UNITED STATES
                     SECURITIES AND EXCHANGE COMMISSION
                          Washington, D.C. 20549

                               SCHEDULE 13G

                 Under the Securities Exchange Act of 1934
                          (Amendment No.   10  )*
                                         ------

                               Coherent, Inc.
                     ----------------------------------
                              (Name of Issuer)

                                  Common
                     ----------------------------------
                       (Title of Class of Securities)

                                 192479103
                     ----------------------------------
                              (CUSIP Number)


   Check the following box if a fee is being paid with this statement /  /.  (A
fee is not required  only if the filing  person:  (1) has a  previous statement
on file reporting  beneficial ownership of  more than five percent of the class
of securities  described in Item 1;  and (2) has filed no  amendment subsequent
thereto reporting  beneficial ownership of five percent or less of such class.)
(See Rule 13d-7).

   *The remainder of  this cover  page  shall  be  filled  out  for a reporting
person's  initial  filing on this  form with  respect to the  subject  class of
securities,  and for any  subsequent  amendment  containing  information  which
would alter the disclosures provided in a prior cover page.

   The information  required in the  remainder of this  cover page shall not be
deemed to be "filed"  for the purpose of  Section 18 of the Securities Exchange
Act of 1934  ("Act") or otherwise subject to the liabilities of that section of
the Act but shall be subject to all other  provisions of the Act  (however, see
the Notes).


                        (Continued on following page(s))


                              Page 1 of  4  Pages
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CUSIP No. 192479103                   13G                 Page  2  of  4  Pages
          ---------                                            ---    ---

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 (1) Names of Reporting Persons.  S.S. or I.R.S. Identification Nos. of Above
     Persons

     PRIMECAP Management Company         95-3868081
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 (2) Check the Appropriate Box if a Member     (a)  / /
     of a Group*                               (b)  / /
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 (3) SEC Use Only

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 (4) Citizenship or Place of Organization

     225 So. Lake Avenue #400, Pasadena, CA 91101
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Number of Shares              (5) Sole Voting
 Beneficially                       Power                 -0-
 Owned by                    --------------------------------------------------
 Each Reporting               (6) Shared Voting
 Person With                        Power                 -0-
                             --------------------------------------------------
                              (7) Sole Dispositive
                                    Power                 2,420,000
                             --------------------------------------------------
                              (8) Shared Dispositive
                                    Power                 -0-
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 (9) Aggregate Amount Beneficially Owned by Each Reporting Person

     2,420,000
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(10) Check Box if the Aggregate Amount in Row (9) Excludes Certain Shares*


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(11) Percent of Class Represented by Amount in Row (9)

     9.94%
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(12) Type of Reporting Person*

     IA
-------------------------------------------------------------------------------
                    *SEE INSTRUCTION BEFORE FILLING OUT!



                                                          Page  3  of  4  Pages
                                                               ---    ---


ITEM 1(A).  NAME OF ISSUER

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ITEM 1(B).  ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES

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ITEM 2(A).  NAME OF PERSON(S) FILING

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ITEM 2(B).  ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE

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ITEM 2(C).  CITIZENSHIP

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ITEM 2(D).  TITLE OF CLASS OF SECURITIES

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ITEM 2(E).  CUSIP NUMBER

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ITEM 3.  IF THIS STATEMENT IS FILED PURSUANT TO RULES 13D-1(B), OR 13D-2(B),
  CHECK WHETHER THE PERSON FILING IS A

    (a) / / Broker or Dealer registered under Section 15 of the Act

    (b) / / Bank as defined in section 3(a)(6) of the Act

    (c) / / Insurance Company as defined in section 3(a)(19) of the Act

    (d) / / Investment Company registered under section 8 of the Investment
            Company Act

    (e) / / Investment Adviser registered under section 203 of the Investment
            Advisers Act of 1940

    (f) / / Employee Benefit Plan, Pension Fund which is subject to the
            provisions of the Employee Retirement Income Security Act of 1974
            or Endowment Fund; see Rule 13d-1(b)(1)(ii)(F)

    (g) / / Parent Holding Company, in accordance with Rule 13d-1(b)(ii)(G)
            (Note: See Item 7)

    (h) / / Group, in accordance with Rule 13d-1(b)(1)(ii)(H)


                                                            Page 4 of 4 pages
                                                                ---  ---

ITEM 4.  OWNERSHIP

    (a) Amount Beneficially Owned:

    ---------------------------------------------------------------------------

    (b) Percent of Class:

    ---------------------------------------------------------------------------


    (c)  Number of shares as to which such person has:

         (i)  sole power to vote or to direct the vote
        (ii)  shared power to vote or to direct the vote
       (iii)  sole power to dispose or to direct the disposition of
        (iv)  shared power to dispose or to direct the disposition of

INSTRUCTION: For computations regarding securities which represent a right to
acquire an underlying security see Rule 13d-3(d)(1).

ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS
     If this statement is being filed to report the fact that as of the date
hereof the reporting person has ceased to be the beneficial owner of more than
five percent of the class of securities, check the following / /.

INSTRUCTION: Dissolution of a group requires a response to this item.

ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.
     If any other person is known to have the right to receive or the power to
direct the receipt of dividends from, or the proceeds from the sale of, such
securities, a statement to that effect should be included in response to this
item and, if such interest relates to more than five percent of the class, such
person should be identified.  A listing of the shareholders of an investment
company registered under the Investment Company Act of 1940 or the beneficiaries
of employee benefit plan, pension fund or endowment fund is not required.

ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE
        SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY
     If a parent holding company has filed this schedule, pursuant to Rule
13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the
identity and the Item 3 classification of the relevant subsidiary.  If a parent
holding company has filed this schedule pursuant to Rule 13d-1(c), attach an
exhibit stating the identification of the relevant subsidiary.

ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP
     If a group has filed this schedule pursuant to Rule 13d-1(b)(ii)(H), so
indicate under Item 3(h) and attach an exhibit stating the identity and Item 3
classification of each member of the group.  If a group has filed this schedule
pursuant to Rule 13d-1(c), attach an exhibit stating the identity of each member
of the group.

ITEM 9. NOTICE OF DISSOLUTION OF GROUP
     Notice of dissolution of a group may be furnished as an exhibit stating the
date of the dissolution and that all further filings with respect to
transactions in the security reported on will be filed, if required, by members
of the group, in their individual capacity.  See Item 5.

ITEM 10. CERTIFICATION
     The following certification shall be included if the statement is filed
pursuant to Rule 13d-1(b):
     By signing below I certify that, to the best of my knowledge and belief,
the securities referred to above were acquired in the ordinary course of
business and were not acquired for the purpose of and do not have the effect of
changing or influencing the control of the issuer of such securities and were
not acquired in connection with or as a participant in any transaction having
such purposes or effect.

                                      SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.
                                                          1/31/2001
                                                --------------------------------
                                                             Date

                                                    /s/ Theo A. Kolokotrones
                                                --------------------------------
                                                           Signature

                                                 Theo A. Kolokotrones, President
                                                --------------------------------
                                                          Name/Title