CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jul. 03, 2020		Jun. 28, 2019		Jul. 03, 2020		Jun. 28, 2019
Income Statement [Abstract]
Revenue	$ 144,728		$ 155,145		$ 300,196		$ 312,331
Cost of revenue	86,026		89,363		177,049		180,260
Gross profit	58,702		65,782		123,147		132,071
Operating expenses:
Research and development and engineering	14,440		13,388		29,774		27,385
Selling, general and administrative	24,908		29,204		55,663		61,051
Amortization of purchased intangible assets	3,410		3,772		6,855		7,770
Restructuring, acquisition, and related costs	2,243		4,313		3,904		6,367
Total operating expenses	45,001		50,677		96,196		102,573
Operating income	13,701		15,105		26,951		29,498
Interest income (expense), net	(1,701)		(2,160)		(3,379)		(4,204)
Foreign exchange transaction gains (losses), net	(282)		27		(28)		68
Other income (expense), net	(22)		(70)		61		(138)
Income before income taxes	11,696		12,902		23,605		25,224
Income tax provision (benefit)	36		2,522		(2)		2,591
Consolidated net income	$ 11,660	[1]	$ 10,380	[2]	$ 23,607	[1]	$ 22,633	[2]
Earnings per common share (Note 5):
Basic	$ 0.33	[1]	$ 0.30	[2]	$ 0.67	[1]	$ 0.65	[2]
Diluted	$ 0.33	[1]	$ 0.29	[2]	$ 0.66	[1]	$ 0.64	[2]
Weighted average common shares outstanding—basic	35,137	[1]	34,998	[2]	35,145	[1]	34,981	[2]
Weighted average common shares outstanding—diluted	35,579	[1]	35,503	[2]	35,570	[1]	35,491	[2]

[1] 71 thousand non-GAAP EPS performance-based restricted stock units granted to certain members of the executive management team and 213 thousand shares of restricted stock issued to the former Laser Quantum non-controlling interest shareholders are considered contingently issuable shares and were excluded from the calculation of the denominator as the contingent conditions had not been met as of July 3, 2020.

[2] 45 thousand non-GAAP EPS performance-based restricted stock units granted to certain members of the executive management team and 213 thousand shares of restricted stock issued to the former Laser Quantum non-controlling interest shareholders were considered contingently issuable shares and were excluded from the calculation of the denominator as the contingent conditions had not been met as of June 28, 2019.