Exhibit 10.6

                         MASTER GUARANTEE REIMBURSEMENT
                               AND LOAN AGREEMENT


             This AGREEMENT  is  entered  into  as of  the  24th day  of
        November, 1997  by and among Thermo Instrument  Systems Inc. (the
        "Parent") and  those  of  its subsidiaries  that  join  in  this
        Agreement by executing the  signature page hereto (the  "Majority
        Owned Subsidiaries").

                                   WITNESSETH:

             WHEREAS,  the Majority  Owned   Subsidiaries
        wholly-owned subsidiaries  wish to enter  into  various financial
        transactions, such as convertible or nonconvertible debt,  loans,
        and 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 the Parent ("Credit Support Obligations"); 

             WHEREAS, the  Majority  Owned Subsidiaries  and  the  Parent
        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 the Parent (a "Parent Guarantee")  or
        without obtaining Credit Support Obligations from other  Majority
        Owned Subsidiaries;

             WHEREAS,  the   Majority   Owned  Subsidiaries and  their
        wholly-owned subsidiaries   may borrow funds  from the Parent, and
        the Parent may loan funds or provide credit to the Majority Owned
        Subsidiaries and their wholly-owned subsidiaries, on a short-term
        and unsecured basis; and

             WHEREAS,  the Parent  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 and to borrow funds, 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.   If the Parent provides a  Parent Guarantee of an  Underlying
             Obligation, and the beneficiary(ies) of the Parent Guarantee
             enforce the Parent Guarantee,  or the Parent 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
PAGE
<PAGE>
             Underlying Obligation shall indemnify and save harmless  the
             Parent  from  any   liability,  cost,   expense  or   damage
             (including  reasonable  attorneys'  fees)  suffered  by  the
             Parent 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
             the Parent, 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 the  Parent 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.

        2.   For purposes of this  Agreement, the term "guarantee"  shall
             include not only  a formal guarantee  of an obligation,  but
             also any other  arrangement where the  Parent is liable  for
             the obligations  of  a  Majority  Owned  Subsidiary   or its
             wholly-owned subsidiarie s.  Such other arrangements include
             (a) representations,  warranties and/or  covenants or  other
             obligations joined in by the  Parent, whether on a joint  or
             joint and several  basis, for  the benefit  of the  Majority
             Owned Subsidiary or its wholly-owned subsidiarie   s and (b)
             responsibility of the  Parent 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.

        3.   Promptly after the Parent receives notice that a beneficiary
             of a  Parent Guarantee  is  seeking to  enforce such  Parent
             Guarantee,  the  Parent  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, the Parent  will not perform under  the
             relevant Parent Guarantee unless and until, in the  Parent's
             reasonable judgment, the Parent is obligated under the terms
             of such  Parent  Guarantee  to  perform.    Subject  to  the
PAGE
<PAGE>
             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
             the Parent  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  the
             Parent.   The  Parent  shall  have the  right,  at  its  own
             expense, to contest the claim  of such beneficiary .  If the
             Parent or the subsidiary of  the Parent 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  the Parent  or  the
             subsidiary of the Parent 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
             the Parent's obligation to  promptly indemnify the  Majority
             Owned  Subsidiary   or  its   wholly-owned  subsidiary,   as
             applicable, hereunder.  

        4.   Upon the request of a Majority Owned Subsidiary, the  Parent
             may make loans and advances to the Majority Owned Subsidiary
             or its  wholly-owned subsidiaries on a short-term, revolving
             credit basis, from time to time in such amounts as  mutually
             determined by the Parent and the Majority Owned  Subsidiary.
             The aggregate principal  amount of such  loans and  advances
             shall be reflected on the books and records of the  Majority
             Owned Subsidiary (or wholly-owned subsidiary, as applicable)
             and the Parent.  All such loans and advances shall be on  an
             unsecured basis  unless specifically  provided otherwise  in
             loan documents executed  at that time.   The Majority  Owned
             Subsidiary or its wholly-owned subsidiarie s, as applicable,
             shall pay interest on the aggregate unpaid principal  amount
             of such  loans  from time  to  time outstanding  at  a  rate
             ("Interest Rate") equal to the rate of the Commercial  Paper
             Composite Rate for 90-day maturities as reported by  Merrill
             Lynch Capital  Markets,  as  an average  of  the  last  five
             business days  of such  Majority Owned  Subsidiary's  latest
             fiscal quarter  then  ended,  plus  twenty-five  (25)  basis
             points.  The Interest  Rate shall be  adjusted on the  first
             business day of each fiscal  quarter of such Majority  Owned
             Subsidiary pursuant to the  Interest Rate formula  contained
             in the preceding  sentence and  shall be in  effect for  the
             entirety of such fiscal quarter.  Interest shall be computed
             on  a   360-day  basis.    The  aggregate  principal  amount
             outstanding and accrued interest thereon shall be payable on
PAGE
<PAGE>
             demand.  The principal and  accrued interest may be paid  by
             the  Majority  Owned  Subsidiaries  or  their   wholly-owned
             subsidiaries, as applicable,  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.   Principal and interest  shall be payable  in
             lawful money of the United States of America, in immediately
             available funds, at the principal office of the Parent or at
             such other place as  the Parent may  designate from time  to
             time in  writing  to the  Majority  Owned Subsidiary.    The
             unpaid principal amount of any such borrowings, and  accrued
             interest thereon, shall become immediately due and  payable,
             without demand,  upon  the  failure of  the  Majority  Owned
             Subsidiary or its wholly-owned subsidiary, as applicable, to
             pay its  debts as  they become  due, the  insolvency of  the
             Majority Owned Subsidiary or its wholly-owned subsidiary, as
             applicable,the  filing by  or  against the  Majority  Owned
             Subsidiary or its wholly-owned subsidiary, as applicable, 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  Majority   Owned
             Subsidiary or its wholly-owned subsidiary, as applicable, 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 property of the Majority Owned Subsidiary
             or its wholly-owned subsidiary, as applicable .  In case any
             payments of principal  and interest shall  not be paid  when
             due, the  Majority  Owned  Subsidiary  or its  wholly-owned
             subsidiary, as applicable,  further promises to pay all cost
             of collection, including reasonable attorneys' fees.   

        5.   All payments  required  to  be  made  by  a  Majority  Owned
             Subsidiary or its wholly-owned subsidiaries, as  applicable,
             shall be made within two  days after receipt of notice  from
             the Parent. All payments required  to be made by the  Parent
             shall be made  within two days after  receipt of notice from
             the Majority Owned Subsidiary.  

        6.   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.


             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 INSTRUMENT SYSTEMS INC.
PAGE
<PAGE>
                                      By:  /s/Earl R. Lewis
                                           ------------------------------
                                      Title:    President


                                      THERMO VISION CORPORATION


                                      By:  /s/Kristine Stotz Langdon
                                           ------------------------------
                                      Title:    President