EXHIBIT 5.1
                                                                     -----------




                       WILSON SONSINI GOODRICH & ROSATI
                           PROFESSIONAL CORPORATION

                              650 PAGE MILL ROAD
                       PALO ALTO, CALIFORNIA 94304-1050
                 TELEPHONE 650-493-9300 - FACSIMILE 650-493-6811
                                 WWW.WSGR.COM


                                                                February 8, 2001

PALO ALTO, CALIFORNIA
KIRKLAND, WASHINGTON
AUSTIN, TEXAS



Rudolph Technologies, Inc.
One Rudolph Road
Flanders, NJ 07836

        Re: Registration Statement on Form S-3

Ladies and Gentlemen:

        We have examined the Registration Statement on Form S-3 filed by you
with the Securities and Exchange Commission on February 2, 2001, (Registration
No. 333-54860), including all amendments thereto through the date hereof (the
"Registration Statement"), in connection with the registration under the
Securities Act of 1933, as amended, of up to 4,025,000 shares of your Common
Stock (the "Shares"), including an option granted to the underwriters to
purchase up to an additional 525,000 shares to cover over-allotments. We
understand that you are selling the Shares to the underwriters for resale to the
public as described in the Registration Statement. As your legal counsel, we
have examined the proceedings taken, and are familiar with the proceedings
proposed to be taken, by you in connection with the sale and issuance of the
Shares.

        It is our opinion that, upon completion of the proceedings being taken
or proposed to be taken by us, as your legal counsel, prior to the issuance of
the Shares, the Shares will be legally issued, fully paid and non-assessable
when sold in the manner described in the Registration Statement.

        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, including the Prospectus constituting a part thereof,
and any amendments thereto.



                                        Very truly yours,


                                        WILSON SONSINI GOODRICH & ROSATI
                                        Professional Corporation

                                        /s/ Wilson Sonsini Goodrich & Rosati