UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No.)*

GSI Group Inc.
(Name of Issuer)

Common stock, no par value
(Title of Class of Securities)

36191C205
(CUSIP Number)

July 9, 2015
(Date of Event which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

[_] Rule 13d-1(b)

[x] Rule 13d-1(c)

[_] Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Page 1 of 8

SCHEDULE 13G

CUSIP No.        36191C205

1	Names of Reporting Persons
	Polar Securities Inc.
2	Check the appropriate box if a member of a Group (see instructions)
	(a) [   ]
	(b) [   ]
3	Sec Use Only
4	Citizenship or Place of Organization
	Canada

	5	Sole Voting Power
Number of		0
Shares	6	Shared Voting Power
Beneficially
Owned by Each		1,741,438
Reporting Person	7	Sole Dispositive Power
With:
		0
	8	Shared Dispositive Power
		1,741,438

9	Aggregate Amount Beneficially Owned by Each Reporting Person 1,741,438
10	Check box if the aggregate amount in row (9) excludes certain shares (See Instructions) [   ]
11	Percent of class represented by amount in row (9) 5.06%
12	Type of Reporting Person (See Instructions) IA

Page 2 of 8

SCHEDULE 13G

CUSIP No.        36191C205

1	Names of Reporting Persons
	Altairis Offshore Levered
2	Check the appropriate box if a member of a Group (see instructions)
	(a)   [   ]
	(b)   [   ]
3	Sec Use Only
4	Citizenship or Place of Organization
	Cayman Islands

	5	Sole Voting Power
Number of		0
Shares	6	Shared Voting Power
Beneficially
Owned by Each		1,741,438
Reporting Person	7	Sole Dispositive Power
With:
		0
	8	Shared Dispositive Power
		1,741,438

9	Aggregate Amount Beneficially Owned by Each Reporting Person 1,741,438
10	Check box if the aggregate amount in row (9) excludes certain shares (See Instructions) [   ]
11	Percent of class represented by amount in row (9) 5.06%
12	Type of Reporting Person (See Instructions) CO

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SCHEDULE 13G

CUSIP No.        36191C205

Item 1.

(a)	Name of Issuer:
	The name of the issuer is GSI Group Inc. (the “Company”).
(b)	Address of Issuer’s Principal Executive Offices:
	The Company’s principal executive offices are located at 125 Middlesex Turnpike, Bedford, Massachusetts, USA.

Item 2.

(a)	Name of Person Filing:
	This statement is filed by:

(i) Altairis Offshore Levered ("Altairis"), a Cayman Islands exempted company, with respect to the Shares (defined in item 2(d) below) reported in this Schedule 13G directly held by it; and

(ii) Polar Securities Inc. ("Polar Securities"), a company incorporated under the laws on Ontario, Canada, serving as investment advisor to Altairis with respect to the Shares reported in this Schedule 13G directly held by Altairis.

	The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons."
(b)	Address of Principal Business Office or, if None, Residence:
	The address of the business office of each of the Reporting Persons is 401 Bay Street, Suite 1900, PO Box 19, Toronto, Ontario M5H 2Y4, Canada.
(c)	Citizenship:
	The citizenship of each of the Reporting Persons is set forth above.
(d)	Title and Class of Securities:
	Common stock, no par value
	CUSIP No.:
	36191C205

Item 3. If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)	[_]	Broker or dealer registered under Section 15 of the Act;
(b)	[_]	Bank as defined in Section 3(a)(6) of the Act;

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SCHEDULE 13G

CUSIP No.        36191C205

(c)	[_]	Insurance company as defined in Section 3(a)(19) of the Act;
(d)	[_]	Investment company registered under Section 8 of the Investment Company Act of 1940;
(e)	[_]	An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);
(f)	[_]	An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F);
(g)	[_]	A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G);
(h)	[_]	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	[_]	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940;
(j)	[_]	A non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J);
(k)	[_]	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
If filing as a non-U.S. institution in accordance with Rule 240.13d-1(b)(1)(ii)(J), please specify the type of institution:_____

Item 4.	Ownership
	The percentages used herein are calculated based upon 34,406,281 Shares reported to be outstanding as of April 29, 2015 as reported on Form 10-Q filed by the Company on May 7, 2015.

A.	Polar Securities
	(a)	Amount Beneficially Owned: 1,741,438
	(b)	Percent of Class: 5.06%
	(c)	Number of shares as to which such person has:
		(i)	Sole power to vote or to direct the vote: 0
		(ii)	Shared power to vote or to direct the vote: 1,741,438
		(iii)	Sole power to dispose or to direct the disposition of: 0
		(iv)	Shared power to dispose or to direct the disposition of: 1,741,438

B.	Altairis
	(a)	Amount Beneficially Owned: 1,741,438
	(b)	Percent of Class: 5.06%
	(c)	Number of shares as to which such person has:
		(i)	Sole power to vote or to direct the vote: 0
		(ii)	Shared power to vote or to direct the vote: 1,741,438
		(iii)	Sole power to dispose or to direct the disposition of: 0
		(iv)	Shared power to dispose or to direct the disposition of: 1,741,438

Item 5.	Ownership of Five Percent or Less of a Class.
	If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following [   ].

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SCHEDULE 13G

CUSIP No.        36191C205

Item 6.	Ownership of more than Five Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and classification of the subsidiary which acquired the security being reported on by the parent holding company or control person.
	Not Applicable
Item 8.	Identification and classification of members of the group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable
Item 10.	Certifications.
	Each of the Reporting Persons hereby makes the following certification:
	By signing below each Reporting Person certifies that, to the best of his or its knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

Page 6 of 8

SCHEDULE 13G

CUSIP No.        36191C205

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: July 17, 2015

POLAR SECURITIES INC.

/s/ Robyn Schultz

Name:      Robyn Schultz

Title:        Chief Compliance Officer

ALTAIRIS OFFSHORE LEVERED
By: Polar Securities Inc., its investment manager

/s/ Robyn Schultz

Name:      Robyn Schultz

Title:        Chief Compliance Officer

Page 7 of 8

SCHEDULE 13G

CUSIP No.        36191C205

EXHIBIT 1

JOINT FILING AGREEMENT
PURSUANT TO RULE 13d-1(k)

The undersigned acknowledge and agree that the foregoing statement on Schedule 13G is filed on behalf of each of the undersigned and that all subsequent amendments to this statement on Schedule 13G shall be filed on behalf of each of the undersigned without the necessity of filing additional joint filing agreements. The undersigned acknowledge that each shall be responsible for the timely filing of such amendments, and for the completeness and accuracy of the information concerning him or it contained herein and therein, but shall not be responsible for the completeness and accuracy of the information concerning the others, except to the extent that he or it knows or has reason to believe that such information is inaccurate.

Dated July 17, 2015

POLAR SECURITIES INC.

/s/ Robyn Schultz

Name:      Robyn Schultz

Title:        Chief Compliance Officer

ALTAIRIS OFFSHORE LEVERED
By: Polar Securities Inc., its investment manager

/s/ Robyn Schultz

Name:      Robyn Schultz

Title:        Chief Compliance Officer

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