<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 JULY 3, 1999 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS. </LEGEND> <MULTIPLIER> 1,000 <PERIOD-TYPE> 6-MOS <FISCAL-YEAR-END> JAN-01-2000 <PERIOD-END> JUL-03-1999 <CASH> 55,054 <SECURITIES> 0 <RECEIVABLES> 95,594 <ALLOWANCES> 4,321 <INVENTORY> 67,609 <CURRENT-ASSETS> 246,969 <PP&E> 98,885 <DEPRECIATION> 40,089 <TOTAL-ASSETS> 539,196 <CURRENT-LIABILITIES> 131,906 <BONDS> 69,082 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 518 <OTHER-SE> 324,513 <TOTAL-LIABILITY-AND-EQUITY> 539,196 <SALES> 216,305 <TOTAL-REVENUES> 216,305 <CGS> 115,846 <TOTAL-COSTS> 115,846 <OTHER-EXPENSES> 14,196 <LOSS-PROVISION> (85) <INTEREST-EXPENSE> 2,544 <INCOME-PRETAX> 28,436 <INCOME-TAX> 11,387 <INCOME-CONTINUING> 17,049 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 17,049 <EPS-BASIC> 0.33 <EPS-DILUTED> 0.32