1 ================================================================================ SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 ---------------------------------------------------- SCHEDULE TO/A TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934 (AMENDMENT NO. 1) ---------------------------------------------------- THERMEDICS DETECTION INC. (Name of Subject Company) DETECTION ACQUISITION, INC. (Offeror) CORPAK INC. (Offeror) THERMEDICS INC. (Offeror) THERMO ELECTRON CORPORATION (Offeror) COMMON STOCK, PAR VALUE $0.10 PER SHARE (Title of Class of Securities) 88355E 10 5 (CUSIP Number of Class of Securities) Seth H. Hoogasian, Esq. General Counsel Thermo Electron Corporation 81 Wyman Street Waltham, Massachusetts 02454-9046 Telephone: (781) 622-1000 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications on Behalf of Filing Persons) with a copy to: David E. Redlick, Esq. Hale and Dorr LLP 60 State Street Boston, Massachusetts 02109-1803 Telephone: (617) 526-6000 ================================================================================ 2 CALCULATION OF FILING FEE Transaction Valuation(1): $26,472,976.00 Amount of Filing Fee(2): $5,294.60 - ------------- (1) For purposes of calculating fee only. This amount is based upon (a) the maximum number of Shares to be purchased pursuant to the Offer and (b) the price offered per Share. (2) The amount of the filing fee, calculated in accordance with Regulation 240.0-11 under the Securities Exchange Act of 1934, as amended, equals 1/50 of one percent of the Transaction Valuation. [X] Check the box if any part of the fee is offset as provided by Rule 0-11(a)(2) and identify the filing with which the offsetting fee was previously paid. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing. Amount Previously Paid: $5,294.60 Form or Registration No.: Schedule TO Filing Party: Thermedics Inc. Date Filed: March 10, 2000 [ ] Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer. Check the appropriate boxes below to designate any transactions to which the statement relates: [X] third-party tender offer subject to Rule 14d-1. [ ] issuer tender offer subject to Rule 13e-4. [X] going-private transaction subject to Rule 13e-3. [X] amendment to Schedule 13D under Rule 13d-2. Check the following box if the filing is a final amendment reporting the results of the tender offer: [ ] SCHEDULE 13D INFORMATION - -------------------------------------------------------------------------------- 1. NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Thermo Electron Corporation IRS No. 04-2209186 - -------------------------------------------------------------------------------- 2. CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) [ ] (b) [X] - -------------------------------------------------------------------------------- 3. SEC USE ONLY - -------------------------------------------------------------------------------- 4. SOURCE OF FUNDS* WC - -------------------------------------------------------------------------------- 5. CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) [ ] - -------------------------------------------------------------------------------- 6. CITIZENSHIP OR PLACE OF ORGANIZATION State of Delaware - -------------------------------------------------------------------------------- 3 - -------------------------------------------------------------------------------- NUMBER OF 7. SOLE VOTING POWER SHARES BENEFICIALLY 19,088,136 OWNED BY --------------------------------------------- EACH REPORTING 8. SHARED VOTING POWER PERSON WITH 0 - -------------------------------------------------------------------------------- 9. SOLE DISPOSITIVE POWER 19,088,136 - -------------------------------------------------------------------------------- 10. SHARED DISPOSITIVE POWER 0 - -------------------------------------------------------------------------------- 11. AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 19,088,136 - -------------------------------------------------------------------------------- 12. CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES [ ] - -------------------------------------------------------------------------------- 13. PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 98.8% - -------------------------------------------------------------------------------- 14. TYPE OF REPORTING PERSON* CO - -------------------------------------------------------------------------------- 4 This Amendment No. 1 amends and supplements the Tender Offer Statement on Schedule TO (the "Schedule TO") relating to the offer by Detection Acquisition, Inc., a Delaware corporation (the "Purchaser") and an indirect wholly-owned subsidiary of Thermedics Inc., a Massachusetts corporation ("Thermedics"), to purchase all outstanding shares of common stock, par value $0.10 per share (the "Shares"), of Thermedics Detection Inc., a Massachusetts corporation (the "Company"), at a purchase price of $8.00 per Share net to the Seller in cash, without interest thereon, upon the terms and subject to the conditions set forth in the Offer to Purchase dated March 10, 2000 (the "Offer to Purchase") and in the related Letter of Transmittal (which, together with any amendments or supplements hereto or thereto, collectively constitute the "Offer"), copies of which are attached as Exhibits (a)(1) and (a)(2) to the Schedule TO. ITEMS 1 THROUGH 9 AND ITEMS 11 AND 13 Items 1 through 9 and Items 11 and 13 of the Schedule TO, which incorporate by reference the information contained in the Offer to Purchase, are hereby amended and supplemented by adding thereto the following: The Offer expired at 12:00 midnight, New York City time, on Thursday, April 6, 2000. Pursuant to the Offer, based upon a preliminary report from American Stock Transfer & Trust Company (the "Depositary"), the Purchaser accepted for payment 1,916,715 Shares (including Shares tendered pursuant to guaranteed delivery). Following the acceptance for payment of such Shares, Thermo Electron Corporation, a Delaware corporation, and its subsidiaries, including Thermedics, collectively own approximately 98.8% of the outstanding Shares. On April 7, 2000, Thermedics issued a press release announcing the closing of the tender offer and affirming its intention to cause the Company to merge with and into the Purchaser in a short-form merger. Thermedics expects to complete this merger by Tuesday, April 11, 2000, or as soon thereafter as practicable. The full text of Thermedics' April 7, 2000 press release is attached as Exhibit (a)(11) hereto and incorporated herein by reference. ITEM 12 EXHIBITS Item 12 of the Schedule TO is hereby amended by adding thereto the following: (a)(11) Press Release issued by Thermedics on April 7, 2000 5 SIGNATURE After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. DETECTION ACQUISITION, INC. By: /s/ John T. Keiser ------------------ Name: John T. Keiser Title: President CORPAK INC. By: /s/ Sandra L. Lambert --------------------- Name: Sandra L. Lambert Title: Clerk THERMEDICS INC. By: /s/ John T. Keiser ------------------ Name: John T. Keiser Title: President and Chief Executive Officer THERMO ELECTRON CORPORATION By: /s/ Theo Melas-Kyriazi ---------------------- Name: Theo Melas-Kyriazi Title: Vice President and Chief Financial Officer Dated: April 7, 2000 6 EXHIBIT INDEX EXHIBIT DESCRIPTION 12(a)(1)* Offer to Purchase dated March 10, 2000 12(a)(2)* Letter of Transmittal 12(a)(3)* Notice of Guaranteed Delivery 12(a)(4)* Letter from the Dealer Managers to Brokers, Dealers, Commercial Banks, Trust Companies and Nominees 12(a)(5)* Letter to Clients for use by Brokers, Dealers, Commercial Banks, Trust Companies and Nominees 12(a)(6)* Summary Advertisement as published on March 10, 2000 12(a)(7)* Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9 12(a)(8)* Press Release issued by Thermedics on January 31, 2000 (incorporated herein by reference to Exhibit 99 to the Current Report on Form 8-K of Thermedics filed with the Commission on February 1, 2000) 12(a)(9)* Press Release issued by Thermo Electron on January 31, 2000 (incorporated herein by reference to Exhibit 99 to the Current Report on Form 8-K of Thermo Electron filed with the Commission on February 1, 2000) 12(a)(10)* Press Release issued by Thermedics on March 10, 2000 12(a)(11) Press Release issued by Thermedics on April 7, 2000 12(b)* Loan Agreement dated as of March 1, 2000 between Thermo Electron and Thermedics 12(c)* Opinion of J.P. Morgan Securities Inc. and The Beacon Group Capital Services, LLC dated January 29, 2000 12(d)* Not applicable 12(e)* Not applicable 12(f)* Summary of Appraisal Rights (Included in Exhibit 12(a)(1) in the section captioned "The Merger; Appraisal Rights") 12(g)* Slide Presentation of Thermo Electron to Financial Analysts 12(h)* Not applicable - -------------------- * Previously filed