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                                                      Direct Dial No.
                                                      (612) 347-7067
                                                      rranum@fredlaw.com

                                  May 15, 2000



August Technology Corporation
4900 West 78th Street
Bloomington, MN 55435

         RE:      REGISTRATION STATEMENT ON FORM S-1 - EXHIBIT 5.1

Gentlemen/Ladies

         We have acted as counsel for August Technology Corporation (the
"Company") in connection with the Company's filing of a Registration Statement
on Form S-1 (the "Registration Statement") relating to the registration under
the Securities Act of 1933 (the "Act") of 3,450,000 shares of Common Stock,
including 450,000 shares subject to an over-allotment option which are being
sold by certain selling shareholders of the Company (collectively, the
"Shares").

         In connection with rendering this opinion, we have reviewed the
following:

         1.       The Company's Articles of Incorporation, as amended.

         2.       The Company's Bylaws, as amended; and

         3.       Certain corporate resolutions, including resolutions of the
                  Company's Board of Directors pertaining to the issuance by the
                  Company of Shares covered by the Registration Statement.

         Based upon the following and upon the representations and information
provided by the Company, we hereby advise you that in our opinion:

         1.       The Company's Articles of Incorporation validly authorize the
                  issuance of the Shares registered pursuant to the Registration
                  Statement.

         2.       Upon the delivery and payment therefor in accordance with the
                  terms of the Registration Statement and the Underwriting
                  Agreement described in the Registration Statement, the Shares
                  to be issued and sold by the Company will be validly issued,
                  fully paid and nonassessable.

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May 15, 2000
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         3.       The Shares to be sold by the selling shareholders named in the
                  Registration Statement are validly issued, fully paid and
                  nonassessable.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our firm under the caption "Legal
Matters" included in the Registration Statement and the related Prospectus.

                                        Very truly yours,

                                        FREDRIKSON & BYRON, P.A.


                                        By   /s/ Robert K. Ranum
                                          ------------------------------------
                                                 Robert K. Ranum

