Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Oct. 02, 2011	Sep. 30, 2012	Oct. 02, 2011
Revenue
Product	$ 72,437	$ 74,165	$ 222,293	$ 220,608
Service	7,639	5,920	19,818	17,264
Total revenue	80,076	80,085	242,111	237,872
Cost of revenue
Product	15,863	15,705	49,054	47,258
Service	3,643	3,248	10,059	9,457
Total cost of revenue	19,506	18,953	59,113	56,715
Gross margin
Product	56,574	58,460	173,239	173,350
Service	3,996	2,672	9,759	7,807
Total gross margin	60,570	61,132	182,998	181,157
Research, development, and engineering expenses	10,002	10,608	30,663	30,596
Selling, general, and administrative expenses	28,765	28,135	89,441	86,762
Operating income	21,803	22,389	62,894	63,799
Foreign currency loss	(409)	(231)	(1,077)	(80)
Investment income	823	917	3,596	2,219
Other expense	(131)	(156)	(227)	(509)
Income before income tax expense	22,086	22,919	65,186	65,429
Income tax expense	4,281	4,882	13,332	14,659
Net income	$ 17,805	$ 18,037	$ 51,854	$ 50,770
Earnings per weighted-average common and common-equivalent share:
Basic	$ 0.42	$ 0.43	$ 1.21	$ 1.22
Diluted	$ 0.41	$ 0.42	$ 1.19	$ 1.19
Weighted-average common and common-equivalent shares outstanding:
Basic	42,912	42,128	42,777	41,765
Diluted	43,629	42,976	43,610	42,682
Cash dividends per common share	$ 0.11	$ 0.09	$ 0.32	$ 0.26