MASTER CASH MANAGEMENT, GUARANTEE
                        REIMBURSEMENT AND LOAN AGREEMENT


        This AGREEMENT is entered into as of the 1st day of June, 1999 by and
between Thermo Electron Corporation, a Delaware corporation ("Thermo Electron")
and Thermo Optek Corporation, a Delaware corporation (the "Subsidiary").

                                   WITNESSETH:

        WHEREAS, Thermo Electron and the Subsidiary are party to a Master
Repurchase Agreement, as amended and restated, which contains terms governing a
cash management arrangement between them and a Master Guarantee Reimbursement
and Loan Agreement, as amended and restated, which contains terms relating to
intercompany credit support and a short term borrowing facility;

        WHEREAS, Thermo Electron and the Subsidiary desire to establish a new
cash management arrangement and short term borrowing facility between them in
lieu of the arrangements set forth in the Master Repurchase Agreement and the
Master Guarantee Reimbursement and Loan Agreement and also to consolidate the
terms relating to intercompany credit support in one agreement;

        WHEREAS, the Subsidiary and other majority owned subsidiaries of Thermo
Electron that join in this Agreement (collectively, the "Majority-Owned
Subsidiaries") and their wholly-owned subsidiaries wish to enter into various
financial transactions, such as convertible or nonconvertible debt, loans,
equity offerings, and other contractual arrangements with third parties (the
"Underlying Obligations") and may provide credit support to, on behalf of or for
the benefit of, other subsidiaries of Thermo Electron ("Credit Support
Obligations");

        WHEREAS, the Majority Owned Subsidiaries and Thermo Electron acknowledge
that the Majority Owned Subsidiaries and their wholly-owned subsidiaries may be
unable to enter into many kinds of Underlying Obligations without a guarantee of
their performance thereunder from Thermo Electron (a "Parent Guarantee") or
without obtaining Credit Support Obligations from other Majority Owned
Subsidiaries;

        WHEREAS, certain Majority Owned Subsidiaries ("Second Tier Majority
Owned Subsidiaries") may themselves be majority owned subsidiaries of other
Majority Owned Subsidiaries ("First Tier Majority Owned Subsidiaries");

        WHEREAS, for various reasons, Parent Guarantees of a Second Tier
Majority Owned Subsidiary's Underlying Obligations may be demanded and given
without the respective First Tier Majority Owned Subsidiary also issuing a
guarantee of such Underlying Obligation;

        WHEREAS, Thermo Electron may itself make a loan or provide other credit
to a Second Tier Majority Owned Subsidiary or its wholly-owned subsidiaries
under circumstances where the applicable First Tier Majority Owned Subsidiary
does not provide such credit; and

        WHEREAS, Thermo Electron is willing to consider continuing to issue
Parent Guarantees and providing credit, and the Majority Owned Subsidiaries are
willing to consider continuing to provide Credit Support Obligations, on the
terms and conditions set forth below;

        NOW, THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged by each party hereto, the parties agree as follows:

        1. Cash Management Arrangement. The Subsidiary directly, or through its
wholly-owned U.S. subsidiaries, may, from time to time, lend its excess cash to
Thermo Electron (a "Transaction"), on an unsecured basis, bearing interest at a
rate equal to the 30-day Dealer Commercial Paper Rate as reported in the Wall
Street Journal (the "DCP Rate") plus 50 basis points, which rate shall be
adjusted on the second business day of each fiscal month of the Subsidiary and
shall be in effect for the entirety of such fiscal month. The Subsidiary shall
institute a Transaction by depositing its excess cash in the Subsidiary's
concentration account at BankBoston Corporation ("BankBoston") or other bank
designated by Thermo Electron. At the end of each business day, the cash balance
deposited in the Subsidiary's concentration account shall be transferred to
Thermo Electron's intercompany account at BankBoston or other bank designated by
Thermo Electron. Thermo Electron shall indicate on its books the balance of the
Subsidiary's cash held by Thermo Electron under this arrangement. After each
fiscal month end, Thermo Electron shall provide the Subsidiary a report
indicating the Subsidiary's aggregate cash balance ("Excess Cash") held by
Thermo Electron hereunder. The Subsidiary shall have the right to withdraw all
or part of its Excess Cash upon 30 days' prior notice to Thermo Electron. Within
30 days of receipt of such withdrawal notice, Thermo Electron shall transfer the
portion of the Excess Cash requested for withdrawal to an account designated by
the Subsidiary. Thermo Electron shall maintain, at all times, cash, cash
equivalents and/or immediately available bank lines of credit equal to at least
50% of the cash balances of the Subsidiary and of all other participating
subsidiaries of Thermo Electron, other than wholly-owned subsidiaries of Thermo
Electron, held by Thermo Electron under this arrangement. Interest shall be
payable on the Excess Cash by Thermo Electron to the Subsidiary each fiscal
month in arrears. In addition, the Subsidiary's non-U.S. subsidiaries may, from
time to time, lend or advance their excess cash to Thermo Electron, on an
unsecured basis, bearing interest at rates set by Thermo Electron at the
beginning of each month, based to the extent practicable on comparable interest
rates generally available in the local jurisdiction of such participating
non-U.S. subsidiary. Further, Thermo Electron and such non-U.S. subsidiaries
participating in the cash management arrangement with Thermo Electron shall
establish mutually agreeable procedures governing such cash management
arrangement.

        2. Loans and Advances. Upon request from the Subsidiary, Thermo Electron
may make loans and advances to the Subsidiary on a short-term, revolving credit
basis, from time to time, in such amounts as mutually determined by Thermo
Electron and the Subsidiary. The aggregate principal amount of such loans and
advances shall be reflected on the books and records of the Subsidiary and
Thermo Electron. All such loans and advances shall be on an unsecured basis
unless specifically provided otherwise in separate loan documents executed at
that time. The Subsidiary shall pay interest on the aggregate unpaid principal
amount of such loans from time to time outstanding at a rate equal to the DCP
Rate plus one hundred fifty (150) basis points, which rate shall be adjusted on
the second business day of each fiscal month of the Subsidiary and shall be in
effect for the entirety of such fiscal month. If, however, one or more of the
Subsidiary's majority-owned U.S. subsidiaries (i.e., not wholly-owned) is also
participating in the cash management arrangement with Thermo Electron, then the
rate payable on the Subsidiary's outstanding principal balance shall be
calculated as follows: If the aggregate amount of the Subsidiary's
majority-owned U.S. subsidiaries' cash balances under the cash management
arrangement ("Majority-Owned Excess Cash") equals or exceeds the Subsidiary's
outstanding principal balance, then the Subsidiary shall pay interest on the
aggregate unpaid principal amount of such loans at a rate per annum equal to the
DCP Rate plus fifty (50) basis points. If the aggregate amount of the
Majority-Owned Excess Cash is less than the Subsidiary's outstanding principal
balance, then (A) the Subsidiary shall pay interest at a rate per annum equal to
the DCP Rate plus fifty (50) basis points on that portion of the unpaid
principal amount equal to the Majority-Owned Excess Cash, and (B) the Subsidiary
shall pay interest at a rate per annum equal to the DCP Rate plus one hundred
fifty (150) basis points on that portion of the unpaid principal amount equal to
(i) the Subsidiary's outstanding principal balance, minus (ii) the
Majority-Owned Excess Cash. The interest rates set forth in the prior two
sentences shall be adjusted on the second business day of each fiscal month of
the Subsidiary and shall be in effect for the entirety of such fiscal month.
Interest shall be computed on a 360-day basis. Interest is payable each fiscal
month in arrears. The aggregate principal amount outstanding shall be payable
within 30 days of demand by Thermo Electron. Overdue principal and interest
shall bear interest at a rate per annum equal to the rate of interest published
from time to time in the Wall Street Journal as the "prime rate" plus one
percent (1%). The principal and accrued interest may be paid by the Subsidiary
at any time or from time to time, in whole or in part, without premium or
penalty. All payments shall be applied first to accrued interest and then to
principal. At the end of each business day, Thermo Electron shall apply the
balance of the Subsidiary's Excess Cash held by Thermo Electron under the cash
management arrangement toward the payment of any loans or advances to the
Subsidiary. Principal and interest shall be payable in lawful money of the
United States of America, in immediately available funds, at the principal
office of Thermo Electron or at such other place as Thermo Electron may
designate from time to time in writing to the Subsidiary. The unpaid principal
amount of any such borrowings, and accrued interest thereon, shall become
immediately due and payable, without demand, upon occurrence of any of the
following events:

        (a) the failure of the Subsidiary to pay any amount due hereunder within
        fifteen (15) days of the date when due;

        (b) the failure of the Subsidiary to pay its debts as they become due,
        the filing by or against the Subsidiary of any petition under the U.S.
        Bankruptcy Code (or the filing of any similar petition under the
        insolvency law of any jurisdiction), or the making by the Subsidiary of
        an assignment or trust mortgage for the benefit of creditors or the
        appointment of a receiver, custodian or similar agent with respect to,
        or the taking by any such person of possession of, any material property
        of the Subsidiary;

        (c) the sale by the Subsidiary of all or substantially all of its
        assets;

        (d) the merger or consolidation of the Subsidiary with or into any other
        corporation in a transaction in which the Subsidiary is not the
        surviving entity;

        (e) the issuance of any writ of attachment, by trustee process or
        otherwise, or any restraining order or injunction against or affecting
        the person or property of the Subsidiary that is not removed, repealed
        or dismissed within thirty (30) days of issuance and as a result has a
        material adverse effect on the business, operations, assets or
        condition, financial or otherwise, of the Subsidiary or its ability to
        discharge any of its liabilities or obligations to Thermo Electron; and

        (f) the suspension of the transaction of the usual business of the
        Subsidiary.

        3.      Guarantee Arrangements.

        (a) If Thermo Electron provides a Parent Guarantee of an Underlying
        Obligation, and the beneficiary(ies) of the Parent Guarantee enforce the
        Parent Guarantee, or Thermo Electron performs under the Parent Guarantee
        for any other reason, then the Majority Owned Subsidiary that is
        obligated, either directly or indirectly through a wholly-owned
        subsidiary, under such Underlying Obligation shall indemnify and save
        harmless Thermo Electron from any liability, cost, expense or damage
        (including reasonable attorneys' fees) suffered by Thermo Electron as a
        result of the Parent Guarantee. If the Underlying Obligation is issued
        by a Second Tier Majority Owned Subsidiary or a wholly-owned subsidiary
        thereof, and such Second Tier Majority Owned Subsidiary is unable to
        fully indemnify Thermo Electron (because of the poor financial condition
        of such Second Tier Majority Owned Subsidiary, or for any other reason),
        then the First Tier Majority Owned Subsidiary that owns the majority of
        the stock of such Second Tier Majority Owned Subsidiary shall indemnify
        and save harmless Thermo Electron from any remaining liability, cost,
        expense or damage (including reasonable attorneys' fees) suffered by
        Thermo Electron as a result of the Parent Guarantee. If a Majority Owned
        Subsidiary or a wholly-owned subsidiary thereof provides a Credit
        Support Obligation for any subsidiary of Thermo Electron, other than a
        subsidiary of such Majority Owned Subsidiary, and the beneficiary(ies)
        of the Credit Support Obligation enforce the Credit Support Obligation,
        or the Majority Owned Subsidiary or its wholly-owned subsidiary performs
        under the Credit Support Obligation for any other reason, then Thermo
        Electron shall indemnify and save harmless the Majority Owned Subsidiary
        or its wholly-owned subsidiary, as applicable, from any liability, cost,
        expense or damage (including reasonable attorneys' fees) suffered by the
        Majority Owned Subsidiary or its wholly-owned subsidiary, as applicable,
        as a result of the Credit Support Obligation. Without limiting the
        foregoing, Credit Support Obligations include the deposit of funds by a
        Majority Owned Subsidiary or a wholly-owned subsidiary thereof in a
        credit arrangement with a banking facility whereby such funds are
        available to the banking facility as collateral for overdraft
        obligations of other Majority Owned Subsidiaries or their subsidiaries
        also participating in the credit arrangement with such banking facility.
        Nothwithstanding the foregoing, in order to obtain the benefits of the
        indemnification obligations of the First Tier Majority Owned Subsidiary
        set forth above in this Section 3(a), Thermo Electron must have notified
        the First Tier Majority Owned Subsidiary prior to guaranteeing the
        obligations of the Second Tier Majority Owned Subsidiary. If after five
        (5) business days, Thermo Electron has not received from the First Tier
        Majority Owned Subsidiary a notice of objection stating that the First
        Tier Majority Owned Subsidiary objects to Thermo Electron guaranteeing
        the obligations of the Second Tier Majority Owned Subsidiary, then
        Thermo Electron may proceed to issue its guarantee of the Underlying
        Obligation and such guarantee shall be subject to the benefits of the
        indemnification obligations of the First Tier Majority Owned Subsidiary
        set forth above in this Section 3(a). If Thermo Electron does receive
        such notice of objection, then Thermo Electron's guarantee shall not be
        subject to the indemnification obligations of the First Tier Majority
        Owned Subsidiary set forth above in this Section 3(a).

        (b) For purposes of this Agreement, the term "guarantee" shall include
        not only a formal guarantee of an obligation, but also any other
        arrangement where Thermo Electron is liable for the obligations of a
        Majority Owned Subsidiary or its wholly-owned subsidiaries. Such other
        arrangements include (a) representations, warranties and/or covenants or
        other obligations joined in by Thermo Electron, whether on a joint or
        joint and several basis, for the benefit of the Majority Owned
        Subsidiary or its wholly-owned subsidiaries and (b) responsibility of
        Thermo Electron by operation of law for the acts and omissions of the
        Majority Owned Subsidiary or its wholly-owned subsidiaries, including
        controlling person liability under securities and other laws.

        (c) Promptly after Thermo Electron receives notice that a beneficiary of
        a Parent Guarantee is seeking to enforce such Parent Guarantee, Thermo
        Electron shall notify the Majority Owned Subsidiary(s) obligated, either
        directly or indirectly through a wholly-owned subsidiary, under the
        relevant Underlying Obligation. Such Majority Owned Subsidiary(s) or
        wholly-owned subsidiary thereof, as applicable, shall have the right, at
        its own expense, to contest the claim of such beneficiary. If a Majority
        Owned Subsidiary or wholly-owned subsidiary thereof, as applicable, is
        contesting the claim of such beneficiary, Thermo Electron will not
        perform under the relevant Parent Guarantee unless and until, in Thermo
        Electron's reasonable judgment, Thermo Electron is obligated under the
        terms of such Parent Guarantee to perform. Subject to the foregoing, any
        dispute between a Majority Owned Subsidiary or wholly-owned subsidiary
        thereof, as applicable, and a beneficiary of a Parent Guarantee shall
        not affect such Majority Owned Subsidiary's obligation to promptly
        indemnify Thermo Electron hereunder. Promptly after a Majority Owned
        Subsidiary or wholly-owned subsidiary thereof, as applicable, receives
        notice that a beneficiary of a Credit Support Obligation is seeking to
        enforce such Credit Support Obligation, the Majority Owned Subsidiary
        shall notify Thermo Electron. Thermo Electron shall have the right, at
        its own expense, to contest the claim of such beneficiary. If Thermo
        Electron or the subsidiary of Thermo Electron on whose behalf the Credit
        Support Obligation is given is contesting the claim of such beneficiary,
        the Majority Owned Subsidiary or wholly-owned subsidiary thereof, as
        applicable, will not perform under the relevant Credit Support
        Obligation unless and until, in the Majority Owned Subsidiary's
        reasonable judgment, the Majority Owned Subsidiary or wholly-owned
        subsidiary thereof, as applicable, is obligated under the terms of such
        Credit Support Obligation to perform. Subject to the foregoing, any
        dispute between Thermo Electron or the subsidiary of Thermo Electron on
        whose behalf the Credit Support Obligation was given, on the one hand,
        and a beneficiary of a Credit Support Obligation, on the other, shall
        not affect Thermo Electron's obligation to promptly indemnify the
        Majority Owned Subsidiary or its wholly-owned subsidiary, as applicable,
        hereunder.

        (d) If Thermo Electron makes a loan or provides other credit ("Credit
        Extension") to a Second Tier Majority Owned Subsidiary, the First Tier
        Majority Owned Subsidiary that owns the majority of the stock of such
        Second Tier Majority Owned Subsidiary hereby guarantees the Second Tier
        Majority Owned Subsidiary's obligations to Thermo Electron thereunder.
        Such guaranty shall be enforced only after Thermo Electron, in its
        reasonable judgment, determines that the Second Tier Majority Owned
        Subsidiary is unable to fully perform its obligations under the Credit
        Extension. If Thermo Electron provides Credit Extension to a
        wholly-owned subsidiary of a Second Tier Majority Owned Subsidiary, the
        Second Tier Majority Owned Subsidiary hereby guarantees it wholly-owned
        subsidiary's obligations to Thermo Electron thereunder and the First
        Tier Majority Owned Subsidiary that owns the majority of the stock of
        such Second Tier Majority Owned Subsidiary hereby guarantees the Second
        Tier Majority Owned Subsidiary's obligations to Thermo Electron
        hereunder. Such guaranty by the First Tier Majority Owned Subsidiary
        shall be enforced only after Thermo Electron, in its reasonable
        judgment, determines that the Second Tier Majority Owned Subsidiary is
        unable to fully perform its guaranty obligation hereunder.
        Notwithstanding the foregoing, in order for a Credit Extension to be
        deemed guaranteed by the First Tier Majority Owned Subsidiary as set
        forth above in this Section 3(d), Thermo Electron must have notified the
        First Tier Majority Owned Subsidiary prior to providing the Credit
        Extension to the Second Tier Majority Owned Subsidiary. If after five
        (5) business days, Thermo Electron has not received from the First Tier
        Majority Owned Subsidiary a notice of objection stating that the First
        Tier Majority Owned Subsidiary objects to Thermo Electron providing a
        Credit Extension to the Second Tier Majority Owned Subsidiary, then
        Thermo Electron may proceed to issue the Credit Extension to the Second
        Tier Majority Owned Subsidiary and the First Tier Majority Owned
        Subsidiary shall be deemed to have guaranteed such Credit Extension as
        set forth above in this Section 3(d). If Thermo Electron does receive
        such notice of objection, then Thermo Electron's Credit Extension shall
        not be deemed guaranteed by the First Tier Majority Owned Subsidiary as
        set forth in this Section 3(d).

        (e) All payments required to be made under this Section 3 by a Majority
        Owned Subsidiary or its wholly-owned subsidiaries, as applicable, shall
        be made within two days after receipt of notice from Thermo Electron.
        All payments required to be made under this Section 3 by Thermo Electron
        shall be made within two days after receipt of notice from the Majority
        Owned Subsidiary.

        4. Waivers. No delay or omission on the part of either party in
exercising any right hereunder shall operate as a waiver of such right or of any
other right of the party, nor shall any delay, omission or waiver on any one
occasion be deemed a bar to or waiver of the same or any other right on any
future occasion. The Subsidiary hereby waives demand, notice of prepayment,
protest and all other demands and notices in connection with the delivery,
acceptance, performance, default or enforcement of the Subsidiary's obligations
hereunder. The Subsidiary hereby assents to any indulgence and any extension of
time for payment of any indebtedness hereunder granted or permitted by the
party.

        5. Governing Law. This Agreement shall be governed by and construed in
accordance with the laws of the Commonwealth of Massachusetts applicable to
contracts made and performed therein without giving effect to any choice of law
provision or rule that would cause the application of laws of any jurisdiction
other than the Commonwealth of Massachusetts.

        6. Severability. Each provision and agreement herein shall be treated as
separate and independent from any other provision or agreement herein and shall
be enforceable notwithstanding the unenforceability of any such other provision
or agreement.

        7. Non-assignability. The rights and obligations of the parties under
this Agreement shall not be assigned by either party without the prior written
consent of the other party. Subject to the foregoing, this Agreement shall be
binding upon and shall inure to the benefit of the parties and their respective
successors and assigns.

        8. Other Agreements. The parties agree that, effective as of the date
hereof, each of the Master Repurchase Agreement, as amended and restated,
between the Subsidiary and Thermo Electron and the Master Guarantee
Reimbursement and Loan Agreement, as amended and restated, between the
Subsidiary and Thermo Electron, is hereby terminated and is of no further force
and effect.



<PAGE>





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


                                            THERMO ELECTRON CORPORATION


                                            By:    _____________________________
                                                   /s/ Theo Melas-Kyriazi

                                            Title: Vice President &
                                                   Chief Financial Officer


                                            THERMO OPTEK CORPORATION


                                            By:    _____________________________
                                                   /s/ Barry S. Howe

                                            Title: President &
                                                   Chief Executive Officer