AGREEMENT FOR SALE OF SHARES


      Thermo Electron Corporation, a Delaware corporation with a principal place
of business at 81 Wyman Street, Waltham, Massachusetts 02454-9046 (the
"Purchaser"), and ThermoTrex Corporation, a Delaware corporation with a
principal place of business at 10455 Pacific Center Court, San Diego, California
92121 (the "Seller"), hereby agree as follows:

      1. The Seller hereby agrees to sell, and the Purchaser hereby agrees to
purchase, 3,712,072 shares of the Seller's common stock, $.01 par value per
share (the "Common Stock"), for consideration of $11.25 per share in cash, and
the Seller and the Purchaser agree to execute any and all further documents
necessary to complete the transfer of the shares sold hereunder (the "Shares")
to the Purchaser.

      2. The Seller represents and warrants that (i) the Shares are not subject
to any encumbrance of any nature, and (ii) it does not need the consent of any
person to sell the Shares to the Purchaser.

      3. (a) The Purchaser represents and warrants to, and covenants with, the
Seller that: (i) the Purchaser is acquiring the Shares being purchased by it for
its own account for investment and with no present intention of distributing
such Shares; and (ii) the Purchaser will not, directly or indirectly,
voluntarily offer, sell, pledge, transfer or otherwise dispose of (or solicit
any offers to buy, purchase or otherwise acquire or take a pledge of) any of the
Shares except in compliance with the Securities Act and the rules and
regulations promulgated thereunder.

            (b) The Purchaser acknowledges, represents and agrees that:

                  (i) certificates evidencing the Shares will be delivered to it
upon the purchase thereof with a legend substantially to the following effect:

      THE SECURITIES  EVIDENCED BY THIS  CERTIFICATE WERE ACQUIRED FOR
      INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT
      OF 1933, AS AMENDED.  SUCH SECURITIES MAY NOT BE OFFERED,  SOLD,
      TRANSFERRED,  PLEDGED, HYPOTHECATED OR OTHERWISE DISPOSED OF, IN
      THE ABSENCE OF AN EFFECTIVE  REGISTRATION  STATEMENT  UNDER SAID
      ACT  OR AN  OPINION  (WHICH  SHALL  BE  IN  FORM  AND  SUBSTANCE
      SATISFACTORY  TO THE  SELLER)  OF  COUNSEL  SATISFACTORY  TO THE
      SELLER, THAT SUCH REGISTRATION IS NOT REQUIRED.

      The Purchaser agrees that any sale, transfer, pledge, hypothecation or
other disposition made by it shall be made in compliance with such legend; and

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                  (ii) it understands that it must bear the economic risk of its
investment for an indefinite period of time because the Shares have not been
registered under the Securities Act and, therefore, cannot be sold unless
subsequently registered under the Securities Act or an exemption from such
registration is available.

      4. The closing of the sale of the Shares will take place on June 8, 1999.

      IN WITNESS WHEREOF,  the parties hereto have executed this Agreement as of
June 4, 1999.


                                          THERMO ELECTRON CORPORATION



                                          By:/s/ Theo Melas-Kyriazi
                                             -----------------------
                                          Theo Melas-Kyriazi
                                          Chief Financial Officer


                                          THERMOTREX CORPORATION




                                          By: /s/ John T. Keiser
                                             ------------------------
                                          John T. Keiser
                                          Chairman of the Board of Directors