<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>                                                 95,712
<SECURITIES>                                                0
<RECEIVABLES>                                         100,104
<ALLOWANCES>                                            5,579
<INVENTORY>                                            69,197
<CURRENT-ASSETS>                                      277,471
<PP&E>                                                 93,055
<DEPRECIATION>                                         32,078
<TOTAL-ASSETS>                                        590,580
<CURRENT-LIABILITIES>                                 197,323
<BONDS>                                                81,286
<PREFERRED-MANDATORY>                                       0
<PREFERRED>                                                 0
<COMMON>                                                  517
<OTHER-SE>                                            296,615
<TOTAL-LIABILITY-AND-EQUITY>                          590,580
<SALES>                                               113,799
<TOTAL-REVENUES>                                      113,799
<CGS>                                                  60,959
<TOTAL-COSTS>                                          60,959
<OTHER-EXPENSES>                                        6,384
<LOSS-PROVISION>                                           85
<INTEREST-EXPENSE>                                      1,902
<INCOME-PRETAX>                                        16,769
<INCOME-TAX>                                            6,959
<INCOME-CONTINUING>                                     9,810
<DISCONTINUED>                                              0
<EXTRAORDINARY>                                             0
<CHANGES>                                                   0
<NET-INCOME>                                            9,810
<EPS-PRIMARY>                                            0.19
<EPS-DILUTED>                                            0.18