As filed with the Securities and Exchange Commission on August 3, 1998 Registration No. 33-99110 SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form S-3 Post-Effective Amendment No. 3 To Registration Statement Under The Securities Act of 1933 ThermoSpectra Corporation (Exact name of registrant as specified in charter) Delaware 04-3242970 (State or other jurisdiction of (IRS Employer Identification Number) incorporation or organization) 81 Wyman Street P.O. Box 9046 Waltham, Massachusetts 02454-9046 (781) 622-1000 (Address, including zip code, and telephone number, including area code, of registrant's principal executive offices) Sandra L. Lambert, Secretary ThermoSpectra Corporation c/o Thermo Electron Corporation 81 Wyman Street P.O. Box 9046 Waltham, Massachusetts 02454-9046 (781) 622-1000 (Name, address, including zip code, and telephone number, including area code, of agent for service) Copies to: Seth H. Hoogasian, Esq. General Counsel ThermoSpectra Corporation c/o Thermo Electron Corporation 81 Wyman Street P.O. Box 9046 Waltham, Massachusetts 02454-9046 (781) 622-1000 ---------------------- Approximate date of commencement of proposed sale to public: As soon as practicable after the Registration Statement has become effective. If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box. [X] If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act of 1933, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. [ ] If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act of 1933, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. [ ] ---------------------- This post-effective amendment removes from registration any of the securities which remained unsold as of the date of the filing of this post-effective amendment. The registration is hereby terminated. SIGNATURES Pursuant to the requirements of the Securities Act of 1933, the Registrant has duly caused this Post-Effective Amendment No. 3 to Registration Statement on Form S-3 to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Waltham, Commonwealth of Massachusetts, on this 3rd day of August, 1998. THERMOSPECTRA CORPORATION By: /s/ Barry S. Howe ------------------------------ Barry S. Howe President and Chief Executive Officer Signature Title Date - --------- ----- ---- Chief Executive Officer, August 3, 1998 /s/ Barry S. Howe President and Director - ------------------ (Principal Executive Officer) Barry S. Howe /s/ John N. Hatsopoulos* Chief Financial Officer and August 3, 1998 - ------------------------- Senior Vice President John N. Hatsopoulos (Principal Financial Officer) /s/ Paul F. Kelleher* Chief Accounting Officer August 3, 1998 - ------------------------- (Principal Accounting Paul F. Kelleher Officer) - ------------------------- Director August __, 1998 Robert E. Finnigan /s/ Elias P. Gyftopoulos* Director August 3, 1998 - ------------------------- Elias P. Gyftopoulos /s/ Earl R. Lewis* Director August 3, 1998 - ------------------- Earl R. Lewis /s/ Theo Melas-Kyriazi* Director August 3, 1998 - ------------------------- Theo Melas-Kyriazi /s/ Arvin H. Smith* Director August 3, 1998 - -------------------- Arvin H. Smith *By:/s/ Seth H. Hoogasian --------------------- Seth H. Hoogasian Attorney-in-Fact