EXHIBIT 2.2


                            AMENDMENT NO. 1 TO THE
                AGREEMENT AND PLAN OF MERGER AND REORGANIZATION
                              DATED MAY 16, 2001

     This Amendment No. 1 (the "Amendment") is made as of June 1, 2001 by and
among Credence Systems Corporation, a Delaware Corporation ("Parent"), Iguana
Acquisition Corporation, an Oregon corporation ("Merger Sub") and wholly owned
subsidiary of Parent, and Integrated Measurement Systems, Inc., an Oregon
corporation ("Company"). This Amendment amends the Agreement and Plan of Merger
and Reorganization dated May 16, 2001, among Parent, Merger Sub and the Company
(the "Merger Agreement"). Capitalized terms used but not defined in this
Amendment shall have the meanings given to them in the Merger Agreement.

     WHEREAS, Parent, Merger Sub and the Company have entered into the Merger
Agreement and Parent, Merger Sub and the Company mutually desire to amend the
Merger Agreement in accordance with Section 7.4 thereof;

     NOW THEREFORE, in consideration of the premises and the covenants and
agreements contained herein, the parties hereto agree as follows:

     1.   Section 1.6(c) is deleted in its entirety and the following is
substituted in lieu thereof:

          "(c) Company Stock Option Plans and Company ESPP. At the Effective
               -------------------------------------------
     Time, Company's 1995 Stock Incentive Plan, 1995 Stock Option Plan for Non-
     Employee Directors and 2000 Nonqualified Stock Option Plan (collectively
     the "Company Stock Option Plans"), the Company ESPP (as defined below) and
          --------------------------
     all options to purchase Company Common Stock then outstanding under the
     Company Stock Option Plans and all obligations of Company under the Company
     ESPP shall be assumed by Parent in accordance with Section 5.9."

     2.   The 11th and 12th sentences of Section 2.2 which state "The current
"Offering Period" (as defined in the Company ESPP) commenced under the Company
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ESPP on February 1, 2000 and will end on the date provided for in Section
5.9(c), and except for the purchase rights granted on such commencement date to
participants in the current Offering Period, there are no other purchase rights
or options outstanding under the Company ESPP.  The terms of the Company ESPP
permit the Company to shorten and terminate Offering Periods without the consent
or approval of participants in the ESPP, shareholders, or otherwise." are
deleted in their entirety and the following is substituted in lieu thereof:

          "The current "Offering Period" (as defined in the Company ESPP)
                        ---------------
     commenced under the Company ESPP on February 1, 2000 and will end on
     January 31, 2002, and except for the purchase rights granted on such
     commencement date to participants in the current Offering Period, there are
     no other purchase rights or options outstanding under the Company ESPP."


     3.   Section 2.14(j) is hereby deleted in its entirety.

     4.   Section 5.9(c) is hereby deleted in its entirety and the following is
substituted in lieu thereof:

          "(c)  Outstanding options under the Company ESPP shall be assumed by
     the Parent and shall be exercised on January 31, 2002, for Parent Common
     Stock.  For purposes of such exercise, the per share Purchase Price for a
     Participant, as such terms are defined in the Company ESPP, is an amount
     equal to 85% of (i) the fair market value of a share of Company Common
     Stock on the Participant's Enrollment Date, divided by the Exchange Ratio
     and rounded up to the nearest whole cent, or (ii) the fair market value of
     a share of Parent Common Stock on January 31, 2002, whichever is lower. The
     number of whole shares purchased by each Participant will be based on the
     total amount of payroll deductions accumulated for each Participant and
     retained in each Participant's account divided by the Participant's
     Purchase Price, as adjusted above. The Company ESPP shall terminate on
     January 31, 2002, immediately following the purchase.  Company employees
     who meet the eligibility requirements for participation in the Parent
     Employee Stock Purchase Plan shall be eligible to begin participation in
     the Parent Employee Stock Purchase Plan as of the first Semi-Annual Entry
     Date, as such term is defined in the Parent Employee Stock Purchase Plan,
     after January 31, 2002."

     5.   Section 5.10 is hereby deleted in its entirety and the following is
substituted in lieu thereof:

          "5.10  Form S-8.  Parent agrees to file, no later than 30 business
                 --------
     days after the Closing (provided, that, Parent has received within 10
                             ---------
     business days after the Closing all option documentation it requires
     relating to the outstanding options), a registration statement on Form S-8
     under the Securities Act covering the shares of Parent Common Stock
     issuable pursuant to outstanding options and outstanding purchase rights
     granted to individuals, for which a Form S-8 registration statement is
     available hereto, under the Company Stock Option Plans and Company ESPP
     assumed by Parent pursuant to this Agreement.  Company shall cooperate and
     assist Parent with the preparation of such registration statement."

     6.   Each of the parties hereto shall execute such documents and take such
further actions as may be reasonably required or desirable to carry out the
provisions hereof and the transactions contemplated hereby.

     7.   Except as amended by this Amendment, all of the terms and conditions
of the Merger Agreement remain in full force and effect in all respects and,
except to the extent the context of the Merger Agreement otherwise requires,
each reference in the Merger Agreement to the Agreement shall be deemed to refer
to the Merger Agreement as amended hereby.

     8.   This Amendment shall be governed by and construed in accordance with
the laws of the State of California, without regard to the laws that might
otherwise govern under

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applicable principles of conflicts of laws (except for matters required to be
governed by, and construed in accordance with, the corporate law of Delaware or
Oregon (as applicable)).

     9.   This Amendment may be signed in original or by fax in counterparts,
each of which will be deemed to be an original, and the counterparts together
will constitute one complete document.

                           [signature page follows.]

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     IN WITNESS WHEREOF, Company, Parent and Merger Sub have caused this
Amendment to be executed and delivered by their respective officers thereunto
duly authorized, all as of the date first written above.


                           CREDENCE SYSTEMS CORPORATION


                           By: /s/ John R. Detwiler
                              --------------------------------
                           Name:  John R. Detwiler
                           Title: Senior V.P. & CFO


                           INTEGRATED MEASUREMENT SYSTEMS, INC.


                           By: /s/ Keith L. Barnes
                              --------------------------------
                           Name:  Keith L. Barnes
                           Title: Chairman & CEO


                           IGUANA ACQUISITION CORPORATION


                           By: /s/ John R. Detwiler
                              --------------------------------
                           Name:  John R. Detwiler
                           Title: CFO


                          SIGNATURE PAGE TO AMENDMENT
               TO AGREEMENT AND PLAN OF MERGER AND REORGANIZATION