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                                                             Exhibit 31.2

CERTIFICATION OF THE CHIEF FINANCIAL OFFICER

I, Ingrid Mittelstaedt, Chief Financial Officer, of Rofin-Sinar
Technologies, Inc., certify that:

1.  I have reviewed this quarterly report on Form 10-Q of Rofin-Sinar
    Technologies Inc.;

2.  Based on my knowledge, this quarterly report does not contain any untrue
    statement of a material fact or omit to state a material fact necessary
    to make the statements made, in light of the circumstances under which
    such statements were made, not misleading with respect to the period
    covered by this quarterly report;

3.  Based on my knowledge, the financial statements, and other financial
    information included in this quarterly report, fairly present in all
    material respects the financial condition, results of operations and
    cash flows of the registrant as of, and for, the periods presented in
    this quarterly report;

4.  The registrant's other certifying officer and I are responsible for
    establishing and maintaining disclosure controls and procedures (as
    defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal
    control over financial reporting (as defined in Exchange Act Rules 13a-
    15(f) and 15d-15(f)) for the registrant and have:

    a)  designed such disclosure controls and procedures, or caused such
        disclosure controls and procedures to be designed under our
        supervision, to ensure that material information relating to the
        registrant, including its consolidated subsidiaries, is made known
        to us by others within those entities, particularly during the
        period in which this quarterly report is being prepared;

    b)  designed such internal control over financial reporting, or caused
        such internal control over financial reporting to be designed under
        our supervision, to provide reasonable assurance regarding the
        reliability of financial reporting and the preparation of financial
        statements for external purposes in accordance with generally
        accepted accounting principles;

    c)  evaluated the effectiveness of the registrant's disclosure controls
        and procedures presented in this quarterly report our conclusions
        about the effectiveness of the disclosure controls and procedures,
        as of the end of the period covered by this quarterly report,
        based on such evaluation; and

    d)  disclosed in this quarterly report any change in the registrant's
        internal control over financial reporting that occurred during the
        registrant's most recent fiscal quarter that has materially
        affected, or is reasonably likely to materially affect, the
        registrant's internal control over financial reporting; and




5.  The registrant's other certifying officer and I have disclosed, based on
    our most recent evaluation of internal control over financial reporting,
    to the registrant's auditors and the audit committee of registrant's
    board of directors:

    a)  all significant deficiencies and material weaknesses in the design
        or operation of internal controls over financial reporting which are
        reasonably likely to adversely affect the registrant's ability to
        record, process, summarize and report financial information; and

    b)  any fraud, whether or not material, that involves management or
        other employees who have a significant role in the registrant's
        internal controls over financial reporting.





Date:   August 9, 2010

                                            /s/ Ingrid Mittelstaedt
                                         -------------------------------
                                              Ingrid Mittelstaedt

                                          Chief Financial Officer,
                                          Executive Vice President,
                                          Finance and Administration,
                                          and Treasurer