your
number, obtain Form SS-5, Application for a Social Security Number Card (for
individuals), or Form SS-4, Application for Employer Identification Number (for
businesses and all other entities), at the local office of the Social Security
Administration or the Internal Revenue Service and apply for a number.

PAYEES EXEMPT FROM BACKUP WITHHOLDING
Payees specifically exempted from backup withholding on ALL payments include the
following (Section references are to the Internal Revenue Code):
  - A corporation.
  - A financial institution.
  - An organization exempt from tax under section 501(a), or an individual
    retirement plan, or a custodial account under section 403(b)(7).
  - The United States or any agency or instrumentality thereof.
  - A State, the District of Columbia, a possession of the United States, or any
    subdivision or instrumentality thereof.
  - A foreign government, a political subdivision of a foreign government, or
    any agency or instrumentality thereof.
  - An international organization or any agency, or instrumentality thereof.
  - A registered dealer in securities or commodities registered in the U.S. or
    possession of the U.S.
  - A real estate investment trust.
  - A common trust fund operated by a bank under section 584(a).
  - An exempt charitable remainder trust, or a non-exempt trust described in
    section 4947(a)(1).
  - An entity registered at all times under the Investment Company Act of 1940.
  - A foreign central bank of issue.
Payments of dividends and patronage dividends not generally subject to backup
withholding include the following:
  - Payments to nonresident aliens subject to withholding under section 1441.
  - Payments to partnerships not engaged in a trade or business in the U.S. and
    which have at least one nonresident partner.
  - Payments of patronage dividends where the amount received is not paid in
    money.
  - Payments made by certain foreign organizations.
  - Payments made to a nominee.
Payments of interest not generally subject to backup withholding include the
following:
  - Payments of interest on obligations issued by individuals.

NOTE: You may be subject to backup withholding if this interest is $600 or more
and is paid in the course of the payer's trade or business and you have not
provided your correct taxpayer identification number to the payer.
  - Payments of tax-exempt interest (including exempt-interest dividends under
    section 852).
  - Payments described in section 6049(b)(5) to nonresident aliens.
  - Payments on tax-free government bonds under section 1451.
  - Payments made by certain foreign organizations.
  - Payments made to a nominee.
Exempt payees described above should file the Substitute Form W-9 to avoid
possible erroneous backup withholding. FILE THIS FORM WITH THE PAYER, FURNISH
YOUR TAXPAYER IDENTIFICATION NUMBER, WRITE "EXEMPT" ON THE FACE OF THE FORM,
SIGN AND DATE THE FORM AND RETURN IT TO THE PAYER.

Certain payments other than interest, dividends, and patronage dividends that
are not subject to information reporting are also not subject to backup
withholding. For details, see sections 6041, 6041A(a), 6042, 6044, 6045, 6049,
6050A and 6050N, and the regulations under those sections.

PRIVACY ACT NOTICE.  Section 6109 requires most recipients of dividend,
interest, or other payments to give taxpayer identification numbers to payers
who must report the payments to the IRS. The IRS uses the numbers for
identification purposes and to help verify the accuracy of tax returns. Payers
must be given the numbers whether or not recipients are required to file a tax
return. Payers must generally withhold 31% of taxable interest, dividend, and
certain other payments to a payee who does not furnish a taxpayer identification
number to a payer. Certain penalties may also apply.

PENALTIES
(1) PENALTY FOR FAILURE TO FURNISH TAXPAYER IDENTIFICATION NUMBER.  If you fail
to furnish your taxpayer identification number to a payer, you are subject to a
penalty of $50 for each such failure unless your failure is due to reasonable
cause and not to willful neglect.
(2) FAILURE TO REPORT CERTAIN DIVIDEND AND INTEREST PAYMENTS. If you fail to
include any portion of an includible payment for interest, dividends or
patronage dividends in gross income, such failure is strong evidence of
negligence. If negligence is shown, you will be subject to a penalty of 20% on
any portion of an underpayment attributable to that failure.
(3) CIVIL PENALTY FOR FALSE INFORMATION WITH RESPECT TO WITHHOLDING.  If you
make a false statement with no reasonable basis which results in no imposition
of backup withholding, you are subject to a penalty of $500.
(4) CRIMINAL PENALTY FOR FALSIFYING INFORMATION.  Willfully falsifying
certifications or affirmations may subject you to criminal penalties including
fines and/or imprisonment.

 FOR ADDITIONAL INFORMATION CONTACT YOUR TAX CONSULTANT OR THE INTERNAL REVENUE
                                    SERVICE.


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