


                                   EXHIBIT 2.1

                 AMENDMENT NO. 2 TO AGREEMENT AND PLAN OF MERGER
                             AMONG AMVC, KEY AND KTC



                               AMENDMENT NO. 2 TO
                          AGREEMENT AND PLAN OF MERGER
                          ----------------------------

     Key Technology, Inc. ("Parent"), KTC Acquisition Corp. ("Sub") and Advanced
Machine  Vision  Corporation  ("Company")  entered into an Agreement and Plan of
Merger  effective  February 15, 2000 and Amendment No. 1 effective  February 25,
2000.  The parties  hereby enter into this Amendment No. 2 effective as of April
24, 2000 to provide for the following modifications to the Merger Agreement:

     1.   Amendment of Sections 2.5 and 2.6.
          ----------------------------------

     Key,  Sub and AMVC hereby  agree that,  effective  with the  execution  and
delivery of this  Agreement,  Sections 2.5 and 2.6 of the Merger  Agreement  are
amended and restated to read as follows:

          "2.5  Conversion  and  Exchange  of  Shares.  The  manner and basis of
          converting  at the Effective  Time Company  Common Stock into cash and
          shares of Parent's Series B Convertible  Preferred  Stock,  $10.00 par
          value,  having the rights and  preferences  set forth in the  attached
          Exhibit 2.5A (the "Series B Preferred")  with the attached  redeemable
          Warrant  to  purchase  shares  of  Parent's  Common  Stock in the form
          attached as Exhibit 2.5B, the exchange of certificates  therefor,  the
          manner and basis of converting  the Company  Series B Preferred  Stock
          into Parent's Series C Convertible  Preferred Stock, $20.00 par value,
          having the rights and  preferences  set forth in the attached  Exhibit
          2.5C (the "Series C Preferred") with the attached  redeemable  Warrant
          to purchase  shares of Parent's  Common Stock in the form  attached as
          Exhibit 2.5B and the manner and basis of  converting  Company  Options
          outstanding at the Effective Time shall be as set forth herein.

          Conversion of Shares.
          ---------------------

               (i) (A) Each  share of Company  Common  Stock  (both  Class A and
          Class B) issued and  outstanding  immediately  prior to the  Effective
          Time (except  Dissenting  Shares)  shall,  by virtue of the Merger and
          without  any action on the part of the holder  thereof,  be  converted
          into the right to receive  $1.00 in cash and  one-tenth  of a share of
          Series B  Preferred,  with  each  share of  Series B  Preferred  to be
          accompanied  by a  Warrant,  redeemable  at any time by the holder for
          $2.50 in cash and  exercisable  at any time to purchase .25 of a share
          of Parent's Common Stock at a price of $15.00 per share (such Series B
          Preferred shares and attached  Warrants to be issued for each share of
          Company Common Stock constituting the "AMVC Common Conversion Ratio").

               (B) Each  Dissenting  Share shall be converted  into the right to
          receive payment from the Surviving Corporation with respect thereto in
          accordance with the provisions of the CCL.

               (ii)  Each  share  of  the  Company  Series  B  Preferred   Stock
          outstanding at the Effective  Date shall,  by virtue of the Merger and
          without  any action on the part of the holder  thereof,  be  converted
          into the right to receive one share of Series C  Preferred,  with each
          share of Series C Preferred to be accompanied by a Warrant, redeemable
          at any time by the  holder  for $2.50 in cash and  exercisable  at any
          time to purchase .25 of a share of Parent's Common Stock at a price of
          $15.00 per share (such Series C Preferred shares and attached Warrants
          to be  issued  for each  share of  Company  Series B  Preferred  Stock
          constituting  the "Series B Conversion  Ratio" and,  together with the
          AMVC Conversion Ratio, the "Conversion Ratios").

               (iii) Each share of Sub Common Stock issued and outstanding as of
          the  Effective  Time,  shall,  by virtue of the Merger and without any
          action  on the  part of  Parent,  the  sole  stockholder  of  Sub,  be
          converted into one share of legally and validly issued, fully paid and
          nonassessable  Common  Stock,  without  par  value,  of the  Surviving
          Corporation.  The stock certificate of Sub evidencing ownership of Sub
          Common  Stock  shall by virtue of the  Merger  evidence  ownership  of
          Common Stock of the Surviving Corporation.

               (iv)   In  the   event   of   any   stock   split,   combination,
          reclassification,  recapitalization, exchange, stock dividend or other
          distribution  payable in Parent Common Stock with respect to shares of
          Parent  Common  Stock (or if a record date with  respect to any of the
          foregoing  should  occur)  during the period  between the date of this
          Agreement and the Effective Time,  then the Conversion  Ratios will be
          appropriately  adjusted  to  reflect  such stock  split,  combination,
          reclassification,  recapitalization, exchange, stock dividend or other
          distribution.

               2.6 Exchange of  Certificates;  Payment.
                   ------------------------------------
          Series B Preferred and attached  Warrants  into which  Company  Common
          Stock shall be converted pursuant to the Merger and Series C Preferred
          and attached  Warrants  into which  Company  Series B Preferred  Stock
          shall be converted pursuant to the Merger shall be deemed to have been
          issued at the Effective Time. At the Closing,  Parent shall deliver to
          the Transfer  Agent  certificates  evidencing  the number of shares of
          Series B Preferred and attached  Warrants to which that Stockholder is
          entitled under Section 2.5, together with the cash payment  applicable
          thereto.  The  Company  will cause to be  delivered  such  transmittal
          letters,  documents  and  instruments  as Parent or Parent's  transfer
          agent may reasonably  request,  each in form reasonably  acceptable to
          Parent or such  transfer  agent.  Parent  shall  also  deliver  to the
          Transfer Agent certificates  evidencing the number of shares of Series
          C Preferred  and  attached  Warrants to be issued  pursuant to section
          2.5(ii) above with respect to any shares of Company Series B Preferred
          Stock outstanding on the Effective Date."

               2. Construction.
                  -------------

     This  Amendment  is part of the Merger  Agreement,  and is  governed by the
general terms and conditions thereof.


                                     KEY TECHNOLOGY, INC.

                                     By  /s/ Thomas C. Madsen
                                     -----------------------------------
                                         Thomas C. Madsen
                                         President



                                     KTC ACQUISITION CORP.

                                     By  /s/ Thomas C. Madsen
                                     -----------------------------------
                                         Thomas C. Madsen
                                         President



                                     ADVANCED MACHINE VISION CORPORATION

                                     By  /s/ William J. Young
                                     -----------------------------------
                                         William J. Young
                                         President


