Document:

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                                                                     EXHIBIT 4.6

                             [FORM OF CERTIFICATE]

               INCORPORATED UNDER THE LAWS OF THE STATE OF OREGON

No. B-                                                          _________ SHARES
                                                        Series B Preferred Stock

                                                        CUSIP

                              KEY TECHNOLOGY, INC.

                            Series B Preferred Stock

        THIS CERTIFIES THAT is the record holder of fully paid and nonassessable
Shares of Series B Preferred Stock, $.01 par value, of KEY TECHNOLOGY, INC.
transferable only on the Books of the Company by the holder hereof in person or
by duly authorized Attorney on surrender of this Certificate properly endorsed.
This Certificate is not valid until countersigned by the Transfer Agent and
registered by the Registrar.

        WITNESS the facsimile seal of the Company and the facsimile signatures
of its duly authorized officers.

Dated

SECRETARY                                     CHAIRMAN & CHIEF EXECUTIVE OFFICER

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                     [FORM OF REVERSE SIDE OF CERTIFICATE]

THE CORPORATION WILL FURNISH TO ANY SHAREHOLDER UPON REQUEST AND WITHOUT CHARGE
A FULL STATEMENT OF THE DESIGNATIONS, PREFERENCES, LIMITATIONS AND RELATIVE
RIGHTS OF THE SHARES OF EACH CLASS AUTHORIZED TO BE ISSUED, AND THE VARIATIONS
IN THE RELATIVE RIGHTS AND PREFERENCES BETWEEN THE SHARES OF EACH SERIES OF ANY
CLASS TOGETHER WITH THE AUTHORITY OF THE BOARD OF DIRECTORS TO FIX AND DETERMINE
THE RELATIVE RIGHTS AND PREFERENCES OF SUBSEQUENT SERIES.<PAGE>   1
                                                                     EXHIBIT 4.7
                             [FORM OF CERTIFICATE]

                       SEE RESTRICTIVE LEGEND ON REVERSE

               INCORPORATED UNDER THE LAWS OF THE STATE OF OREGON

No. C-1
    ---
                                                             119,106 SHARES
                                                        Series C Preferred Stock

                              KEY TECHNOLOGY, INC.

                            Series C Preferred Stock

        THIS CERTIFIES THAT FMC CORPORATION is the record holder of 119,106
fully paid and nonassessable Shares of Series C Preferred Stock, $.01 par value,
of KEY TECHNOLOGY, INC. transferable only on the Books of the Company by the
holder hereof in person or by duly authorized Attorney on surrender of this
Certificate properly endorsed. This Certificate is not valid until countersigned
by the Transfer Agent and registered by the Registrar.

        WITNESS the facsimile signatures of Company's duly authorized officers.

Dated

-------------------------------------         ----------------------------------
SECRETARY                                     CHAIRMAN & CHIEF EXECUTIVE OFFICER

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                     [FORM OF REVERSE SIDE OF CERTIFICATE]

THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933 AND NO SALE, TRANSFER OR OTHER DISPOSITION OF THE SHARES
OR ANY PART THEREOF MAY BE MADE EXCEPT PURSUANT TO A REGISTRATION STATEMENT
FILED WITH THE SECURITIES AND EXCHANGE COMMISSION UNDER THE ACT OR AFTER HAVING
PROVIDED THE CORPORATION WITH AN OPINION OF COUNSEL, IN FORM AND FROM COUNSEL
ACCEPTABLE TO THE CORPORATION, THAT SUCH SALE, TRANSFER OR DISPOSITION IS
PURSUANT TO AN EXEMPTION FROM THE REGISTRATION REQUIREMENTS UNDER FEDERAL AND
STATE SECURITIES LAWS.

THE CORPORATION WILL FURNISH TO ANY SHAREHOLDER UPON REQUEST AND WITHOUT CHARGE
A FULL STATEMENT OF THE DESIGNATIONS, PREFERENCES, LIMITATIONS AND RELATIVE
RIGHTS OF THE SHARES OF EACH CLASS AUTHORIZED TO BE ISSUED, AND THE VARIATIONS
IN THE RELATIVE RIGHTS AND PREFERENCES BETWEEN THE SHARES OF EACH SERIES OF ANY
CLASS TOGETHER WITH THE AUTHORITY OF THE BOARD OF DIRECTORS TO FIX AND DETERMINE
THE RELATIVE RIGHTS AND PREFERENCES OF SUBSEQUENT SERIES.<PAGE>   1
                                                                     EXHIBIT 4.8
                                    FORM OF

                                     OPTION

THE OPTION REPRESENTED BY THIS CERTIFICATE HAS NOT BEEN REGISTERED WITH THE
SECURITIES AND EXCHANGE COMMISSION UNDER THE SECURITIES ACT OF 1933, AS AMENDED
(THE "ACT"), AND MAY NOT BE OFFERED OR SOLD IN THE ABSENCE OF SUCH REGISTRATION
OR THE AVAILABILITY OF AN EXEMPTION FROM SUCH REGISTRATION. THIS OPTION MAY NOT
BE SOLD, TRANSFERRED OR ASSIGNED EXCEPT UPON COMPLIANCE WITH THE REQUIREMENTS
FOR TRANSFER SET FORTH HEREIN.

     This is to certify that, for value received, FMC Corporation ("Holder"), is
the registered owner of the Option set forth below, which entitles the Holder,
subject to the terms and conditions set forth hereinafter, to purchase shares of
Series B Convertible Preferred Stock of Key Technology, Inc., an Oregon
corporation ("Key" or the "Company") with attached warrants to purchase Common
Stock of the Company, at the "Option Exercise Price" (as defined below).

     This Option is the Option issued in connection with the Agreement between
FMC, Key, Advanced Machine Vision Corporation ("AMVC") and KTC Acquisition Corp.
("Sub") dated April 24, 2000, and other good an valuable consideration (the
receipt, adequacy and sufficiency of which are hereby acknowledged).

     This Option is subject to the following terms and provisions:

     1. Option to Purchase Shares.

        This Option, effective at the Effective Time (as defined in the
Agreement and Plan of Merger dated February 15, 2000 between AMVC, Sub and Key
(the "Merger Agreement")), is issued in exchange for and replaces the option
dated October 14, 1998 granted to FMC by AMVC for the purchase of Class A Common
Stock of AMVC, and represents an option to purchase 210,000 Shares of Series B
Convertible Preferred Stock of the Company (the "Option Shares"), with an
attached redeemable warrant to purchase 52,500 shares of the Company's Common
Stock (the "Warrant"). The terms of the Option Shares and the Warrant are
attached as Exhibits A and B. The Option Shares with the attached Warrant shall
be purchasable during the Option Term (as defined below) for an aggregate
exercise price of $2.52 million dollars, subject to adjustment as provided in
Section 11 below (the "Option Exercise Price").

     2. Option Term.

        This Option is effective on the date hereof and shall expire unless
previously exercised at the close of business on October 14, 2003, or if such
day is not a Trading Day, on the immediately following Trading Day (the "Option
Term"). This Option is exercisable by presentation and surrender of the original
of this Option Certificate to the Company at is principal place of business (the
"Option Office"), together with the Notice of Election to Exercise (the
"Exercise Notice") attached hereto, duly executed and accompanied by payment to
the Company of the Option Exercise Price. If this Option is not exercised on or
prior to the expiration of the Option Term it shall become void and all rights
in respect thereof shall cease as of such time. For purposes of this Option,
"Trading Day" shall mean each Monday, Tuesday,

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Wednesday, Thursday and Friday, other than any day on which securities are not
traded on the exchange or market where the Company's Common Stock is listed or
sold.

     3. Manner of Exercising Option.

        This Option may only be exercised with respect to all of the Option
Shares with the attached Warrant. In order to exercise this Option, the Holder
must pay the Option Exercise Price for the purchased securities either by full
payment in cash or check or wire transfer, or any other form approved by the
Board of Directors of the Company at the time of exercise.

     4. Absolute Owner.

        Prior to due presentment for registration or transfer of this Option,
the Company may deem and treat a Holder thereof as the absolute owner of the
Option (notwithstanding any notation of ownership or other writing made thereon
by anyone other than the Company), for the purpose of any exercise thereof and
for all other purposes, and the Company shall not be affected by any notice to
the contrary.

     5. Issuance of Certificates.

        Upon surrender of the Notice of Election and payment of the Option
Exercise Price, the Company shall issue and cause to be delivered with all
reasonable dispatch to or upon the written order of the Holder and in such name
or names as the Holder may designate, a certificate or certificates for the
Options Shares with the attached Warrant.

     6. Payment of Taxes and Other Governmental Charges.

        The Company shall pay any documentary stamp taxes attributable to the
original issuance of the Option Shares with the attached Warrant; provided,
however, that the Company shall not be required to (a) pay any tax or other
governmental charge which may be payable in respect of any transfer involving
the transfer and delivery of this Option or the issuance or delivery of
certificates for Options Shares with the attached Warrant in a name other than
that of FMC or (b) issue or deliver any certificate for Options Shares with the
attached Warrant upon the exercise of this Option until any such tax or charge
required to be paid under clause (a) shall have been paid, all such taxes or
charges being payable by the Holder.

     7. Reservation of Option Shares.

        The Company shall at all times reserve for issuance and delivery upon
exercise of this Option such number of Option Shares or other shares of capital
stock of the Company as may be issuable from time to time upon exercise of this
Option. All such shares shall be duly authorized and, when issued upon such
exercise and receipt by the Company of payment in full of the Option Exercise
Price, shall be validly issued, fully paid and nonassessable, free and clear of
all liens, security interests, charges and other encumbrances or restrictions on
sale and free and clear of all preemptive rights.

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     8. Registration of the Option Shares and the Attached Warrant.

        The Option Shares and the attached Warrant have been registered under
the Securities Act pursuant to a registration statement on Form S-4 (File No.
333-36920) declared effective under the Securities Act (the "Registration
Statement"). The Company covenants and agrees:

             (a) it will prepare and file with the Commission such amendments
and supplements to the Registration Statement and the prospectus used in
connection therewith as may be necessary to keep the Registration Statement
effective through the termination of the Option Term or until such earlier time
as no options remain outstanding;

             (b) as expeditiously as possible, to register or qualify the Option
Shares and the attached Warrant under the securities or "Blue Sky" laws of each
jurisdiction in which such registration or qualification is necessary; and

             (c) to pay all expenses incurred by the Company in complying with
this Section 0, including, without limitation (A) all registration and filing
fees, (B) all printing expenses, (C) all fees and disbursements of counsel and
independent public accountants for the Company, (D) all NASD and "Blue Sky" fees
and expenses (including fees and expenses of counsel in connection with any
"Blue Sky" surveys) and (E) the entire expense of any special audits incident to
or required in connection with any such registration.

     9. Mutilated or Missing Option.

        In the event that this Option shall be mutilated, lost, stolen or
destroyed, the Company may in its discretion issue upon the request of a Holder,
in exchange for and upon cancellation of any such mutilated option, or in
substitution for any such lost, stolen or destroyed option, a new option of like
tenor and evidencing the same number of Option Shares with the attached Warrant
as were evidenced by such mutilated, lost, stolen or destroyed option, but only
upon receipt of evidence satisfactory to the Company of such loss, theft or
destruction of such option and an indemnity, if requested, reasonably
satisfactory to the Company. A Holder shall also comply with such other
reasonable regulations and pay such other reasonable charges as the Company may
prescribe. Any such new option shall constitute an original contractual
obligation of the Company, whether or not the allegedly mutilated, lost, stolen
or destroyed option shall be enforceable by any person at any time thereafter.

     10. Restrictions on Transfer.

         10.1 Securities Law Restrictions. Regardless of whether the offering
and sale of Options Shares with the attached Warrant have been registered under
the Securities Act or have been registered or qualified under the securities
laws of any state, the Company at its discretion may impose restrictions upon
the sale, pledge or other transfer of such Options Shares with the attached
Warrant (including the placement of appropriate legends on stock certificates or
the imposition of stop-transfer instructions) if, in the judgment of the
Company, such restrictions are necessary or desirable in order to achieve
compliance with the Securities Act, the securities laws of any state or any
other law.

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         10.2 Administration. Any determination by the Company and its counsel
in connection with any of the matters set forth in this Section 10 shall be
conclusive and binding on a Holder and all other persons.

     11. Antidilution Provisions.

         The Option Exercise Price and the number of Option Shares that may be
purchased upon the exercise of this Option shall be subject to change or
adjustment from time to time as follows:

         11.1 Stock Splits. If at any time during the Option Term the number of
outstanding shares of Series B Convertible Preferred Stock shall have been
increased by a subdivision or split-up of shares of such shares, then, on the
record date fixed for the determination of holders of Series B Convertible
Preferred Stock immediately after the effective date of such subdivision or
split-up, the number of shares to be delivered upon exercise of the Option will
be appropriately increased so that each Holder thereafter will be entitled to
receive the number of shares of Series B Convertible Preferred Stock that such
Holder would have owned immediately following such action had such option been
exercised immediately prior thereto, and the Option Exercise Price will be
appropriately adjusted. The time of occurrence of an event giving rise to an
adjustment made pursuant to this Section 11.1 shall be deemed to be the
effective date thereof.

         11.2 Combination of Stock. If the number of shares of Series B
Convertible Preferred Stock outstanding at any time during the Option Term is
decreased by a combination of the outstanding shares of Series B Convertible
Preferred Stock, then, immediately after the effective date of such combination,
the number of shares of Series B Convertible Preferred Stock to be delivered
upon exercise of this Option shall be appropriately decreased so that the Holder
of such Option thereafter will be entitled to receive the number of shares of
Series B Convertible Preferred Stock that such Holder would have owned
immediately following such action had such option been exercised immediately
prior thereto, and the Option Exercise Price shall be appropriately adjusted.

         11.3 No Adjustments to Option Exercise Price. No adjustment of the
Option Exercise Price in accordance with the provisions of paragraph (a) or (b)
above shall be made in an amount of less than $0.01; provided, however, that the
amount by which any adjustment is not made by reason of the provisions of this
Section shall be carried forward and taken into account at the time of any
subsequent adjustment in the Option Exercise Price.

         11.4 Readjustments, Etc. If an adjustment is made under paragraph 11.1
or 11.2 above, and the event to which the adjustment relates does not occur,
then any adjustments in the Option Exercise Price or Option Shares that were
made in accordance with such paragraphs shall be adjusted back to the Option
Exercise Price and the number of Option Shares that were in effect immediately
prior to the record date for such event.

         11.5 Officer's Certificate. Whenever the number of Option Shares that
may be purchased upon exercise of the Option is adjusted as required by the
provisions of this Option, the Company shall mail to the Holder of such option
an officer's certificate indicating the

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adjusted number of Option Shares that may be purchased upon exercise of the
Option and the adjusted Option Exercise Price, determined as herein provided,
and setting forth in reasonable detail the facts requiring such adjustment and
the manner of computing such adjustment.

     12. Privilege of Stock Ownership.

         The Holder of this Option shall not have any of the rights of a
shareholder with respect to the Option Shares until such individual shall have
exercised the Option and paid the Option Exercise Price. Upon exercise of this
Option, such Holder shall for all purposes be deemed to have become the holder
of record of the Option Shares and such certificate shall be dated the date upon
which the Notice of Election was duly surrendered and payment of the Option
Exercise Price (and any applicable transfer taxes or governmental charges
pursuant to Section 6 hereof) was made; provided, however, that if the date of
such surrender and payment is a date upon which the transfer books of the
Company are closed, the Holder shall be deemed to have become the record holder
of such Option Shares on, and such certificate shall be dated, the next
succeeding Business Day on which the transfer books of the Company are open. For
purposes of this Section, "Business Day" shall mean any day other than a
Saturday, a Sunday or a day on which banking institutions in the State of Oregon
or the city in which the office of the transfer agent of the Company is located
are authorized or obligated by law or executive order to close.

     13. Successors and Assigns.

         The provisions of this Option shall inure to the benefit of, and be
binding upon, the successors and assigns of the Company.

     14. Notices.

         Any notice required to be given or delivered to the Company under the
terms of this Option shall be in writing and addressed to the Company in care of
the Corporate Secretary at its principal corporate offices. Any notice required
to be given or delivered to a Holder shall be in writing and addressed to such
Holder at the address indicated on the Company's records. Any notice or other
communication required or which may be given hereunder shall be in writing and
shall be delivered personally, telegraphed, telexed or sent by facsimile, or
sent by certified, registered or express mail, postage prepaid and shall be
deemed given when so delivered personally, telegraphed or telexed or sent by
facsimile or computer transmission, or if mailed, three days after the date of
mailing.

     15. Governing Law.

         The interpretation, performance, and enforcement of this Option shall
be governed by the laws of the State of Oregon.

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     16. Headings.

         The headings of sections of this Option have been inserted for
convenience of reference only, are not to be considered a part hereof, and shall
in no way modify or restrict any of the terms or provisions hereof.

     17. Amendments.

         This Option may be amended only by the written consent of the Company
and the written consent of the Holder.

     18. Severability.

         If any provision of this Option is held to be invalid, illegal or
unenforceable in any respect, such provision will be enforced to the maximum
extent possible and such invalidity, illegality or unenforceability will not
affect any other provision of this Option.

     19. Entire Agreement.

         This Option constitutes the entire agreement of the parties with
respect to the specific subject matter hereof and supersedes in their entirety
all prior agreements or understandings between the parties hereto with respect
to such subject matter.

         IN WITNESS WHEREOF, the Company has caused this Option Certificate to
be duly executed by its Chief Executive Officer and President and its Secretary

                                    KEY TECHNOLOGY, INC.

                                    By ____________________________
                                       Thomas C. Madsen
                                       Chief Executive Officer
                                       and President

                                    By ____________________________
                                       Gordon Wicher
                                       Secretary

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                      NOTICE OF ELECTION TO EXERCISE OPTION

               Pursuant to the Option (the "Option ") dated __________, 2000
granted to FMC CORPORATION ("Optionee") by KEY TECHNOLOGY, INC., an Oregon
corporation (the "Company"), and pursuant to which Optionee was granted an
option to purchase up to 210,000 Shares of Series B Convertible Preferred Stock
of the Company (the "Option Shares"), with an attached redeemable warrant to
purchase 52,500 shares of the Company's Common Stock (the "Warrant"), Optionee
hereby gives notice of its election to exercise the Option with respect to all
210,000 Option Shares with the attached redeemable Warrant at an exercise price
of $2.52 million. A check in the amount of the exercised price is enclosed.

               Dated:  ______________, _____

                             Optionee:         FMC CORPORATION

                                               By ____________________________

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