SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                 -------------------------------------------


                                    FORM 8-K


                                 CURRENT REPORT

                       Pursuant to Section 13 or 15(d) of
                       the Securities Exchange Act of 1934



                                 Date of Report
                      (Date of earliest event reported):

                                 January 7, 1999

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                         THERMO INSTRUMENT SYSTEMS INC.
             (Exact name of Registrant as specified in its charter)


Delaware                       1-9786                     04-2925809
(State or other               (Commission              (I.R.S. Employer
jurisdiction of               File Number)             Identification Number)
incorporation or
organization)


860 West Airport Freeway
Suite 301
Hurst, Texas                                                76054
(Address of principal executive offices)                 (Zip Code)


                                (817) 485-6663
                         (Registrant's telephone number
                              including area code)












      This Form 8-K 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 the
Registrant's  Annual  Report on Form 10-K for the year  ended  January  3, 1998.
These include risks and uncertainties relating to: the Registrant's  acquisition
and spinout  strategies,  competition  and  technological  change,  intellectual
property  rights and  litigation,  dependence  on  certain  key  industries  and
international operations, possible changes in governmental regulations,  capital
spending and government  funding policies,  and the potential impact of the year
2000 on processing date-sensitive information.

Item 5.     Other Events

      On January 7, 1999, the Registrant issued a press release  announcing that
it  will   commence  a  cash  tender  offer  for  all   outstanding   shares  of
Spectra-Physics  AB for 160  Swedish  krona  per  share  (approximately  $20 per
share).  Spectra-Physics  AB is a public  company  headquartered  in  Stockholm,
Sweden, with its shares listed on the Stockholm Stock Exchange.  Spectra-Physics
AB's board of directors has recommended that its shareholders  accept the offer.
Spectra-Physics AB has approximately  17.62 million shares  outstanding,  giving
the offer a value of  approximately  $355 million.  The offer will not extend to
shareholders   in  the  United  States  or  to  any  other   shareholder   whose
participation  in the offer  would  require  any  prospectus,  registration,  or
measures other than those required by Swedish law.

      Spectra-Physics    AB   manufactures   a   wide   range   of   laser-based
instrumentation   systems,   primarily  for  the   process-control,   industrial
measurement,   construction,   research,  commercial,  and  government  markets.
Spectra-Physics  AB  employs  approximately  2,800  people  and has  significant
manufacturing  and marketing  operations at various  locations  throughout North
America   and  Europe,   in   addition  to  a  presence  in  the  Pacific   Rim.
Spectra-Physics AB is organized into five operating groups, as follows:

     (a)  Spectra-Physics  Lasers, Inc. - serves the OEM and industrial markets,
as well as the research and development  market,  with high-power  semiconductor
lasers,  semiconductor laser-pumped solid-state lasers, conventional lasers, and
laser   disk-texturing   products.   Spectra-Physics   Lasers,  Inc.  is  an  80
percent-owned public subsidiary of Spectra-Physics AB, and its shares are traded
on NASDAQ (SPLI);


      (b) Spectra Precision Group - serves the construction  instruments  market
with    surveying    instruments,     laser-based    positioning    instruments,
heavy-construction  equipment position and control systems, and related software
products;

      (c)  Industrial  Measurement  Group -  provides  industrial  weighing  and
force-measurement systems, laser-based wear control and measurement systems, and
laser systems and components for certain process-control industries;

      (d) Pharos  Marine/Automatic  Power  Group -  provides  the  offshore  oil
platform and the port and lighthouse  authority  markets with marine  navigation
equipment  and systems  such as flashing and rotating  beacons,  radar  beacons,
radar target enhancers,  GPS reference stations,  and remote monitoring systems;
and

      (e) FLIR Systems,  Inc. - serves the government,  public safety,  defense,
commercial,  and industrial  markets with thermal imaging systems used to detect
infrared heat or radiation.  FLIR Systems,  Inc. is a public  company  traded on
NASDAQ.  Spectra-Physics  AB holds  approximately  35 percent of the outstanding
shares of FLIR Systems, Inc.

      Final  closure  of the  transaction  is  subject  to  certain  conditions,
including the successful  and timely  completion of the public cash tender offer
yielding over 90 percent of Spectra-Physics AB shares, and antitrust  regulatory
clearances in the United States and in certain European countries.


Item 7.     Financial Statements, Pro Forma Financial Information and Exhibits

      (a)    Financial Statements of Business Acquired: not
            applicable.

      (b)   Pro Forma Financial Information: not applicable.

      (c)   Exhibits: not applicable.







                                    SIGNATURE



      Pursuant to the  requirements of the Securities  Exchange Act of 1934, the
Registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned, thereunto duly authorized, on this 8th day of January, 1999.



                                    THERMO INSTRUMENT SYSTEMS INC.


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