S-3

QuickLinks -- Click here to rapidly navigate through this document

As Filed With the Securities and Exchange Commission on March 25, 2002
Registration No. 333-      

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-3
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

COHERENT, INC.
(Exact name of Registrant as specified in its charter)

Delaware
(State or other jurisdiction of
incorporation or organization) 3674
(Primary Standard Industrial
Classification Code Number) 94-1622541
(IRS Employer
Identification Number)

5100 Patrick Henry Drive
Santa Clara, California 95054
(408) 764-4000
(Address, including zip code, and telephone number, including area code, of Registrant's principal executive offices)

Bernard J. Couillaud
President and Chief Executive Officer
Coherent, Inc.
5100 Patrick Henry Drive
Santa Clara, California 95054
(408) 764-4000
(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copy to:

David Segre
Bret M. DiMarco
Edward F. Vermeer
Wilson Sonsini Goodrich & Rosati
Professional Corporation
650 Page Mill Road
Palo Alto, CA 94304-1050
(650)493-9300

Approximate date of commencement of proposed sale to the public:
From time to time after the effective date of this Registration Statement.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box.    o

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, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box.    ý

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

If delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box.    o

CALCULATION OF REGISTRATION FEE

Title of Each Class of Securities to be Registered	Amount to be Registered	Proposed Maximum Offering Price Per Share (1)	Proposed Maximum Aggregate Offering Price (1)	Amount of Registration Fee
Common Stock, $0.01 par value per share	59,246 shares	$33.70	$1,996,590	$184

⁽¹⁾

Estimated solely for the purpose of calculating the registration fee pursuant to Rule 457(c) of the Securities Act of 1933, based on the average of the high and low sales prices of the common stock, as reported on the Nasdaq National Market on March 21, 2002.

The registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the registration statement shall become effective on such date as the Securities and Exchange Commission, acting pursuant to such Section 8(a), may determine.

Subject to Completion

PRELIMINARY PROSPECTUS                                                                                                                  March 25, 2002

The information contained in this prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these securities in any state where the offer or sale is not permitted.

59,246 Shares

COHERENT, INC.

Common Stock

        In connection with our acquisition of a majority ownership interest in Tutcore Oy, Ltd., a company registered under the laws of Finland, we issued 59,246 shares of our common stock to the shareholders of Tutcore Oy. This prospectus may be used by shareholders of Tutcore Oy to resell shares of our common stock issued to them in the Tutcore Oy acquisition.

        The prices at which these shareholders may sell these shares will be determined by the prevailing market price for shares of our common stock or in negotiated transactions. We will not receive any of the proceeds from the sale of these shares.

        Our common stock is quoted on The Nasdaq National Market under the symbol "COHR." On March 21, 2002, the last sale price of our common stock as reported on The Nasdaq National Market was $34.06.

INVESTING IN OUR COMMON STOCK INVOLVES RISKS. SEE THE SECTIONS ENTITLED "RISK FACTORS" IN THE DOCUMENTS WE FILE WITH THE SECURITIES AND EXCHANGE COMMISSION THAT ARE INCORPORATED BY REFERENCE IN THIS PROSPECTUS FOR CERTAIN RISKS AND UNCERTAINTIES THAT YOU SHOULD CONSIDER.

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE ADEQUACY OR ACCURACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

The date of this prospectus is March    , 2002

Where You Can Find More Information

        We have filed with the Securities and Exchange Commission, or SEC, a registration statement on Form S-3, including exhibits, under the Securities Act with respect to the shares being offered by and for the account of the selling shareholders. This prospectus does not contain all the information set forth in the registration statement. For further information about us, please refer to the registration statement and the documents incorporated by reference in this prospectus.

        We file annual, quarterly and special reports, proxy statements and other information with the SEC. You may read and copy all or any portion of the registration statement or any reports, statements, or other information that we file with the SEC at the SEC's Public Reference Room at 450 Fifth Street, N.W., Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the operation of the Public Reference Room. Our SEC filings, including the registration statement, are also available to the public at the SEC's web site at http://www.sec.gov.

Incorporation of Certain Documents by Reference

        The SEC allows us to incorporate by reference into this prospectus the information we file with the SEC, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus, and the information we file later with the SEC will automatically update and supersede that information. We incorporate by reference the documents listed below and any future filings made with the SEC under Section 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934 after the date of this prospectus and until the time all of the securities offered by this prospectus have been sold. The documents we are incorporating by reference are as follows:

        (a)  our Proxy Statement for the 2002 Annual Meeting of the Stockholders, as filed with the SEC on February 15, 2002;

        (b)  our Annual Report on Form 10-K for the fiscal year ended September 30, 2001, as filed with the SEC on December 18, 2001, as amended by our 10-K/A, filed with the SEC on January 25, 2002;

        (c)  our Quarterly Report on Form 10-Q for the fiscal quarter ended December 29, 2001, as filed with the SEC on February 12, 2002;

        (d)  the description of our common stock contained in our registration statement on Form 8-A as filed with the SEC, including any amendments or reports filed for the purpose of updating that description; and

        (e)  the description of the common stock purchase rights for our common stock, par value $0.01 per share, contained in our registration statement on Form 8-A/A filed with the SEC on July 1, 1998, including any amendments or reports filed for the purpose of updating that description.

        Any statement contained in a document that is incorporated by reference will be modified or superseded for all purposes to the extent that a statement contained in this prospectus (or in any other document that is subsequently filed with the SEC and incorporated by reference) modifies or is contrary to that previous statement. Any statement so modified or superseded will not be deemed a part of this prospectus except as so modified or superseded.

2

        You may request a copy of any or all of the information that has been incorporated by reference in this prospectus, but not delivered with this prospectus, at no cost by writing or telephoning us at the following address:

Coherent, Inc.
Investor Relations
5100 Patrick Henry Drive
Santa Clara, CA 95054
(408) 764-4000

        You should rely only on the information incorporated by reference or provided in this prospectus or any prospectus supplement. We have not authorized anyone to provide you with different information.

The Company

        Our principal executive offices are located at 5100 Patrick Henry Drive, Santa Clara, California 95054. Our telephone number is (480) 764-4000. Our web site on the Internet is located at http://www.coherentinc.com. We do not intend the information found on our web site to be part of this prospectus.

Plan of Distribution

        We are registering 59,246 shares of our common stock on behalf of the selling shareholders. As used herein, "selling shareholders" includes the selling shareholders named in the table below and pledgees, donees, transferees or other successors-in-interest selling shares received from a named selling shareholder as a gift, partnership distribution or other non-sale-related transfer after the date of this prospectus. The selling shareholders may sell the shares from time to time and may also decide not to sell all the shares they are allowed to sell under this prospectus. The selling shareholders will act independently of us in making decisions with respect to the timing, manner and size of each sale. The sales may be made on one or more exchanges or in the over-the-counter market or otherwise, at prices and at terms then prevailing or at varying prices related to the then current market prices, or at negotiated prices. The selling shareholders may effect such transactions by selling the shares directly or, alternatively, to or through broker-dealers or other agents. The shares may be sold by one or more of, or a combination of, the following:

•

a block trade in which the broker-dealer so engaged will attempt to sell shares as agent but may position and resell a portion of the block as principal to facilitate the transaction;



•

purchases by a broker-dealer as principal and resale by such broker-dealer for its account pursuant to this prospectus;



•

an exchange distribution in accordance with the rules of such exchange;



•

ordinary brokerage transactions and transactions in which the broker solicits purchasers; and



•

privately negotiated transactions.

        To the extent required, this prospectus may be amended or supplemented from time to time to describe a specific plan of distribution. In effecting sales, broker-dealers engaged by the selling shareholders may arrange for other broker-dealers to participate in the resales.

        The selling shareholders may enter into hedging transactions with broker-dealers in connection with distributions of shares or otherwise. In such transactions, broker-dealers may engage in short sales of shares in the course of hedging the positions they assume with selling shareholders. The selling shareholders also may sell shares short and redeliver shares to close out such short positions. The

3

selling shareholders may enter into option or other transactions with broker-dealers which require the delivery of shares to the broker-dealer. The broker-dealer may then resell or otherwise transfer such shares pursuant to this prospectus. The selling shareholders also may loan or pledge shares to a broker-dealer. The broker-dealer may sell the shares so loaned, or upon a default the broker-dealer may sell the shares so pledged, pursuant to this prospectus.

        Broker-dealers or agents may receive compensation in the form of commissions, discounts or concessions from selling shareholders. Broker-dealers or agents may also receive compensation from the purchasers of shares for whom they act as agents or to whom they sell as principals, or both. Compensation as to a particular broker-dealer might be in excess of customary commissions and will be in amounts to be negotiated in connection with transactions involving shares. Broker-dealers or agents and any other participating broker-dealers or the selling shareholders may be deemed to be "underwriters" within the meaning of Section 2(11) of the Securities Act of 1933 in connection with sales of shares. Accordingly, any such commission, discount or concession received by them and any profit on the resale of shares purchased by them may be deemed to be underwriting discounts or commissions under the Securities Act of 1933. Because selling shareholders may be deemed to be "underwriters" within the meaning of Section 2(11) of the Securities Act of 1933, the selling shareholders will be subject to the prospectus delivery requirements of the Securities Act of 1933. In addition, any shares of a selling shareholder covered by this prospectus which qualify for sale pursuant to Rule 144 promulgated under the Securities Act of 1933 may be sold under Rule 144 rather than pursuant to this prospectus. The selling shareholders have advised us that they have not entered into any agreements, understandings or arrangements with any underwriters or broker-dealers regarding the sale of their shares.

        The shares may be sold by selling shareholders only through registered or licensed brokers or dealers if required under applicable state securities laws. In addition, in certain states the shares may not be sold unless they have been registered or qualified for sale in the applicable state or an exemption from the registration or qualification requirement is available and is complied with.

        Under applicable rules and regulations under the Exchange Act of 1934, any person engaged in the distribution of shares may not simultaneously engage in market making activities with respect to our common stock for a period of two business days prior to the commencement of such distribution. In addition, each selling shareholder will be subject to applicable provisions of the Exchange Act of 1934 and the associated rules and regulations under the Exchange Act of 1934, including Regulation M, which provisions may limit the timing of purchases and sales of shares of our common stock by the selling shareholders. We will make copies of this prospectus available to the selling shareholders and have informed them of the need for delivery of copies of this prospectus to purchasers at or prior to the time of any sale of the shares.

        We will file a supplement to this prospectus, if required, pursuant to Rule 424(b) under the Securities Act of 1933 upon being notified by a selling shareholder that any material arrangement has been entered into with a broker-dealer for the sale of shares through a block trade, special offering, exchange distribution or secondary distribution or a purchase by a broker or dealer. Such supplement will disclose:

•

the name of each such selling shareholder and of the participating broker-dealer(s);



•

the number of shares involved;



•

the price at which such shares were sold;



•

the commissions paid or discounts or concessions allowed to such broker-dealer(s), where applicable;

4

•

that such broker-dealer(s) did not conduct any investigation to verify the information set out or incorporated by reference in this prospectus; and



•

other facts material to the transaction.

        We will bear all costs, expenses and fees in connection with the registration of the shares identified in this prospectus. The selling shareholders will bear all commissions and discounts, if any, attributable to the sales of the shares. The selling shareholders may agree to indemnify any broker-dealer or agent that participates in transactions involving sales of the shares against certain liabilities, including liabilities arising under the Securities Act.

5

Selling Shareholders

        All of the securities being registered are being offered by and for the account of the selling shareholders described in this section. None of the selling shareholders has had a material relationship with us within the past three years other than as a result of the ownership of our common stock or other securities of ours or as a result of their employment with us as of and since the date of the closing of the acquisition of Tutcore Oy. No estimate can be given as to the amount of our common stock that will be beneficially owned by the selling shareholders after completion of this offering because the selling shareholders may offer all, some or none of the shares of our common stock beneficially owned by them or that may hereafter be acquired by them. The following table sets forth certain information as of March 25, 2002 concerning the number of shares beneficially owned by each selling shareholder and the number of shares being registered by this prospectus that may be offered and sold from time to time by the selling shareholders named below.

Name of Selling Shareholder	Number of Shares Beneficially Owned	Percent of Outstanding Shares	Number of Shares Registered for Sale Hereby
Harry Mikael Asonen	11,566	*	7,959
Rauno Asonen	3,537	*	3,537
Simo Matti Asseri Arra	3,896	*	3,896
Juha Hautala	1,074	*	884
Leena Kivipelto-Mattila	4,616	*	4,062
Hannu Arvi Ilmari Kojola	3,896	*	3,896
Jouko Ilmari Haapamaa	7,973	*	7,779
Jari Tapani Nappi	8,828	*	7,959
Markus Pessa	7,959	*	7,959
Keijo Rakennus	7,091	*	6,010
Mika Antero Toivonen	3,718	*	3,537
Arto Salokatve	2,956	*	1,768
Totals	67,110		59,246

*

Represents beneficial ownership of less than one percent.

(1)

Computed in accordance with Rule 13d-3(d)(i) promulgated under the Securities Exchange Act of 1934, as amended, and based upon 28,678,579 shares of common stock outstanding as of February 8, 2002.

(2)

The preceding table has been prepared based solely upon information furnished to us as of the date of this prospectus by the selling shareholders listed above. The selling shareholders identified above may have sold, transferred or otherwise disposed of, in transactions exempt from the registration requirements of the Securities Act, all or a portion of their shares since the date on which the information in the preceding table is presented.

6

Use of Proceeds

        We will not receive any proceeds from the sale of the shares by the selling shareholders.

Legal matters

        The validity of the common stock offered hereby will be passed upon for us by Wilson Sonsini Goodrich & Rosati, Professional Corporation, Palo Alto, California.

Experts

        The financial statements and the related financial statement schedule of the Company and its consolidated subsidiaries, except Lambda Physik AG and subsidiaries (as described below), as of September 30, 2001 and 2000, and for each of the three years in the period ended September 30, 2001, incorporated by reference in this prospectus from the Company's Annual Report on Form 10-K for the year ended September 30, 2001 have been audited by Deloitte & Touche LLP as stated in their report, which is incorporated herein by reference, and have been so incorporated in reliance upon the report of such firm given upon their authority as experts in accounting and auditing. The financial statements of Lambda Physik AG and subsidiaries (consolidated with those of the Company) not presented separately therein as of September 30, 2001 and for the year then ended have been audited by Arthur Andersen Wirtschaftsprüfungsgesellschaft Steuerberatungsgesellschaft mbH, as stated in their report incorporated herein by reference. Such financial statements of the Company and its consolidated subsidiaries are included herein in reliance upon the respective reports of such firms given upon their authority as experts in accounting and auditing. All of the foregoing firms are independent auditors.

7

59,246 Shares

COHERENT, INC.

Common Stock

        We have not authorized any person to give any information or make any statement that differs from what is in this prospectus. If any person does make a statement that differs from what is in this prospectus, you should not rely on it. This prospectus is not an offer to sell, nor is it seeking an offer to buy, these securities in any state in which the offer or sale is not permitted. The information in this prospectus is complete and accurate as of its date, but the information may change after that date. Under no circumstances shall the delivery of this prospectus or any sale made pursuant to this prospectus create any implication that the information contained in this prospectus is complete and accurate as of any time subsequent to the date of this prospectus.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14.    Other Expenses of Issuance and Distribution

        The following table sets forth the costs and expenses in connection with the sale and distribution of the securities being registered, other than underwriting discounts and commissions, which expenses will be borne by the selling shareholders. All of the amounts shown are estimates except the Securities and Exchange Commission registration fee.

		To be Paid by the Registrant
SEC registration fee		$	184
Accounting fees and expenses			5,000
Legal fees and expenses			10,000
Miscellaneous fees and expenses			816
	Total	$	16,000

Item 15.    Indemnification of Directors and Officers

        Section 145 of the Delaware General Corporation Law, or DGCL, permits indemnification of officers, directors and other corporate agents under certain circumstances and subject to certain limitations. Our Certificate of Incorporation and Bylaws provide that we shall indemnify our directors, officers, employees and agents to the fullest extent permitted by the DGCL, against judgments and monetary damages as a result of such individual serving as a director, officer or agent, including in circumstances in which indemnification is otherwise discretionary under such law. Our Bylaws also provide that we shall advance expenses incurred by a director, officer or agent in advance of a final disposition of such action provided we receive an undertaking by such individual to repay the amounts advanced if it is ultimately determined that he or she is not entitled to be indemnified. In addition, with the approval of our Board of Directors and our stockholders, we have entered into separate indemnification agreements with our directors, officers and certain employees that require us, among other things, to indemnify them to the fullest extent permitted by law against any judgments, amounts paid in settlement and all expenses incurred in connection with defending any action that may arise by reason of their status or service (other than liabilities arising from willful misconduct of a culpable nature) and to obtain directors' and officers' insurance, if available on reasonable terms. We are required to advance expenses incurred by a party to such indemnification agreement in advance of a determination or judgment subject to a determination by our Board of Directors or another party who is not a party or defendant to such claim that the party to the indemnification agreement would not be permitted to be indemnified under applicable law. Parties to the indemnification agreements would not be indemnified for any acts, omissions or transactions for which they are prohibited from receiving indemnification under applicable law.

        These indemnification provisions may be sufficiently broad to permit indemnification of our officers, directors and other corporate agents for liabilities (including reimbursement of expenses incurred) arising under the Securities Act of 1933.

Item 16.    Exhibits

        The following exhibits are filed with this Registration Statement:

Exhibit No.		Description of Exhibit
4.1	*	Restated and Amended Certificate of Incorporation
4.2	**	First Amended and Restated Common Shares Rights Agreement dated as of June 24, 1998, between Coherent Inc. and BankBoston, N.A.
4.3		Stock Purchase Agreement, made as of December 11, 1996, by and between Coherent, Inc. and the beneficial owners of shares of Tutcore Oy Ltd., a company registered under the laws of Finland.
5.1		Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation
23.1		Consent of Deloitte & Touche LLP, Independent Auditors
23.2		Consent of Arthur Andersen Wirtschaftsprüfungsgesellschaft Steuerberatungsgesellschaft mbH, Independent Auditors
23.3		Consent of Wilson Sonsini Goodrich & Rosati, Professional Corporation (included in Exhibit 5.1)
24.1		Power of Attorney (included in the Signature Page contained in Part II of the Registration Statement)

*

Incorporated by reference to Exhibit 3.1 included in our Annual Report on Form 10-K for the fiscal year ended September 29, 1990.

**

Incorporated by reference to Exhibit 1 (included in our registration statement on Form 8-A/A filed as of July 1, 1998 (File No. 000-05255)).

Item 17.    Undertakings

A.

The registrant hereby undertakes:

(1)

To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i)

To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

(ii)

To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than a 20% change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective registration statement;

(iii)

To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

II-2

        Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the registration statement is on Form S-3 or Form S-8, and the information required to be included in a post-effective amendment by those paragraphs is contained in periodic reports filed by the registrant pursuant to section 13 or section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement.

(2)

That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.



(3)

To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

B.

The registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

C.

Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to the directors, officers, and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue.

II-3

Signatures

        Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized in the City of Santa Clara, State of California on March 25, 2002.

COHERENT, INC.
By:	/s/  BERNARD J. COUILLAUD Bernard J. Couillaud President and Chief Executive Officer

        KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Bernard J. Couillaud and Robert J. Quillinan, and each of them, as his true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for him and in his name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement on Form S-3 and any Registration Statement filed pursuant to Rule 462(b) promulgated under the Securities Act of 1933, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorney-in-fact and agent, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent, or his substitutes, may lawfully do or cause to be done by virtue hereof.

        Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated:

Signature	Title	Date
/s/  BERNARD J. COUILLAUD Bernard J. Couillaud	Director, President and Chief Executive Officer (Principal Executive Officer)	March 25, 2002
/s/  ROBERT J. QUILLINAN Robert J. Quillinan	Director, Executive Vice President and Chief Financial Officer (Principal Financial and Accounting Officer)	March 25, 2002
/s/  HENRY E. GAUTHIER Henry E. Gauthier	Chairman of the Board of Directors of the Company	March 25, 2002
/s/  CHARLES W. CANTONI Charles W. Cantoni	Director	March 25, 2002
Frank P. Carrubba	Director
John H. Hart	Director
/s/  JERRY E. ROBERTSON Jerry E. Robertson	Director	March 25, 2002

II-4

Index to Exhibits

Exhibit No.	Description of Exhibit
4.1*	Restated and Amended Certificate of Incorporation
4.2**	First Amended and Restated Common Shares Rights Agreement dated as of June 24, 1998, between Coherent Inc. and BankBoston, N.A.
4.3	Stock Purchase Agreement, made as of December 11, 1996, by and between Coherent, Inc. and the beneficial owners of shares of Tutcore Oy Ltd., a company registered under the laws of Finland.
5.1	Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation
23.1	Consent of Deloitte & Touche LLP, Independent Auditors
23.2	Consent of Arthur Andersen Wirtschaftsprüfungsgesellschaft Steuerberatungsgesellschaft mbh, Independent Auditors
23.3	Consent of Wilson Sonsini Goodrich & Rosati, Professional Corporation (included in Exhibit 5.1)
24.1	Power of Attorney (included in the Signature Page contained in Part II of the Registration Statement)

*

Incorporated by reference to Exhibit 3.1 included in our Annual Report on Form 10-K for the fiscal year ended September 29, 1990.

**

Incorporated by reference to Exhibit 1 (included in our registration statement on Form 8-A/A filed as of July 1, 1998 (File No. 000-05255)).

QuickLinks

Where You Can Find More Information
Incorporation of Certain Documents by Reference
The Company
Plan of Distribution
Selling Shareholders
Use of Proceeds
Legal matters
Experts
PART II INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution
Item 15. Indemnification of Directors and Officers
Item 16. Exhibits
Item 17. Undertakings

Signatures

Index to Exhibits

EX-4.3

QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 4.3

STOCK PURCHASE AGREEMENT

        THIS AGREEMENT is made this 11 day of December 1996 BY AND BETWEEN:

1.

Coherent Inc., a company incorporated in Delaware in the United States of America, whose registered office is at 5100 Patrick Henry Drive, Santa Clara, CA 95054, United States of America (hereinafter referred to as the "Purchaser");

2.

Mr Harry Asonen (050556-029M), Koivikonkatu 23, 33820 Tampere, Finland;
Mr Rauno Asonen (280448-4517), Pihatanhua 11, 33480 Mutala, Finland;
Mr Simo Arra (310146-5691), 36420 Sahalahti, Finland;
Mr Juha Hautala (190963-0158), Seljatie 12, 36200 Kangasala, Finland;
Mrs Leena Kivipelto-Mattila (300453-236V), Järveläntie 6, 37800 Toijala, Finland;
Mr Hannu Kojola (171144-451R), Turuntie 346, 21870 Riihikoski, Finland;
Mr Jouko Lammasniemi (230863-189M), Vilppulanpolku 4 A 1, 33720 Tampere, Finland;
Mr Jari Näppi (021162-175T), Sammonkatu 27 E 67, 33540 Tampere, Finland;
Mr Aleksander Ovtchinnikov (250161-217N), Lehtikatu 7 E 25, 33340 Tampere, Finland;
Mr Markus Pessa (211141-1594), Miekkakatu 13 C 11, 33530 Tampere, Finland;
Mr Keijo Rakennus (110461-137F), Kyläojankatu 1 B 9, 33700 Tampere, Finland;
Mr Mika Toivonen (140466-111V), Miekkakatu 13 A, 33530 Tampere, Finland;
Mr Arto Salokatve (051061-171J), Lindforsinkatu 8 B 33, 33720 Tampere, Finland and
Mr Pekka Savolainen (160269-1010), Arkkitehdinkatu 28 B 27, 33720 Tampere, Finland
(hereinafter referred all together to as the "Vendors")

        WHEREAS:

(A)

Tutcore Oy Ltd. is a company registered in Tampere in Finland under number 516.984 (hereinafter referred to as the "Company");

(B)

The Vendors are each the beneficial owners in the following proportions of the ordinary voting shares of FIM 100 each in the Company, which shares in aggregate represent the entire issued share capital FIM 560.000 of the Company:

Mr Harry Asonen		720 shares;
Mr Rauno Asonen		320 shares;
Mr Simo Arra		352 shares;
Mr Juha Hautala		80 shares;
Mrs Leena Kivipelto-Mattila		368 shares;
Mr Hannu Kojola		352 shares;
Mr Jouko Lammasniemi		704 shares;
Mr Jari Näppi		720 shares;
Mr Aleksander Ovtchinnikov		80 shares;
Mr Markus Pessa		720 shares;
Mr Keijo Rakennus		544 shares;
Mr Mika Toivonen		320 shares;
Mr Arto Salokatve		160 shares	and
Mr Pekka Savolainen		160 shares
	Total: 5.600 shares

(C)

The Purchaser and the Vendors have agreed to enter into this Agreement for the purpose of which is the acquisition of the Company through sale and purchase of the shares of the Company. By this Agreement the Purchaser shall purchase 80% of the shares of the Company in proportions they are owned by the Vendors. Further, the Purchaser shall have an option to acquire the remaining

20% of the shares of the Company from the Vendors at the end of the fifth year from the date of this Agreement in accordance with the terms of Clause 6 of this Agreement.

(D)

The Vendors have agreed to sell and the Purchaser has agreed to purchase, in reliance upon the representations, warranties, indemnities and undertakings hereinafter contained or referred to, the shares of the Company on and subject to the terms and conditions hereinafter appearing.

        NOW, IT IS HEREBY AGREED AS FOLLOWS:

        Interpretation

In this agreement, unless the contrary intention appears, the following definitions apply:

Effective Date shall mean the date of this Agreement;

Third Year shall mean the calendar year 1999 and Three Years shall mean the time from the Effective Date till the end of calendar year 1999;

Fifth Year shall mean the calendar year 2001 and Five Years shall mean the time from the Effective Date till the end of calendar year 2001;

Semiconductor Products shall mean the products produced or intended to be produced by the Company as defined in Enclosure 1;

Shares shall mean the shares, specified in Clause 2 below, of the Company that are sold with this Agreement;

Remaining Shares shall mean the shares of the Company that will be subject to the option right of the Purchaser in accordance with the terms in Clause 6;

Warranties shall mean the warranties and representations by the Vendors in Clause 12.

Words denoting the single number only include the plural and viceversa.

The headings in this Agreement are inserted for convenience only and do not affect its construction.

1.

Agreement for sale

1.1

Subject to the terms and conditions of this agreement, the Vendors shall sell as beneficial owners and with full title and the Purchaser shall purchase the Shares free from all liens, charges and encumbrances and with all rights attaching to them and with effect from the date of this Agreement.

1.2

Each of the Vendors hereby waives any pre-emption rights he may have in relation to any of the Shares under the Articles of Association of the Company or otherwise.

2.

The object of the sale and purchase

The object of the sale and purchase is 4.480 shares in the Company, which shares in aggregate represent 80% of the all of the Shares as well as 80% of all of the voting rights in the Company. The Shares to be sold hereunder shall be divided between the Vendors as specified in Enclosure 2 hereto.

3.

Purchase consideration

3.1

The aggregate purchase consideration for the Shares shall be the sum of USD four million (4.000.000) as First Instalment together with additional payments specified in Clauses 4 and 5 respectively.

3.2

From the First Instalment 75 per cent, i.e USD 3.000.000, shall be paid in cash to the Vendors at the Effective Date. The balance of the First Instalment, i.e USD 1.000.000, shall be paid by way of

2

depositing the sum in an interest bearing escrow account to secure the liability of the Vendors as set forth in Clause 13 hereinbelow. The deposition shall be made at Merita Bank Ltd. Finland, in terms agreed by both parties. This sum shall be released to the Vendors as soon as the time whereby the Purchaser is to present its claims pursuant to Clause 13 has lapsed, provided that the Purchaser has not made any claims.

3.3

The Vendors shall be entitled to the purchase consideration and first and second additional payments mentioned in Clauses 4. and 5. and payments made under the Option Right mentioned in Clause 6 as nearly as may be in proportion to their holdings of the Shares.

4.

First additional payment

4.1

After Three Years the Purchaser shall pay to the Vendors the sum calculated in accordance with the following formula:

USD Three-Year Semiconductor Sales USD 59.000.000 x USD 2.000.000

in which the value of the Semiconductor Sales shall be the net sales value of the sold Semiconductor Products during the Three Years (Enclosure 3).

4.2

Notwithstanding the foregoing the first additional payment shall in no event exceed USD 2.000.000.

4.3

The payment shall be made in cash within Sixty Days from the end of the Third Year.

5.

Second additional payment

5.1

After Five Years the Purchaser shall pay to the Vendors the sum calculated in accordance with the following formula:

USD Five-Year Semiconductor Sales USD 160.000.000 x USD 2.000.000

in which the value of the Semiconductor Sales shall be the net sales value of the sold Semiconductor Products during the Five Years (Enclosure 3).

5.2

Each of the Vendors shall have an individual right to choose the way of payment of their proportion out of second additional payment as follows:

(a)

in cash
or

(b)

in shares of Coherent Inc. common stock

in which calculation the shares of Coherent Inc. shall be valued as to the closing price quoted by the NASDAQ stock market at the Effective Date. In case there will be any stock splits, stock dividends or similar capital reorganisations the value of shares shall be adjusted.

5.3

Notwithstanding the above the portion of the second additional payment to be paid in the shares of Coherent Inc. common stock shall not exceed in value USD 2.000.000. The balance between the aggregate second additional payment and the portion of the same to be paid in shares of Coherent Inc. shall be paid in cash. Each Vendor has right for payment in shares in proportion of their ownership of the Shares when the demand of shares exceeds the limit value of USD 2.000.000. If one or more of the Vendors decides not elect the payment in shares, these shares shall not be divided to other Vendors.

3

5.4

The payment shall be made within 60 days following the end of the Fifth Year. The Vendors shall deliver a written notice of their intent to choose shares of Coherent Inc. as a way of payment to the Purchaser latest 30 days after the end of the Fifth Year. Otherwise the Purchaser shall have the option to choose the way of payment.

5.5

In case the Vendors choose shares of Coherent Inc. as a way of payment according to Clauses 5.2 to 5.4 above following terms on request for registration shall apply:

(a)    If the Purchaser shall receive a written request from the holders of not less than fifty percent (50%) of the shares of Coherent Inc. mentioned in Clauses 5.2 to 5.4 that the Purchaser file a registration statement under the Securities Act of 1933, as amended (the "Act"), then the Purchaser shall promptly notify all other holders of such request and shall use its best efforts to cause all shares of Coherent Inc. mentioned in Clauses 5.2 to 5.4 that holders have requested to be registered on Form S-3 under the Act;

(b)    The Purchaser shall be obligated to effect only one registration pursuant to this paragraph. The Purchaser shall have no obligation pursuant to this paragraph if, in the opinion of counsel to the Purchaser, the shares of Coherent Inc. mentioned in Clauses 5.2 to 5.4 can be freely transferred without registration under Rule 144 promulgated under the Securities Exchange Act of 1934;

(c)    The Purchaser's obligations set forth above are conditioned upon the Vendors cooperating with the furnishing of information to be included in the registration, and the Vendors signing a standard stockholders agreement whereby they agree to coordinate the sale of shares of Coherent Inc. mentioned in Clauses 5.2 to 5.4 with the Purchaser to ensure compliance with the Act;

(d)    All expenses relating to the registration, other than underwriting discounts, selling commissions and stock transfer taxes applicable to the Shares to be registered, shall be paid by the Purchaser;

(e)    Words "register", "registered" and "registration" refer in the context above to a registration effected by preparing and filing a registration statement in compliance with the Act and the declaration or ordering of the effectiveness of such registration statement.

6.

Option for redemption of the Remaining Shares

6.1

At end of Fifth Year the Vendors shall have the right to require that the Purchaser shall purchase the Remaining Shares and the Purchaser shall have the right to require that the Vendors shall sell all or some of the Remaining Shares to the Purchaser to a price determined in the following formula ("The Option Right"):

USD Five-Year Semiconductor Sales USD 160.000.000 x USD 2.940.000

in which the value of the Semiconductor Sales shall be the net sales value of the sold Semiconductor Products during the Five Years.

6.2

The Option Right shall be exercised by delivery of a written notice by the party wishing to exercise the Option Right to the other parties within 90 days following the end of the Fifth Year.

6.3

The parties shall be bound to complete the sale and purchase of the Remaining Shares 14 days after date of service of the notice of exercise of the Option Right.

4

6.4	Completion of the sale and purchase shall take place at the offices of Merilampi, Marttila & Laitasalo in Tampere or at such other place as the parties shall mutually agree not later than 3.00 p.m. on the relevant day. The Vendors shall then deliver to the Purchaser (i) a duly executed transfer of the Remaining Shares accompanied by the relative share certificates, (ii) a waiver of any applicable rights of pre-emption, duly signed by all the other members of the Company, and (iii) such other deeds and documents as may be necessary to transfer to the Purchaser or as it may direct the unencumbered beneficial ownership of the Remaining Shares.
6.5	All rights attached to the Remaining Shares shall accrue to the Purchaser on the date of service of the notice exercising the Option Right and, following the exercise of the Option Right, the Vendors shall account to the Purchaser for all dividends or other distributions of the Company declared or paid by reference to a record date which is subsequent to the date of service and shall exercise all voting and other rights at the direction of the Purchaser.
6.6	Each of the Vendors hereby warrant to the Purchaser that he is and will remain until the exercise or expiry of the Option Right the beneficial owner of the Remaining Shares, subject only to the Option Right, and has and will have full power and authority to grant an option in respect of the same upon the terms and conditions of this agreement. The Vendors shall not prior to the exercise of expiry of the Option Right transfer, dispose of, charge, pledge or encumber in any way its interest in any of the Remaining Shares and the Remaining Shares shall upon completion be sold free of any liens, charges or encumbrances.
7.	Late payment
	For any delay in the payments referred to in Clauses from 3 to 6 the Purchaser is liable to pay an annual interest of 18%.
8.	Conditions and rescission
8.1	The purchase of the Shares is conditional upon the respective approvals of the Board of Directors of Coherent Inc.;
8.2	The Purchaser shall be entitled to rescind this agreement by notice in writing to the Vendors if prior to completion it appears that the above condition shall not be met or any of the warranties is not or was not true and accurate in all respects of if any act or event occurs which, had it occurred on or before the date of this agreement, would have constituted a breach of any of the warranties or if there is any material breach or nonfulfilment of any of the warranties which (being cable of remedy), is not remedied prior to completion.
9.	Completion
	Provided that it has not been rescinded in accordance with clause 8 the completion shall take place after signing without delay and on December 15, 1996 at the latest when all the transactions mentioned in the following subclauses shall be completed:
	(a)        The 75 per cent of the First Instalment of the purchase consideration shall be paid in cash into the account directed by the Vendors in proportions directed by the Vendors;
	(b)        The balance of the First Instalment shall be paid to the escrow account;
	(c)        The Vendors shall deliver to the Purchaser duly completed and signed transfers in favour of the Purchaser or as it may direct in respect of the Shares together with the relative share certificates;
	(d)        The Company shall execute contracts of employment and contracts of consulting mentioned in Clause 14;
	(e)        The title to the Shares shall pass to the Purchaser as the Shares are delivered.

5

10.	Stamp duty
	The stamp duty payable on this sale and purchase shall be paid by the Purchaser.
11.	Confidentiality
	The parties shall keep confidential all information acquired from the other parties in connection with entering into or negotiating this Stock Purchase Agreement as well as the terms of this Agreement, except if the party is liable to reveal such information pursuant to laws or regulations or if the information is already in public domain.
12.	Representations and Warranties by the Vendors
	The Vendors jointly and severally represent and warrant to the Purchaser that
12.1	The following representations and warranties of the Vendors are accurate and in full force as at the date of signing of this stock purchase agreement and at the Effective Date, unless the wording of the warranty otherwise implies;
12.2	The accounts for the period ended December 31, 1995 and for the preceding three accounting periods of the Company were prepared in accordance with the historical cost convention, and the basis and policies of accounting adopted in preparing the accounts are the same as those adopted in preparing the accounts of the Company in respect of the three last preceding accounting periods;
12.3	The accounts of the Company give a true and fair view of the assets and liabilities of the company and its profits for the financial period ended on relevant last accounts date, comply with the requirements of Finnish Companies Act, Bookkeeping Act, good accounting principles and any other relevant statute, properly reflect the financial position of the Company as at their date, fully disclose all the assets of the Company as at their date and make full provision or reserve for all liabilities and capital commitments outstanding at the relevant last accounts date, including contingent, unquantified or disputed liabilities.
12.4	The execution of this stock purchase agreement will not violate any agreement that the Company is a party to, or any laws, rules or regulations and no consents are required from the government or any third parties to complete the transaction. This warranty considers the financial support contracts between TEKES and the Company and between European Communities and the Company which have been presented to the Purchaser;
12.5	The information regarding the Company given by the Vendors to the Purchaser is correct, the Vendors have given to the Purchaser all information required by the Purchaser and the Vendors have not failed to inform the Purchaser of any material information regarding the Company or the Shares;
12.6	There are no pending amendments to the information contained in the extract from Trade Registry as at 8.11.1996 and the Articles of Association as at 13.3.1996 of the Company, and the organs of the Company have not made any resolutions, which should have been entered into the Trade Registry.
12.7	The Company is duly organized, validly existing and in good standing under the laws of Finland and has all the requisite corporate power and authority to own, lease and operate its properties and assets as in the present time owned, leased and operated and to carry on its business as in the present time being conducted;

6

12.8	The entire paid up share capital of the Company is FIM 560.000 and the property given as subscription in kind, which has been transferred to the Company to cover its share capital, correspond in value the amount for which the Vendors have subscribed for shares in the Company against property given as subscription in kind, and such property is in the possession of the Company;
12.9	The Company has not resolved to increase or decrease its share capital, to obtain loans with equity warrants or loans with convertible debentures, to alter the nominal value of the shares or any other resolutions which might have effect on the shareholders' equity of the Company, which have not been informed to the Purchaser excluding resolutions relating to the normal business of the Company;
12.10	The Vendors own, they have the unencumbered right and they are legally permitted to transfer the Shares which shares in aggregate represent 80% of all of the shares in the Company as well as 80% of the total voting rights vested to all of the shares of the Company, and the Shares are not subject to any pledges, liens, encumbrances or other third-party rights;
12.11	To the knowledge of the Vendors the Company has from the point of view of its business no substantial financial liabilities (to include latent liabilities, off-balance sheet debts and tax liabilities), which do not appear from the list delivered by the Vendors (Enclosure 4). Should such liabilities nevertheless arise, the Vendors shall be responsible for them, to the extent they relate to time prior to Effective Date in accordance with clause 13 hereinafter;
12.12	The property of the Company is not subject to other charges, pledge rights, securities, material third-party rights or other substantial encumbrances than those specified in the list delivered by the Vendors (Enclosure 5). The Vendors have not made any promises to create such rights or encumbrances;
12.13	The property of the Company is not as a security for third-party debts or liabilities and the Company has not given any commitments for the benefit of third-party liabilities;
12.14	The receivables of the Company do not contain any exceptional payment terms or risk of bad debt, which have not been separately informed to the Purchaser;
12.15	The Company has good, marketable and unencumbered title to all of the assets (including liquid assets, floating assets and fixed assets) specified in the list delivered by the Vendors (Enclosure 6). The assets are free and clear of any other pledges, liens, encumbrances or other third-party rights other than these mentioned in Enclosure 5.
12.16	The agreement between Tampere University of Technology and the Company relating to the possession and use of the premises being possessed under lease agreement are in full force and this agreement has no effect to the mentioned lease agreement;
12.17	The Company has an insurance coverage, which in accordance with normal insurance practice covers the assets of the Company as well as, taking into consideration the special aspects relating to the business of the Company, the need for insurance coverage required otherwise in its activities;
12.18	To the best of the Vendors' knowledge all material industrial and intellectual property rights as well as manufacturing rights and knowhow, which are necessary to maintain and develope the activities of the Company, are freely at the use of the Company without charge. Except for the industrial and intellectual property owned, licensed or freely used by the Company, no other intellectual property rights are required for the conduct the business of the Company. This warranty shall not apply to the joint developement project between the Company and IVO and the rights of the IVO which are based on this project. The Purchaser is aware of the project mentioned;

7

12.19	No right or license on industrial and intellectual property of the Company has been granted to any person to use in any manner. This warranty shall not apply to the product developement agreements between the Company and EG & G dated 24.101994 and 14.7.1995 which the Purchaser is aware of;
12.20	The Company has not transferred its fixed assets nor has it made any agreement of such transfer, and the Company has not acquired or made an agreement to acquire property or assets other than within its normal business;
12.21	Any and all agreements material to the business of the Company have been specified in Enclosure 7 hereto;
12.22	All agreements, to which the Company is a party and which have material effect to the financial status or business of the Company, comply as at the date of this Agreement with following terms:
	(i)        the agreements have not been terminated, either prematurely or otherwise or be breached so that there would exist grounds for termination or premature termination,
	(ii)        the agreements are not subject to termination on grounds that the ownership of the Company is changed in accordance with this agreement on sale and purchase;
12.23	All permits, licences, authorizations and agreements necessary for the conduct of the Company's activities are as at the date of this agreement in full force, and to the knowledge of the Vendors they have not been breached or terminated and there has been no disturbances in the same, and any of the above is neither expected to the knowledge of the Vendors;
12.24	All returns, notifications, computations and payments which should have been made or given by the Company for any taxation purpose were made or given within the requisite periods and are up-to-date, correct on a proper basis and none of them is or is likely to be a subject of any dispute with the taxation authorities.
12.25	As at the date of this agreement the Company has no pending of threatened litigations or arbitration procedures or other legal investigations and the assets of the Company are not subject to tax complaints, precautionary measures, administrative measures by the authorities or other similar measures, and to the knowledge of the Vendors no such measures are expected to arise;
12.26	To the best of Vendors' knowledge, after a reasonable investigation, the Company has complied with the liabilities under environmental laws and especially with the liability under laws on storage or transportation of hazardous materials, and it is not expected that the Company would be faced with liability thereon;
12.27	The pension liabilities of the employees have been fully covered and the pension benefits have been arranged in accordance with the normal practice in this field;
12.28	All information given by any of the Vendors or on behalf of them relating to the Company or its business was, when given, and is now accurate and comprehensive in all respects, and there are no material facts or circumstances, in relation to the Company or its business, which have not been fully and fairly disclosed to the Purchaser and which, if disclosed, might reasonably have been expected to affect the desision of the Purchaser to enter into this agreement;
12.29	The Company shall continue its business in the ordinary course from the date of this agreement to the Effective Date and report to the Purchaser any indication of potential material adverse factors in its business, such as loss of distributors, new announcements in competitive technology, intentions of key employees to resign or leave, or any other adverse factors;
12.30	The Vendors shall have no claim or right to any of the earnings of the Company for the five year period ending December 31, 2001

8

12.31	In case the Company and / or the Vendors in spite of above warranty has failed to comply with any of the above liabilities or the Company otherwise is liable to act as referred to above, the Vendors shall indemnify the Company against so caused detrimental financial consequences in accordance with Clause 13 below to the extent they relate to time prior to the Effective Date of this Agreement.
13.	Indemnities
13.1	In the event that:

—

the Company lacks assets, which it pursuant to this stock purchase agreement and Vendors' warranties should have;



—

the Company has or it contains or acquires liabilities, debts or other such financial consequences, which relate or are based on time prior to the Effective Date, which do not appear from this stock purchase agreement or from the information, which the Vendors have otherwise given to the Purchaser or which do not belong to normal business;



—

the representation and warranties given by the Vendors in this agreement or otherwise would not be true;



—

any environmental matter or matter on hazardous materials will cause claims against or costs to the Company which claims or costs have their origin or basis in the time prior to the Effective Date;



—

the Company otherwise deviates from which the Vendors have in this agreement or otherwise informed;



—

the Vendors have otherwise committed a breach of the terms of this agreement;

	the Purchaser shall be entitled to reduction of purchase price or indemnification which is equal to the proportion such lack of funds, excessive liabilities, taxes of other detrimental financial consequences are in proportion to its shareholding or, at its sole discretion, to claim that the terms of this agreement are fulfilled. The amount of indemnification the Vendors may be liable for shall not exceed the purchase consideration, first and second additional payments and the payments made under option right which are defined in clauses 3-6.
13.2	The Purchaser shall be liable to notify all indemnification and purchase price reduction claims pursuant to this agreement to the Vendors by one year from the Effective Date at the latest. The Purchaser shall be entitled to and is liable, however, to notify the claims relating to taxes within three months from the date the Purchaser has been informed of the tax decision for the Company concerning the accounting period which ends on 31.12.1996.
13.3	The Vendors shall be liable to pay for the indemnification or for the reduced purchase price to the Purchaser interest in accordance with the act on interest.
13.4	If a breach of Clauses 14 and 15 constituting liability according to Clause 13 is committed by a single Vendor the other Vendors shall be free from liability based on such breach or act.

9

14.  Key employees and consultants of the Company

14.1

The following Vendors

Mr Harry Asonen
Mrs Leena Kivipelto-Mattila
Mr Jari Näppi
Mr Aleksander Ovtchinnikov
Mr Keijo Rakennus
Mr Juha Hautala
Mr Mika Toivonen
Mr Arto Salokatve
Mr Pekka Savolainen
Mr Jouko Lammasniemi


shall each remain in the service of the Company by entering into contracts of employment or contracts of consulting with substantially in the form and terms annexed hereto as Enclosure 8.

14.2

The above mentioned Vendors shall be obliged to fulfil their employment or consultancy contracts with their best efforts and not to terminate any or all of the contracts in 5 years from the Effective Date. This clause shall not prevent the Company from terminating any or all of the contracts.

15.  Prohibition of the competition

15.1

For the purpose of assuring to the Purchaser the full benefit of the business and goodwill of the Company, each of the Vendors shall not directly or indirectly for seven years after the Effective Date either on his own account or for any other person:

(a)

engage in competition with the Company;

(b)

hold any intrest in any business which is or shall be wholly or partly in competition with the business of the Company (other than an intrest of not more than 5% of the outstanding stock of any publicity traded company);

(c)

serve as an employee or consultant to any company engaged in a business competive to the Company; or

(d)

solicit, employ, interfere with or attemp to entice away from the Company any person who is employed by the Company.

15.2

For purposes of this agreement, a business competive to the Company shall mean any company that manufactures or sells semiconductor laser products, diode-pumped solid-state lasers, or the materials used to produce them.

15.3

Notwithstanding the foregoing, the obligation set forth in this Clause 15 shall terminate:

(a)

In the case of Vendors who are employees of the Company, six months after such employment with the Company is involuntarily terminated. In event mentioned in 43 § of the finnish Employment Contract Act the Company has right to terminate the employment or consultant agreement without influence on the prohibition according to this Clause 15.

(b)

In the event Mr Aleksander Ovtchinnikov is prohibited from continuing to work in Finland because of legal restrictions.

15.4

Nothing in this Clause 15 shall prohibit any Vendor from conducting research on laser devices in an academic setting in Finland so long as no products are manufactured in commercial quantities or offered for sale to the public or prohibit a Vendor from working for a company where an insubstansial part of its business involves manufacturing or selling semiconductor laser products, diode-pumped solid-state lasers, or the materials used to produce them, so long as the Vendor is

10

not working in the part of business manufacturing or selling semiconductor laser products, diode-pumped solid-state lasers or the materials used to produce them. An insubstantial part shall mean less than 5 per cent of total annual revenues.

16.  Location of the business

The Purchaser intends to keep the business and the operations of the Company in Tampere, Finland, except in extraordinary circumstances. Extraordinary circumstances shall be defined to be any unforeseen event where it would be reasonable under the circumstances for the Purchaser to move the business and the operations. In case the Purchaser closes the business and the operations of the Company in Tampere the obligations in Clause 14.2 and the noncompete provisions in Clause 15 above shall expire in six months after the move.

17.  Announcement of the stock purchase

The Vendors and the Purchaser shall be bound to make only a joint public announcement of this stock purchase transaction in a way that will be mutually agreed.

18.  Governing law

This Agreement shall be governed by and construed in accordance with Finnish law.

19.  Disputes

Any and all disputes arising out of the Agreement, which may not be settled by the parties' negotiation, shall be finally settled in arbitration to be conducted in accordance with the rules of the International Chamber of Commerce in Stockholm. The place of arbitration shall be Stockholm, Sweden.

        IN WITNESS whereof the parties hereto have executed this Agreement on the date first above written.

        This Stock Purchase Agreement has been executed in fifteen identical copies, one for the Purchaser and one for each Vendor.

11

For and on behalf of COHERENT INC.

By:	Scott H. Miller Vice President & General Counsel
SIGNED and DELIVERED by HARRY ASONEN
SIGNED and DELIVERED by RAUNO ASONEN
SIGNED and DELIVERED by SIMO ARRA
JUHA HAUTALA signed by Harry Asonen by proxy
SIGNED and DELIVERED by LEENA KIVIPELTO-MATTILA
SIGNED and DELIVERED by HANNU KOJOLA
SIGNED and DELIVERED by JOUKO LAMMASNIEMI
SIGNED and DELIVERED by JARI NÄPPI
SIGNED and DELIVERED by ALEKSANDER OVTCHINNIKOV
SIGNED and DELIVERED by MARKUS PESSA
SIGNED and DELIVERED by KEIJO RAKENNUS
SIGNED and DELIVERED by MIKA TOIVONEN
SIGNED and DELIVERED by ARTO SALOKATVE
SIGNED and DELIVERED by PEKKA SAVOLAINEN

12

QuickLinks

EXHIBIT 4.3

STOCK PURCHASE AGREEMENT

EX-5.1

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 5.1

March 25, 2002

Coherent, Inc.
5100 Patrick Henry Drive
Santa Clara, CA 95054

Re:

REGISTRATION STATEMENT ON FORM S-3

Ladies and Gentlemen:

        We have examined the Registration Statement on Form S-3 filed by you with the Securities and Exchange Commission on March 25, 2002 (the "Registration Statement"), in connection with the registration under the Securities Act of 1933, as amended, of 59,246 shares of your common stock, $0.01 par value per share (the "Shares"). We understand that the Shares were issued in connection with your acquisition of a majority ownership interest in Tutcore Oy, Ltd., a company registered under the laws of Finland, and that the Registration Statement may be used by shareholders of Tutcore Oy to resell their Shares. As your legal counsel, we have examined the proceedings taken, and are familiar with the proceedings proposed to be taken, by you in connection with the issuance of the Shares by you.

        Based upon the foregoing, we are of the opinion that the Shares, as issued in the manner described in the Registration Statement, are duly authorized, validly issued, fully paid and non-assessable.

        We consent to the use of this opinion as an exhibit to the Registration Statement and further consent to the use of our name wherever appearing in the Registration Statement, including the Prospectus constituting a part thereof, and any amendments thereto.

Very truly yours,

WILSON SONSINI GOODRICH & ROSATI
Professional Corporation

/s/ Wilson Sonsini Goodrich & Rosati, P.C.

QuickLinks

Exhibit 5.1

EX-23.1

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 23.1

CONSENT OF DELOITTE & TOUCHE LLP, INDEPENDENT AUDITORS

We consent to the incorporation by reference in this Registration Statement of Coherent, Inc. on Form S-3 of our report dated October 29, 2001, appearing in the Annual Report on Form 10-K of Coherent, Inc. for the year ended September 30, 2001 and to the reference to us under the heading "Experts" in the Prospectus, which is part of this Registration Statement.

/s/ Deloitte & Touche LLP

San Jose, California
March 19, 2002

QuickLinks

Exhibit 23.1

CONSENT OF DELOITTE & TOUCHE LLP, INDEPENDENT AUDITORS

EX-23.2

QuickLinks -- Click here to rapidly navigate through this document

Exhibit 23.2

CONSENT OF INDEPENDENT AUDITORS

As independent auditors, we hereby consent to the reference in "Item 16. Exhibits" to our firm in the Registration Statement (Form S-3) and related Prospectus of Coherent, Inc. for the registration of 59,246 shares of its common stock and to the incorporation by reference of our report dated October 29, 2001 with respect to the consolidated financial statements of Lambda Physik AG as of September 30, 2001 included in Coherent, Inc.'s Form 10-K for the year ended September 29, 2001. It should be noted that we have not audited any financial statements of Lambda Physik AG subsequent to September 30, 2001 or performed any audit procedures subsequent to the date of our report.

Arthur Andersen
Wirschaftspruefungsgesellschaft
Steuerberatungsgesellschaft mbH

/s/  HENTSCHEL WIRTSCHAFTSPRUEFER	/s/  BOELSEMS WIRTSCHAFTSPRUEFER
Hentschel Wirtschaftspruefer	Boelsems Wirtschaftspruefer

Hanover, March 20, 2002

QuickLinks

Exhibit 23.2

CONSENT OF INDEPENDENT AUDITORS