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Exhibit 10.4

As of March 31, 2008

StockerYale, Inc.

32 Hampshire Road

Salem, New Hampshire 03079

Attention:        Chief Financial Officer

(Issue Date: June 10, 2004)

Ladies and Gentlemen:

Reference is made to (a) that certain Common Stock Purchase Warrant No. 2003-1 issued by StockerYale, Inc., a Massachusetts corporation (the “Company”) on June 10, 2004 in favor of PSource Structured Debt Limited (as partial assignee of Laurus Master Fund, Ltd.) (the “Holder”), providing for the purchase of up to an aggregate amount of 400,000 shares of Common Stock of the Company (the “Warrant”) and (b) that certain lockup agreement dated as of the date hereof, made by the Holder in favor of the Company with respect to the Securities defined therein. Capitalized terms used herein that are not defined shall have the meanings given to them in the Warrant.

In consideration of the foregoing and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties hereto hereby agree that “Expiration Date” (as defined in the Warrant) is hereby amended such that “Expiration Date” shall hereafter mean June 10, 2016.

This letter agreement shall become effective upon receipt by the Holder of a copy of this letter agreement executed by the Company.

Except as specifically amended herein, the Warrant shall remain in full force and effect, and are hereby ratified and confirmed. The execution, delivery and effectiveness of this letter agreement shall not operate as a waiver of any right, power or remedy of the Holder, nor constitute a waiver of any provision of the Warrant. This letter agreement shall be binding upon and inure to the benefit of the parties hereto and their respective successors and assigns and shall be governed by and construed in accordance with the laws of the State of New York.

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This letter agreement may be executed by the parties hereto in one or more counterparts, each of which shall be deemed an original and all of which when taken together shall constitute one and the same agreement. Any signature delivered by a party by facsimile transmission shall be deemed to be an original signature hereto.

AMENDMENT TO WARRANT NO. 2003-1

(ISSUE DATE: JUNE 10, 2004)