EXHIBIT 23.1

CONSENT OF INDEPENDENT CHARTERED ACCOUNTANTS

We consent to the incorporation by reference in the Registration Statements
(Form S-8, numbers 333-43080, 333-76849 and 333-73666), pertaining to the 1995
Stock Plan for Employees and Directors of GSI Lumonics Inc., the General
Scanning, Inc. 1992 Stock Option Plan, the General Scanning, Inc. 1995
Directors' Warrant Plan and the GSI Lumonics Inc. Employee Stock Purchase Plan,
of our report dated February 21, 2003 (except with respect to note 15, which is
as at June 26, 2003), with respect to the consolidated financial statements and
schedules of GSI Lumonics Inc. included in its Annual Report on Form 10-K/A
Amendment No. 3 (File No. 000-25705) for the year ended December 31, 2002.

June 27, 2003                          /s/ Ernst & Young LLP
Ottawa, Canada                         Chartered Accountants