SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ------------------------------------------- FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): March 23, 1999 ---------------------------------------- THERMO OPTEK CORPORATION (Exact name of Registrant as specified in its charter) Delaware 1-11757 04-3283973 (State or other (Commission (I.R.S. Employer jurisdiction of File Number) Identification Number) incorporation or organization) 8 East Forge Parkway Franklin, Massachusetts 02038 (Address of principal executive offices) (Zip Code) (508) 553-1700 (Registrant's telephone number including area code) Item 5. Other Events On March 23, 1999, the Registrant issued a press release announcing the resignation of its president and chief executive officer, Dr. Robert J. Rosenthal. Barry S. Howe, president and chief executive officer of ThermoSpectra Corporation, will serve as interim president pending a permanent replacement. The Registrant and ThermoSpectra Corporation are both majority-owned subsidiaries of Thermo Instrument Systems Inc., which in turn is a majority-owned subsidiary of Thermo Electron Corporation. Item 7. Financial Statements, Pro Forma Financial Information and Exhibits (a) Financial Statements of Business Acquired: not applicable. (b) Pro Forma Financial Information: not applicable. (c) Exhibits: not applicable. SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized, on this 26th day of March, 1999. THERMO OPTEK CORPORATION By:/s/ Theo Melas-Kyriazi ---------------------------------- Theo Melas-Kyriazi Chief Financial Officer