<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 3, 1999
AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER>        1,000
       
                              
<PERIOD-TYPE>                                 3-MOS
<FISCAL-YEAR-END>                             JAN-01-2000
<PERIOD-END>                                  APR-03-1999
<CASH>                                                 57,273
<SECURITIES>                                                0
<RECEIVABLES>                                         103,635
<ALLOWANCES>                                            4,882
<INVENTORY>                                            66,791
<CURRENT-ASSETS>                                      245,135
<PP&E>                                                100,072
<DEPRECIATION>                                         38,853
<TOTAL-ASSETS>                                        546,341
<CURRENT-LIABILITIES>                                 142,385
<BONDS>                                                69,038
<PREFERRED-MANDATORY>                                       0
<PREFERRED>                                                 0
<COMMON>                                                  518
<OTHER-SE>                                            321,130
<TOTAL-LIABILITY-AND-EQUITY>                          546,341
<SALES>                                               106,163
<TOTAL-REVENUES>                                      106,163
<CGS>                                                  57,021
<TOTAL-COSTS>                                          57,021
<OTHER-EXPENSES>                                        7,111
<LOSS-PROVISION>                                          196
<INTEREST-EXPENSE>                                      1,311
<INCOME-PRETAX>                                        12,001
<INCOME-TAX>                                            4,894
<INCOME-CONTINUING>                                     7,107
<DISCONTINUED>                                              0
<EXTRAORDINARY>                                             0
<CHANGES>                                                   0
<NET-INCOME>                                            7,107
<EPS-PRIMARY>                                            0.14
<EPS-DILUTED>                                            0.14