Exhibit 31.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER PURSUANT TO

EXCHANGE ACT RULE 13a-14(a)/15d-14(a)

AS ADOPTED PURSUANT TO SECTION 302

OF THE SARBANES-OXLEY ACT OF 2002

I, John R. Ambroseo, certify that:

1.I have reviewed this Annual Report on Form 10-K/A of Coherent, Inc.; and

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report.

Date: January 31, 2005

By:	/s/ JOHN R. AMBROSEO
	John R. Ambroseo
	President and Chief Executive Officer