<ARTICLE>      5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THERMO OPTEK
CORPORATION'S REPORT ON FORM 10-Q FOR THE PERIOD ENDED SEPTEMBER 27, 1997 AND IS
QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER>   1,000
       
                     
<PERIOD-TYPE>                    9-MOS
<FISCAL-YEAR-END>                JAN-03-1998
<PERIOD-END>                     SEP-27-1997
<CASH>                                51,642
<SECURITIES>                               0
<RECEIVABLES>                        117,628
<ALLOWANCES>                           6,713
<INVENTORY>                           86,552
<CURRENT-ASSETS>                     273,060
<PP&E>                                99,744
<DEPRECIATION>                        31,458
<TOTAL-ASSETS>                       626,799
<CURRENT-LIABILITIES>                223,954
<BONDS>                              101,873
<PREFERRED-MANDATORY>                      0
<PREFERRED>                                0
<COMMON>                                 505
<OTHER-SE>                           283,558
<TOTAL-LIABILITY-AND-EQUITY>         626,799
<SALES>                              373,214
<TOTAL-REVENUES>                     373,214
<CGS>                                200,806
<TOTAL-COSTS>                        200,806
<OTHER-EXPENSES>                      22,371
<LOSS-PROVISION>                         222
<INTEREST-EXPENSE>                     7,925
<INCOME-PRETAX>                       51,335
<INCOME-TAX>                          22,044
<INCOME-CONTINUING>                   29,291
<DISCONTINUED>                             0
<EXTRAORDINARY>                            0
<CHANGES>                                  0
<NET-INCOME>                          29,291
<EPS-PRIMARY>                           0.58
<EPS-DILUTED>                           0.55