Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jun. 25, 2016	Jul. 01, 2017	Jun. 25, 2016
Net revenues:
Products	$ 53,576	$ 47,445	$ 101,751	$ 86,659
Service	10,851	8,322	21,990	16,597
Total net revenues	64,427	55,767	123,741	103,256
Costs of net revenues:
Cost of products	25,337	21,736	50,815	39,815
Cost of service	5,417	5,164	10,754	9,648
Amortization of intangible assets	52	442	104	877
Total costs of net revenues	30,806	27,342	61,673	50,340
Gross profit	33,621	28,425	62,068	52,916
Operating expenses:
Research and development	9,139	7,511	17,833	15,579
Selling	7,239	7,823	15,177	15,072
General and administrative	6,591	5,755	12,898	11,175
Amortization of intangible assets	0	0	0	24
Total operating expenses	22,969	21,089	45,908	41,850
Income from operations	10,652	7,336	16,160	11,066
Other income (expense):
Interest income	3	12	4	21
Interest expense	(19)	(67)	(59)	(184)
Other income (expense), net	274	(394)	271	(169)
Total other income (expense), net	258	(449)	216	(332)
Income before income taxes	10,910	6,887	16,376	10,734
Provision for income taxes	2,622	856	2,736	1,236
Net income	$ 8,288	$ 6,031	$ 13,640	$ 9,498
Net income per share:
Basic (in dollars per share)	$ 0.33	$ 0.25	$ 0.54	$ 0.39
Diluted (in dollars per share)	$ 0.32	$ 0.24	$ 0.53	$ 0.38
Weighted average shares used in per share calculation:
Basic (in shares)	25,307	24,524	25,220	24,416
Diluted (in shares)	25,906	24,927	25,880	24,773