EXHIBIT 4.2


                              AMENDMENT NUMBER ONE

                         DATED AS OF DECEMBER 20, 2000,

                                       TO

                 AGREEMENT OF MERGER AND PLAN OF REORGANIZATION

                          DATED AS OF NOVEMBER 4, 2000,

                                  BY AND AMONG

                     EXFO ELECTRO-OPTICAL ENGINEERING INC.,

                                 EXFO SUB, INC.,

                           BURLEIGH INSTRUMENTS, INC.,

                             ROBERT G. KLIMASEWSKI,

                               WILLIAM G. MAY, JR,

                                DAVID J. FARRELL

                                       AND

                               WILLIAM S. GORNALL


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                             AMENDMENT NUMBER ONE TO

                 AGREEMENT OF MERGER AND PLAN OF REORGANIZATION

         This AMENDMENT NUMBER ONE (this "AMENDMENT") dated as of December 20,
2000 amends that certain AGREEMENT OF MERGER AND PLAN OF REORGANIZATION (the
"AGREEMENT") dated as of November 4, 2000 among EXFO Electro-Optical Engineering
Inc., incorporated pursuant to the CANADA BUSINESS CORPORATIONS ACT (the
"BUYER"), EXFO Sub, Inc., a corporation organized under the laws of the State of
New York ("BUYER SUB"), Burleigh Instruments, Inc., a corporation organized
under the laws of the State of New York (the "Company"), Robert G. Klimasewski,
("KLIMASEWSKI"), William G. May, Jr., ("MAY"), David J. Farrell ("FARRELL") and
William S. Gornall ("GORNALL" and, together with Klimasewski, May and Farrell,
the "SHAREHOLDERS"). Defined terms not otherwise defined herein shall have the
meaning ascribed to them in the Agreement.

                                    RECITALS

         WHEREAS, the Shareholders, the Company, the Buyer and the Buyer Sub
wish to amend the Agreement to reallocate the Merger Consideration to be
received by each of the Shareholders.

         WHEREAS, the Shareholders, the Company, the Buyer and the Buyer Sub
wish to further amend the Agreement to reduce the Stock Consideration to enable
the Buyer to institute a restricted stock retention program for the Company's
employees, utilizing the value of certain Stock Consideration voluntarily
relinquished by certain of the Shareholders.

         NOW THEREFORE, in consideration of the representations, warranties,
covenants and agreements set forth in the Agreement and in this Amendment, the
parties hereto hereby agree as follows:

1.       Section 1.3 of the Agreement is hereby amended in its entirety to read
as follows:

                  EFFECTIVE TIME. The consummation of the Merger shall be
                  effected as promptly as practicable, but in no event more than
                  three business days after the satisfaction or waiver of the
                  conditions set forth in ARTICLE 5 of this Agreement (other
                  than those conditions which by their nature are to be
                  satisfied at the Closing, but subject to satisfaction of those
                  conditions), and the parties hereto will cause a copy of the
                  Articles of Merger attached hereto as Exhibit A (the "ARTICLES
                  OF MERGER") and including a Plan of Merger (the "PLAN OF
                  MERGER") to be executed, delivered and filed with the
                  Secretary of State of the State of New York in accordance with
                  the BCL. The Merger shall become effective upon the delivery
                  of the properly executed Articles of Merger to the Secretary
                  of State of the State of New York for filing. The date and
                  time on which the Merger shall become effective is referred to
                  herein as the "EFFECTIVE TIME".

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2.       Section 1.7(b)(i) of the Agreement is hereby amended in its entirety to
read as follows:

                           "(i)     Buyer shall deliver to each Shareholder, as
                  applicable: (i) the aggregate amount of the Cash Consideration
                  payable to such Shareholder in United States dollars in
                  immediately available funds by wire transfer to one or more
                  accounts designated prior to the Effective Time in writing by
                  each such Shareholder for said purpose, subject to Section
                  1.13; (ii) stock certificates representing the Buyer Shares
                  (other than Escrow Shares) registered in each Shareholder's
                  name and in such denominations as set forth on Exhibit C,
                  which shall be agreed upon by the parties at the Closing and
                  which shall be determined by reference to the Closing Price;
                  and (iii) all documents, instruments and writings required to
                  have been delivered at or prior to the Effective Time by the
                  Buyer or by Buyer Sub pursuant to this Agreement;"

3.       Section 1.8 of the Agreement is hereby amended in its entirety to read
as follows:

                  (a)      "The total consideration to be paid by Buyer in the
         Merger shall be $256,240,641 (the "MERGER CONSIDERATION") consisting of
         (a) $33,593,141 payable in cash, subject to Section 1.13 (the "CASH
         CONSIDERATION") and (b) $222,647,500 (the "STOCK CONSIDERATION")
         payable in the form of Buyer Subordinate Voting Shares (the "BUYER
         SHARES"). In addition, Buyer shall assume and pay certain obligations
         of the Company pursuant to Section 1.13. The aggregate number of Buyer
         Shares payable shall be determined by dividing the Stock Consideration
         by the Closing Price. The "CLOSING PRICE" shall be the average closing
         price of Buyer Subordinate Voting Shares for the five trading days
         ending with December 18, 2000, as reported by the Nasdaq National
         Market; provided, however, that for purposes of this Agreement, if the
         Closing Price is less than 90% of the Signing Price, the Closing Price
         shall be 90% of the Signing Price, and if the Closing Price is greater
         than 110% of the Signing Price, the Closing Price shall be 110% of the
         Signing Price. The "SIGNING PRICE" is $38.125, representing the closing
         price of the Buyer Subordinate Voting Shares, as reported by the Nasdaq
         National Market, at closing of trading on October 31, 2000. If, prior
         to the Closing, there is any stock dividend, stock split or other
         change in the character or amount of the outstanding Buyer Subordinate
         Voting Shares, then in such event any and all new, substituted or
         additional securities to which the Shareholders would have been
         entitled by reason of their ownership of the Buyer Shares had the
         Closing occurred prior to such event shall be considered Buyer Shares
         for purposes of this Agreement and the consideration to be received by
         each Shareholder shall be adjusted accordingly. At the Effective Time,
         by virtue of the Merger and without further action on the part of
         Buyer, Buyer Sub or the Company, the shares of Company Common Stock
         issued and outstanding immediately prior to Closing shall be conceded
         and extinguished and shall be converted into the right to receive the
         Merger Consideration, such that each share of Company Common Stock
         issued and outstanding immediately prior to the Effective Time shall be
         converted into the right to receive the Merger Consideration, which
         Merger Consideration shall be paid to each Shareholder in such amount
         of Stock Consideration and Cash Consideration, as the case may be, as
         set forth on Schedule 1.8 attached hereto. The number of shares of
         Buyer Stock

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         constituting the Stock Consideration and the amount of Cash
         Consideration to be received by each Shareholder is set forth on
         Schedule 1.8 attached hereto. Each share of common stock, par value of
         $0.01 per share of Buyer Sub issued and outstanding immediately prior
         to the Effective Time shall be converted into and shall become one
         validly issued fully paid and non-assessable share of Surviving
         Corporation Common Stock as of the Effective Time, and the Surviving
         Corporation shall become a wholly-owned subsidiary of Buyer. In
         exchange for and in consideration of the issuance of the Merger
         Consideration, Buyer will be entitled to subscribe and undertakes and
         agrees to subscribe, at the Effective Time, for the Surviving
         Corporation Common Stock. The Surviving Corporation Common Stock will
         at the Effective Time have been duly authorized and, when issued to
         Buyer, will be validly issued and outstanding as fully paid and
         non-assessable. The number of shares of Company Common Stock held by
         each Shareholder and to be converted into the right to receive the
         Merger Consideration is set forth opposite each Shareholder's name on
         Exhibit C. No fraction of a share of Buyer Subordinate Voting Shares
         shall be issued, and each fractional share thereof shall be rounded up
         to the nearest whole number. Until surrendered and exchanged, each
         outstanding certificate which, prior to the Effective Time, represented
         shares of Company Common Stock shall be deemed to represent and
         evidence only the right to receive the Merger Consideration to be paid
         therefore as set forth in this Section 1.8. No interest shall accrue or
         be payable with respect to any Cash Consideration which any Shareholder
         shall be entitled to receive. Buyer shall be authorized to pay Merger
         Consideration attributable to any certificate theretofore issued which
         has been lost or destroyed, upon receipt of satisfactory evidence of
         ownership of the shares of Company Common Stock represented thereby and
         of appropriate indemnification. It being agreed that the Merger
         Consideration received by Messrs. Farrell and Gornall shall be reduced
         on a dollar for dollar basis equal to six (6) months of their
         respective annual remuneration in the event that Messrs. Farrell or
         Gornall terminate unilaterally their respective employment agreement
         with the Surviving Corporation prior to the second anniversary of the
         Effective Time."

                  (b)      It is acknowledged by the parties that the Merger
         Consideration payable hereunder has been reduced by agreement of the
         parties by the sum of $12,352,500 to reflect the voluntary contribution
         of 360,000 Buyer Shares (valued at the Closing Price) by Klimasewski,
         May and Farrell to a Restricted Stock Award Plan (the "Plan") to be
         created by Buyer for the benefit of the Company's Employees. A copy of
         the Plan is attached hereto as Exhibit A. The parties agree that
         Klimasewski and May have each contributed the value of 151,285 Buyer
         Shares to the Plan, and that Farrell has contributed the value of
         57,430 shares to the Plan. The Buyer agrees that to the extent any
         award of Buyer Shares is forfeited in whole or in part by an employee
         of the Company, the Buyer Shares so forfeited as well as any
         unallocated Buyer Shares as of January 31, 2001 shall increase the
         Merger Consideration and shall be paid to Klimasewski, May and Farrell
         in proportion to their contribution of Buyer Shares to the Plan (the
         "Additional Shares"). The Additional Shares shall be paid to
         Klimasewski, May and Farrell as soon as practicable, but in no event
         later than ten (10) business days, following each Vesting Date (as
         defined in the Plan) with respect to all

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         Additional Shares forfeited by employees on or before such Vesting Date
         or January 31, 2001, as applicable.

4.       Section 1.9 of the Agreement is hereby amended in its entirety to read
as follows:

         "Simultaneously with the Merger and at the Effective Time, an aggregate
         15% of the Stock Consideration will be delivered to the Escrow Agent
         (as such term is defined in the Escrow Agreement attached hereto as
         Exhibit D (the "ESCROW AGREEMENT")). Such shares of Buyer Shares shall
         constitute an escrow fund (the "ESCROW FUND") to be governed by the
         terms set forth in the Escrow Agreement. Each Shareholder shall
         contribute such number of Buyer Shares received by him to the Escrow
         Fund as is set forth on Schedule 1.8 attached hereto. The portion of
         the Escrow Fund contributed on behalf of each of the Shareholders shall
         be in proportion to the Merger Consideration which such holder would
         otherwise be entitled under Section 1.8. The Escrow Fund shall
         terminate in accordance with the terms of the Escrow Agreement. The
         provisions of the Escrow Agreement shall govern in the event of any
         conflict between the Escrow Agreement and this Section 1.9. The
         Shareholders may withdraw shares of Buyer Shares (the "WITHDRAWN
         SHARES") and substitute cash in lieu thereof at any time, provided that
         the amount deposited in substitution for the Withdrawn Shares is equal
         to the product of (i) the Closing Price, and (ii) the number of
         Withdrawn Shares."

5.       Section 1.13 of the Agreement is hereby amended in its entirety to read
as follows:

         "At the Closing, the Buyer hereby assumes and agrees to pay directly
         the legal fees incurred by the Company in connection with the
         transactions contemplated hereby and further assumes and agrees to pay
         directly the investment banking fees incurred by the Company and
         payable as of the Closing (collectively, the "EXPENSES"). The
         Shareholders hereby jointly and severally assume and agree to pay
         directly the investment banking fees of the Company arising out of the
         transactions contemplated hereby and payable following the Closing with
         respect to the portion of the Stock Consideration placed in escrow
         pursuant to the Escrow Agreement. At the Closing, the Buyer shall pay
         the Expenses in cash, in the currency requested by the service
         provider, by wire transfer of immediately available funds. The Company
         shall, at least two business days prior to the Closing Date, advise the
         Buyer in writing of the amount of the Expenses, together with wire
         transfer instructions for such payments. Farrell and Gornall
         acknowledge that, as a result of the assumption and payment of the
         Expenses by the Buyer, that the number of shares of Buyer Stock to be
         received by them as part of the Merger Consideration shall be adjusted
         as set forth on Schedule 1.8 "

6.       Section 2.8 of the Agreement is hereby amended in its entirety to read
as follows:

         "The Shareholders (a) have delivered to the Buyer on or prior to the
         execution of this Agreement complete and correct copies of the
         Company's audited combined consolidated balance sheet as of December
         31, 1999 and 1998, and the related statements of operations,
         shareholders' equity and cash flows (together with the auditors' report
         thereon) for the year ended December 31, 1999 and 1998, together with
         notes to such financial statements (the "AUDITED FINANCIAL

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         STATEMENTS"), and (b) have delivered to the Buyer on or about December
         19, 2000 complete and correct copies of the Company's unaudited
         combined consolidated balance sheet as at September 30, 2000, and the
         related statements of operations, stockholders' equity and cash flows
         for the nine month periods ended September 30, 2000 (the "INTERIM
         FINANCIAL STATEMENTS") (the Audited Financial Statements and Interim
         Financial Statements are herein collectively referred to as the
         "FINANCIAL STATEMENTS"). The Financial Statements are in accordance
         with the books and records of the Company and have been prepared in
         accordance with generally accepted accounting principles ("GAAP")
         consistently applied throughout the periods covered thereby and present
         fairly in all material respects, as of their respective dates, the
         financial condition and results of operations of the Company (subject,
         in the case of Interim Financial Statements, to normal, recurring
         year-end adjustments that may be required upon audit). No information
         has become available to the Company that would render the Financial
         Statements materially and adversely incomplete or inaccurate."

7.       Section 5.2(m) is hereby amended to read in its entirety as follows:

                  (m)      SEC FINANCIAL STATEMENTS. The Shareholders shall have
         delivered (i) consolidated, combined audited balance sheets of the
         Company and its Subsidiaries as of the end of the two most recent
         fiscal years, (ii) a consolidated, combined unaudited balance sheet as
         of the end of the most recent quarter preceding the Closing, (iii)
         consolidated, combined audited statements of income and cash flows for
         each of the three fiscal years preceding the Closing, and (iv)
         consolidated, combined unaudited statements of income and cash flows
         for the interim period between the latest audited balance sheet date
         and the date of the balance sheet being provided pursuant to clause
         (ii), in each case meeting the requirements of the SEC that would be
         applicable to the Company as if its securities were registered under
         Section 12 of the SECURITIES AND EXCHANGE ACT OF 1934, as amended
         (collectively, the "SEC FINANCIAL STATEMENTS").

8.       Section 5.2(n) is hereby amended to read in its entirety as follows:

                  (n)      The Buyer shall have received confirmation that KPMG
         LLP, the Company's auditors, are independent certified public
         accountants qualified to deliver the accountant's report on the SEC
         Financial Statements as required by the SEC.

9.       The parties to this Amendment agree to take all actions, including the
execution of additional documents, as may be reasonably requested by the other
parties hereto to effect the intent and purposes of this Amendment.

10.      This Amendment shall be governed in all respects by the provisions of
the Agreement, which shall remain in full force and effect, as modified by this
Amendment.


                  [Remainder of Page Intentionally Left Blank]

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                       [Amendment No. One Signature Page]



         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed by their respective authorized signatories as of the date first
indicated above.


                                        BURLEIGH INSTRUMENTS, INC.

                              By:       /s/  David J. Farrell
                                        ---------------------------------------
                              Name:     David J. Farrell
                              Title:    President


                                        EXFO ELECTRO-OPTICAL
                                        ENGINEERING INC.

                              By:       /s/  Germain Lamonde
                                        ---------------------------------------
                              Name:     Germain Lamonde
                              Title:    President and Chief Executive Officer


                                        EXFO SUB, INC.

                              By:       /s/  Germain Lamonde
                                        ---------------------------------------
                              Name:     Germain Lamonde
                              Title:    President


                                        /s/  Robert G. Klimasewski
                                        ---------------------------------------
                                        Robert G. Klimasewski


                                        /s/  William G. May, Jr.
                                        ---------------------------------------
                                        William G. May, Jr.


                                        /s/  David J. Farrell
                                        ---------------------------------------
                                        David J. Farrell


                                        /s/  William S. Gornall
                                        ---------------------------------------
                                        William S. Gornall