Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Net revenues:
Products	$ 214,877	$ 185,066	$ 146,945
Service	43,744	36,063	40,422
Total net revenues	258,621	221,129	187,367
Costs of net revenues:
Cost of products	100,910	85,391	76,224
Cost of service	20,804	20,160	19,450
Amortization of intangible assets	206	1,454	2,026
Total costs of net revenues	121,920	107,005	97,700
Gross profit	136,701	114,124	89,667
Operating expenses:
Research and development	36,716	31,443	32,701
Selling	30,839	30,181	28,055
General and administrative	26,340	23,381	22,444
Amortization of intangible assets		24	114
Restructuring charge			1,380
Total operating expenses	93,895	85,029	84,694
Income from operations	42,806	29,095	4,973
Other (income) expense:
Interest income	8	35	71
Interest expense	(92)	(285)	(289)
Other income, net	576	290	813
Total other income, net	492	40	595
Income before income taxes	43,298	29,135	5,568
Provision for (benefit from) income taxes	13,096	(14,900)	2,663
Net income	$ 30,202	$ 44,035	$ 2,905
Net income per share:
Basic (in dollars per share)	$ 1.19	$ 1.79	$ 0.12
Diluted (in dollars per share)	$ 1.17	$ 1.75	$ 0.12
Weighted average shares used in per share calculation:
Basic (in shares)	25,334	24,655	24,059
Diluted (in shares)	25,919	25,153	24,375