Filer: Thermo Electron Corporation
                                                Subject Company: Thermedics Inc.
                                   Subject Company Exchange Act File No.: 1-9567
                                           Registration Statement No.: 333-35982
PRESS RELEASE:

                            Thermo Electron Commences
                      Exchange Offer for Thermedics Shares

WALTHAM,  Mass., May 1, 2000 - Thermo Electron Corporation  (NYSE-TMO) announced
today that it has commenced its exchange offer to acquire all outstanding shares
of Thermedics Inc.  (ASE-TMD)  common stock.  Under the exchange  offer,  Thermo
Electron  will  exchange  0.45 shares of Thermo  Electron  common stock for each
Thermedics  share.  The exchange offer is scheduled to expire at midnight on May
26, 2000, unless the offer is extended.

      Thermo  Electron   currently  owns   approximately  75.5  percent  of  the
outstanding shares of Thermedics common stock. The goal of the exchange offer is
to  bring  Thermo  Electron's  equity  ownership  in  Thermedics  to at least 90
percent.  If Thermo Electron achieves this 90-percent  ownership  threshold,  it
plans to acquire all remaining  outstanding  shares of  Thermedics  common stock
through a "short-form" merger. In the short-form merger, public shareholders who
do not  participate  in the exchange  offer would also receive  shares of Thermo
Electron  common stock at the same  exchange  ratio that is being offered in the
exchange offer.

      The  exchange  offer and proposed  subsequent  short-form  merger  require
Securities  and  Exchange  Commission   clearance  of  necessary  filings.   The
short-form merger would not require Thermedics board or shareholder approval.

      Upon  completion  of the exchange  offer and the merger,  Thermo  Electron
would  assume  the  outstanding   obligations  under   Thermedics'   convertible
debentures,  and these debentures would become convertible into shares of Thermo
Electron common stock.

      Thermo  Electron  is mailing  today to  registered  holders of  Thermedics
shares a preliminary  prospectus  regarding  the exchange  offer and the merger,
accompanied by a letter of transmittal  that Thermedics  shareholders can use to
tender their  shares in the  exchange  offer.  Beneficial  owners of  Thermedics
shares holding in street name through their brokers can receive the  preliminary
prospectus and letter of transmittal  from their broker and should contact their
brokers for those documents.  In any case, copies of the preliminary  prospectus
and letter of  transmittal  may be requested  from D.F.  King & Co.,  Inc.,  the
information agent for the exchange offer, by calling (800) 290-6433.

                                       -more-



      Thermo  Electron  Corporation  is a leading  provider  of  analytical  and
monitoring instruments used in a broad range of applications, from life sciences
research to  telecommunications  to food and beverage  production.  In addition,
Thermo  Electron  serves  the  healthcare  market  through a family  of  medical
companies,  and is a major  producer of paper  recycling  systems  and  provides
water-clarification  and fiber-recovery  products and services.  As announced on
January 31, 2000,  the company has initiated a major  reorganization  that would
transform  it into one company  focused on its core  measurement  and  detection
instruments  business.   More  information  is  available  on  the  Internet  at
http://www.thermo.com.

OTHER IMPORTANT INFORMATION:

We urge  investors and security  holders to read the following  documents,  when
they become available,  regarding the exchange offer and the merger described in
this announcement, because they contain important information:

     -    Thermo Electron's preliminary  prospectus,  any prospectus supplement,
          final prospectus, and other exchange offer materials.

     -    Thermo Electron's  registration statement on Form S-4 and Schedule TO,
          as amended,  which contain or  incorporate  by reference the documents
          listed above and other information.

     -    Thermedics' solicitation/recommendation statement on Schedule 14D-9.

     -    These documents and amendments to these documents have been or will be
          filed with the SEC. When these and other  documents are filed with the
          SEC,  they  may  be  obtained  for  free  at the  SEC's  Web  site  at
          www.sec.gov.  You may also  obtain  for free each of these  documents,
          when available, from us. You can call us at (781) 622-1111 or write to
          us at:

          Investor Relations  Department
          Thermo Electron Corporation
          81 Wyman Street,
          P.O. Box 9046
          Waltham, MA 02454-9046

The following constitutes a "Safe Harbor" statement under the Private Securities
Litigation  Reform Act of 1995:  This  press  release  contains  forward-looking
statements that involve a number of risks and  uncertainties.  Important factors
that could cause actual  results to differ  materially  from those  indicated by
such forward-looking statements are set forth under the heading "Forward-Looking
Statements" in Exhibit 13 to Thermo  Electron's  annual report on Form 10-K, for
the year ended January 1, 2000. These include risks and  uncertainties  relating
to:  the  company's  corporate  reorganization,   acquisition  strategy,  growth
strategy,   international  operations,  product  development  and  technological
change,  possible changes in governmental  regulations,  changes in both capital
spending by commercial customers and government funding policies, and dependence
on intellectual property rights.