<PAGE>

                                                                    Exhibit 10.2
                                 AMENDMENT TO
                           LEAVE OF ABSENCE AGREEMENT



     This Amendment to Leave of Absence Agreement (the "Amendment"), dated
February 13, 2001, is entered into between Therma-Wave, Inc. ("Company") and Dr.
Allan Rosencwaig ("Executive") and the shareholders listed on the signature page
hereto
(the "Stockholders").

    WHEREAS, the Company, Executive and the Stockholders are parties to that
Leave of Absence Agreement dated May 16, 2000, and subsequently amended by the
letter of June 13, 2000 (and approved by the Board of Directors on July 31,
2000) and by the attached Amendment No.1, (the twice- amended Leave of Absence
Agreement is henceforth referred to as the "LOA Agreement"); and

    WHEREAS, the Executive, the Company and the Stockholders desire to amend
certain provisions of the LOA Agreement.

    NOW THEREFORE, the Company, the Executive and the Stockholders hereby agree
as follows:

    1. The Company accepts Executive's resignation for Disability at the end of
       his leave of absence on February 21, 2001, in accordance with the
       provisions of the LOA Agreement.

    2. Executive agrees to continue to serve on the Board of the Company as a
       Director and to provide consulting services to the Company from time to
       time.

    3. All restrictions on transfer or sale of Executive's stock as recited in
       Executive's Executive Stock Agreement, dated May 16, 1997, and in
       particular those restrictions stated in Section 5 of that Agreement, are
       hereby terminated as of February 13, 2001. Restrictions under SEC Rule
       144 remain in effect.

    4. Except for the foregoing, all the terms and conditions of the LOA
       Agreement shall remain in full force and effect and nothing in this
       Amendment shall be deemed to alter, amend or otherwise change any of the
       terms and conditions thereof.

    5. This Amendment may be signed in two or more counterparts, each of which
       shall be deemed to be an original but all of which together should
       constitute one and the same document

    6. This Amendment shall be governed by the laws of the State of California.

                                      -1-
<PAGE>

                         Therma-Wave, Inc.


                         By:  /s/ Martin M. Schwartz
                         Its  CEO


                         /s/ Dr. Allan Rosencwaig
                         Dr. Allan Rosencwaig


                         Bain Capital Fund V, L.P.

                         By:  Bain Capital Partners V, L.P.
                         Its: General Partner

                         By:  Bain Capital Investors V, Inc.
                         Its: General Partner


                         By:  /s/ Ian K. Loring
                         Its: Managing Director



                         Bain Capital Fund V-B, L.P.

                         By:  Bain Capital Partners V, L.P.
                         Its: General Partner

                         By:  Bain Capital Investors V, Inc.
                         Its: General Partner

                         By:  /s/ Ian K. Loring
                         Its: Managing Director

                                      -2-
<PAGE>

                               AMENDMENT NO.1 TO
                          LEAVE OF ABSENCE AGREEMENT


          This Amendment No.1 to Leave of Absence Agreement (the "Amendment"),
dated January __, 2001, is entered into between Therma-Wave, Inc. ("Company")
and Dr. Allan Rosencwaig ("Executive") and the stockholders listed on the
signature page hereto (the "Stockholders").

          WHEREAS, the Company, Executive and the Stockholders are parties to
that Leave of Absence Agreement dated May 16, 2000 (the "Original Agreement");
and

          WHEREAS, the Executive, the Company and the Stockholders desire to
amend certain provisions of the Original Agreement.

           NOW THEREFORE, the Company, the Executive and the Stockholders hereby
agree as follows:

           I     Paragraph 5 of Exhibit A to the Original Agreement hereby is
                 -----------
amended to read as follows:

          "Subject to the applicable restrictions under the Securities Act and
     the Company's insider trading policy, Dr. Rosencwaig will be permitted to
     sell up to 500.000 shares of the Company's common stock during the quarter
     ended March 3 1.2001, up to 250.000 shares during the quarter ended June
     30.2001, and up to 250.000 shares during the quarter ended September 30,
     2001. Any shares that are eligible to be sold by Dr. Rosencwaig during any
     quarter referenced above but are not so sold for any reason shall be
     eligible to be sold at any time thereafter."

          2.  Except for the foregoing, all of the terms and conditions of the
Original Agreement shall remain in full force and effect and nothing in this
Amendment shall be deemed to alter, amend or otherwise change any of the terms
and conditions thereof.

          3.  This Amendment may be signed in two or more counterparts. each of
which shall be deemed to be an original but all of which together should
constitute one and the same document.

          4   This Amendment shall be governed by the laws of the State of
California

                           Therma-Wave, Inc.
                           By:


                           Dr. Allan Rosencwaig

                                      -3-
<PAGE>

                          Bain Capital Fund V, L.P.

                          By:  Bain Capital Partners V, L.P.
                          Its: General Partner

                          By:  Baln Capital Investors V, Inc.
                          Its: General Partner


                          Bain Capital Fund V-B. L.P.

                          By:  Ham Capital Partners V, L.P.
                          Its: General Partner

                          By:  Bain Capital Investors y, Inc.
                          Its: General Partner

                                      -4-
<PAGE>

              RESOLUTIONS TO BE ADOPTED BY THE BOARD OF DIRECTORS
                             BY THERMA-WAVE, INC.


          RESOLVED, that at the request of Dr. Allan Rosencwaig and in
recognition of the outstanding contributions made to the Company by Dr.
Rosencwaig, the Board of Directors hereby approves a leave of absence from the
Company for Dr. Rosencwaig on a one-time non-precedent setting basis;

          FURTHER RESOLVED, that the terms and conditions of the leave of
absence shall be as set forth on EXHIBIT A attached hereto and incorporated by
                                 ---------
reference herein; and

          FURTHER RESOLVED, in order to fully implement the terms and conditions
of the leave of absence and its impact under the various agreements between Dr.
Rosencwaig and the Company, the form, terms and provisions of the agreement
substantially in the form attached hereto as EXHIBIT B is hereby in all respects
                                             ---------
approved; and further resolved that the chief executive officer or chief
financial officer of the Company, and each of them, is hereby empowered,
authorized and directed to execute such agreement in the name and on behalf of
the Company, substantially in the form approved hereby.

                                      -5-
<PAGE>

                                   EXHIBIT A
                     SUMMARY OF TERMS OF LEAVE OF ABSENCE

          1.   The leave of absence from Dr. Rosencwaig's position as the
Company's Chief Technology Officer will commence on July 10, 2000 and end on
January 10, 2001, or on such other dates as may be mutually agreed to in writing
by Dr. Rosencwaig and the Board. During the leave of absence, Dr. Rosencwaig
will continue to serve as the Company's Chairman of the Board and shall, to the
extent possible, attend all meetings of the Board and perform such duties
incident to such office.

          2.   During the leave of absence, Dr. Rosencwaig will be entitled to
receive a base pay of $475,000 per year, all of his current benefits and a bonus
equal to 50% of his base salary. All such payments shall be in accordance with
the Company's general compensation practices.

          3.   During the leave of absence, Dr. Rosencwaig will continue to be
treated as an employee of the Company under various agreements between him and
the Company and other shareholders; provided, however, that during the leave of
                                    --------- -------
absence the Time Vesting Stock and Management Options (each as defined in the
Executive Stock Agreement) will cease to vest.

          4.   At the end of the leave of absence, Dr. Rosencwaig and the Board
will mutually agree as to whether and in what capacity Dr. Rosencwaig will
return to the Company or, at Dr. Rosencwaig's election, Dr. Rosencwaig will be
entitled to  submit his resignation from the Company due to Disability (as
defined in his Employment Agreement). If Dr. Rosencwaig submits his resignation
for Disability, the Board will promptly and unconditionally accept his
resignation for Disability, which shall be deemed effective as of July 10, 2000
or such other date that the leave of absence commenced. Thereafter, Dr.
Rosencwaig will be entitled to the compensation, benefits and rights as provided
to him under resignation for Disability in the various agreements between him
and the Company and other shareholders. Such benefits will be determined as if
Dr. Rosencwaig's termination for Disability occurred on July 10, 2000. Dr.
Rosencwaig will continue to be bound by the obligations set forth in these
various agreements. In the event Dr. Rosencwaig returns to the Company, the
vesting of his Time Vesting Stock and Management Options will resume and he will
be given full credit during the leave of absence with respect to such vesting.

                                      -6-
<PAGE>

                                   EXHIBIT B
                          LEAVE OF ABSENCE AGREEMENT


          This Leave of Absence Agreement, dated May ___, 2000, is entered into
between Therma-Wave, Inc. ("Company") and Dr. Allan Rosencwaig ("Executive").

          WHEREAS, the Executive has requested, and the Company has agreed to
permit the Executive to take, a leave of absence from his employment with the
Company;

          WHEREAS, the Executive and the Company are parties to various
agreements that, among other things, set forth the terms and conditions of the
Executive's employment with the Company and establish each parties rights and
obligations with respect to equity securities of the Company owned by the
Executive;

          WHEREAS, the Executive and the Company desire to fully set forth the
terms and conditions of the leave of absence and the impact of such leave of
absence under the various agreements referred above.

          NOW THEREFORE, the Company and the Executive hereby agree as follows:

          1.   In recognition of the outstanding contributions of the Executive
to the Company over the past 18 years, the Company hereby grants to the
Executive a leave of absence from his employment with the Company.

          2.   The terms and conditions of the leave of absence are as set forth
on Exhibit A hereto, which is hereby incorporated by this reference.
   ---------

          3.   During the leave of absence, all agreements between the Company
and Executive shall remain in full force and effect and nothing in this
agreement shall be deemed to amend, modify or alter such agreements.

          4.   This agreement may be signed in two or more counterparts, each of
which shall be deemed to be an original but all of which together should
constitute one and the same document.

                                      -7-
<PAGE>

          5.   This agreement shall be governed by the laws of the State of
California.



                              Therma-Wave, Inc.



                              By: _______________________________________



                              ___________________________________________
                                         Dr. Allan Rosencwaig

                                      -8-