<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THERMO OPTEK
CORPORATION'S QUARTERLY REPORT ON FORM 10-Q FOR THE PERIOD ENDED APRIL 4, 1998
AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                          JAN-02-1999
<PERIOD-END>                               APR-04-1998
<CASH>                                          93,065
<SECURITIES>                                         0
<RECEIVABLES>                                   91,399
<ALLOWANCES>                                     4,975
<INVENTORY>                                     62,852
<CURRENT-ASSETS>                               261,606
<PP&E>                                          83,291
<DEPRECIATION>                                  29,487
<TOTAL-ASSETS>                                 556,254
<CURRENT-LIABILITIES>                          180,524
<BONDS>                                         81,286
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           496
<OTHER-SE>                                     279,109
<TOTAL-LIABILITY-AND-EQUITY>                   556,254
<SALES>                                        103,554
<TOTAL-REVENUES>                               103,554
<CGS>                                           55,472
<TOTAL-COSTS>                                   55,472
<OTHER-EXPENSES>                                 5,599
<LOSS-PROVISION>                                   102
<INTEREST-EXPENSE>                               1,792
<INCOME-PRETAX>                                 15,777
<INCOME-TAX>                                     6,556
<INCOME-CONTINUING>                              9,221
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                     9,221
<EPS-PRIMARY>                                      .19
<EPS-DILUTED>                                      .18