Novanta (NOVT) 10-Q 2013 Q1 Quarterly report

Exhibit 32.1

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of GSI Group Inc. (the “Company”) on Form 10-Q for the period ended March 29, 2013 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, John A. Roush, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to the best of my knowledge:

(1) the Report fully complies with the requirements of section 13(a) or 15(d), as applicable, of the Securities Exchange Act of 1934; and

(2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ John A. Roush

John A. Roush

Chief Executive Officer

May 8, 2013

This Certification shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liability of that section, or incorporated by reference into any of the Company’s filings with the Securities and Exchange Commission by implication or by any reference in any such filings to the Report.

A signed original of this written statement required by Section 906 has been provided to GSI Group Inc. and will be retained by GSI Group Inc. and furnished to the Securities and Exchange Commission or its staff upon request.