Exhibit 99.1

GSI Lumonics Announces Agreement to Acquire MicroE Systems

Billerica, MA (April 12, 2004) GSI Lumonics Inc. (NASDAQ: GSLI and TSX: LSI)
today announced the signing of a definitive agreement under which GSI Lumonics
will acquire all the shares of MicroE Systems Corp for an all-cash purchase
price of US$55.0 million. The transaction was approved by the Board of Directors
of both companies and will be completed subject to customary closing conditions.

MicroE Systems, located in Natick, MA, is recognized as a technology leader in
the design and manufacture of position encoders for precision motion control
applications in data storage, semiconductor and electronics, industrial
automation and medical markets. Company estimated revenue for the quarter ending
April 4, 2004 was US$7.65 million.

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Charles Winston, GSI Lumonics' President and Chief Executive Officer said, "The
agreement to acquire MicroE Systems is consistent with the Company's stated
acquisition strategy. MicroE Systems products and technology will complement GSI
Lumonics' existing portfolio of enabling precision motion component and
subsystems. It is expected that this acquisition will be accretive to earnings
in the first full quarter following the transaction's completion."


GSI Lumonics supplies precision motion control components, lasers and
laser-based advanced manufacturing systems to the global medical, semiconductor,
electronics, and industrial markets. GSI Lumonics' common shares are listed on
NASDAQ (GSLI) and The Toronto Stock Exchange (LSI).
Certain statements in this news release may constitute forward-looking
statements within the meaning of the United States Private Securities Litigation
Reform Act of 1995, Section 27A of the United States Securities Act of 1933 and
Section 21E of the United States Securities Exchange Act of 1934. These
forward-looking statements may relate to anticipated financial performance,
management's plans and objectives for future operations, business prospects,
outcome of regulatory proceedings, market conditions, tax issues and other
matters. All statements contained in this news release that do not relate to
matters of historical fact should be considered forward-looking statements, and
are generally identified by words such as "anticipate," "believe," "estimate,"
"expect," "intend," "plan," "objective" and other similar expressions. Readers
should not place undue reliance on the forward-looking statements contained in
this news release. Such statements are based on management's beliefs and
assumptions and on information currently available to management and are subject
to risks, uncertainties and changes in condition, significance, value and
effect. Other risks include the fact that the Company's sales have been and are
expected to continue to be dependent upon customer capital equipment
expenditures, which are, in turn, affected by business cycles in the markets
served by those customers. Other factors include volatility in the semiconductor
industry, the risk of order delays and cancellations, the risk of delays by
customers in introducing their new products and market acceptance of products
incorporating subsystems supplied by the Company, similar risks to the Company
of delays in its new products, our ability to continue to reduce costs and
capital expenditures, our ability to focus R&D investment and other risks
detailed in reports and documents filed by the Company with the United States
Securities and Exchange Commission and with securities regulatory authorities in
Canada. Such risks, uncertainties and changes in condition, significance, value
and effect, many of which are beyond the Company's control, could cause the
Company's actual results and other future events to differ materially from those
anticipated. The Company does not, however, assume any obligation to update
these forward-looking statements to reflect actual results, changes in
assumptions or changes in other factors affecting such forward-looking
statements.


For more information contact:
Investor Relations, 613-224-4868, Ann Dempsey, (ext. 2)