Exhibit 10.27

                         THERMO INSTRUMENT SYSTEMS INC.
             THERMO OPTEK CORPORATION NONQUALIFIED STOCK OPTION PLAN


        1.   Purpose

             This Nonqualified Stock Option Plan (the "Plan") is intended
        to encourage  ownership of  Common Stock,  $0.01 par  value  (the
        "Common Stock"), of  Thermo Optek  Corporation  ("Subsidiary"), a
        subsidiary of Thermo Instrument Systems Inc.  (the "Company"), by
        persons selected  by  the  Board of  Directors  (or  a  committee
        thereof) in its sole  discretion, including directors,  executive
        officers, key employees  and consultants of  the Company and  its
        subsidiaries, and  to provide  additional incentive  for them  to
        promote  the  success  of  the   business  of  the  Company   and
        Subsidiary.   The Plan  is intended  to be  a nonstatutory  stock
        option plan.

        2.   Effective Date of the Plan

             The Plan shall become effective when adopted by the Board of
        Directors of the Company.

        3.   Stock Subject to Plan

             At no time shall  the number of shares  of the Common  Stock
        then outstanding  which  are  attributable  to  the  exercise  of
        options granted under  the Plan  plus the number  of shares  then
        issuable upon the exercise  of outstanding options granted  under
        the Plan  exceed 1,000,000 shares  (as adjusted  to reflect  the
        three-for-two stock split  effected in  the form of  a 50%  stock
        dividend in April 1996), subject  however,  to the provisions  of
        paragraph 11 of the Plan.  Shares to be issued upon the  exercise
        of options granted under the  Plan shall be shares of  Subsidiary
        beneficially owned  by the  Company.   If any  option expires  or
        terminates for any reason without having been exercised in  full,
        the unpurchased shares subject  thereto shall again be  available
        for options thereafter to be granted.

        4.   Administration

             The  Plan  shall  be   administered  by  a  committee   (the
        "Committee") composed of the members of the Board of Directors of
        the Company,  no  member  of  which shall  act  upon  any  matter
        exclusively affecting  any option  granted or  to be  granted  to
        himself or herself under the Plan.  Subject to the provisions  of
        the Plan, the  Committee shall  have complete  authority, in  its
        discretion, to make the following determinations with respect  to
        each option to  be granted  by the Company:   (a)  the person  to
        receive the option (the "Optionee"); (b) the time of granting the
        option; (c) the number of shares subject thereto; (d) the  option
        price; (e) the option period; and (f) the terms of the option and
        form of option agreement (which need not be identical, but  which
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        shall conform to the applicable terms and conditions of the  Plan
        and contain such other provisions as the Board of Directors deems
        advisable and not inconsistent  with the Plan).   In making  such
        determinations, the Committee may take into account the nature of
        the  services  rendered  by  the  Optionees,  their  present  and
        potential contributions to the success of the Company and/or  one
        or more  of  its subsidiaries,  and  such other  factors  as  the
        Committee in its discretion shall deem relevant.  Subject to  the
        provisions of the  Plan, the Committee  shall also have  complete
        authority to interpret the Plan, to prescribe, amend, and rescind
        rules and regulations relating to it, to determine the terms  and
        provisions of the respective option agreements (which need not be
        identical), and  to make  all other  determinations necessary  or
        advisable for the  administration of the  Plan.  The  Committee's
        determinations on the  matters referred  to in  this paragraph  4
        shall be conclusive.

        5.   Eligibility

             An option  may be  granted  to any  person selected  by  the
        Committee in its sole discretion.

        6.   Time of Granting Options

             The granting  of an  option  shall take  place at  the  time
        specified by the Committee.  Only if expressly so provided by the
        Committee shall the granting of  an option be regarded as  taking
        place at the time when a written option agreement shall have been
        duly executed and delivered  by or on behalf  of the Company  and
        the Optionee to whom such option shall be granted.  The agreement
        shall provide, among other things,  that it does not confer  upon
        an Optionee any right  to continue in the  employ of the  Company
        and/or one  or more  of  its subsidiaries  or  to continue  as  a
        director or  consultant of  the  Company, and  that it  does  not
        interfere in any way  with the right of  the Company or any  such
        subsidiary to terminate  the employment  of the  Optionee at  any
        time if the Optionee is an employee, to remove the Optionee as  a
        director of the  Company if  the Optionee  is a  director, or  to
        terminate the  services of  the  Optionee if  the Optionee  is  a
        consultant.

        7.   Option Period

             An option  may become  exercisable  immediately or  in  such
        installments, cumulative or noncumulative,  as the Committee  may
        determine.  

        8.   Exercise of Option

             An option may be exercised  in accordance with its terms  by
        written notice of intent to  exercise the option, specifying  the
        number of shares  of stock with  respect to which  the option  is
        then being exercised.  The notice shall be accompanied by payment
        in the form  of cash or  shares of Subsidiary  Common Stock  (the
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        "Tendered Shares") with a then current market value equal to  the
        option price of  the shares to  be purchased; provided,  however,
        that such  Tendered  Shares  shall  have  been  acquired  by  the
        Optionee more  than six  months prior  to the  date of  exercise,
        unless such  requirement is  waived in  writing by  the  Company.
        Against such payment  the Company  shall deliver or  cause to  be
        delivered to the Optionee a certificate for the number of  shares
        then being purchased, registered in  the name of the Optionee  or
        other person exercising  the option.   If any  law or  applicable
        regulation of  the Securities  and Exchange  Commission or  other
        body having  jurisdiction  in  the  premises  shall  require  the
        Company, Subsidiary  or  the  Optionee  to  take  any  action  in
        connection with  shares  being  purchased upon  exercise  of  the
        option, exercise of the option and delivery of the certificate or
        certificates for such shares shall be postponed until  completion
        of the necessary action,  which shall be  taken at the  Company's
        expense.

        9.   Transferability

             Options shall not be transferable, otherwise than by will or
        the laws of descent and distribution, except as may be authorized
        by the Committee, in its  sole discretion. T he Committee may, in
        its discretion, determine the extent to which options granted  to
        an Optionee shall be transferable, and such provisions permitting
        transfer shall  be  set forth  in  the written  option  agreement
        executed and delivered  by or on  behalf of the  Company and  the
        Optionee.

        10.  Vesting, Restrictions and Termination of Options

             The Committee,  in its  sole discretion,  may determine  the
        manner in which options shall vest, the rights of the Company  to
        repurchase the shares issued upon the exercise of any option  and
        the manner in which such rights  shall lapse, and the terms  upon
        which any option granted shall terminate.  The Board of Directors
        shall have the right  to accelerate the date  of exercise of  any
        installment  or  to  accelerate   the  lapse  of  the   Company's
        repurchase rights.   All of such  terms shall be  specified in  a
        written option agreement executed and  delivered by or on  behalf
        of the Company  and the  Optionee to  whom such  option shall  be
        granted.

        11.  Adjustment of Number of Shares

             Each stock option agreement shall provide that in the  event
        of any stock dividend payable in the Common Stock or any split-up
        or contraction  in  the number  of  shares of  the  Common  Stock
        occurring after  the  date of  the  agreement and  prior  to  the
        exercise in full of  the option, the number  of shares for  which
        the option may thereafter  be exercised shall be  proportionately
        adjusted and the price to be  paid for each share subject to  the
        option shall be  proportionately adjusted.   Each such  agreement
        shall also provide that in case of any reclassification or change
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        of outstanding  shares of  the Common  Stock or  in case  of  any
        consolidation or  merger  of  Subsidiary  with  or  into  another
        company or in case of any  sale or conveyance to another  company
        or  entity  of  the  property   of  Subsidiary  as  a  whole   or
        substantially as a  whole, the Optionee  shall, upon exercise  of
        the option,  be entitled  to  receive shares  of stock  or  other
        securities in its  place equivalent  in kind and  value to  those
        shares which  he would  have  received if  he had  exercised  the
        option  in  full  immediately  prior  to  such  reclassification,
        change,  consolidation,  merger,  sale  or  conveyance  and   had
        continued to hold the shares subject to the option (together with
        all other  shares,  stock  and securities  thereafter  issued  in
        respect thereof)  to the  time  of the  exercise of  the  option;
        provided, that if any recapitalization is to be effected  through
        an increase  in the  par value  of the  Common Stock  without  an
        increase in  the number  of authorized  shares and  such new  par
        value will  exceed the  option price  under such  agreement,  the
        Company   shall   notify   the   Optionee   of   such    proposed
        recapitalization, and  the Optionee  shall then  have the  right,
        exercisable at any time  prior to such recapitalization  becoming
        effective, to purchase all  of the shares  subject to the  option
        which  he  has  not  theretofore  purchased  (anything  in   such
        agreement to the contrary  notwithstanding), but if the  Optionee
        fails to exercise such right before such recapitalization becomes
        effective,  the  option  price  under  such  agreement  shall  be
        appropriately  adjusted.    Each  such  agreement  shall  further
        provide that upon dissolution  or liquidation of Subsidiary,  the
        option shall  terminate, but  the  Optionee (if  at the  time  an
        employee or director of the Company and/or any one or more of its
        subsidiaries) shall  have the  right, immediately  prior to  such
        dissolution or liquidation,  to exercise the  option to the  full
        extent not theretofore exercised; that no adjustment provided for
        above shall apply to any share  with respect to which the  option
        has  been  exercised  prior  to   the  effective  date  of   such
        adjustment; and that no fraction of a share or fractional  shares
        shall be purchasable or deliverable under such agreement, but  in
        the event  any  adjustment thereunder  of  the number  of  shares
        covered by  the  option shall  cause  such number  to  include  a
        fraction of  a share,  such  fraction shall  be adjusted  to  the
        nearest smaller whole number of shares.  In the event of  changes
        in the outstanding Common Stock by reason of any stock  dividend,
        split-up, contraction, reclassification, or change of outstanding
        shares of the  Common Stock  of the nature  contemplated by  this
        paragraph 11, the number of shares of Common Stock available  for
        the purpose of the Plan as stated in paragraph 3 hereof shall  be
        correspondingly adjusted by the Committee.

        12.  Limitation of Rights in Option Stock

             The Optionees  shall  have  no  rights  as  stockholders  in
        respect of shares as to which  their options shall not have  been
        exercised, certificates  issued  and  delivered  and  payment  as
        herein provided  made in  full,  and shall  have no  rights  with
        respect to such shares not expressly conferred by this Plan.
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        13.  Stock Reserved

             The Company  shall  at all  times  during the  term  of  the
        options reserve and keep available  such number of shares of  the
        Common Stock as will be sufficient to satisfy the requirements of
        this Plan and shall pay  all other fees and expenses  necessarily
        incurred by the Company in connection therewith.

        14.  Securities Laws Restrictions

             Each Optionee exercising  an option, at  the request of  the
        Company, will  be  required  to give  a  representation  in  form
        satisfactory  to  counsel  for  the  Company  that  he  will  not
        transfer, sell or otherwise dispose  of the shares received  upon
        exercise of  the  option  at  any time  purchased  by  him,  upon
        exercise of any portion  of the option, in  a manner which  would
        violate  the  Securities  Act  of  1933,  as  amended,  and   the
        regulations of the Securities and Exchange Commission  thereunder
        and the Company  may, if required  or at its  discretion, make  a
        notation on any certificates issued  upon exercise of options  to
        the effect that  such certificate may  not be transferred  except
        after  receipt  by   the  Company  of   an  opinion  of   counsel
        satisfactory to  it to  the effect  that such  transfer will  not
        violate such Act and such regulations.

        15.  Tax Withholding

             The Company shall have the right to deduct from payments  of
        any kind otherwise due to an Optionee any federal, state or local
        taxes of any kind required by law to be withheld with respect  to
        any shares issued upon  exercise of options  under the Plan  (the
        "withholding requirements").  The  Committee will have the  right
        to require that the Optionee or other appropriate person remit to
        the Company  an  amount  sufficient to  satisfy  the  withholding
        requirements, or  make  other arrangements  satisfactory  to  the
        Committee with regard to such requirements, prior to the delivery
        of any Common Stock pursuant to exercise of an option.  If and to
        the extent that such withholding  is required, the Committee  may
        permit the Optionee or  such other person to  elect at such  time
        and in such manner as the Committee provides to have the  Company
        hold back from the shares to  be delivered, or to deliver to  the
        Company, Common Stock  having a value  calculated to satisfy  the
        withholding requirements.

        16.  Termination and Amendment of Plan

             The Board of  Directors may at  any time, and  from time  to
        time, modify or amend the Plan in any respect.

             Notwithstanding any other provisions hereof, the Plan  shall
        terminate on December 31,  2006 and no  options shall be  granted
        hereunder thereafter.
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