S-8

QuickLinks -- Click here to rapidly navigate through this document

As filed with the Securities and Exchange Commission on April 8, 2002
Registration No. 333-                      

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-8
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

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

Delaware
(State of Incorporation) 94-1622541
(I.R.S. Employer Identification Number)

5100 Patrick Henry Drive
Santa Clara, California 95056
(Address of Principal Executive Offices)

2001 STOCK PLAN
(Full title of the plan)

Robert J. Quillinan
Executive Vice President and Chief Financial Officer
COHERENT, INC.
5100 Patrick Henry Drive
Santa Clara, California 95056
(Name and address of agent for service)
(408) 764-4000
(Telephone number, including area code, of agent for service)

Copy to:
Larry M. Sonsini, Esq.
David R. Segre, Esq.
WILSON SONSINI GOODRICH & ROSATI,
PROFESSIONAL CORPORATION
650 Page Mill Road
Palo Alto, California 94304-1050
Telephone: (650) 493-9300

CALCULATION OF REGISTRATION FEE

Title of Securities to be Registered	Amount to be Registered(1)	Proposed Maximum Offering Price Per Share(2)	Proposed Maximum Aggregate Offering Price(2)	Amount of Registration Fee(3)
Common Stock, $0.01 par value per share, to be issued under the 2001 Stock Plan	2,800,000	$33.66	$94,248,000	$8,670.82

(1)

Amount of securities to be registered computed in accordance with Rule 457(h) of the Securities Act of 1933, as amended, as the maximum number of the Registrant's Common Stock issuable under the 2001 Stock Plan covered by this registration statement.

(2)

Proposed maximum offering price per share and the proposed maximum aggregate offering price for the shares of Common Stock to be issued under the 2001 Stock Plan was calculated in accordance with Rule 457(c) and (h) of the Securities Act, based upon the average high and low prices of the Registrant's Common Stock as reported by the Nasdaq NMS on April 5, 2002, because the prices at which the options to be granted in the future may be exercised, and the prices at which shares will be purchased in the future, are not currently determinable.

(3)

Amount of registration fee was calculated pursuant to Section 6(b) of the Securities Act which provides that the fee shall be .000092 of the proposed maximum aggregate offering price of the securities proposed to be registered.

PART II

INFORMATION REQUIRED IN REGISTRATION STATEMENT

Item 3.    Incorporation of Documents by Reference.

        The following documents and information heretofore filed by Registrant with the Securities and Exchange Commission are hereby incorporated by reference in this Registration Statement:

        1.    The Registrant's Annual Report on Form 10-K, as amended, for the fiscal year ended September 29, 2001, filed pursuant to Section 13(a) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"); and

        2.    The description of the Registrant's Common Stock contained in the Registration Statement on Form 8-A filed pursuant to Section 12 of the Exchange Act, including any amendment or report filed for the purpose of updating any such description.

        All documents subsequently filed by the Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act on or after the date of this Registration Statement and prior to the filing of a post-effective amendment which indicates that all securities offered have been sold or which deregisters all securities then remaining unsold, shall be deemed to be incorporated by reference in this Registration Statement and to be part hereof from the date of filing of such documents.

Item 4.    Description of Securities.

        Not applicable.

Item 5.    Interests of Named Experts and Counsel.

        Not applicable.

Item 6.    Indemnification of Directors and Officers.

        Section 145 of the Delaware General Corporations Law authorizes a court to award, or a corporation's Board of Directors to grant, indemnification to directors and officers in terms sufficiently broad to permit such indemnification under certain circumstances for liabilities (including reimbursement for expenses incurred) arising under the Act. The Registrant's Bylaws provides for the mandatory indemnification of its directors and officers and permissible indemnification of employees and other agents to the maximum extent permitted by Delaware General Corporation Law. The Registrant has entered into an indemnification agreement with each of its officers and directors that provides the Registrant's officers and directors with indemnification to the maximum extent permitted by the Delaware General Corporation Law. In addition, the Registrant's Certificate of Incorporation provides that, pursuant to Delaware law, its directors shall not be liable for monetary damages for a breach of the directors' fiduciary duty as a director to the Registrant and its stockholders, provided that such liability does not arise from certain proscribed conduct. The Registrant also currently maintains officer and director liability insurance.

Item 7.    Exemption from Registration Claimed.

        Not Applicable.

II-1

Item 8.    Exhibits.

Exhibit Number	Description
4.1	2001 Stock Plan
5.1	Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation, counsel to the Registrant.
23.1	Consent of Deloitte and Touche LLP, Independent Auditors.
23.2	Consent of Arthur Andersen Wirtschaftsprufungsgesellschaft Steurberatungsgesellschaft mbH, Independent Auditors.
23.3	Consent of Wilson Sonsini Goodrich & Rosati, Professional Corporation, counsel to the Registrant (contained in Exhibit 5.1).
24.1	Power of Attorney (see page II-3).

Item 9.    Undertakings.

        A. The undersigned 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 to include any material information with respect to the plan of distribution not previously disclosed in this Registration Statement or any material change to such information in this Registration Statement.

        (2)  That, for the purpose of determining any liability under the Securities Act, 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 undersigned Registrant hereby undertakes that, for purposes of determining any liability under the Securities Act, each filing of the Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and, where applicable, each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference in this 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 may be permitted to 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 its 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 and will be governed by the final adjudication of such issue.

II-2

SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 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 April 8, 2002.

COHERENT, INC.
By:	/s/ Robert J. Quillinan Robert J. Quillinan, Executive Vice President and Chief Financial Officer

POWER OF ATTORNEY

        KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Robert J. Quillinan and Scott H. Miller, and each of them acting individually, as his or her true and lawful attorneys-in-fact and agents, each with full power of substitution, to sign and execute on behalf of the undersigned any and all amendments (including post-effective amendments) to this Registration Statement, any registration statement for the same offering covered by this Registration Statement that is to be effective upon filing pursuant to Rule 462(b) promulgated under the Securities Act of 1933, as amended, and all post-effective amendments thereto, and to file the same, with all exhibits thereto and all documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, 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 and about the foregoing, as fully to all intents and purposes as the undersigned might or could do in person, and each of the undersigned does hereby ratify and confirm all that such attorneys-in-fact and agents or any of them, or any substitutes, may lawfully do or cause to be done by virtue hereof.

        Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the date indicated.

Signature	Title	Date
/s/ Bernard J. Couillaud Bernard J. Couillaud	Director, President and Chief Executive Officer (Principal Executive Officer)	April 8, 2002
/s/ Robert J. Qullinan Robert J. Quillinan	Director, Executive Vice President and Chief Financial Officer (Principal Financial and Accounting Officer)	April 8, 2002
/s/ Henry E. Gauthier Henry E. Gauthier	Chairman of the Board of Directors	April 8, 2002

II-3

/s/ Frank P. Carrubba Frank P. Carrubba	Director	April 8, 2002
/s/ Charles W. Cantoni Charles W. Cantoni	Director	April 8, 2002
/s/ Jerry E. Robertson Jerry E. Robertson	Director	April 8, 2002
/s/ John H. Hart John H. Hart	Director	April 8, 2002

II-4

INDEX TO EXHIBITS

Exhibit Number	Description
4.1	2001 Stock Plan
5.1	Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation, counsel to the Registrant.
23.1	Consent of Deloitte & Touche LLP, Independent Auditors.
23.2	Consent of Arthur Andersen Wirtschaftsprufungsgesellschaft Steurberatungsgesellschaft mbH, Independent Auditors.
23.3	Consent of Wilson Sonsini Goodrich & Rosati, Professional Corporation, counsel to the Registrant (contained in Exhibit 5.1).
24.1	Power of Attorney (see page II-3).

QuickLinks

PART II INFORMATION REQUIRED IN REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference .
Item 4. Description of Securities .
Item 5. Interests of Named Experts and Counsel .
Item 6. Indemnification of Directors and Officers .
Item 7. Exemption from Registration Claimed .
Item 8. Exhibits .
Item 9. Undertakings .

SIGNATURES
POWER OF ATTORNEY
INDEX TO EXHIBITS

EX-4.1

QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 4.1

COHERENT, INC.

2001 STOCK PLAN

        1.    Purposes of the Plan.    The purposes of this 2001 Stock Plan are:

•

to attract and retain the best available personnel for positions of substantial responsibility,



•

to provide additional incentive to Employees, Directors and Consultants, and



•

to promote the success of the Company's business by motivating the Employees and Consultants to superior performance.

        Options granted under the Plan may be Incentive Stock Options or Nonstatutory Stock Options, as determined by the Administrator at the time of grant.

        2.    Definitions.    As used herein, the following definitions shall apply:

        (a)  "Administrator" means the Board or any of its Committees as shall be administering the Plan, in accordance with Section 4 of the Plan.

        (b)  "Applicable Laws" means the requirements relating to the administration of stock option plans under U. S. state corporate laws, U.S. federal and state securities laws, the Code, any stock exchange or quotation system on which the Common Stock is listed or quoted and the applicable laws of any foreign country or jurisdiction where Options are, or will be, granted under the Plan.

        (c)  "Board" means the Board of Directors of the Company.

        (d)  "Code" means the Internal Revenue Code of 1986, as amended.

        (e)  "Committee" means a committee of Directors appointed by the Board in accordance with Section 4 of the Plan, which shall consist solely of Independent Directors who are not eligible to receive stock option grants under the Plan.

        (f)    "Common Stock" means the common stock of the Company.

        (g)  "Company" means Coherent, Inc., a Delaware corporation.

        (h)  "Consultant" means any natural person, including an advisor, engaged by the Company or a Parent or Subsidiary to render services to such entity.

        (i)    "Director" means a member of the Board.

        (j)    "Disability" means total and permanent disability as defined in Section 22(e)(3) of the Code.

        (k)  "Employee" means any person, including Officers and Directors, employed by the Company or any Parent or Subsidiary of the Company. A Service Provider shall not cease to be treated as an Employee in the case of (i) any leave of absence approved by the Company or (ii) transfers between locations of the Company or between the Company, its Parent, any Subsidiary, or any successor. For purposes of Incentive Stock Options, no such leave may exceed ninety days, unless reemployment upon expiration of such leave is guaranteed by statute or contract. If reemployment upon expiration of a leave of absence approved by the Company is not so guaranteed, on the 181st day of such leave any Incentive Stock Option held by the Optionee shall cease to be treated as an Incentive Stock Option and shall be treated for tax purposes as a

Nonstatutory Stock Option. Neither service as a Director nor payment of a director's fee by the Company shall be sufficient to constitute "employment" by the Company.

        (l)    "Exchange Act" means the Securities Exchange Act of 1934, as amended.

        (m)  "Fair Market Value" means, as of any date, the value of Common Stock determined as follows:

          (i)  If the Common Stock is listed on any established stock exchange or a national market system, including without limitation the Nasdaq National Market or The Nasdaq SmallCap Market of The Nasdaq Stock Market, its Fair Market Value shall be the closing sales price for such stock (or the closing bid, if no sales were reported) as quoted on such exchange or system for the last market trading day prior to the time of determination, as reported in The Wall Street Journal or such other source as the Administrator deems reliable;

        (ii)  If the Common Stock is regularly quoted by a recognized securities dealer but selling prices are not reported, the Fair Market Value of a Share of Common Stock shall be the mean between the high bid and low asked prices for the Common Stock on the last market trading day prior to the day of determination, as reported in The Wall Street Journal or such other source as the Administrator deems reliable; or

        (iii)  In the absence of an established market for the Common Stock, the Fair Market Value shall be determined in good faith by the Administrator.

        (n)  "Incentive Stock Option" means an Option intended to qualify as an incentive stock option within the meaning of Section 422 of the Code and the regulations promulgated thereunder.

        (o)  "Independent Director" means a Director of the Company who is not also an Employee of the Company and who qualifies as an "outside director" within the meaning of Code Section 162(m) and Section 16(b) of the Exchange Act.

        (p)  "Nonstatutory Stock Option" means an Option not intended to qualify as an Incentive Stock Option.

        (q)  "Notice of Grant" means a written or electronic notice evidencing certain terms and conditions of an individual Option grant. The Notice of Grant is part of the Option Agreement.

        (r)  "Officer" means a person who is an officer of the Company within the meaning of Section 16 of the Exchange Act and the rules and regulations promulgated thereunder.

        (s)  "Option" means a stock option granted pursuant to the Plan.

        (t)    "Option Agreement" means an agreement between the Company and an Optionee evidencing the terms and conditions of an individual Option grant. The Option Agreement is subject to the terms and conditions of the Plan.

        (u)  "Optioned Stock" means the Common Stock subject to an Option.

        (v)  "Optionee" means the holder of an outstanding Option granted under the Plan.

        (w)  "Parent" means a "parent corporation," whether now or hereafter existing, as defined in Section 424(e) of the Code.

2

        (x)  "Plan" means this Coherent, Inc. 2001 Stock Plan.

        (y)  "Rule 16b-3" means Rule 16b-3 of the Exchange Act or any successor to Rule 16b-3, as in effect when discretion is being exercised with respect to the Plan.

        (z)  "Section 16(b)" means Section 16(b) of the Exchange Act.

        (aa) "Service Provider" means an Employee or Consultant.

        (bb) "Share" means a share of the Common Stock, as adjusted in accordance with Section 12 of the Plan.

        (cc) "Subsidiary" means a "subsidiary corporation", whether now or hereafter existing, as defined in Section 424(f) of the Code.

        3.    Stock Subject to the Plan.    Subject to the provisions of Section 12 of the Plan, the maximum aggregate number of Shares that may be optioned and sold under the Plan is 2,800,000 Shares. The Shares may be authorized, but unissued, or reacquired Common Stock.

        If an Option expires or becomes unexercisable without having been exercised in full, or is surrendered pursuant to an Option Exchange Program, the unpurchased Shares which were subject thereto shall become available for future grant or sale under the Plan (unless the Plan has terminated); provided, however, that Shares that have actually been issued under the Plan upon exercise of an Option shall not be returned to the Plan and shall not become available for future distribution under the Plan.

        4.    Administration of the Plan.

        (a)  Procedure.

          (i)  Section 162(m). To the extent that the Administrator determines it to be desirable to qualify Options granted hereunder as "performance-based compensation" within the meaning of Section 162(m) of the Code, the Plan shall be administered by a Committee of two or more Independent Directors.

        (ii)  Rule 16b-3. To the extent desirable to qualify transactions hereunder as exempt under Rule 16b-3, the transactions contemplated hereunder shall be structured to satisfy the requirements for exemption under Rule 16b-3.

        (iii)  Other Administration. Other than as provided above, the Plan shall be administered by (A) the Board or (B) a Committee of Independent Directors with the ability to obtain the advice of independent counsel, which committee shall be constituted to satisfy Applicable Laws.

        (b)  Powers of the Administrator. Subject to the provisions of the Plan, including, without limitation Section 9(a)(iii), and in the case of a Committee, subject to the specific duties delegated by the Board to such Committee, the Administrator shall have the authority, in its discretion:

          (i)  to determine the Fair Market Value;

        (ii)  to select the Service Providers to whom Options may be granted hereunder;

        (iii)  to determine the number of shares of Common Stock to be covered by each Option granted hereunder;

3

        (iv)  to approve forms of agreement for use under the Plan;

        (v)  to determine the terms and conditions, not inconsistent with the terms of the Plan, of any Option granted hereunder. Such terms and conditions include, but are not limited to, the exercise price, the time or times when Options may be exercised (which may be based on performance criteria), any vesting acceleration or waiver of forfeiture restrictions, and any restriction or limitation regarding any Option or the shares of Common Stock relating thereto, based in each case on such factors as the Administrator, in its sole discretion, shall determine;

        (vi)  to construe and interpret the terms of the Plan and awards granted pursuant to the Plan;

      (vii)  to prescribe, amend and rescind rules and regulations relating to the Plan, including rules and regulations relating to sub-plans established for the purpose of qualifying for preferred tax treatment under foreign tax laws;

      (viii)  to modify or amend each Option (subject to Section 14(c) of the Plan), including the discretionary authority to extend the post-termination exercisability period of Options longer than is otherwise provided for in the Plan;

        (ix)  to allow Optionees to satisfy withholding tax obligations by electing to have the Company withhold from the Shares to be issued upon exercise of an Option that number of Shares having a Fair Market Value equal to the amount required to be withheld. The Fair Market Value of the Shares to be withheld shall be determined on the date that the amount of tax to be withheld is to be determined. All elections by an Optionee to have Shares withheld for this purpose shall be made in such form and under such conditions as the Administrator may deem necessary or advisable;

        (x)  to authorize any person to execute on behalf of the Company any instrument required to effect the grant of an Option previously granted by the Administrator;

        (xi)  to make all other determinations deemed necessary or advisable for administering the Plan.

        (c)  Effect of Administrator's Decision. The Administrator's decisions, determinations and interpretations shall be final and binding on all Optionees and any other holders of Options.

        5.    Eligibility.    Nonstatutory Stock Options may be granted to Service Providers. Incentive Stock Options may be granted only to Employees.

        6.    Limitations.

        (a)  Each Option shall be designated in the Option Agreement as either an Incentive Stock Option or a Nonstatutory Stock Option. However, notwithstanding such designation, to the extent that the aggregate Fair Market Value of the Shares with respect to which Incentive Stock Options are exercisable for the first time by the Optionee during any calendar year (under all plans of the Company and any Parent or Subsidiary) exceeds $100,000, such Options shall be treated as Nonstatutory Stock Options. For purposes of this Section 6(a), Incentive Stock Options shall be taken into account in the order in which they were granted. The Fair Market Value of the Shares shall be determined as of the time the Option with respect to such Shares is granted.

4

        (b)  Neither the Plan nor any Option shall confer upon an Optionee any right with respect to continuing the Optionee's relationship as a Service Provider with the Company, nor shall they interfere in any way with the Optionee's right or the Company's right to terminate such relationship at any time, with or without cause.

        (c)  The following limitations shall apply to grants of Options:

          (i)  No Service Provider shall be granted, in any fiscal year of the Company, Options to purchase more than 250,000 Shares.

        (ii)  In connection with his or her initial service, a Service Provider may be granted Options to purchase up to an additional 250,000 Shares, which shall not count against the limit set forth in subsection (i) above.

        (iii)  The foregoing limitations shall be adjusted proportionately in connection with any change in the Company's capitalization as described in Section 12.

        7.    Term of Plan.    Subject to Section 18 of the Plan, the Plan shall become effective upon its adoption by the Board. It shall continue in effect for a term of ten (10) years unless terminated earlier under Section 14 of the Plan.

        8.    Term of Option.    The term of each Option shall be stated in the Option Agreement. In the case of an Incentive Stock Option, the term shall be ten (10) years from the date of grant or such shorter term as may be provided in the Option Agreement. Moreover, in the case of an Incentive Stock Option granted to an Optionee who, at the time the Incentive Stock Option is granted, owns stock representing more than ten percent (10%) of the total combined voting power of all classes of stock of the Company or any Parent or Subsidiary, the term of the Incentive Stock Option shall be five (5) years from the date of grant or such shorter term as may be provided in the Option Agreement.

        9.    Option Exercise Price and Consideration.

        (a)  Exercise Price. The per share exercise price for the Shares to be issued pursuant to exercise of an Option shall be determined by the Administrator, subject to the following:

          (i)  In the case of an Incentive Stock Option:

        (A)  granted to an Employee who, at the time the Incentive Stock Option is granted, owns stock representing more than ten percent (10%) of the voting power of all classes of stock of the Company or any Parent or Subsidiary, the per Share exercise price shall be no less than 110% of the Fair Market Value per Share on the date of grant.

        (B)  granted to any Employee other than an Employee described in paragraph (A) immediately above, the per Share exercise price shall be no less than 100% of the Fair Market Value per Share on the date of grant.

        (ii)  In the case of a Nonstatutory Stock Option, the per Share exercise price shall be no less than 100% of the Fair Market Value per Share on the date of grant.

        (iii)  The exercise price for the Shares to be issued pursuant to an already granted Option may not be changed without the consent of the Company's shareholders. This shall include, without limitation, a repricing of the Option as well as an option exchange program whereby the Optionee agrees to cancel an existing

5

Option in exchange for an Option to be granted in the future with an exercise price equal to the Fair Market Value of the Shares on the date of grant.

        (b)  Waiting Period and Exercise Dates. At the time an Option is granted, the Administrator shall fix the period within which the Option may be exercised and shall determine any conditions that must be satisfied before the Option may be exercised.

        (c)  Form of Consideration. The Administrator shall determine the acceptable form of consideration for exercising an Option, including the method of payment. In the case of an Incentive Stock Option, the Administrator shall determine the acceptable form of consideration at the time of grant. Such consideration may consist entirely of:

          (i)  cash;

        (ii)  check;

        (iii)  other Shares which (A) in the case of Shares acquired upon exercise of an option, have been owned by the Optionee for more than six months on the date of surrender, and (B) have a Fair Market Value on the date of surrender equal to the aggregate exercise price of the Shares as to which said Option shall be exercised;

        (iv)  any combination of the foregoing methods of payment; or such other consideration and method of payment for the issuance of Shares to the extent permitted by Applicable Laws; or

        (v)  such other consideration and method of payment for the issuance of Shares to the extent permitted by Applicable Laws.

        10.    Exercise of Option.

        (a)  Procedure for Exercise; Rights as a Shareholder. Any Option granted hereunder shall be exercisable according to the terms of the Plan and at such times and under such conditions as determined by the Administrator and set forth in the Option Agreement. Unless the Administrator provides otherwise, vesting of Options granted hereunder shall be tolled during any unpaid leave of absence. An Option may not be exercised for a fraction of a Share.

        An Option shall be deemed exercised when the Company receives: (i) written or electronic notice of exercise (in accordance with the Option Agreement) from the person entitled to exercise the Option, and (ii) full payment for the Shares with respect to which the Option is exercised. Full payment may consist of any consideration and method of payment authorized by the Administrator and permitted by the Option Agreement and the Plan. Shares issued upon exercise of an Option shall be issued in the name of the Optionee or, if requested by the Optionee, in the name of the Optionee and his or her spouse. Until the Shares are issued (as evidenced by the appropriate entry on the books of the Company or of a duly authorized transfer agent of the Company), no right to vote or receive dividends or any other rights as a shareholder shall exist with respect to the Optioned Stock, notwithstanding the exercise of the Option. The Company shall issue (or cause to be issued) such Shares promptly after the Option is exercised. No adjustment will be made for a dividend or other right for which the record date is prior to the date the Shares are issued, except as provided in Section 12 of the Plan.

6

        Exercising an Option in any manner shall decrease the number of Shares thereafter available, both for purposes of the Plan and for sale under the Option, by the number of Shares as to which the Option is exercised.

        (b)  Termination of Relationship as Service Provider. If an Optionee ceases to be a Service Provider, other than upon the Optionee's death or Disability, the Optionee may exercise his or her Option within such period of time as is specified in the Option Agreement to the extent that the Option is vested on the date of termination (but in no event later than the expiration of the term of such Option as set forth in the Option Agreement). In the absence of a specified time in the Option Agreement, the Option shall remain exercisable for ninety (90) days following the Optionee's termination. If, on the date of termination, the Optionee is not vested as to his or her entire Option, the Shares covered by the unvested portion of the Option shall revert to the Plan. If, after termination, the Optionee does not exercise his or her Option within the time specified by the Administrator, the Option shall terminate, and the Shares covered by such Option shall revert to the Plan.

        (c)  Disability of Optionee. If an Optionee ceases to be a Service Provider as a result of the Optionee's Disability, the Optionee may exercise his or her Option within such period of time as is specified in the Option Agreement to the extent the Option is vested on the date of termination (but in no event later than the expiration of the term of such Option as set forth in the Option Agreement). In the absence of a specified time in the Option Agreement, the Option shall remain exercisable for twelve (12) months following the Optionee's termination. If, on the date of termination, the Optionee is not vested as to his or her entire Option, the Shares covered by the unvested portion of the Option shall revert to the Plan. If, after termination, the Optionee does not exercise his or her Option within the time specified herein, the Option shall terminate, and the Shares covered by such Option shall revert to the Plan.

        (d)  Death of Optionee. If an Optionee dies while a Service Provider, the Option may be exercised within such period of time as is specified in the Option Agreement (but in no event later than the expiration of the term of such Option as set forth in the Notice of Grant), by the Optionee's estate or by a person who acquires the right to exercise the Option by bequest or inheritance, but only to the extent that the Option is vested on the date of death. In the absence of a specified time in the Option Agreement, the Option shall remain exercisable for twelve (12) months following the Optionee's termination. If, at the time of death, the Optionee is not vested as to his or her entire Option, the Shares covered by the unvested portion of the Option shall immediately revert to the Plan. The Option may be exercised by the executor or administrator of the Optionee's estate or, if none, by the person(s) entitled to exercise the Option under the Optionee's will or the laws of descent or distribution. If the Option is not so exercised within the time specified herein, the Option shall terminate, and the Shares covered by such Option shall revert to the Plan.

        (e)  Buyout Provisions. The Administrator may at any time offer to buy out for a payment in cash or Shares an Option previously granted based on such terms and conditions as the Administrator shall establish and communicate to the Optionee at the time that such offer is made.

        11.    Non-Transferability of Options.    Unless determined otherwise by the Administrator, an Option may not be sold, pledged, assigned, hypothecated, transferred, or disposed of in any manner other than

7

by will or by the laws of descent or distribution and may be exercised, during the lifetime of the Optionee, only by the Optionee. If the Administrator makes an Option transferable, such Option shall contain such additional terms and conditions as the Administrator deems appropriate.

        12.    Adjustments Upon Changes in Capitalization, Dissolution, Merger or Asset Sale.

        (a)  Changes in Capitalization. Subject to any required action by the shareholders of the Company, the number of shares of Common Stock covered by each outstanding Option and the number of shares of Common Stock which have been authorized for issuance under the Plan but as to which no Options have yet been granted or which have been returned to the Plan upon cancellation or expiration of an Option, as well as the price per share of Common Stock covered by each such outstanding Option, shall be proportionately adjusted for any increase or decrease in the number of issued shares of Common Stock resulting from a stock split, reverse stock split, stock dividend, combination or reclassification of the Common Stock, or any other increase or decrease in the number of issued shares of Common Stock effected without receipt of consideration by the Company; provided, however, that conversion of any convertible securities of the Company shall not be deemed to have been "effected without receipt of consideration." Such adjustment shall be made by the Board, whose determination in that respect shall be final, binding and conclusive. Except as expressly provided herein, no issuance by the Company of shares of stock of any class, or securities convertible into shares of stock of any class, shall affect, and no adjustment by reason thereof shall be made with respect to, the number or price of shares of Common Stock subject to an Option.

        (b)  Dissolution or Liquidation. In the event of the proposed dissolution or liquidation of the Company, the Administrator shall notify each Optionee as soon as practicable prior to the effective date of such proposed transaction. The Administrator in its discretion may provide for an Optionee to have the right to exercise his or her Option until ten (10) days prior to such transaction as to all of the Optioned Stock covered thereby, including Shares as to which the Option would not otherwise be exercisable. In addition, the Administrator may provide that any Company repurchase option applicable to any Shares purchased upon exercise of an Option shall lapse as to all such Shares, provided the proposed dissolution or liquidation takes place at the time and in the manner contemplated. To the extent it has not been previously exercised, an Option will terminate immediately prior to the consummation of such proposed action.

        (c)  Merger or Asset Sale. In the event of a merger of the Company with or into another corporation, or the sale of substantially all of the assets of the Company, each outstanding Option shall be assumed or an equivalent option substituted by the successor corporation or a Parent or Subsidiary of the successor corporation. In the event that the successor corporation refuses to assume or substitute for the Option, the Optionee shall fully vest in and have the right to exercise the Option as to all of the Optioned Stock, including Shares as to which it would not otherwise be vested or exercisable. If an Option becomes fully vested and exercisable in lieu of assumption or substitution in the event of a merger or sale of assets, the Administrator shall notify the Optionee in writing or electronically that the Option shall be fully vested and exercisable for a period of fifteen (15) days from the date of such notice, and the Option shall terminate upon the expiration of such period. For the purposes of this paragraph, the Option shall be considered assumed if, following the merger or sale of assets, the option confers the right to purchase or receive, for each Share of Optioned Stock subject to the Option immediately prior to the merger or sale of assets, the consideration (whether stock, cash, or other securities or property) received in the merger or

8

sale of assets by holders of Common Stock for each Share held on the effective date of the transaction (and if holders were offered a choice of consideration, the type of consideration chosen by the holders of a majority of the outstanding Shares); provided, however, that if such consideration received in the merger or sale of assets is not solely common stock of the successor corporation or its Parent, the Administrator may, with the consent of the successor corporation, provide for the consideration to be received upon the exercise of the Option, for each Share of Optioned Stock subject to the Option, to be solely common stock of the successor corporation or its Parent equal in fair market value to the per share consideration received by holders of Common Stock in the merger or sale of assets.

        13.    Date of Grant.    The date of grant of an Option shall be, for all purposes, the date on which the Administrator makes the determination granting such Option, or such other later date as is determined by the Administrator. Notice of the determination shall be provided to each Optionee within a reasonable time after the date of such grant.

        14.    Amendment and Termination of the Plan.

        (a)  Amendment and Termination. The Board may at any time amend, alter, suspend or terminate the Plan.

        (b)  Shareholder Approval. The Company shall obtain shareholder approval of any Plan amendment to the extent necessary and desirable to comply with Applicable Laws.

        (c)  Effect of Amendment or Termination. No amendment, alteration, suspension or termination of the Plan shall impair the rights of any Optionee, unless mutually agreed otherwise between the Optionee and the Administrator, which agreement must be in writing and signed by the Optionee and the Company. Termination of the Plan shall not affect the Administrator's ability to exercise the powers granted to it hereunder with respect to Options granted under the Plan prior to the date of such termination.

        15.    Conditions Upon Issuance of Shares.

        (a)  Legal Compliance. Shares shall not be issued pursuant to the exercise of an Option unless the exercise of such Option and the issuance and delivery of such Shares shall comply with Applicable Laws and shall be further subject to the approval of counsel for the Company with respect to such compliance.

        (b)  Investment Representations. As a condition to the exercise of an Option, the Company may require the person exercising such Option to represent and warrant at the time of any such exercise that the Shares are being purchased only for investment and without any present intention to sell or distribute such Shares if, in the opinion of counsel for the Company, such a representation is required.

        16.    Inability to Obtain Authority.    The inability of the Company to obtain authority from any regulatory body having jurisdiction, which authority is deemed by the Company's counsel to be necessary to the lawful issuance and sale of any Shares hereunder, shall relieve the Company of any liability in respect of the failure to issue or sell such Shares as to which such requisite authority shall not have been obtained.

        17.    Reservation of Shares.    The Company, during the term of this Plan, will at all times reserve and keep available such number of Shares as shall be sufficient to satisfy the requirements of the Plan.

        18.    Shareholder Approval.    The Plan shall be subject to approval by the shareholders of the Company within twelve (12) months after the date the Plan is adopted. Such shareholder approval shall be obtained in the manner and to the degree required under Applicable Laws.

9

QuickLinks

EXHIBIT 4.1

COHERENT, INC. 2001 STOCK PLAN

EX-5.1

QuickLinks -- Click here to rapidly navigate through this document

EXHIBIT 5.1

April 8, 2002

Coherent, Inc.
5100 Patrick Henry Drive
Santa Clara, CA 95056

Re:

Registration Statement on Form S-8

Ladies and Gentlemen:

        We have examined the Registration Statement on Form S-8 to be filed by you with the Securities and Exchange Commission on or about April 8, 2002 (the "Registration Statement") in connection with the registration under the Securities Act of 1933, as amended (the "Act"), of 2,800,000 shares of your common stock (the "Shares") reserved for issuance under the 2001 Stock Plan (the "Plan"). As your legal counsel in connection with this transaction, we have examined the proceedings taken and are familiar with the proceedings proposed to be taken by you in connection with the issuance and sale of the Shares pursuant to the Plan.

        It is our opinion that the Shares, when issued and sold in the manner referred to in the Plan and the agreements which accompany the Plan, will be legally and validly issued, fully paid and nonassessable.

        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 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-8 of our report dated October 29, 2001, appearing in the Annual Report on Form 10-K of Coherent, Inc. for the year ended September 29, 2001.

/s/ Deloitte & Touche LLP

San Jose, California
April 8, 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 8. Exhibits" to our firm in the Registration Statement (Form S-8) of Coherent, Inc. in connection with the registration of 2,800,000 shares of its common stock reserved for issuance under the 2001 stock plan 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.

/s/ Arthur Andersen Wirtschaftsprufungsgesellschaft Steurberatungsgesellschaft mbH

Hanover, Germany
April 8, 2002

QuickLinks

EXHIBIT 23.2

CONSENT OF INDEPENDENT AUDITORS