<ARTICLE>           5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THERMO OPTEK
CORPORATION'S ANNUAL REPORT ON FORM 10-K FOR THE YEAR ENDED JANUARY 3, 1998 AND
IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER>        1,000
       
                              
<PERIOD-TYPE>                                 YEAR
<FISCAL-YEAR-END>                             JAN-03-1998
<PERIOD-END>                                  JAN-03-1998
<CASH>                                                 71,245
<SECURITIES>                                                0
<RECEIVABLES>                                         105,051
<ALLOWANCES>                                            5,709
<INVENTORY>                                            70,095
<CURRENT-ASSETS>                                      263,301
<PP&E>                                                 92,711
<DEPRECIATION>                                         29,970
<TOTAL-ASSETS>                                        580,536
<CURRENT-LIABILITIES>                                 195,709
<BONDS>                                                81,400
<PREFERRED-MANDATORY>                                       0
<PREFERRED>                                                 0
<COMMON>                                                  516
<OTHER-SE>                                            287,777
<TOTAL-LIABILITY-AND-EQUITY>                          580,536
<SALES>                                               512,464
<TOTAL-REVENUES>                                      512,464
<CGS>                                                 276,998
<TOTAL-COSTS>                                         276,998
<OTHER-EXPENSES>                                       30,861
<LOSS-PROVISION>                                          629
<INTEREST-EXPENSE>                                     10,197
<INCOME-PRETAX>                                        72,106
<INCOME-TAX>                                           30,796
<INCOME-CONTINUING>                                    41,310
<DISCONTINUED>                                              0
<EXTRAORDINARY>                                             0
<CHANGES>                                                   0
<NET-INCOME>                                           41,310
<EPS-PRIMARY>                                            0.82
<EPS-DILUTED>                                            0.77