SCHEDULE 14A INFORMATION
 
          PROXY STATEMENT PURSUANT TO SECTION 14(A) OF THE SECURITIES
                              EXCHANGE ACT OF 1934
 
FILED BY THE REGISTRANT /X/       FILED BY A PARTY OTHER THAN THE REGISTRANT / /
 
- --------------------------------------------------------------------------------
 
Check the appropriate box:
 
/X/ Preliminary Proxy Statement
/ / Confidential, for Use of the Commission Only (as permitted by Rule
14a-6(e)(2))
/ / Definitive Proxy Statement
/ / Definitive Additional Materials
/ / Soliciting Material Pursuant to Section240.14a-11(c) or Section240.14a-12
 
                                                THERMEDICS INC.
- --------------------------------------------------------------------------------
                (Name of Registrant as Specified In Its Charter)
 
                                                THERMEDICS INC.
- --------------------------------------------------------------------------------
                   (Name of Person(s) Filing Proxy Statement)
 
PAYMENT OF FILING FEE (CHECK THE APPROPRIATE BOX):
 
   
/ /  No fee required.
/ /  Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.
 
     1)  Title of each class of securities to which transaction applies: Common
         Stock
         -----------------------------------------------------------------------
     2)  Aggregate number of securities to which transaction applies: 4,880,553
         -----------------------------------------------------------------------
     3)  Per unit price or other underlying value of transaction computed
         pursuant to Exchange Act Rule 0-11 (Set forth the amount on which the
         filing fee is calculated and state how it was determined): The filing
         fee of $10,067 represents 1/50 of 1% of $50,330,703, which amount is
         the value of the securities to be issued by the registrant as
         consideration in the transaction (as calculated by multiplying the
         average of the high and low prices of the registrant's common stock on
         December 1, 1998 by the number of shares to be issued).
 
         -----------------------------------------------------------------------
     4)  Proposed maximum aggregate value of transaction: $50,330,703
         -----------------------------------------------------------------------
     5)  Total fee paid: $10,067
         -----------------------------------------------------------------------
 
/X/  Fee paid previously with preliminary materials.
 
/ /  Check box if any part of the fee is offset as provided by Exchange Act Rule
     0-11(a)(2) and identify the filing for which the offsetting fee was paid
     previously. Identify the previous filing by registration statement number,
     or the Form or Schedule and the date of its filing.
 
     1)  Amount Previously Paid:
         -----------------------------------------------------------------------
     2)  Form, Schedule or Registration Statement No.:
         -----------------------------------------------------------------------
 
     3)  Filing Party:
         -----------------------------------------------------------------------
 
     4)  Date Filed:
         -----------------------------------------------------------------------
 
    

THERMEDICS INC.
 
470 Wildwood Street
P.O. Box 2999
Woburn, Massachusetts 01888-1799
 
   
                                           February  , 1999
    
 
Dear Stockholder:
 
    The enclosed Notice calls a Special Meeting of the Stockholders of
Thermedics Inc. I respectfully request all Stockholders to attend this meeting,
if possible.
 
   
    Enclosed with this letter is a proxy authorizing three officers of the
Company to vote your shares for you if you do not attend the meeting. Whether or
not you are able to attend the meeting, I urge you to complete your proxy and
return it to our transfer agent, BankBoston, N.A., in the enclosed addressed,
postage-paid envelope, as a quorum of the Stockholders must be present at the
meeting, either in person or by proxy.
    
 
    I would appreciate your immediate attention to the mailing of this proxy.
 
                                        Yours very truly,
 
   
                                        John T. Keiser
                                        PRESIDENT AND CHIEF EXECUTIVE OFFICER
    

THERMEDICS INC.
 
470 Wildwood Street
P.O. Box 2999
Woburn, Massachusetts 01888-1799
 
                           NOTICE OF SPECIAL MEETING
 
   
                                                               February   , 1999
    
 
To the Holders of the Common Stock of
THERMEDICS INC.
 
   
    A Special Meeting of the Stockholders (the "Meeting") of Thermedics Inc.
(the "Company") will be held on      ,          , 1999, at 10 a.m. at the
offices of Thermo Electron Corporation, 81 Wyman Street, Waltham, Massachusetts
02454. The purpose of the Meeting is to consider and vote upon a proposal to
approve the listing on the American Stock Exchange, Inc. of 4,880,553 shares of
the Company's common stock to be issued in connection with the acquisition of
TMO TCA Holdings, Inc. from Thermo Electron Corporation pursuant to an Agreement
and Plan of Reorganization dated as of October 30, 1998. The sole asset of TMO
TCA Holdings, Inc. is its ownership of 3,355,705 shares of common stock of the
Company's Thermo Cardiosystems Inc. subsidiary.
    
 
   
    The transfer books of the Company will not be closed prior to the Meeting,
but, pursuant to appropriate action by the Board of Directors, the record date
for the determination of the Stockholders entitled to receive notice of and to
vote at the Meeting is February 15, 1999.
    
 
    The By-laws require that the holders of a majority of the stock issued and
outstanding and entitled to vote be present or represented by proxy at the
Meeting in order to constitute a quorum for the transaction of business. It is
important that your shares be represented at the Meeting regardless of the
number of shares you may hold. Whether or not you are able to be present in
person, please sign and return promptly the enclosed proxy in the accompanying
envelope, which requires no postage if mailed in the United States.
 
    This Notice, the proxy and proxy statement enclosed herewith are sent to you
by order of the Board of Directors.
 
                                          SANDRA L. LAMBERT
                                          CLERK

                                PROXY STATEMENT
 
   
    The enclosed proxy is solicited by the Board of Directors of Thermedics Inc.
(the "Company") for use at a Special Meeting of the Stockholders (the "Meeting")
to be held on       ,           , 1999 at 10 a.m. local time at the offices of
Thermo Electron Corporation ("Thermo Electron"), 81 Wyman Street, Waltham,
Massachusetts 02454, and any adjournment thereof. The mailing address of the
executive office of the Company is 470 Wildwood Street, P.O. Box 2999, Woburn,
Massachusetts 01888-1799, and the telephone number for both the Company and
Thermo Electron is (781) 622-1000. This proxy statement and the enclosed proxy
were first furnished to Stockholders of the Company on or about           ,
1999.
    
 
                               VOTING PROCEDURES
 
   
    The Board of Directors intends to present to the Meeting a proposal to
approve the listing on the American Stock Exchange, Inc. of 4,880,533 shares of
the Company's common stock, $.10 par value per share ("Common Stock"), to be
issued in connection with the acquisition by the Company of TMO TCA Holdings,
Inc. from Thermo Electron pursuant to an Agreement and Plan of Reorganization
dated as of October 30, 1998, a copy of which is attached hereto as Appendix A.
The sole asset of TMO TCA Holdings, Inc. is its ownership of 3,355,705 shares of
common stock of the Company's Thermo Cardiosystems Inc. subsidiary.
    
 
    The representation in person or by proxy of a majority of the outstanding
shares of Common Stock entitled to vote at the Meeting is necessary to provide a
quorum for the transaction of business at the Meeting. Shares can only be voted
if the Stockholder is present in person or is represented by returning a
properly signed proxy. Each Stockholder's vote is very important. Whether or not
you plan to attend the Meeting in person, please sign and promptly return the
enclosed proxy card, which requires no postage if mailed in the United States.
All signed and returned proxies will be counted towards establishing a quorum
for the Meeting, regardless of how the shares are voted. Proxies are being
solicited by the Company.
 
    Shares represented by proxy will be voted in accordance with your
instructions. You may specify your choice by marking the appropriate box on the
proxy card. If your proxy card is signed and returned without specifying
choices, your shares will be voted for the management proposal and as the
individuals named as proxy holders on the proxy deem advisable on all other
matters as may properly come before the Meeting.
 
    The affirmative vote of a majority of the shares present in person or
represented by proxy, and entitled to vote on the matter, is necessary for
approval of the management proposal. An instruction to abstain from voting on
the proposal will be treated as shares present and entitled to vote and, for
purposes of determining the outcome of the vote, will have the same effect as a
vote against the proposal. A broker "non-vote" occurs when a nominee holding
shares for a beneficial holder does not have discretionary voting power and does
not receive voting instructions from the beneficial owner. Broker "non-votes"
will not be treated as shares present and entitled to vote on a voting matter
and will have no effect on the outcome of the vote.
 
    A Stockholder who returns a proxy may revoke it at any time before the
Stockholder's shares are voted at the Meeting by written notice to the Clerk of
the Company received prior to the Meeting, by executing and returning a later
dated proxy or by voting by ballot at the Meeting. Representatives of Arthur
Andersen LLP, the Company's independent public accountants since its inception,
are not expected to be present at the Meeting.
 
   
    The outstanding stock of the Company entitled to vote (excluding shares held
in treasury by the Company) as of February 15, 1999 consisted of         shares
of Common Stock. Only Stockholders of record at the close of business on
February 15, 1999 (the "Record Date") are entitled to vote at the Meeting. Each
share is entitled to one vote.
    
 
   
    Thermo Electron has agreed to vote all of the shares of the Common Stock
held by it as of the Record Date in favor of the proposal and all matters
related thereto. As of the Record Date (without giving effect to the issuance of
the 4,880,533 shares contemplated by this proxy statement), Thermo Electron
beneficially owned approximately    % of the outstanding Common Stock.
ACCORDINGLY, APPROVAL OF THE PROPOSAL BY THE STOCKHOLDERS OF THE COMPANY IS
ASSURED.
    
 
                                       1

        PROPOSAL TO APPROVE THE LISTING OF SHARES ISSUABLE IN CONNECTION
                 WITH THE ACQUISITION OF TMO TCA HOLDINGS INC.
 
SUMMARY OF TRANSACTIONS CONTEMPLATED BY THE MERGER AGREEMENT
 
   
    On October 30, 1998, the Company agreed to issue 4,880,533 shares (the "TMD
Shares") of its Common Stock to Thermo Electron Corporation ("Thermo Electron")
in exchange for all of the issued and outstanding shares of TMO TCA Holdings,
Inc. ("TCA Holdings"). TCA Holdings is the owner of 3,355,705 shares (the "TCA
Shares") of common stock of the Company's Thermo Cardiosystems Inc. subsidiary
("Thermo Cardiosystems"). The acquisition, which became legally effective on
January 21, 1999, was made pursuant to an Agreement and Plan of Reorganization
dated as of October 30, 1998 (the "Merger Agreement"), among the Company, Cardio
Acquisition Inc., a wholly owned subsidiary of the Company ("Acquisition"),
Thermo Electron, and TCA Holdings, a wholly owned subsidiary of Thermo Electron.
Under the terms of the Merger Agreement, (i) Acquisition merged with and into
TCA Holdings, (ii) the outstanding shares of TCA Holdings' common stock were
canceled and converted into the right to receive the TMD Shares, (iii) each
outstanding share of Acquisition's common stock was canceled and converted into
one share of the common stock of TCA Holdings, and (iv) TCA Holdings became a
wholly owned subsidiary of the Company.
    
 
   
    Approval of the Merger by the Stockholders of the Company is not required by
the Business Corporation Law of the Commonwealth of Massachusetts or by the
Company's Articles of Organization, as amended or By-Laws, as amended. However,
rules of the American Stock Exchange, Inc. (the "AMEX"), on which the Company's
Common Stock is listed for trading, require that the holders of a majority of
the Company's outstanding shares present and voting at a shareholders' meeting
approve the listing of the TMD Shares prior to their issuance. This approval is
required pursuant to Section 712 of the AMEX Company Guide, which requires
shareholder approval prior to the listing on the AMEX of shares to be issued as
partial consideration for an acquisition if (i) any substantial shareholder of
the listed company has a five percent or greater interest in the company to be
acquired and (ii) the issuance of the new shares could result in an increase in
the outstanding shares of the listed company of five percent or more. Thermo
Electron is a "substantial shareholder" of the Company and also has more than a
five percent interest in TCA Holdings. In addition, the issuance of the TMD
Shares in consideration of the Merger would result in an increase in the
Company's outstanding Common Stock of more than five percent. Thermo Electron
has agreed to vote all of the shares of the Company's Common Stock held by it as
of the record date of the Meeting (the "Record Date") in favor of the listing of
the TMD Shares and all matters related thereto. As of the Record Date, and
without giving effect to the issuance of the TMD Shares pursuant to the Merger
Agreement, Thermo Electron owned approximately      % of the outstanding Common
Stock of the Company. After giving effect to the issuance of the TMD Shares
pursuant to the Merger Agreement, Thermo Electron would have owned approximately
     % of such Common Stock outstanding on the Record Date.
    
 
BACKGROUND OF THE MERGER AGREEMENT
 
    The Company has several majority owned subsidiaries, including Thermo
Cardiosystems, a leader in the research, development and manufacture of
implantable left ventricular-assist systems. Thermo Electron owns all of the
stock of TCA Holdings, which in turn owns the TCA Shares. TCA Holdings had
acquired the TCA Shares in connection with Thermo Cardiosystems' acquisition of
International Technidyne Corporation ("ITC") from Thermo Electron on May 2,
1997. ITC is a leading manufacturer of near-patient, whole-blood coagulation
testing equipment and related disposables.
 
    The Board of Directors of the Company has determined that it is the best
interests of the Company to acquire TCA Holdings in order to increase the
Company's ownership of Thermo Cardiosystems. On February 5, 1998, the Board of
Directors approved the acquisition of TCA Holdings.
 
                                       2

DETERMINATION OF THE CONSIDERATION ISSUABLE FOR TCA HOLDINGS
 
   
    Under the terms of the Merger Agreement, the Company has agreed to issue the
TMD Shares to Thermo Electron in consideration of the acquisition of TCA
Holdings. The consideration to be paid for TCA Holdings was based on the
Company's determination of the fair market value of TCA Holding's sole asset,
its ownership of the TCA Shares. The fair market value of the TCA Shares was
determined based on a per share value of $22.525, which was the average of the
closing prices of Thermo Cardiosystems' common stock as reported on the AMEX for
the five trading days ending on February 4, 1998, the date prior to the date the
Board of Directors of the Company approved the acquisition. The number of shares
of Common Stock to be issued as consideration in the Merger was determined based
on a per share value of $15.488, which was the average of the closing prices of
the Common Stock as reported on the AMEX for the same period. Based on these
calculations, it was determined that the fair market value of the TCA Shares was
$75,587,000. The Company also determined that the consideration to be paid by it
to acquire TCA Holdings would be 4,880,533 shares of Common Stock, which had a
fair market value equal to the value of the TCA Shares.
    
 
REASONS FOR THE MERGER/RECOMMENDATION OF THE BOARD OF DIRECTORS
 
    The Board of Directors believes that the acquisition of TCA Holdings was in
the best interests of the Company. The acquisition provided the Company with a
strategic opportunity to increase its ownership of Thermo Cardiosystems prior to
Thermo Cardiosystems commencing commercial sales of its implantable left
ventricular-assist systems. By increasing its ownership of Thermo Cardiosystems,
the Company reduces the minority interest in Thermo Cardiosystems and is able to
include a greater portion of Thermo Cardiosystems' net income in the Company's
consolidated results of operations. The Board of Directors also believes that
decreasing fractionalized ownership of Thermo Cardiosystems is in the best
interests of both the Company and Thermo Cardiosystems.
 
   
    For federal income tax purposes, no gain or loss will be recognized by the
Company in connection with the Merger. See "Certain Federal Income Tax
Consequences." Further, as the consideration to be paid to Thermo Electron
consists of Common Stock of the Company rather than cash, the transaction will
not impair the Company's working capital.
    
 
    The Board of Directors has unanimously approved the Merger Agreement and the
transactions contemplated thereby and believes that the Merger is fair to and in
the best interests of the Company and its Stockholders. THE BOARD OF DIRECTORS
UNANIMOUSLY RECOMMENDS THAT STOCKHOLDERS VOTE IN FAVOR OF THE LISTING OF THE TMD
SHARES TO BE ISSUED IN CONNECTION WITH THE MERGER AGREEMENT.
 
SUMMARY OF THE MERGER AGREEMENT
 
    GENERAL
 
    On October 30, 1998, the Company, Acquisition, Thermo Electron and TCA
Holdings entered into the Merger Agreement, pursuant to which the Company
acquired TCA Holdings from Thermo Electron in exchange for the right to receive
the TMD Shares. Under the terms of the Merger Agreement (i) Acquisition merged
with and into TCA Holdings, (ii) outstanding shares of TCA Holdings' common
stock were canceled and converted into the right to receive the TMD Shares,
(iii) each outstanding share of Acquisition's common stock was canceled and
converted into one share of the common stock of TCA Holdings, and (iv) TCA
Holdings became a wholly owned subsidiary of the Company. See "Determination of
the Consideration Issuable for TCA Holdings," above for a discussion of the
valuation of the transaction.
 
                                       3

    EFFECTIVE DATE
 
   
    The Merger became legally effective on January 21, 1999, upon the filing of
Articles of Merger with the Secretary of State of the Commonwealth of
Massachusetts pursuant to Section 79 of the Business Corporation Law of the
Commonwealth of Massachusetts and a Certificate of Merger with the Secretary of
State of the State of Delaware pursuant to Section 252 of the General
Corporation Law of the State of Delaware.
    
 
    ISSUANCE OF THE SHARES
 
    Upon the effective date of the Merger, all of the shares of TCA Holdings'
common stock, which were held by Thermo Electron, were canceled and converted
into the right to receive the TMD Shares. Thermo Electron's right to receive the
TMD Shares is conditioned only on the prior listing of the TMD Shares for
trading upon the AMEX. In the Merger Agreement, the Company agreed to take all
action necessary in accordance with applicable law to convene a meeting of its
Stockholders for the purpose of approving the listing of the TMD Shares for
trading upon the AMEX, and to recommend to the Stockholders the approval of such
listing. In the Merger Agreement, Thermo Electron agreed to vote all of the
shares of the Company's Common Stock held by it as of the record date of any
such meeting in favor of such listing. The Agreement provides that, in the event
that the Company is unable to obtain the approval of its Stockholders of the
listing of the TMD Shares on or before December 31, 1999, then, on December 31,
1999, the Company will pay to Thermo Electron the sum of $75,587,000 in cash in
lieu of issuing the TMD Shares.
 
   
    As of the Record Date, and without giving effect to the issuance of the TMD
Shares pursuant to the Merger Agreement, Thermo Electron owned an aggregate of
approximately      % of the outstanding Common Stock of the Company. After
giving effect to the issuance of the TMD Shares pursuant to the Merger
Agreement, Thermo Electron would have owned approximately      % of such Common
Stock outstanding on the Record Date.
    
 
    REPRESENTATIONS AND WARRANTIES; INDEMNIFICATION
 
    In the Merger Agreement, the Company and Acquisition, on the one hand, and
TCA Holdings and Thermo Electron, on the other hand, made certain
representations and warranties to one another with respect to certain customary
matters, such as their respective organization, their respective authority to
enter into the Merger Agreement and the enforceability of the Merger Agreement.
In addition, TCA Holdings and Thermo Electron made certain representations and
warranties to the Company with respect to (i) TCA Holdings' ownership of the TCA
Shares, (ii) the absence of liabilities of TCA Holdings, (iii) the absence of
any trade or business of TCA Holdings, (iv) certain tax matters and (v) other
matters requested by the Company's counsel. Each of these representations and
warranties survives the effectiveness of the Merger indefinitely. Each party has
agreed to indemnify the other for any damages the indemnified party suffers as a
result of breaches of such representations and warranties by the other party.
Notwithstanding this indemnification, the Company would be required to report as
an expense in its results of operations the full amount, including any
reimbursable amount, of any damages, with any indemnification payment it
receives from Thermo Electron being treated as a contribution to stockholders'
investment.
 
    CERTAIN ADJUSTMENTS
 
    The Merger Agreement provides that, in the event that the Company takes
certain actions (such as stock splits, recapitalizations and sales of
substantial portions of the Company's assets) prior to the date of issuance of
the TMD Shares (the "Payment Date"), then the number of shares of the Company's
Common Stock to be issued pursuant to the Merger will be adjusted as required to
put Thermo Electron in the same position as if the record date with respect to
any such transaction or transactions had been immediately after the Payment
Date, or otherwise to carry out the intents and purposes of the Merger
Agreement.
 
                                       4

Similarly, in the event that the Company declares any dividend or other
distribution in respect of the Company's Common Stock payable in cash or other
property other than in shares of Common Stock, then the TMD Shares to be issued
in connection with the Merger shall be deemed to be outstanding as of the record
date with respect to any such dividend or distribution, and the cash or other
property otherwise payable or distributable to Thermo Electron with respect to
such TMD Shares shall be held by the Company for the benefit of Thermo Electron.
Upon the issuance of the TMD Shares to Thermo Electron, such cash or other
property (together with any earnings or interest thereon) will likewise be
distributed by the Company to Thermo Electron.
 
    AMENDMENTS; WAIVERS
 
    Any provision of the Merger Agreement may be amended or waived by the mutual
consent of the parties at any time.
 
CERTAIN FEDERAL INCOME TAX CONSEQUENCES
 
   
    For federal income tax purposes, no gain or loss will be recognized by the
Company in connection with the Merger. Neither the Company nor Thermo Electron
intend to request a ruling from the Internal Revenue Service with respect to the
Merger.
    
 
   
ACCOUNTING TREATMENT
    
 
   
    The transaction has been accounted for as an increase in the number of
outstanding shares of the Company and an increase in the Company's percentage
ownership of Thermo Cardiosystems from the date the transaction was approved by
the Company's Board of Directors.
    
 
REGULATORY APPROVALS
 
    No federal or state regulatory approvals are required in order to issue the
TMD Shares pursuant to the Merger Agreement.
 
NO DISSENTERS' APPRAISAL RIGHTS
 
    Under applicable provisions of the Business Corporation Law of the
Commonwealth of Massachusetts, holders of the Company's Common Stock will not
have any dissenters' appraisal rights in connection with the listing of the TMD
Shares.
 
                  INFORMATION CONCERNING TMO TCA HOLDINGS INC.
 
   
    Under the terms of the Merger Agreement, the Company has acquired all of the
issued and outstanding shares of capital stock of TCA Holdings, a wholly owned
subsidiary of Thermo Electron, in exchange for the right to receive the TMD
Shares. TCA Holdings was incorporated on February 2, 1998, its principal
executive office is located at 81 Wyman Street, Waltham, Massachusetts 02454 and
its telephone number is (781) 622-1000.
    
 
BUSINESS
 
    TCA Holdings is the owner of the TCA Shares. Thermo Cardiosystems, which is
a majority owned subsidiary of the Company, is a leader in the research,
development and manufacture of implantable left ventricular-assist systems. All
of such TCA Shares are owned free and clear of any charges, liens, encumbrances,
security interests or adverse claims. There are no shareholder agreements,
voting trusts, proxies or other agreements, instruments or understandings with
respect to the voting of the TCA Shares.
 
    Other than the TCA Shares, TCA Holdings does not own, lease or use, directly
or indirectly, any assets or other property, whether real or personal, tangible
or intangible. TCA Holdings does not, directly
 
                                       5

or indirectly, own any equity interest in any corporation, partnership joint
venture or other entity. TCA Holdings does not engage, and since its
organization has not engaged, in any trade or business, and it has no
liabilities or obligations of any nature, whether accrued, absolute, contingent
or otherwise. TCA Holdings does not have, nor has it ever had, any employees.
 
MANAGEMENT
 
   
    Theo Melas-Kyriazi, 39, has served as president and sole director of TCA
Holdings since January 1999. In addition, Mr. Melas-Kyriazi was treasurer of the
Company and Thermo Electron from May 1988 to August 1994. From August 1994
through March 1998, he served as president and chief executive officer of
ThermoSpectra Corporation, an affiliate of Thermo Electron, which manufactures
precision imaging, inspection, temperature control and test and measurement
systems. He served as vice president, corporate strategy, of Thermo Electron
from March 1998 through December 1998. As of January 1, 1999, Mr. Melas-Kyriazi
became the chief financial officer of the Company and Thermo Electron. Mr.
Melas-Kyriazi is a director of Thermo Voltek Corp., ThermoRetec Corporation and
ThermoSpectra Corporation.
    
 
                       INFORMATION CONCERNING THE COMPANY
 
MARKET FOR COMPANY'S COMMON STOCK AND RELATED STOCKHOLDER MATTERS
 
    The Company's Common Stock is publicly traded on the AMEX. The following
sets forth, for the fiscal periods indicated, the high and low sales prices as
reported in the consolidated transaction reporting system.
 
   


                                                                              HIGH        LOW
                                                                            ---------  ---------
                                                                                 
FISCAL 1995
  First Quarter...........................................................  $17 1/8    $12 3/4
  Second Quarter..........................................................  19 7/8     15 5/8
  Third Quarter...........................................................  21 1/2     18 1/8
  Fourth Quarter..........................................................  27 1/2     17 3/4
 
FISCAL 1996
  First Quarter...........................................................  29 7/8     23 5/8
  Second Quarter..........................................................  31 3/4     24 7/8
  Third Quarter...........................................................  28 3/4     20 3/4
  Fourth Quarter..........................................................  26 3/8     18
 
FISCAL 1997
  First Quarter...........................................................  21 1/8     16 7/8
  Second Quarter..........................................................  19         15
  Third Quarter...........................................................  19 9/16    15 11/16
  Fourth Quarter..........................................................  20 3/16    15 1/16
 
FISCAL 1998
  First Quarter...........................................................  17 13/16   14 15/16
  Second Quarter..........................................................  17 1/2     12 3/8
  Third Quarter...........................................................  12 13/16   7 7/16
  Fourth Quarter..........................................................  11         6 15/16
 
FISCAL 1999
  First Quarter (through                 , 1999)..........................

    
 
                                       6

   
    The high, low and closing prices of the Company's Common Stock on the AMEX
on February 4, 1998, the date prior to the date the Board of Directors of the
Company approved the Merger were $16, $15 3/16 and $16, respectively. On
February 15, 1999, the closing price of the Common Stock on the AMEX was $
per share. There were         holders of Common Stock of record as of February
15, 1999. Holders of Common Stock do not have any preemptive rights to subscribe
for additional issuances of Common Stock or securities convertible into Common
Stock.
    
 
    The Company has never paid any cash dividends because its policy is to use
earnings to finance expansion and growth. The Company's Board of Directors
anticipates that for the foreseeable future no cash dividends will be paid on
the Company's Common Stock.
 
SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (IN THOUSANDS EXCEPT PER SHARE
  AMOUNTS)
 


                                                                                                1998
                                                                                   -------------------------------
                                                                                     FIRST     SECOND      THIRD
                                                                                   ---------  ---------  ---------
                                                                                                
Revenues.........................................................................  $  75,611  $  76,711  $  81,515
Gross Profit.....................................................................     37,000     37,839     37,454
Income Before Extraordinary Item.................................................      5,368      5,274      4,278
Net Income.......................................................................      6,573      8,707      4,278
Earnings per Share Before Extraordinary Item:
  Basic..........................................................................        .13        .13        .10
  Diluted........................................................................        .13        .12        .10
Earnings per Share:
  Basic..........................................................................        .16        .21        .10
  Diluted........................................................................        .16        .20        .10

 


                                                                                           1997
                                                                        ------------------------------------------
                                                                                             
                                                                          FIRST     SECOND      THIRD     FOURTH
                                                                        ---------  ---------  ---------  ---------
Revenues..............................................................  $  72,057  $  75,996  $  76,217  $  83,396
Gross Profit..........................................................     35,096     37,856     37,784     41,250
Net Income............................................................     21,966      5,506      6,664      7,356
Earnings per Share:
  Basic...............................................................        .60        .15        .18        .20
  Diluted.............................................................        .56        .14        .17        .19

 


                                                                                           1996
                                                                        ------------------------------------------
                                                                                             
                                                                          FIRST     SECOND      THIRD     FOURTH
                                                                        ---------  ---------  ---------  ---------
Revenues..............................................................  $  68,994  $  71,094  $  74,202  $  77,787
Gross Profit..........................................................     33,185     34,121     37,668     38,966
Net Income............................................................      5,257      9,754      6,359      7,768
Earnings per Share:
  Basic...............................................................        .15        .27        .17        .21
  Diluted.............................................................        .14        .25        .16        .20

 
                                       7

SELECTED FINANCIAL INFORMATION
 
    The selected financial information included below for the Company as of and
for the fiscal years ended January 3, 1998, and December 28, 1996, and for the
fiscal year ended December 30, 1995, has been derived from the Company's
Consolidated Financial Statements, which have been audited by Arthur Andersen
LLP, independent public accountants, as indicated in their report incorporated
by reference herein. The selected financial information as of December 30, 1995,
and as of and for the fiscal years ended December 31, 1994, and January 1, 1994,
has been derived from the Company's Consolidated Financial Statements, which
have been audited by Arthur Andersen LLP, but have not been included in this
Proxy Statement or incorporated by reference herein. The selected financial
information as of and for the nine months ended October 3, 1998, and September
27, 1997, has not been audited but, in the opinion of the Company, includes all
adjustments (consisting only of normal, recurring adjustments) necessary to
present fairly such information in accordance with generally accepted accounting
principles applied on a consistent basis. The results of operations for the nine
months ended October 3, 1998, are not necessarily indicative of results for the
entire year.
 


                                        NINE MONTHS ENDED
                                    --------------------------                       FISCAL YEAR
                                    OCTOBER 3,   SEPTEMBER 27,  -----------------------------------------------------
                                       1998          1997         1997       1996       1995       1994       1993
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
                                                                                       
                                                         (IN THOUSANDS EXCEPT PER SHARE AMOUNTS)
STATEMENT OF INCOME DATA:
Revenues..........................   $ 233,887     $ 224,270    $ 307,666  $ 292,077  $ 208,041  $ 183,753  $ 104,545
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
Costs and Operating Expenses:
  Cost of revenues................     121,594       113,534      155,680    148,137    110,935     99,328     56,484
  Selling, general, and
    administrative
    expenses......................      66,671        63,851       86,308     85,045     55,951     49,813     28,614
  Research and development
    expenses......................      19,543        17,752       24,270     21,363     14,874     14,143      9,212
  Nonrecurring costs..............      --            --           --         17,637     --         --         --
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
                                       207,808       195,137      266,258    272,182    181,760    163,284     94,310
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
Operating Income..................      26,079        29,133       41,408     19,895     26,281     20,469     10,235
Interest and Other Income, Net....       6,009         7,715       10,414      7,951      5,831      4,989      4,582
Gain on Issuance of Stock by
  Subsidiaries....................      --            17,075       17,075     23,651      3,455     --         --
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
Income Before Provision for Income
  Taxes, Minority Interest, and
  Extraordinary Item..............      32,088        53,923       68,897     51,497     35,567     25,458     14,817
Provision for Income Taxes........      12,604        14,391       19,675     13,969     11,781      9,680      5,862
Minority Interest Expense.........       4,564         5,396        7,730      8,390      6,612      3,083      1,322
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
Income Before Extraordinary
  Item............................      14,920        34,136       41,492     29,138     17,174     12,695      7,633
Extraordinary Item, Net of
  Provision for Income Taxes......       4,638        --           --         --         --         --         --
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
Net Income........................   $  19,558     $  34,136    $  41,492  $  29,138  $  17,174  $  12,695  $   7,633
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
Earnings per Share:
  Basic...........................   $     .48     $     .93    $    1.13  $     .80  $     .51  $     .39  $     .25
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
  Diluted.........................   $     .46     $     .88    $    1.07  $     .75  $     .48  $     .38  $     .25
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
Weighted Average Shares:
  Basic...........................      41,065        36,695       36,700     36,417     33,660     32,878     30,291
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
  Diluted.........................      43,061        38,913       38,911     38,202     35,036     33,108     30,509
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
                                    -----------  -------------  ---------  ---------  ---------  ---------  ---------
BALANCE SHEET DATA (AT END OF
  PERIOD):
Working Capital...................   $ 232,596     $ 289,325    $ 309,363  $ 208,170  $ 114,340  $ 131,578  $ 135,992
Total Assets......................     559,019       535,601      536,552    456,699    386,249    306,691    251,874
Long-term Obligations.............     122,678       143,464      142,771     74,359     45,201     82,551     59,130
Shareholders' Investment..........     243,608       220,596      227,346    211,582    172,751    136,783    122,186

 
                                       8

   
PROPOSED REORGANIZATION
    
 
   
    On August 12, 1998 and December 10, 1998, Thermo Electron issued press
releases announcing a proposed reorganization involving itself and certain of
its subsidiaries, including the Company.
    
 
   
    As part of the proposed reorganization, in an integrated series of
transactions, the Company's equity interest in each of Thermo Sentron Inc.
("Thermo Sentron"), Thermedics Detection Inc. ("Thermedics Detection") and
Thermo Voltek Corp. ("Thermo Voltek"), each currently majority owned, publicly
traded subsidiaries of the Company would be transferred, along with additional
shares of the Company's Common Stock, to Thermo Electron in exchange for Thermo
Electron's wholly owned biomedical group. In addition, the Company has entered
into a definitive merger agreement with Thermo Voltek pursuant to which, if
required shareholder approvals are obtained, Thermo Voltek will be taken
private. Under the terms of the merger agreement, the Company will acquire all
of the outstanding shares of common stock of Thermo Voltek that it and Thermo
Electron do not own at a price of $7.00 per share.
    
 
   
    The completion of each of these transactions is subject to numerous
conditions including one or more of the following: the establishment of prices
and exchange ratios; confirmation of anticipated tax consequences; the approval
by the Board of Directors of the Company (including its independent directors);
negotiation and execution of definitive agreements; clearance by the Securities
and Exchange Commission of any necessary documents in connection with the
proposed transactions; approval by the Board of Directors of Thermo Electron;
and receipt of fairness opinions from one or more investment banking firms on
certain financial aspects of the transactions.
    
 
                                       9

                           FORWARD-LOOKING STATEMENTS
 
    In connection with the "safe harbor" provisions of the Private Securities
Litigation Reform Act of 1995, the Company wishes to caution readers that the
following important factors, among others, in some cases have affected, and in
the future could affect, the Company's actual results and could cause its actual
results in 1998 and beyond to differ materially from those expressed in any
forward-looking statements made by, or on behalf of, the Company.
 
    RISKS ASSOCIATED WITH ACQUISITION STRATEGY.  The Company's strategy includes
the acquisition of businesses and technologies that complement or augment its
existing product lines. Promising acquisitions are difficult to identify and
complete for a number of reasons, including competition among prospective buyers
and the need for regulatory approval, including antitrust approvals. There can
be no assurance that the Company will be able to complete future acquisitions or
that it will be able to successfully integrate any acquired business. In order
to finance such acquisitions, it may be necessary for the Company to raise
additional funds through public or private financings. Any equity or debt
financing, if available at all, may be on terms which are not favorable to the
Company and, in the case of equity financing, may result in dilution to the
Company's stockholders.
 
    RISKS ASSOCIATED WITH SPIN-OUT OF SUBSIDIARIES.  The Company has adopted a
strategy of spinning out certain of its businesses into separate subsidiaries
and having these subsidiaries sell a minority interest to outside investors. As
a result of the sale of stock by subsidiaries, the issuance of stock by
subsidiaries upon conversion of convertible debentures and similar transactions,
the Company records gains that represent the increase in the Company's net
investment in the subsidiaries. These gains have represented a substantial
portion of the net income reported by the Company in certain periods. The size
and timing of these transactions are dependent on market and other conditions
that are beyond the Company's control. Accordingly, there can be no assurance
that the Company will be able to generate gains from such transactions in the
future.
 
    In addition, in October 1995, the Financial Accounting Standards Board
("FASB") issued an exposure draft of a Proposed Statement of Financial
Accounting Standards, "Consolidated Financial Statements: Policy and Procedures"
(the "Proposed Statement"). The Proposed Statement would establish new rules for
how consolidated financial statements should be prepared. If the Proposed
Statement is adopted, there could be significant changes in the way the Company
records certain transactions of its controlled subsidiaries. Among those
changes, any sale of the stock of a subsidiary that does not result in a loss of
control would be accounted for as a transaction in equity of the consolidated
entity with no gain or loss being recorded. The exposure draft addresses the
consolidation issues in two parts: consolidation procedures, which includes
proposed rule changes affecting the Company's ability to recognize gains on
issuances of subsidiary stock, and consolidation policy, which does not address
accounting for such gains. During 1997, the FASB decided to focus its efforts on
the consolidation policy part of the exposure draft and to consider resuming
discussion on consolidation procedures after completion of the efforts on
consolidation policy. The timing and content of any final statement are
uncertain.
 
    INTERNATIONAL OPERATIONS.  Sales outside the U.S. have accounted for a
significant percentage of the Company's total revenues. The Company intends to
continue to expand its presence in international markets. International sales
are subject to a number of risks, including the following: agreements may be
difficult to enforce and receivables difficult to collect through a foreign
country's legal system; foreign customers may have longer payment cycles;
foreign countries may impose additional withholding taxes or otherwise tax the
Company's foreign income, impose tariffs, or adopt other restrictions on foreign
trade; fluctuations in exchange rates may affect product demand and adversely
affect the profitability in U.S. dollars of products and services provided by
the Company in foreign markets where payment for the Company's products and
services is made in the local currency; U.S. export licenses may be difficult to
obtain; and the protection of intellectual property in foreign countries may be
more difficult to enforce. There can be no assurance that any of these factors
will not have a material adverse effect on the
 
                                       10

Company's business and results of operations. During fiscal year 1997, the
Company had exports from its U.S. and foreign operations to Asia of
approximately 8% of total revenues. Exports to Asia in fiscal year 1997 were
primarily to Japan, China, and South Korea. Asia is experiencing a severe
economic crisis, which has been characterized by sharply reduced economic
activity and liquidity, highly volatile foreign-currency-exchange and interest
rates, and unstable stock markets. The Company's export sales could be adversely
affected by the unstable economic conditions in Asia.
 
    TECHNOLOGICAL CHANGE AND COMPETITION.  The market for many of the Company's
products is characterized by changing technology, evolving industry standards,
and new product introductions. The Company's future success will depend, in
part, upon its ability to enhance its existing products and to develop and
introduce new products and technologies to meet changing customer requirements.
The Company is currently devoting significant resources toward the enhancement
of its existing products and the development of new products and technologies.
There can be no assurance that the Company will successfully complete the
enhancement and development of these products in a timely fashion, or that these
products will compete successfully with those of the Company's competitors. The
Company is aware of one other company that has received premarket approval from
the FDA for an implantable LVAS that competes with the Company's LVAS. Certain
of the Company's competitors, including its competitor in the implantable LVAS
market, have greater resources, manufacturing and marketing capabilities,
technical staff, and production facilities than those of the Company. As a
result, they may be able to adapt more quickly to new or emerging technologies
and changes in customer requirements, or to devote greater resources to the
promotion and sale of their products than can the Company. Competition could
increase if new companies enter the market, or if existing competitors expand
their product lines.
 
    INTELLECTUAL PROPERTY RIGHTS.  The Company relies upon trade secret
protection and patents to protect its proprietary rights. There can be no
assurance that patents will issue from any pending or future patent applications
owned by or licensed to the Company, or that the claims allowed under any issued
patents will be sufficiently broad to protect the Company's technology. In the
absence of patent protection, the Company may be vulnerable to competitors who
attempt to copy the Company's products or gain access to its trade secrets and
know-how. Proceedings initiated by the Company to protect its proprietary rights
could result in substantial costs to the Company. The Company has received
correspondence from a third party alleging that the textured surface of the left
ventricular-assist systems ("LVAS") infringes certain patent rights of such
third party. The Company believes that it has meritorious defenses to the claims
of the third party. However, no assurance can be given that the Company would be
successful if litigation were commenced or that others will not claim that the
Company infringes their intellectual property rights. There can be no assurance
that competitors of the Company will not initiate litigation to challenge the
validity of the Company's patents, or that they will not use their resources to
design comparable products that do not infringe the Company's patents. There may
also be pending or issued patents held by parties not affiliated with the
Company that relate to the Company's products or technologies. The Company may
need to acquire licenses to, or contest the validity of, any such patents. There
can be no assurance that any license required under any such patent would be
made available on acceptable terms, or that the Company would prevail in any
such contest. The Company could incur substantial costs in defending itself in
suits brought against it, or in suits in which the Company may assert its patent
rights against others. If the outcome of any such litigation is unfavorable to
the Company, the Company's business and results of operations could be
materially adversely affected. In addition, the Company relies on trade secrets
and proprietary know-how which it seeks to protect, in part, by confidentiality
agreements with its collaborators, employees, and consultants. There can be no
assurance that these agreements will not be breached, that the Company would
have adequate remedies for any breach, or that the Company's trade secrets will
not otherwise become known or be independently developed by competitors.
 
    UNCERTAINTY OF REGULATORY APPROVAL FOR BIOMEDICAL DEVICES.  Thermo
Cardiosystems' biomedical devices, including its LVAS, are subject to approval
by the U.S. Food and Drug Administration ("FDA") before commercial sale of such
devices may commence in the U.S. Thermo Cardiosystems is also subject to
 
                                       11

regulatory requirements in foreign countries in which Thermo Cardiosystems
markets its devices. The process of obtaining regulatory approvals is lengthy,
expensive, and inherently uncertain. Even after FDA and other regulatory
approvals have been obtained, such approvals can be suspended or revoked if
Thermo Cardiosystems' products do not continue to satisfy regulatory
requirements. Failure to comply with applicable regulatory requirements can
result in, among other things, fines, suspensions of approvals, recalls of
products, operating restrictions, and criminal prosecutions.
 
    In October 1994, Thermo Cardiosystems received FDA approval for the
commercial sale of its pneumatic LVAS. In April 1994, Thermo Cardiosystems
received the CE Mark for commercial sale of the pneumatic LVAS in all European
Union countries. Thermo Cardiosystems' HeartPak-TM- portable console received
the CE Mark in February 1995 and the HeartPak is currently in Phase I clinical
trials in the U.S. In September 1998, Thermo Cardiosystems' electric LVAS
received premarket approval by the FDA for use as a bridge to transplant. The
electric LVAS received the CE Mark in August 1995 for use as a bridge to
transplant and as an alternative to transplant. Thermo Cardiosystems' electric
LVAS is currently in use in clinical trials in the U.S. testing the safety and
efficacy of the device as an alternative to transplant.
 
    Significant design changes to Thermo Cardiosystems' LVAS, including use of
the portable console for the pneumatic LVAS, must be approved pursuant to a
supplement to an approved PMA application. Failure of Thermo Cardiosystems to
obtain FDA approval for the commercial sale of the electric LVAS as an
alternative to transplant would have a material adverse effect on Thermo
Cardiosystems' long-term growth prospects. In addition, failure of Thermo
Cardiosystems to obtain approval for the HeartPak portable console would likely
require patients supported by the pneumatic LVAS to remain hospitalized. This
could materially restrict the market for the pneumatic LVAS.
 
    UNCERTAINTY OF PATIENT REIMBURSEMENT.  The cost of implanting a cardiac
support system is substantial. In addition, Thermo Cardiosystems' coagulation
testing equipment can cost several thousand dollars per instrument. Without the
financial support of the government or third-party insurers, the market for
Thermo Cardiosystems' devices and equipment will be limited. Medicare and
Medicaid limit the reimbursement that U.S. hospitals receive for treating
certain medical conditions by setting maximum fees that can be charged to their
patients. Under these systems, hospitals are paid a fixed amount for treating
each patient with a particular diagnosis. Private insurers also have initiated
reimbursement systems designed to slow the escalation of healthcare costs. In
addition, the federal government is considering, and certain state governments
are considering or have adopted, new healthcare policies intended to curb rising
costs. Such policies include rationing of government-funded reimbursement for
healthcare services and imposing price controls upon providers of medical
products and services. These policies could have the effect of limiting the
availability of reimbursement for procedures, such as the implantation of an
LVAS, that involve prolonged treatment of critically ill patients.
 
    In November 1995, the U.S. Health Care Finance Administration ("HCFA")
issued a decision that extends Medicare coverage to LVAS devices used as a
bridge to heart transplant, which fulfill certain Medicare coverage criteria.
This decision, updated in April 1998, has applied to Thermo Cardiosystems'
pneumatic LVAS and is expected to extend to the electric LVAS. Several major
non-government insurers have also agreed to offer coverage for LVAS devices.
This coverage has been applied to the pneumatic LVAS and is expected to extend
to the electric LVAS; however, no assurance can be given that third party payers
will cover the electric LVAS immediately because of the device's intended
out-patient use. Even though reimbursement has been established by HCFA and by
certain non-government insurers for LVAS devices, the Medicare coverage criteria
could be amended or revised by HCFA, the amount of available reimbursement may
change, and reimbursement may be denied by an insurer under certain
circumstances, including if it is determined that a procedure was not the most
cost-effective treatment method, was experimental, or was used for an unapproved
indication. No assurance can be given that additional third-party reimbursement
for the LVAS devices will be granted within a reasonable period of time, or at
all. The unavailability of third-party reimbursement for procedures involving
Thermo Cardiosystems' systems or for
 
                                       12

Thermo Cardiosystems' biomedical devices would have a material adverse effect on
the Company's business.
 
    UNCERTAINTY OF OPINION LEADER ACCEPTANCE AND SUPPORT.  A limited number of
cardiac surgeons and cardiologists influence medical device selection and
purchase decisions for a large portion of the target patient population. The
Company will achieve its business objectives only if its LVAS are recommended
for use by such opinion leaders. In addition, acceptance by these physicians of
Thermo Cardiosystems' whole-blood coagulation monitoring systems and Coumadin
monitors is also important to the success of Thermo Cardiosystems' business.
Thermo Cardiosystems has developed working relationships with a number of
leading medical centers, and its existing and proposed LVAS and its blood
coagulation monitoring systems have been well received by opinion leaders in
cardiac surgery and cardiology. Moreover, since the inception of its work on
cardiac support systems in 1966, Thermo Cardiosystems has relied upon surgical
teams at medical institutions to perform clinical trials that are necessary for
obtaining FDA approvals. A continuing working relationship with those and other
institutions will be important to the success of Thermo Cardiosystems. No
assurance can be given that existing relationships and arrangements can be
maintained or that new relationships will be established. Furthermore, economic,
psychological, ethical, and other concerns may limit acceptance of heart-assist
devices in general, and there can be no assurance that markets of sufficient
size will develop for Thermo Cardiosystems' LVAS.
 
    AVAILABILITY OF COMPONENTS AND RAW MATERIALS.  Thermo Cardiosystems relies
on a number of custom-designed components and materials supplied by other
companies to manufacture its LVAS. Thermo Cardiosystems is making efforts to
minimize the risks associated with sole sources and ensure long-term
availability, including qualifying alternative materials and components or
developing alternative sources for materials and components supplied by a single
source. Although the Company believes that it has adequate supplies of materials
and components to meet demand for its products for the foreseeable future, no
assurance can be given that Thermo Cardiosystems will not experience shortages
of certain materials or components in the future that could delay shipments of
its products. The cost to Thermo Cardiosystems to evaluate and test alternative
materials and components and the time necessary to obtain FDA approval for these
materials are inherently difficult to determine because both time and cost are
dependent on at least two factors: the similarity of the alternative material or
component to the original material or component, and the amount of third-party
testing that may have already been completed on alternative materials or
components. There can be no assurance that the substitution of alternative
materials or components would not cause delays in Thermo Cardiosystems' LVAS
development programs or adversely affect the Company's ability to manufacture
and ship LVAS to meet demand.
 
    LIMITED MANUFACTURING AND MARKETING EXPERIENCE OF THERMO
CARDIOSYSTEMS.  Prior to FDA approval of commercial sale of the pneumatic LVAS,
Thermo Cardiosystems' LVAS business was engaged only in research and
development. Since that time, Thermo Cardiosystems has been building its
manufacturing, marketing, and sales capabilities. Although Thermo Cardiosystems
has not experienced difficulties in manufacturing its LVAS at volume, cost, and
quality levels sufficient to satisfy the increased demand resulting from
commercial approval, no assurance can be given that Thermo Cardiosystems will
not encounter difficulties as sales volumes increase or new products and/or
components are approved for commercial sale. Thermo Cardiosystems does not have
experience in the large-scale commercialization of LVAS medical devices.
Although Thermo Cardiosystems has added sales and marketing staff and is
expanding its distribution capabilities worldwide, no assurance can be given
that Thermo Cardiosystems will be able to market and sell its LVAS products
successfully in high volumes.
 
    PRODUCT LIABILITY.  Thermo Cardiosystems faces an inherent business risk of
exposure to product liability claims relating to the use of its products.
Although Thermo Cardiosystems currently maintains product liability insurance
against this risk, there can be no assurance that it will continue to be able to
obtain such coverage at economically feasible rates, if at all, or that such
coverage will be adequate in
 
                                       13

terms and scope to completely protect Thermo Cardiosystems in the event of a
successful product liability claim.
 
    EFFECT OF GOVERNMENT REGULATIONS AND APPROVALS ON MARKET FOR THERMO
SENTRON'S PRODUCTS.  The market for certain of the Company's Thermo Sentron Inc.
("Thermo Sentron") subsidiary's products, both in the United States and abroad,
is subject to or influenced by various domestic and foreign clean air and
consumer protection laws. Thermo Sentron designs, develops, and markets its
products to meet customer needs created by existing and anticipated regulations,
and any changes in these regulations may adversely affect consumer demand for
Thermo Sentron's products. In addition, the marketing of certain of Thermo
Sentron's products is dependent upon the receipt of regulatory and other
approvals, including industry association approvals of the design, construction,
and accuracy of Thermo Sentron's products. Delays in obtaining, or the failure
to obtain, any such approvals could have a material adverse effect on Thermo
Sentron's business and results of operations.
 
    EFFECT OF ELECTRICAL STANDARDS ON DEMAND FOR THERMO VOLTEK'S
PRODUCTS.  Demand for the Company's Thermo Voltek Corp. ("Thermo Voltek")
subsidiary's electromagnetic compatibility ("EMC") testing products and services
is driven to a large extent by mandatory government standards and voluntary
industry standards relating to electromagnetic compatibility. In particular,
demand for many of Thermo Voltek's products results from efforts by
manufacturers to comply with IEC 801, the European Union directive that became
effective on January 1, 1996. As the number of noncomplying manufacturers is
reduced over time, demand for Thermo Voltek's products is likely to be adversely
affected. In addition, if new EMC standards requiring new testing capabilities
are enacted less frequently or if EMC standards become less strict or not
strictly enforced, demand for Thermo Voltek's products could be adversely
affected.
 
    DEPENDENCE OF EXPLOSIVES-DETECTION MARKET ON GOVERNMENT REGULATION AND
AIRLINE INDUSTRY.  The Company's Thermedics Detection Inc. ("Thermedics
Detection") subsidiary's sales of its explosives-detection systems for use in
airports has been and will continue to be dependent on governmental initiatives
to require, or support, the screening of checked luggage, carry-on items and
personnel with advanced explosives-detection equipment. Substantially all of
such systems have been installed at airports in countries other than the United
States, in which the applicable government or regulatory authority overseeing
the operations of the airport has mandated such screening. Such mandates are
influenced by many factors outside of the control of Thermedics Detection,
including political and budgetary concerns of governments, airlines, and
airports. Of the more than 600 commercial airports worldwide, more than 400 are
located in the United States. Accordingly, Thermedics Detection believes that
the size of the market for explosives-detection equipment is, and will
increasingly be, significantly influenced by United States government
regulation. In the United States, the Aviation Security Act of 1990 directed the
Federal Aviation Administration (the "FAA") to develop a standard for
explosives-detection systems and required airports in the United States to
deploy systems meeting this standard in 1993. To date, no system has
demonstrated that it meets all FAA standards under realistic airport operating
conditions. As a result, the FAA has not mandated the installation of automated
explosives-detection systems, and only a limited number of these systems have
been deployed in the United States. The FAA first certified a computed X-ray
tomography system for checked luggage in December 1994. Thermedics Detection's
systems are trace detectors for which no FAA certification process for checked
baggage, carry-on, or personal screening exists to date. Currently, Thermedics
Detection is seeking FAA approval for its EGIS and EGIS II systems for use by
airlines in screening carry-on electronic items and luggage searches. There can
be no assurance, however, that such FAA approvals will be obtained. Each airline
must seek this approval for each application. Although the FAA has provided
significant funding to Thermedics Detection in connection with the development
of its explosives-detection technology, there can be no assurance that any of
Thermedics Detection's systems will ever meet this or any other United States
certification standard. Any product utilizing a technology ultimately
recommended or required by the FAA will have a significant competitive advantage
in the market for explosives-detection devices. Unless the FAA takes action with
 
                                       14

respect to a particular explosives-detection product or technology, airlines
will not be required to purchase or upgrade their security systems, including
upgrading existing metal-detection equipment. Earnings of U.S. air carriers
tends to fluctuate significantly from time to time. Any depression in the
financial condition of such carriers would likely result in lower capital
spending for discretionary items. Moreover, there can be no assurance that
additional countries will mandate the implementation of effective explosives
screening for airline baggage, carry-on items or personnel, or that, if
mandated, Thermedics Detection's systems will meet the certification or other
requirements of the applicable government authority. Even if Thermedics
Detection's systems were to meet the applicable requirements, there can be no
assurance that Thermedics Detection would be able to market its systems
effectively.
 
    In October 1996, the United States enacted legislation which includes a
$144.2 million allocation to purchase explosives-detection systems and other
advanced security equipment, including trace detection equipment such as the
systems manufactured by Thermedics Detection, for carry-on and checked baggage
screening. The FAA has made purchases of, or placed orders for the purchase of,
security equipment under this legislation, including an order to purchase $5.8
million of Thermedics Detection's EGIS systems. There can be no assurance,
however, that this legislation will not be modified to reduce the funding for
advanced explosives equipment, that the necessary appropriations will be made to
fund further purchases of advanced explosives-detection equipment contemplated
by the legislation, that trace-detection equipment such as the systems
manufactured by Thermedics Detection will be mandated, or that, even if further
appropriations are made and such equipment is mandated, any of Thermedics
Detection's explosives-detection systems will be purchased for installation at
any airports in the United States. Further, there can be no assurance that the
U.S. will mandate the widespread use of these systems after completion of the
initial purchases.
 
    SIGNIFICANCE OF CERTAIN CUSTOMERS TO THERMEDICS DETECTION.  Sales of process
detection instruments and services to bottlers licensed by The Coca-Cola Company
("Coca-Cola Bottlers") were $4,369,000, $13,939,000, $10,641,000, and
$9,974,000, for the first nine months of 1998, and in 1997, 1996, and 1995,
respectively, or 14%, 13%, 11%, and 31% of Thermedics Detection's revenues,
respectively, during such periods. In 1997, Thermedics Detection completed the
fulfillment of a mandated product-line upgrade for the Coca-Cola Bottlers.
Although Thermedics Detection anticipates that it will continue to derive
revenues from the sale of upgrades and new systems to new plants, as well as
services to the Coca-Cola Bottlers, Thermedics Detection does not expect that
revenues derived from these customers will continue at a rate comparable to
prior years. Further, Thermedics Detection intends to continue to develop and
introduce new process detection products for the food, beverage and other
markets. There can be no assurance, however, that Thermedics Detection will be
successful in the introduction of new process detection products or that any
sales of these products will be sufficient to maintain a rate of growth
equivalent to prior years.
 
   
    RISKS OF THE COMPANY'S YEAR 2000 ISSUES.  While the Company is attempting to
minimize any negative consequences arising from the year 2000 issue, there can
be no assurance that year 2000 problems will not have a material adverse impact
on the Company's business, operations, or financial condition. While the Company
expects that upgrades to its internal business systems will be completed in a
timely fashion, there can be no assurance that the Company will not encounter
unexpected costs or delays. Despite its efforts to ensure that its material
current products are year 2000 compliant, the Company may see an increase in
warranty and other claims, especially those related to Company products that
incorporate, or operate using, third-party software or hardware. In addition,
certain of the Company's older products, which it no longer manufactures or
sells, may not be year 2000 compliant, which may expose the Company to claims.
If any of the Company's material suppliers, vendors, or customers experience
business disruptions due to year 2000 issues, the Company might also be
materially adversely affected. There is expected to be a significant amount of
litigation relating to the year 2000 issue and there can be no assurance that
the Company will not incur material costs in defending or bringing lawsuits. Any
unexpected costs or delays
    
 
                                       15

arising from the year 2000 issue could have a significant adverse impact on the
Company's business, operations, and financial condition.
 
            INTERESTS OF CERTAIN PERSONS IN MATTERS TO BE ACTED UPON
 
   
    Messrs. Peter O. Crisp, George N. Hatsopoulos, John N. Hatsopoulos, John T.
Keiser, Paul F. Kelleher, Theo Melas-Kyriazi and John W. Wood Jr., who are
directors and/or executive officers of the Company, are also directors and/or
executive officers of Thermo Electron.
    
 
   
    Messrs. John T. Keiser, Paul F. Kelleher, Theo Melas-Kyriazi, Victor L.
Poirier and Nicholas T. Zervas, who are directors and/or executive officers of
the Company, are also directors and/or executive officers of Thermo
Cardiosystems.
    
 
   
    Messrs. Elias P. Gyftopoulos, John T. Keiser, Paul F. Kelleher and Theo
Melas-Kyriazi, who are directors and/or executive officers of Thermo Electron,
are also directors and/or executive officers of Thermo Cardiosystems.
    
 
   
    Mr. Theo Melas-Kyriazi, an executive officer of the Company, is a director
and executive officer of TCA Holdings.
    
 
    See "Stock Ownership."
 
                                       16

                                STOCK OWNERSHIP
 
    The following table sets forth the beneficial ownership of Common Stock, as
well as the common stock of Thermo Electron, the Company's parent company, and
of Thermedics Detection, Thermo Cardiosystems, Thermo Sentron and Thermo Voltek,
each a publicly traded majority-owned subsidiary of the Company, as of September
30, 1998, with respect to (i) each director, (ii) the chief executive officer of
the Company and other executive officers of the Company who during the last
completed fiscal year of the Company, met the definition of "highly compensated"
within the meaning of the Securities and Exchange Commission's executive
compensation disclosure rules, and (iii) all directors and current executive
officers as a group. In addition, the following table sets forth the beneficial
ownership of Common Stock, as of September 30, 1998, with respect to each person
who was known by the Company to own beneficially more than 5% of the outstanding
shares of Common Stock.
 
    While certain directors and executive officers of the Company are also
directors and executive officers of Thermo Electron or its subsidiaries other
than the Company, all such persons disclaim beneficial ownership of the shares
of Common Stock owned by Thermo Electron.
 
   


                                                              THERMO      THERMEDICS      THERMO       THERMO     THERMO
                                             THERMEDICS      ELECTRON      DETECTION   CARDIOSYSTEMS   SENTRON    VOLTEK
NAME(1)                                       INC.(2)     CORPORATION(3)    INC.(4)       INC.(5)      INC.(6)   CORP.(7)
- ------------------------------------------  ------------  --------------  -----------  -------------  ---------  ---------
                                                                                               
Thermo Electron Corporation(8)............    24,051,621        --            --            --           --         --
Capital Research and Management Company
  (9).....................................     1,900,000        --            --            --           --         --
T. Anthony Brooks.........................             0              0            0             0            0          0
Peter O. Crisp............................        34,434        101,059        1,500         2,250        1,500      2,250
Paul F. Ferrari...........................        15,457         17,229        1,500        11,500        1,500      5,998
David H. Fine.............................       106,687         71,190      109,967           207        7,500          0
George N. Hatsopoulos.....................        63,681      3,564,258       21,197        11,599       17,000          0
John N. Hatsopoulos.......................        64,630        823,964       21,262           432       37,800          0
John T. Keiser............................        81,793        192,508       17,000        56,773       19,500          0
Victor L. Poirier.........................        70,155         52,982            0       201,127        7,500          0
John W. Wood Jr...........................       157,006        269,366       38,051        46,207       35,000     96,971
Nicholas T. Zervas........................        27,306          1,000        1,500        47,063        1,500      2,250
All directors and current executive
  officers as a group (11 persons)........       641,509      5,223,211      217,077       379,147      133,800    117,469

    
 
- ------------------------
 
(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 beneficially owned by Mr. Crisp, Mr. Ferrari, Dr.
    Fine, Dr. G. Hatsopoulos, Mr. J. Hatsopoulos, Mr. Keiser, Mr. Poirier, Mr.
    Wood, Dr. Zervas and all directors and current executive officers as a group
    include 8,450, 8400, 90,300, 50,000, 50,000, 78,000, 25,700, 99,300, 8,050
    and 437,200 shares, respectively, that such person or group has the right to
    acquire within 60 days of September 30, 1998, through the exercise of stock
    options. Shares beneficially owned by Dr. G. Hatsopoulos, Mr. J. Hatsopoulos
    and all directors and current executive officers as a group include 1,635,
    1,737 and 4,666 whole shares, respectively, allocated through March 1, 1998,
    to their respective accounts maintained pursuant to Thermo Electron's
    employee stock ownership plan (the "ESOP"), of which the trustees, who have
    investment power over its assets, are executive officers of Thermo Electron.
    Shares beneficially owned by Mr. Crisp, Dr. Zervas and all directors and
    current executive officers as a group include 7,879, 8,156 and 16,036 whole
    shares, respectively, that had been allocated through July 4, 1998, to their
    respective accounts maintained under the Corporation's deferred compensation
    plan for directors. Shares beneficially owned by Dr. G. Hatsopoulos include
    
 
                                       17

    562 shares held by Dr. G. Hatsopoulos' spouse and 92 shares allocated to his
    spouse's account maintained pursuant to the ESOP. Shares beneficially owned
    by Mr. Wood include 2,600 shares held in trust for the benefit of two
    children. No director or executive officer beneficially owned more than 1%
    of the Common Stock outstanding as of September 30, 1998; all directors and
    current executive officers as a group beneficially owned 1.74% of the Common
    Stock outstanding as of such date.
 
(3) Shares of the common stock of Thermo Electron beneficially owned by Mr.
    Crisp, Dr. Fine, Dr. G. Hatsopoulos, Mr. J. Hatsopoulos, Mr. Keiser, Mr.
    Poirier, Mr. Wood and all directors and current executive officers as a
    group include 8,125, 54,912, 1,849,500, 762,735, 151,622, 45,225, 228,359
    and 3,198,415 shares, respectively, that such person or group has the right
    to acquire within 60 days of September 30, 1998, through the exercise of
    stock options. Shares beneficially owned by Dr. G. Hatsopoulos, Mr. J.
    Hatsopoulos and all directors and current executive officers as a group
    include 2,266, 2,036 and 5,728 whole shares, respectively, allocated to
    their respective accounts maintained pursuant to the ESOP. Shares
    beneficially owned by Mr. Crisp and all directors and current executive
    officers as a group include 46,040 whole shares allocated through July 4,
    1998, to Mr. Crisp's account maintained pursuant to Thermo Electron's
    deferred compensation plan for directors. Shares beneficially owned by Mr.
    Ferrari include 10,062 shares held by his spouse. Shares beneficially owned
    by Dr. G. Hatsopoulos include 89,601 shares held by his spouse, 168,750
    shares held by a QTIP trust of which his spouse is a trustee, 39,937 shares
    held by a family trust of which his spouse is the trustee and 153 shares
    allocated to his spouse's account maintained pursuant to the ESOP. Shares
    beneficially owned by Dr. G. Hatsopoulos also include 50,000 shares that a
    family trust, of which Dr. G. Hatsopoulos' spouse is the trustee, has the
    right to acquire within 60 days of September 30, 1998, through the exercise
    of stock options. Except for Dr. Hatsopoulos, who beneficially owned 2.22%
    of the Thermo Electron common stock outstanding as of September 30, 1998, no
    director or executive officer beneficially owned more than 1% of such common
    stock outstanding as of such date; all directors and current executive
    officers as a group beneficially owned approximately 3.26% of the Thermo
    Electron common stock outstanding as of September 30, 1998.
 
(4) Shares of the common stock of Thermedics Detection beneficially owned by Mr.
    Crisp, Mr. Ferrari, Dr. Fine, Dr. G. Hatsopoulos, Mr. J. Hatsopoulos, Mr.
    Keiser, Mr. Wood, Dr. Zervas and all directors and current executive
    officers as a group include 1,500, 1,500, 99,967, 20,000, 20,000, 17,000,
    20,800 1,500 and 187,267 shares, respectively, that such person or group has
    the right to acquire within 60 days September 30, 1998, through the exercise
    of stock options. Shares beneficially owned by Dr. G. Hatsopoulos include 57
    shares held by his spouse. No director or executive officer beneficially
    owned more than 1% of the Thermedics Detection common stock outstanding as
    of September 30, 1998; all directors and current executive officers as a
    group beneficially owned approximately 1.12% of such common stock
    outstanding as of such date.
 
(5) Shares of the common stock of Thermo Cardiosystems beneficially owned by Mr.
    Crisp, Mr. Ferrari, Mr. Keiser, Mr. Poirier, Mr. Wood, Dr. Zervas and all
    directors and current executive officers as a group include 2,250, 2,250,
    49,500, 158,750, 23,450, 11,300 and 247,500 shares, respectively, that such
    person or group has the right to acquire within 60 days of September 30,
    1998, through the exercise of stock options. Shares beneficially owned by
    Dr. Zervas and all directors and current executive officers as a group
    include 7,413 shares allocated through July 4, 1998, to Dr. Zervas' account
    maintained pursuant to Thermo Cardiosystems' deferred compensation plan for
    directors. Shares beneficially owned by Mr. Wood include 1,122 shares held
    in trust for the benefit of two children. Shares beneficially owned by Dr.
    Zervas include 19,000 shares held by his spouse. No director or executive
    officer beneficially owned more than 1% of the Thermo Cardiosystems common
    stock outstanding as of September 30, 1998; all directors and current
    executive officers as a group beneficially owned approximately 1.0% of such
    common stock outstanding on such date.
 
(6) Shares of the common stock of Thermo Sentron beneficially owned by Mr.
    Crisp, Mr. Ferrari, Dr. Fine, Dr. G. Hatsopoulos, Mr. J. Hatsopoulos, Mr.
    Keiser, Mr. Poirier, Mr. Wood, Dr. Zervas and all directors and current
    executive officers as a group include 1,500, 1,500, 7,500, 15,000, 15,000,
 
                                       18

    19,500, 7,500, 31,000, 1,500 and 105,000 shares, respectively, that such
    person or group has the right to acquire within 60 days of September 30,
    1998, through the exercise of stock options. No director or executive
    officer beneficially owned more than 1% of the Thermo Sentron common stock
    outstanding as of September 30, 1998; all directors and current executive
    officers as a group beneficially owned approximately 1.42% of such common
    stock outstanding as of such date.
 
(7) Shares of the common stock of Thermo Voltek beneficially owned by Mr. Crisp,
    Mr. Ferrari, Mr. Wood, Dr. Zervas and all directors and current executive
    officers as a group include 2,250, 2,250, 82,350, 2,250 and 89,100 shares,
    respectively, that such person or group has the right to acquire within 60
    days of September 30, 1998, through the exercise of stock options. The
    directors and current executive officers as a group beneficially owned 1.34%
    of the Thermo Voltek common stock outstanding as of September 30, 1998.
 
(8) Thermo Electron beneficially owned approximately 65.34% of the Common Stock
    outstanding as of September 30, 1998. Thermo Electron's address is 81 Wyman
    Street, Waltham, Massachusetts 02454-9046.
 
   
(9) Information regarding the number of shares of the Common Stock beneficially
    owned by Capital Research and Management Company is based on the most recent
    Schedule 13G of Capital Research and Management Company received by the
    Corporation, which reported such ownership as of December 31, 1997. The
    address of Capital Research and Management Company is 333 South Hope Street,
    Los Angeles, California 90071. As of December 31, 1997, Capital Research and
    Management Company beneficially owned approximately 5.2% of the outstanding
    Common Stock. Capital Research and Management Company disclaimed beneficial
    ownership of such shares pursuant to Rule 13d-4 of the Securities Exchange
    Act of 1934, as amended (the "Exchange Act").
    
 
                                 RECOMMENDATION
 
   
    The Board of Directors believes that the proposal is in the best interest of
the Company and its Stockholders and recommends that the Stockholders vote "FOR"
the approval of the listing of 4,880,553 shares of the Company's Common Stock on
the AMEX in connection with the acquisition of TCA Holdings. If not otherwise
specified, proxies will be voted FOR approval of this proposal. Thermo Electron,
which beneficially owned an aggregate of approximately     % of the outstanding
Common Stock as of the Record Date (before giving effect to the issuance of the
TMD Shares pursuant to the Merger Agreement), has sufficient votes to approve
the proposal and has indicated its intention to vote for the proposal.
    
 
                                  OTHER ACTION
 
    Management is not aware at this time of any other matters that will be
presented for action at the Meeting. Should any such matters be presented, the
proxies grant power to the proxy holders to vote shares represented by the
proxies in the discretion of such proxy holders.
 
                             STOCKHOLDER PROPOSALS
 
   
    Proposals of Stockholders intended to be presented at the 1999 Annual
Meeting of the Stockholders of the Company must have been received by the
Company for inclusion in the proxy statement and form of proxy relating to that
meeting no later than December 29, 1998.
    
 
   
    Pursuant to recent amendments to the rules relating to proxy statements
under the Exchange Act, shareholders of the Company are hereby notified that any
shareholder proposal not included in the Company's proxy materials for its 1999
Annual Meeting of Shareholders (the "Annual Meeting") in accordance with Rule
14a-8 under the Exchange Act will be considered untimely for the purposes of
Rules 14a-4 and 14a-5 under the Exchange Act if notice thereof is received by
the Company after March 15, 1999. Management proxies will be authorized to
exercise discretionary voting authority with respect to any shareholder proposal
not included in the Company's proxy materials for the Annual
    
 
                                       19

Meeting unless (a) the Company receives notice of such proposal by March 15,
1999, and (b) the conditions set forth in Rule 14a-4(c)(2)(i)-(iii) under the
Exchange Act are met.
 
                             SOLICITATION STATEMENT
 
    The cost of this solicitation of proxies will be borne by the Company.
Solicitation will be made primarily by mail, but regular employees of the
Company may solicit proxies personally, by telephone or telegram. Brokers,
nominees, custodians and fiduciaries are requested to forward solicitation
materials to obtain voting instructions from beneficial owners of stock
registered in their names, and the Company will reimburse such parties for their
reasonable charges and expenses in connection therewith.
 
                INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE
 
    The following documents filed by the Company with the Commission pursuant to
the Exchange Act are incorporated herein by reference:
 
    (a) The Annual Report of the Company on Form 10-K for its fiscal year ended
       January 3, 1998.
 
    (b) The definitive Proxy Statement of the Company for its Annual Meeting of
       stockholders held on June 1, 1998, as filed with the Commission April 29,
       1998.
 
    (c) The Quarterly Report of the Company on Form 10-Q for its quarter ended
       April 4, 1998
 
    (d) The Quarterly Report of the Company on Form 10-Q for its quarter ended
       July 4, 1998
 
    (e) The Quarterly Report of the Company on Form 10-Q for its quarter ended
       October 3, 1998.
 
    (f) The Current Report of the Company on Form 8-K dated March 30, 1998, as
       filed with the Commission on April 3, 1998.
 
    (g) The Current Report of the Company on Form 8-K dated June 3, 1998, as
       filed with the Commission on June 3, 1998.
 
    (h) The Current Report of the Company on Form 8-K dated August 12, 1998, as
       filed with the Commission on August 13, 1998.
 
    (i) The Current Report of the Company on Form 8-K dated September 29, 1998,
       as filed with the Commission on September 30, 1998.
 
   
    (j) The Current Report of the Company on Form 8-K dated December 10, 1998,
       as filed with the Commission on December 10, 1998.
    
 
   
    (k) All documents filed by the Company with the Commission pursuant to
       Section 13(a), 13(c), 14 or 15(d) of the Exchange Act subsequent to the
       date of this Proxy Statement and prior to the date of the Meeting shall
       be deemed to be incorporated by reference in this Proxy Statement. Any
       statement contained in a document incorporated or deemed to be
       incorporated by reference herein shall be deemed to be modified or
       superseded for purposes of this Proxy Statement to the extent that a
       statement contained herein or in any other subsequently filed document
       which also is or is deemed to be incorporated by reference modifies or
       supersedes such statement. Any such statement so modified or superseded
       shall not be deemed, except as so modified or superseded, to constitute a
       part of this Proxy Statement.
    
 
   
    THIS PROXY STATEMENT INCORPORATES DOCUMENTS BY REFERENCE WHICH ARE NOT
PRESENTED HEREIN OR DELIVERED HEREWITH. COPIES OF ANY SUCH DOCUMENTS, OTHER THAN
EXHIBITS TO SUCH DOCUMENTS WHICH ARE NOT SPECIFICALLY INCORPORATED BY REFERENCE
THEREIN, ARE AVAILABLE WITHOUT CHARGE TO ANY PERSON TO WHOM THIS PROXY STATEMENT
IS DELIVERED, UPON WRITTEN OR ORAL REQUEST TO SANDRA L. LAMBERT, CLERK,
THERMEDICS INC., 81 WYMAN STREET, P.O. BOX 9046, WALTHAM, MASSACHUSETTS
02454-9046 (TELEPHONE NUMBER: (781) 622-1000)). IN ORDER TO ENSURE TIMELY
DELIVERY OF THE DOCUMENTS, ANY REQUEST SHOULD BE RECEIVED BY THE COMPANY BY
            , 1999.
    
 
   
Woburn, Massachusetts
            , 1999
    
 
                                       20

   
                         INDEX TO FINANCIAL STATEMENTS
    
 
   

                                                                                     
PRO FORMA CONSOLIDATED FINANCIAL INFORMATION OF THERMEDICS INC. AND TMO TCA HOLDINGS
  INC. (UNAUDITED)
  Pro Forma Consolidated Statement of Income for the year ended January 3, 1998.......        F-2
  Pro Forma Consolidated Statement of Income for the nine months ended October 3,
    1998..............................................................................        F-3
  Notes to Pro Forma Consolidated Statement of Income.................................        F-4

    
 
                                      F-1

   
                                THERMEDICS INC.
    
 
   
                   PRO FORMA CONSOLIDATED STATEMENT OF INCOME
                           YEAR ENDED JANUARY 3, 1998
    
 
   
                                  (UNAUDITED)
    
 
   


                                                                                                  PRO FORMA
                                                                                          -------------------------
                                                                              HISTORICAL   ADJUSTMENTS    COMBINED
                                                                              ----------  -------------  ----------
                                                                                                
                                                                                 (IN THOUSANDS, EXCEPT PER SHARE
                                                                                            AMOUNTS)
REVENUES....................................................................  $  307,666    $  --        $  307,666
                                                                              ----------       ------    ----------
 
Costs and Operating Expenses:
  Cost of revenues..........................................................     155,680       --           155,680
  Selling, general, and administrative expenses.............................      86,308       --            86,308
  Research and development expenses.........................................      24,270       --            24,270
                                                                              ----------       ------    ----------
                                                                                 266,258       --           266,258
                                                                              ----------       ------    ----------
Operating Income............................................................      41,408       --            41,408
Interest Income.............................................................      13,326       --            13,326
Interest Expense............................................................      (3,398)      --            (3,398)
Gain on Issuance of Stock by Subsidiaries...................................      17,075       --            17,075
Gain on Sale of Investments, Net............................................         432       --               432
Other Income................................................................          54       --                54
                                                                              ----------       ------    ----------
Income Before Provision for Income Taxes and Minority Interest..............      68,897       --            68,897
Provision for Income Taxes..................................................      19,675       --            19,675
Minority Interest Expense (Income)..........................................       7,730         (763)        6,967
                                                                              ----------       ------    ----------
NET INCOME..................................................................  $   41,492    $     763    $   42,255
                                                                              ----------       ------    ----------
                                                                              ----------       ------    ----------
EARNINGS PER SHARE:
  Basic.....................................................................  $     1.13    $  --        $     1.02
                                                                              ----------       ------    ----------
                                                                              ----------       ------    ----------
  Diluted...................................................................  $     1.07    $  --        $     0.97
                                                                              ----------       ------    ----------
                                                                              ----------       ------    ----------
 
WEIGHTED AVERAGE SHARES:
  Basic.....................................................................      36,700        4,881        41,581
                                                                              ----------       ------    ----------
                                                                              ----------       ------    ----------
  Diluted...................................................................      38,911        4,881        43,792
                                                                              ----------       ------    ----------
                                                                              ----------       ------    ----------

    
 
                                      F-2

   
                                THERMEDICS INC.
    
 
   
                   PRO FORMA CONSOLIDATED STATEMENT OF INCOME
                       NINE MONTHS ENDED OCTOBER 3, 1998
                                  (UNAUDITED)
    
 
   


                                                                                                  PRO FORMA
                                                                                          -------------------------
                                                                              HISTORICAL   ADJUSTMENTS    COMBINED
                                                                              ----------  -------------  ----------
                                                                                                
                                                                                 (IN THOUSANDS, EXCEPT PER SHARE
                                                                                            AMOUNTS)
REVENUES....................................................................  $  233,887    $  --        $  233,887
                                                                              ----------        -----    ----------
Costs and Operating Expenses:
  Cost of revenues..........................................................     121,594       --           121,594
  Selling, general, and administrative expenses.............................      66,671       --            66,671
  Research and development expenses.........................................      19,543       --            19,543
                                                                              ----------        -----    ----------
                                                                                 207,808       --           207,808
                                                                              ----------        -----    ----------
Operating Income............................................................      26,079       --            26,079
Interest Income.............................................................      10,045       --            10,045
Interest Expense............................................................      (4,067)      --            (4,067)
Gain on Sale of Investments, Net............................................          31       --                31
                                                                              ----------        -----    ----------
Income Before Provision for Income Taxes, Minority Interest, and
 Extraordinary Item.........................................................      32,088       --            32,088
Provision for Income Taxes..................................................      12,604       --            12,604
Minority Interest Expense (Income)..........................................       4,564         (152)        4,412
                                                                              ----------        -----    ----------
Income Before Extraordinary Item............................................      14,920          152        15,072
Extraordinary Item, Net of Provision for Income Taxes of $3,092.............       4,638       --             4,638
                                                                              ----------        -----    ----------
NET INCOME..................................................................  $   19,558    $     152    $   19,710
                                                                              ----------        -----    ----------
                                                                              ----------        -----    ----------
EARNINGS PER SHARE BEFORE EXTRAORDINARY ITEM:
  Basic.....................................................................  $     0.36    $  --        $     0.36
                                                                              ----------        -----    ----------
                                                                              ----------        -----    ----------
  Diluted...................................................................  $     0.35    $  --        $     0.35
                                                                              ----------        -----    ----------
                                                                              ----------        -----    ----------
EARNINGS PER SHARE:
  Basic.....................................................................  $     0.48    $  --        $     0.47
                                                                              ----------        -----    ----------
                                                                              ----------        -----    ----------
  Diluted...................................................................  $     0.46    $  --        $     0.45
                                                                              ----------        -----    ----------
                                                                              ----------        -----    ----------
WEIGHTED AVERAGE SHARES:
  Basic.....................................................................      41,065          590        41,655
                                                                              ----------        -----    ----------
                                                                              ----------        -----    ----------
  Diluted...................................................................      43,061          590        43,651
                                                                              ----------        -----    ----------
                                                                              ----------        -----    ----------

    
 
                                      F-3

   
                                THERMEDICS INC.
    
 
   
              NOTES TO PRO FORMA CONSOLIDATED STATEMENT OF INCOME
    
 
   
                                  (UNAUDITED)
    
 
   
NOTE 1 - BASIS OF PRESENTATION
    
 
   
    The accompanying pro forma consolidated statements of income are presented
as if the Merger Agreement had become effective at the beginning of 1997.
    
 
   
NOTE 2 - PRO FORMA ADJUSTMENTS TO PRO FORMA CONDENSED STATEMENT OF INCOME (In
thousands, except in text)
    
 
   


                                                                                 YEAR ENDED     NINE MONTHS ENDED
                                                                               JANUARY 3, 1998   OCTOBER 3, 1998
                                                                               ---------------  ------------------
                                                                                         DEBIT (CREDIT)
                                                                                          
MINORITY INTEREST EXPENSE (INCOME)
Decrease in minority interest expense as a result of the Company's increased
  ownership of Thermo Cardiosystems..........................................     $    (763)        $     (152)
                                                                                     ------            -------
WEIGHTED AVERAGE SHARES
Increase in weighted average shares outstanding due to the assumed issuance
  of 4,880,553 shares of the Company's common stock related to the
  acquisition of additional shares of Thermo Cardiosystems as of the
  beginning of 1997 (The Company's historical financial statements include
  such shares as outstanding from February 5, 1998, the date the transaction
  was approved by its board of directors)....................................         4,881                590
                                                                                     ------            -------

    
 
                                      F-4

                                                                      APPENDIX A
 
                      AGREEMENT AND PLAN OF REORGANIZATION
 
   
    THIS AGREEMENT AND PLAN OF REORGANIZATION (this "Agreement") dated October
30, 1998 is among Thermedics Inc. ("Thermedics"), a Massachusetts corporation,
Cardio Acquisition Inc. ("Acquisition"), a Massachusetts corporation and a
wholly-owned subsidiary of Thermedics, Thermo Electron Corporation ("Thermo
Electron"), a Delaware corporation, and TMO TCA Holdings, Inc. ("Holdings"), a
Delaware corporation and a wholly-owned subsidiary of Thermo Electron. The
parties wish to effect the acquisition of Holdings by Thermedics through a
merger of Acquisition with and into Holdings on the terms and conditions hereof.
This Agreement is intended to be a "plan of reorganization" within the meaning
of Section 368(a) of the Internal Revenue Code of 1986, as amended (the "Code").
    
 
    Accordingly, in consideration of the foregoing and the mutual
representations and covenants contained herein, the parties hereto agree as
follows:
 
                                   SECTION 1
                               THE REORGANIZATION
 
   
    1.1  THE MERGER.  Upon the terms and subject to the conditions hereof, and
in accordance with the Business Corporation Law of the Commonwealth of
Massachusetts (the "BCLM") and the General Corporation Law of the State of
Delaware (the "GCLD"), Acquisition shall be merged with and into Holdings (the
"Merger"). The Merger shall occur at the Effective Time (as defined in Section
1.2). Following the Merger, Holdings shall be the surviving corporation (the
"Surviving Corporation") and the separate corporate existence of Acquisition
shall cease.
    
 
   
    1.2  EFFECTIVE TIME.  As soon as practicable after the execution of this
Agreement and satisfaction or waiver of all conditions to the Merger, the
parties shall (i) cause articles of merger (the "Articles of Merger") with
respect to the Merger to be filed and recorded in accordance with Section 79 of
the BCLM (ii) shall cause a certificate of merger (the "Certificate of Merger")
with respect to the Merger to be filed and recorded in accordance with Section
252 of the GCLD and (iii) shall take all such further actions as may be required
by law to make the Merger effective. The Merger shall be effective at such time
as both the Articles of Merger are duly filed with the Secretary of State of the
Commonwealth of Massachusetts in accordance with the BCLM and the Certificate of
Merger is duly filed with the Secretary of State of the State of Delaware in
accordance with the GCLD, or at such later time as is specified in both the
Articles of Merger and the Certificate of Incorporation (the "Effective Time").
The date on which the Merger shall be effective is hereafter referred to as the
"Effective Date."
    
 
   
    1.3  CLOSING.  Immediately prior to the filing of the Articles of Merger and
the Certificate of Merger, a closing (the "Closing") will be held at the offices
of Thermo Electron Corporation, 81 Wyman Street, Waltham, Massachusetts (or such
other place as the parties may agree) for the purpose of confirming satisfaction
or waiver of all conditions to the Merger. The date on which the Closing occurs
is referred to herein as the "Effective Date."
    
 
   
    1.4  CERTIFICATE OF INCORPORATION AND BY-LAWS.  The Certificate of
Incorporation and By-laws of Holdings, in each case as in effect immediately
prior to the Effective Time, shall be the Certificate of Incorporation and
By-laws of the Surviving Corporation immediately after the Effective Time.
    
 
    1.5  DIRECTORS AND OFFICERS.  The directors and officers of Acquisition
immediately prior to the Effective Time shall be the directors and officers of
the Surviving Corporation immediately after the Effective Time.
 
                                      A-1

    1.6  CONVERSION OF STOCK.
 
    At the Effective Time, by virtue of the Merger and without any action on the
part of Thermedics, Acquisition, Thermo Electron or Holdings:
 
        (a) Each share of common stock of Holdings ("Holdings Common Stock")
    outstanding immediately prior to the Effective Time (the "Holdings Shares")
    shall be converted into and become the right to receive a pro rata share of
    a total of 4,880,533 shares (the "Thermedics Shares") of common stock, $.10
    par value per share, of Thermedics ("Thermedics Common Stock"). The
    Thermedics Shares are referred to herein as the "Merger Consideration."
 
        (b) Each share of the common stock of Acquisition ("Acquisition Common
    Stock") outstanding immediately prior to the Effective Time shall be
    converted into and become one validly issued, fully paid and nonassessable
    share of common stock, $0.01 par value per share, of the Surviving
    Corporation.
 
    1.7  PAYMENT FOR HOLDINGS COMMON STOCK.
 
        (a) At the Effective Time, the stock transfer books of Holdings shall be
    closed and no transfers of Holdings Common Stock may be made thereafter.
    Promptly after the later of (i) the listing of the Thermedics Shares for
    trading on the American Stock Exchange, Inc. ("AMEX"), as contemplated by
    Section 4.8 below, and (ii) the proper surrender by Thermo Electron of such
    certificates representing the Holdings Shares, Thermedics shall cause its
    stock transfer agent to issue and deliver to Thermo Electron a certificate
    for the Thermedics Shares. It shall be a condition of such payment and
    delivery that the surrendered certificate(s) be properly endorsed or
    otherwise in proper form for transfer and that Thermo Electron shall pay any
    transfer or other taxes required by reason of such payment or delivery or
    establish, to the satisfaction of Thermedics and the Surviving Corporation
    that such tax has been paid or is not applicable. The date on which all of
    the conditions to the issuance of the certificate representing the
    Thermedics Shares shall have been met is referred to hereinafter as the
    "Payment Date."
 
        (b) Notwithstanding the provisions of subsection (a) of this Section
    1.7, in the event that, notwithstanding Thermedics' best efforts, Thermedics
    is unable to obtain the approval of its stockholders of the listing of the
    Thermedics Shares for trading on AMEX on or before December 31, 1999, then,
    on December 31, 1999, Thermedics will pay to Holdings the sum of $75,587,000
    in cash in lieu of issuing the Thermedics Shares.
 
    1.8  ADJUSTMENTS.
 
        (a) In the event Thermedics shall declare, pay, make or effect between
    the date of this Agreement and the Payment Date, (i) any stock dividend or
    other distribution in respect of the Thermedics Common Stock payable in
    shares of capital stock of Thermedics, (ii) any stock split or other
    subdivision of outstanding shares of Thermedics Common Stock into a larger
    number of shares, (iii) any combination of outstanding shares of Thermedics
    Common Stock into a smaller number of shares, (iv) any reclassification of
    Thermedics Common Stock into other shares of capital stock or securities, or
    (v) any exchange of the outstanding shares of Thermedics Common Stock, in
    connection with a merger or consolidation of Thermedics or sale by
    Thermedics of all or part of its assets, for a different number or class of
    shares of stock or securities of Thermedics or for the share of the capital
    stock or other securities of any other corporation, appropriate adjustment
    shall be made in the number of Thermedics Shares to be issued in connection
    with the Merger as may be required to put Thermo Electron in the same
    position as if the record date, with respect to any such transaction or
    transactions which shall so occur, had been immediately after the Payment
    Date, or otherwise to carry out the intents and purposes of this Agreement.
 
                                      A-2

        (b) In the event Thermedics shall declare, pay, make or effect between
    the date of this Agreement and the Payment Date any dividend or other
    distribution in respect of the Thermedics Common Stock payable in cash or
    other property other than in shares of capital stock of Thermedics, then the
    Thermedics Shares to be issued in connection with the Merger shall be deemed
    to be outstanding as of the record date with respect to any such dividend or
    distribution, and the cash or other property otherwise payable or
    distributable to Thermo Electron with respect to such Thermedics Shares
    shall be held by Thermedics for the benefit of Thermo Electron; and
    Thermedics shall take all actions reasonably necessary to prevent such cash
    or other property from being or becoming subject to any lien, security
    interest or other encumbrance not for the benefit of Thermo Electron. Upon
    the issuance of the Thermedics Shares to Thermo Electron pursuant to Section
    1.7(a) above, such cash or other property shall likewise be distributed by
    Thermedics to Thermo Electron. In no event shall Thermo Electron be entitled
    to receive interest on such dividends or distributions. In the event that
    Thermedics pays Thermo Electron cash consideration pursuant to Section
    1.7(b) above, then such cash or other property held by Thermedics on behalf
    of Thermo Electron shall not be paid or distributed to Thermo Electron and
    Thermo Electron shall have no further interest therein or claim thereto.
 
    1.9  LOST CERTIFICATES.  In the event any certificate representing Thermo
Electron' Holdings Shares shall have been lost, stolen or destroyed, upon the
making of an affidavit of that fact by Thermo Electron, Thermedics shall issue
in exchange for such lost, stolen or destroyed certificate the consideration
payable in exchange therefor pursuant to this Section 1.
 
    1.10  NO FRACTIONAL SHARES.  No certificates representing fractional
Thermedics Shares shall be issued upon the surrender for exchange of the
Holdings Shares. No fractional interest shall entitle the owner to vote or to
any rights of a security holder. In lieu of a fractional share, Thermo Electron
will receive upon surrender of the Holdings Shares an amount in cash (without
interest) determined by multiplying such fraction by $15.488.
 
                                   SECTION 2
                         REPRESENTATIONS AND WARRANTIES
                        OF THERMO ELECTRON AND HOLDINGS
 
    Thermo Electron and Holdings, jointly and severally, represent and warrant
to Thermedics and Acquisition as follows. The term "knowledge," when used in
this Agreement, shall mean actual knowledge after reasonable investigation.
 
    2.1  ORGANIZATION AND QUALIFICATION.
 
        (a) Each of Thermo Electron and Holdings is a corporation duly
    organized, validly existing and in good standing under the laws of its
    jurisdiction of incorporation and has full corporate power and authority to
    own, lease and operate its assets and to carry on its business as now being
    and as heretofore conducted.
 
        (b) Thermo Electron and Holdings have previously provided to Thermedics
    true and complete copies of their charter and By-laws as in effect on the
    date hereof, and neither of such corporations is in default thereunder.
 
    2.2  AUTHORITY.  Each of Thermo Electron and Holdings has full right, power,
capacity and authority to execute, deliver and perform this Agreement and to
consummate the transactions contemplated hereby. The execution, delivery and
performance of this Agreement, the filing of the Articles of Merger and the
consummation of the transactions contemplated hereby have been duly and validly
authorized by all necessary corporate action on the part of Thermo Electron and
Holdings. This Agreement has been duly and validly executed and delivered by
each of Thermo Electron and Holdings and constitutes the valid and binding
obligation of Thermo Electron and Holdings, enforceable against them in
accordance with the
 
                                      A-3

terms hereof. Neither the execution, delivery and performance of this Agreement,
the filing of the Articles of Merger nor the consummation of the transactions
contemplated hereby will (i) conflict with or result in a violation, breach,
termination or acceleration of, or default under (or would result in a
violation, breach, termination, acceleration or default with the giving of
notice or passage of time, or both) any of the terms, conditions or provisions
of the charter or By-laws of Thermo Electron or Holdings, as amended, or of any
note, bond, mortgage, indenture, license, agreement or other instrument or
obligation to which either of Thermo Electron or Holdings is a party or by which
either of Thermo Electron or Holdings or any of their respective properties or
assets may be bound or affected; (ii) result in the violation of any order,
writ, injunction, decree, statute, rule or regulation applicable to Thermo
Electron or Holdings or any of their respective properties or assets; or (iii)
result in the imposition of any lien, encumbrance, charge or claim upon any of
Thermo Electron' or Holdings' assets. Except for the filing of the Articles of
Merger, no consent or approval by, or notification to or filing with, any court,
governmental authority or third party is required in connection with the
execution, delivery and performance of this Agreement by Thermo Electron and
Holdings or the consummation of the transactions contemplated hereby.
 
    2.3  CAPITALIZATION AND TITLE TO SHARES.
 
        (a) The authorized capital stock of Holdings consists of 1,000 shares of
    Holdings Common Stock, of which 100 shares are issued and outstanding as of
    the date hereof. Thermo Electron is the record and beneficial owner of all
    of such issued and outstanding shares. All of the issued and outstanding
    shares of the capital stock of Holdings are duly authorized and are validly
    issued, fully paid, nonassessable and free of preemptive rights.
 
        (b) Except as set forth above, there are not as of the date hereof, and
    at the Effective Time there will not be, any other shares of capital stock
    of Holdings authorized or outstanding or any subscriptions, options,
    conversion or exchange rights, warrants, repurchase or redemption
    agreements, or other agreements or commitments obligating Holdings to issue,
    transfer, sell, repurchase or redeem any shares of its capital stock or
    other securities of Holdings. There are no written shareholder agreements,
    voting trusts, proxies or other agreements, instruments or understandings
    with respect to the voting of the capital stock of Holdings. The books and
    records of Holdings, including without limitation the minute books, stock
    certificate books and stock ledgers, are complete and correct and accurately
    reflect the conduct of the affairs of Holdings.
 
    2.4  OWNERSHIP OF THE CARDIO SHARES; NO OTHER ASSETS.
 
        (a) Other than 3,335,705 shares (the "Cardio Shares") of the common
    stock of Thermo Cardiosystems Inc., Holdings does not own, lease or use,
    directly or indirectly, any assets or other property, whether real or
    personal, tangible or intangible. All of the Cardio Shares owned by Holdings
    are owned free and clear of any charges, liens, encumbrances, security
    interests or adverse claims. There are no shareholder agreements, voting
    trusts, proxies or other agreements, instruments or understandings with
    respect to the voting of the Cardio Shares.
 
        (b) Holdings does not, directly or indirectly, own any equity interest
    in any corporation, partnership, joint venture or other entity other than
    the Cardio Shares.
 
    2.5  ABSENCE OF LIABILITIES.  Holdings has no liabilities or obligations of
any nature, whether accrued, absolute, contingent or otherwise and whether due
or to become due (including without limitation, liabilities as guarantor or
otherwise with respect to obligations of others or liabilities for taxes due or
then accrued or to become due).
 
    2.6  NO TRADE OR BUSINESS.  Holdings does not engage, and since its
organization has not engaged, in any trade or business.
 
    2.7  TAXES.  Holdings has accurately prepared and duly and timely filed all
federal, state, local or foreign tax and other returns and reports ("Tax
Returns") which were required to be filed, in respect of all
 
                                      A-4

income, franchise, excise, sales, use, property (real and personal), payroll and
other taxes, levies, imports, duties, license and registration fees, charges or
withholdings of any nature whatsoever (collectively "Taxes"). None of the
federal, state, local or foreign Tax returns of Holdings has been audited or
examined by the governmental authority having jurisdiction. No waivers of any
statutes of limitation are in effect in respect of any Taxes.
 
    2.8  NO CONTRACTS.  There exists no contract, agreement or commitment (other
than this Agreement) to which Holdings is a party or to which Holdings or the
Cardio Shares are subject.
 
    2.9  EMPLOYMENT MATTERS.
 
        (a) Holdings does not employ, and since its organization has not
    employed, any persons other than its officers and directors, all of whom
    serve without compensation.
 
        (b) Holdings does not maintain, and since its organization has not
    maintained, any pension, profit-sharing, deferred compensation, incentive
    compensation, severance pay, retirement, welfare benefit or other plan or
    arrangement providing benefits to employees or retirees. Holdings has no
    liability under or with respect to any employee benefit plans or
    arrangements that may be maintained by any other entity.
 
    2.10  LITIGATION OR PROCEEDINGS.  Holdings is not engaged in, or a party to,
or, to the best of Thermo Electron's or Holdings' knowledge, threatened with,
any claim or legal action or other proceeding before any court, any arbitrator
of any kind or any governmental authority, nor does any basis for any claim or
legal action or other proceeding or governmental investigation exist. There are
no orders, rulings, decrees, judgments or stipulations to which Holdings is a
party by or with any court, arbitrator or governmental authority.
 
                                   SECTION 3
                         REPRESENTATIONS AND WARRANTIES
                         OF THERMEDICS AND ACQUISITION
 
    Thermedics and Acquisition, jointly and severally, represent and warrant to
Thermo Electron and Holdings as follows.
 
    3.1  ORGANIZATION.  Each of Thermedics and Acquisition is a corporation duly
organized, validly existing and in good standing under the laws of its state of
incorporation and has full corporate power and authority to own, lease and
operate its assets and to carry on its business as now being and as heretofore
conducted.
 
    3.2  AUTHORITY.  Each of Thermedics and Acquisition has full right, power,
capacity and authority to execute, deliver and perform this Agreement and to
consummate the transactions contemplated hereby. The execution, delivery and
performance of this Agreement, the filing of the Articles of Merger and the
consummation of the transactions contemplated hereby have been duly and validly
authorized by all necessary corporate action on the part of Thermedics and
Acquisition. This Agreement has been duly and validly executed and delivered by
each of Thermedics and Acquisition and constitutes the valid and binding
obligation of Thermedics and Acquisition, enforceable against them in accordance
with the terms hereof. Neither the execution, delivery and performance of this
Agreement, the filing of the Articles of Merger nor the consummation of the
transactions contemplated hereby will (i) conflict with or result in a
violation, breach, termination or acceleration of, or default under (or would
result in a violation, breach, termination, acceleration or default with the
giving of notice or passage of time, or both) any of the terms, conditions or
provisions of the Articles of Organization or By-laws of Thermedics, as amended,
or Articles of Organization or By-laws of Acquisition, as amended, or of any
note, bond, mortgage, indenture, license, agreement or other instrument or
obligation to which either Thermedics or Acquisition is a party or by which
Thermedics or Acquisition or any of their respective properties or assets may be
bound or affected;
 
                                      A-5

(ii) result in the violation of any order, writ, injunction, decree, statute,
rule or regulation applicable to Thermedics or Acquisition or any of their
respective properties or assets; or (iii) result in the imposition of any lien,
encumbrance, charge or claim upon any of Thermedics' or Acquisition's assets.
Except for the filing of the Articles of Merger and the listing of the
Thermedics Shares for trading on the AMEX, no consent or approval by, or
notification to or filing with, any court, governmental authority or third party
is required in connection with the execution, delivery and performance of this
Agreement by Thermedics and Acquisition or the consummation of the transactions
contemplated hereby.
 
    3.3  AUTHORIZED SHARES.  The Thermedics Shares to be delivered to Thermo
Electron pursuant to this Agreement are duly authorized and, when and if so
delivered, will be validly issued, outstanding, fully paid and nonassessable.
 
                                   SECTION 4
                            COVENANTS AND AGREEMENTS
 
    4.1  NEGATIVE COVENANTS PENDING CLOSING.  Holdings will not:
 
        (i) DISPOSITION OF ASSETS. Sell or transfer, or mortgage, pledge or
    create or permit to be created any lien on, any of the Cardio Shares;
 
        (ii) LIABILITIES. Incur any indebtedness, obligation or liability or
    enter into any contracts or commitments;
 
        (iii) CAPITAL STOCK. Make any change in the number of shares of
    Holdings' capital stock authorized, issued or outstanding or grant any
    option, warrant or other right to purchase, or to convert any obligation
    into, shares of Holdings' capital stock, or declare or pay any dividend or
    other distribution with respect to any shares of Holdings' capital stock, or
    sell or transfer any shares of its capital stock;
 
   
        (iv) CHARTER AND BY-LAWS. Amend its Certificate of Incorporation or
    By-laws; or
    
 
        (v) ACQUISITIONS. Make any acquisition of property.
 
    4.2  CORPORATE EXAMINATIONS AND INVESTIGATIONS.  Prior to the Effective
Time, Thermedics shall be entitled, through its employees and representatives,
to have such access to the books, records and assets of Holdings as is
reasonably necessary or appropriate in connection with its investigation of
Holdings with respect to the transaction contemplated hereby. No investigation
by Thermedics shall diminish or obviate any of the representations, warranties,
covenants or agreements of Thermo Electron or Holdings contained in this
Agreement.
 
    4.3  EXPENSES.  Whether or not the Merger is consummated, Thermedics,
Acquisition, Thermo Electron and Holdings shall bear their respective expenses
incurred in connection with the preparation, execution and performance of this
Agreement and the transactions contemplated hereby, including without
limitation, all fees and expenses of agents, representatives, counsel and
accountants.
 
    4.4  AUTHORIZATION FROM OTHERS.  Prior to the Effective Date, the parties
shall use all reasonable efforts to obtain all authorizations, consents and
permits of others required to permit the consummation of the transactions
contemplated by this Agreement.
 
    4.5  CONSUMMATION OF AGREEMENT.  Each party shall use all reasonable efforts
to perform and fulfill all conditions and obligations to be performed and
fulfilled by it under this Agreement and to ensure that to the extent within its
control or capable of influence by it, no breach of any of its respective
representations, warranties and agreements hereunder occurs or exists on or
prior to the Effective Time, all to the end that the transactions contemplated
by this Agreement shall be fully carried out in a timely fashion.
 
                                      A-6

    4.6  FURTHER ASSURANCES.  Each of the parties shall execute such documents,
further instruments of transfer and assignment and other papers and take such
further actions as may be reasonably required or desirable to carry out the
provisions hereof and the transactions contemplated hereby.
 
    4.7  TAX-FREE REORGANIZATION.  Thermedics, Acquisition, Thermo Electron and
Holdings agree that no party shall take any action directly or indirectly that
would prevent the Merger from qualifying as a tax-free reorganization under
Section 368(a) of the Code.
 
    4.8  LISTING OF SHARES.  Promptly after the Effective Date, Thermedics shall
take all action necessary in accordance with applicable law to convene a meeting
of its stockholders to be held for the purpose of approving the listing of the
Thermedics Shares for trading upon AMEX in accordance with Section 712 of AMEX's
Listing Standards, Policies and Requirements. In connection with such meeting,
Thermedics' Board of Directors shall recommend to the Thermedics stockholders
the approval of the listing of the Thermedics Shares pursuant to this Agreement.
Thermedics shall use all reasonable efforts to obtain all votes and approvals of
the Thermedics stockholders necessary for the listing of the Thermedics Shares
and all related matters under the BCLM, and its Articles of Organization and
By-laws. Thermo Electron hereby agrees to vote all of the shares of Thermedics
Common Stock held by it as of the record date of any such meeting in favor of
the listing of the Thermedics Shares and all such related matters.
 
    4.9  PUBLIC ANNOUNCEMENTS AND CONFIDENTIALITY.  Any press release or other
information to the press or any third party with respect to this Agreement or
the transactions contemplated hereby shall require the prior approval of Thermo
Electron and Thermedics, which approval shall not be unreasonably withheld,
provided that a party shall not be prevented from making such disclosure as it
shall be advised by counsel is required by law.
 
    4.10  INDEMNIFICATION.
 
        (A) RIGHT TO INDEMNIFICATION.  Thermedics and Thermo Electron (as the
    case may be, the "Indemnitee") shall be indemnified on its respective demand
    made to the other (the "Indemnitor") for the full amount of all damages (as
    defined below) suffered by it as a direct or indirect result of:
 
           (i) the inaccuracy of any representation or warranty made by the
       Indemnitor in or pursuant to this Agreement; and
 
           (ii) any failure by the Indemnitor to perform any obligation or
       comply with any covenant or agreement specified in this Agreement.
 
For the purpose of this Section 4.10, (a) references to Thermedics shall be
deemed to mean Thermedics and Acquisition; (b) the term "damages" shall be
determined and computed by reference to the effect of the compensable event on
the Indemnitee, and shall be deemed to include (i) all losses, liabilities,
expenses or costs incurred by the Indemnitee, including reasonable attorneys'
fees, and (ii) interest at a rate per annum equal to that announced from time to
time by BankBoston as its "base rate" (or the legal rate of interest, if lower)
from the date 30 days after notice of any such claim for indemnification is
given to the Indemnitor, or if an unliquidated claim, from such later date as
the claim is liquidated, to the date full indemnification is made therefor; and
(c) damages shall not include any amounts for which the Indemnitee actually
receives payment under an insurance policy, excluding self-insured amounts and
deductible amounts.
 
        (B) INDEMNIFICATION PROCEDURES.  The Indemnitee shall give the
    Indemnitor notice of any claim, action or proceeding by a third party which
    is reasonably likely to result in a claim for indemnification under this
    Section 4.10. The Indemnitor shall have the right, at its expense, to
    defend, contest, protest, settle and otherwise control the resolution of any
    such claim, action or proceeding. The Indemnitee shall have the right to
    participate in any such legal proceeding, subject to the Indemnitor's right
    of control thereof, at the expense of the Indemnitee and with counsel
    selected by the Indemnitee.
 
                                      A-7

        (C) LIMITATIONS ON INDEMNIFICATION.  Thermedics' and Thermo Electron's
    rights to be indemnified pursuant to Section 4.10 shall survive the
    Effective Date of this Agreement indefinitely.
 
    4.11  CERTAIN TAX MATTERS.
 
        (A) ALLOCATION OF CERTAIN TAXES.  In the case of any Tax that is
    attributable to a taxable period which begins before the Effective Date and
    ends after the Effective Date, the amount of Taxes attributable to the
    period prior to the Effective Date (the "Pre-Effective Period") and the
    period subsequent to the Effective Date (the "Post-Effective Period") shall
    be determined as follows:
 
           (i) Thermo Electron and Thermedics agree that if Holdings is
       permitted but not required under applicable foreign, state or local Tax
       laws to treat the Effective Date as the last day of a taxable period,
       Thermo Electron and Thermedics shall treat such day as the last day of a
       taxable period.
 
           (ii) Except to the extent provided in clause (i) of this subsection
       4.11(a), in the case of ad valorem Taxes imposed on Holdings and
       franchise or similar Taxes imposed on Holdings based on capital
       (including net worth or long-term debt) or number of shares of stock
       authorized, issued or outstanding, such Taxes shall be allocated between
       the Pre-Effective Period and the Post-Effective Period based upon the
       respective number of days in each such period.
 
           (iii) Except to the extent provided in clauses (i) and (ii) of this
       subsection 4.11(a), all other Taxes shall be allocated between the
       Pre-Effective Period and the Post-Effective Period based upon an interim
       closing of the books of Holdings as of the end of the day of the
       Effective Date, and the computation of the Tax for each resulting period
       as if the period were a separate taxable period; provided, however, that
       in no event shall the hypothetical Tax for any period be less than zero.
 
        (B) WAIVERS OF CARRYBACKS.  Holdings and Thermo Electron agree, to the
    maximum extent permitted, to elect to waive the carryback of any loss,
    credit or deduction incurred in or attributable to any taxable period (or
    portion thereof) after the Effective Date to any taxable period (or portion
    thereof) prior to the Effective Date.
 
                                   SECTION 5
                   CONDITIONS PRECEDENT TO THE OBLIGATIONS OF
              THERMEDICS AND ACQUISITION TO CONSUMMATE THE MERGER
 
    The obligation of Thermedics and Acquisition to consummate the Merger is
subject to the satisfaction or waiver, at or before the Effective Time, of the
following conditions:
 
    5.1  REPRESENTATIONS, WARRANTIES AND COVENANTS.  The representations and
warranties of Thermo Electron and Holdings contained in this Agreement shall be
true and correct in all material respects on and as of the Effective Time with
the same force and effect as though made on and as of the Effective Time. Thermo
Electron and Holdings shall have performed and complied in all material respects
with all covenants and agreements required by this Agreement to be performed or
complied with by them on or prior to the Effective Time and shall have obtained
all required consents and approvals. Thermo Electron and Holdings shall have
delivered to Thermedics a certificate, dated the Effective Time, to the
foregoing effect.
 
    5.2  ARTICLES OF MERGER.  Holdings shall have executed and delivered the
Articles of Merger.
 
    5.3  CERTIFICATES.  Thermo Electron and Holdings shall have furnished
Thermedics and Acquisition with such certificates of public officials and of
Thermo Electron and Holdings officers as may be reasonably requested by
Thermedics and Acquisition.
 
                                      A-8

                                   SECTION 6
                   CONDITIONS PRECEDENT TO THE OBLIGATION OF
             THERMO ELECTRON AND HOLDINGS TO CONSUMMATE THE MERGER
 
    The obligation of Thermo Electron and Holdings to consummate the Merger is
subject to the satisfaction or waiver, at or before the Effective Time, of the
following conditions:
 
    6.1  REPRESENTATIONS, WARRANTIES AND COVENANTS.  The representations and
warranties of Thermedics and Acquisition contained in this Agreement shall be
true and correct in all material respects on and as of the Effective Time with
the same force and effect as though made on and as of the Effective Time.
Thermedics shall have performed and complied in all material respects with all
covenants and agreements required by this Agreement to be performed or complied
with by it on or prior to the Effective Time and shall have obtained all
required consents and approvals. Thermedics and Acquisition shall have delivered
to Holdings a certificate, dated the Effective Time, to the foregoing effect.
 
    6.2  ARTICLES OF MERGER.  Acquisition shall have executed and delivered the
Articles of Merger.
 
    6.3  CERTIFICATES.  Thermedics and Acquisition shall have furnished Thermo
Electron and Holdings with such certificates of public officials and of
Thermedics and Acquisition officers as may be reasonably requested by Thermo
Electron and Holdings.
 
                                   SECTION 7
                       TERMINATION, AMENDMENT AND WAIVER
 
    7.1  TERMINATION.  This Agreement may be terminated at any time prior to the
Effective Time as follows:
 
        (a) by Thermo Electron upon written notice to Thermedics if Thermedics
    or Acquisition has materially breached any representation, warranty,
    covenant or agreement contained herein and has not cured such breach within
    ten (10) business days of receipt of written notice from Thermo Electron;
 
        (b) by Thermedics upon written notice to Thermo Electron if Thermo
    Electron or Holdings has materially breached any representation, warranty,
    covenant or agreement contained herein and has not cured such breach within
    ten (10) business days of receipt of written notice from Thermedics;
 
        (c) by either party if any court of competent jurisdiction or United
    States governmental body shall have issued an order, decree or ruling or
    taken any other action restraining, enjoining or otherwise prohibiting the
    Merger and such order, decree or ruling shall have become final and
    nonappealable; or
 
        (d) at any time with the written consent of Thermo Electron and
    Thermedics.
 
    7.2  EFFECT OF TERMINATION.  If this Agreement is terminated as provided in
Section 7.1, this Agreement shall forthwith become void and have no effect,
except for the provisions of this Section 7.2, Section 4.3 (relating to
expenses) and Section 4.9 (relating to publicity and confidentiality) to the
extent provided therein. If this Agreement is terminated as provided in Section
7.1(c) or (d), none of the parties hereto, nor any or their directors, officers,
stockholders or affiliates, shall have any liability hereunder. Nothing
contained in this Section 7.2 shall relieve any party from liability for any
breach of this Agreement occurring before termination pursuant to Section 7.1(a)
or (b).
 
    7.3  AMENDMENT.  This Agreement may not be amended except by an instrument
signed by each of the parties hereto.
 
                                      A-9

    7.4  WAIVER.  At any time, any party hereto may (a) extend the time for the
performance of any of the obligations or other acts of any other party hereto or
(b) waive compliance with any of the agreements of any other party or any
conditions to its own obligations, in each case only to the extent such
obligations, agreements and conditions are intended for its benefit; provided
that any such extension or waiver shall be binding upon a party only if such
extension or waiver is set forth in a writing executed by such party.
 
                                   SECTION 8
                                 MISCELLANEOUS
 
    8.1  NOTICES.  All notices, requests, demands, consents and other
communications which are required or permitted hereunder shall be in writing,
and shall be deemed given when actually received or if earlier, one day after
deposit with a nationally recognized air courier or express mail, charges
prepaid or three days after deposit in the U.S. mail by certified mail, return
receipt requested, postage prepaid, addressed as follows:
 
    If to Thermedics or Acquisition:
 
       Thermedics Inc.
       470 Wildwood Street
       Woburn, Massachusetts 01888
       Attention: President
 
    With a copy to:
 
       Thermo Electron Corporation
       81 Wyman Street
       Waltham, Massachusetts 02451
       Attention: General Counsel
 
    If to Thermo Electron or Holdings:
 
       Thermo Electron Inc.
       81 Wyman Street
       Waltham, Massachusetts 02451
       Attention: President
 
    With a copy to:
 
       Thermo Electron Corporation
       81 Wyman Street
       Waltham, Massachusetts 02451
       Attention: General Counsel
 
or to such other address as any party hereto may designate in writing to the
other parties, specifying a change of address for the purpose of this Agreement.
 
    8.2  SURVIVAL AND MATERIALITY OF REPRESENTATIONS.  Each of the
representations, warranties and agreements made by the parties hereto shall be
deemed material and shall survive the Effective Date and the consummation of the
transactions contemplated hereby. All statements contained in any certificates
or other instruments delivered by or on behalf of the parties pursuant hereto or
in connection with the transactions contemplated hereby shall be deemed material
and shall constitute representations and warranties by the person making such
statement.
 
    8.3  ENTIRE AGREEMENT.  This Agreement, including the exhibits, the Holdings
Disclosure Schedule and the other documents referred to herein, supersedes any
and all oral or written agreements or
 
                                      A-10

understandings heretofore made relating to the subject matter hereof and
constitutes the entire agreement of the parties relating to the subject matter
hereof.
 
    8.4  PARTIES IN INTEREST.  All covenants and agreements, representations and
warranties contained in this Agreement made by or on behalf of any of the
parties hereto shall bind and inure to the benefit of the parties hereto, and
their respective successors, assigns, heirs, executors, administrators and
personal representatives, whether so expressed or not.
 
    8.5  NO IMPLIED RIGHTS OR REMEDIES.  Except as otherwise expressly provided
herein, nothing herein expressed or implied is intended or shall be construed to
confer upon or to give any person, firm or corporation, other than the parties
hereto, any rights or remedies under or by reason of this Agreement.
 
    8.6  HEADINGS.  The headings in this Agreement are inserted for convenience
of reference only and shall not be a part of or control or affect the meaning
hereof.
 
    8.7  SEVERABILITY.  If any provision of this Agreement shall be declared
void or unenforceable by any judicial or administrative authority, the validity
of any other provision shall not be affected thereby.
 
    8.8  COUNTERPARTS.  This Agreement may be executed in several counterparts,
each of which shall be deemed an original, but all of which together shall
constitute one and the same instrument.
 
    8.9  FURTHER ASSURANCES.  Thermo Electron and Holdings will execute and
furnish to Thermedics and Acquisition all documents and will do or cause to be
done all other things that Thermedics may reasonably request from time to time
in order to give full effect to this Agreement and to effectuate the intent of
the parties.
 
    8.10  GOVERNING LAW.  This Agreement shall be governed by the law of the
Commonwealth of Massachusetts applicable to agreements made and to be performed
wholly within such jurisdiction, without regard to the conflicts of laws
provisions thereof.
 
               [REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK.]
 
                                      A-11

    IN WITNESS WHEREOF, the parties have caused this Agreement to be duly
executed as of the date first written above.
 
   

                                           
THERMO ELECTRON CORPORATION                   TMO TCA HOLDINGS, INC.
 
By: /S/KENNETH J. APICERNO                    By: /S/JOHN N. HATSOPOULOS
 
Name: Kenneth J. Apicerno                     Name: John N. Hatsopoulos
 
Title: Treasurer                              Title: President
 
THERMEDICS INC.                               CARDIO ACQUISITION INC.
 
By: /S/JOHN T. KEISER                         By: /S/THEO MELAS-KYRIAZI
 
Name: John T. Keiser                          Name: Theo Melas-Kyriazi
 
Title: President                              Title: President
 
By: /S/KENNETH J. APICERNO                    By: /S/KENNETH J. APICERNO
 
Name: Kenneth J. Apicerno                     Name: Kenneth J. Apicerno
 
Title: Treasurer                              Title: Treasurer

    
 
                                      A-12



                                      PROXY

                                 THERMEDICS INC.

PROXY FOR SPECIAL MEETING OF STOCKHOLDERS TO BE HELD           , 1999

           THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF DIRECTORS

The undersigned hereby appoints John T. Keiser, Theo Melas-Kyriazi and 
Kenneth J. Apicerno, or any one of them acting in the absence of the others, as
attorneys and proxies of the undersigned, with full power of substitution, for
and in the name of the undersigned, to represent the undersigned at a Special
Meeting of the Stockholders of Thermedics Inc., a Massachusetts corporation (the
"Company"), to be held on       ,           , 1999 at 10:00 a.m. at the offices
of Thermo Electron Corporation, 81 Wyman Street, Waltham, Massachusetts 02454,
and at any adjournment or postponement thereof, and to vote all shares of common
stock of the Company standing in the name of the undersigned on February 15,
1999, with all of the powers the undersigned would possess if personally present
at such meeting.

                   CONTINUED AND TO BE SIGNED ON REVERSE SIDE





                   PLEASE DATE, SIGN AND MAIL YOUR PROXY CARD
                            BACK AS SOON AS POSSIBLE!

                         SPECIAL MEETING OF STOCKHOLDERS

                                 THERMEDICS INC.


                                          , 1999







                 Please mark your
[   X   ]        votes as in this
                 example.

1.       Approve management proposal to list 4,880,553 shares of common stock,
         to be issued in connection with an acquisition, on the American Stock
         Exchange, Inc.

         FOR [    ]    AGAINST [    ]    ABSTAIN [    ]

2.       In their discretion on such other matters as may properly come before
         the Meeting.

The shares represented by this Proxy will be voted "FOR" the management 
proposal set forth above if no instruction to the contrary is indicated or if 
no instruction is given.

                               MARK HERE FOR ADDRESS CHANGE AND NOTE AT LEFT [ ]

Copies of the Notice of Meeting and of the Proxy Statement have been received by
the undersigned.

PLEASE DATE, SIGN AND PROMPTLY RETURN THIS PROXY IN THE ENCLOSED ENVELOPE.

SIGNATURE(S)                                          DATE
            -----------------------------------------     ----------------------
Please sign exactly as name appears at left. When shares are held by joint
tenants, both should sign. When signing as attorney, executor, administrator,
trustee or guardian, please give full title as such. If a corporation, please
sign in full corporate name by President or other authorized officer. If a
partnership, please sign name by authorized person.