<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>                   12-MOS
<FISCAL-YEAR-END>                          JAN-03-1998
<PERIOD-END>                               JAN-03-1998
<CASH>                                          71,109
<SECURITIES>                                         0
<RECEIVABLES>                                   94,559
<ALLOWANCES>                                     5,191
<INVENTORY>                                     64,345
<CURRENT-ASSETS>                               248,576
<PP&E>                                          82,786
<DEPRECIATION>                                  27,573
<TOTAL-ASSETS>                                 546,471
<CURRENT-LIABILITIES>                          179,197
<BONDS>                                         81,400
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           496
<OTHER-SE>                                     270,244
<TOTAL-LIABILITY-AND-EQUITY>                   546,471
<SALES>                                        466,935
<TOTAL-REVENUES>                               466,935
<CGS>                                          252,490
<TOTAL-COSTS>                                  252,490
<OTHER-EXPENSES>                                28,061
<LOSS-PROVISION>                                   593
<INTEREST-EXPENSE>                               9,384
<INCOME-PRETAX>                                 67,309
<INCOME-TAX>                                    28,606
<INCOME-CONTINUING>                                  0
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    38,703
<EPS-PRIMARY>                                      .80
<EPS-DILUTED>                                      .75