Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Net sales	$ 86,164	$ 93,651	$ 281,131	$ 268,614
Cost and expenses:
Cost of sales	51,786	56,742	165,701	162,319
Research and development	11,088	9,609	33,914	28,851
Selling, general and administrative	16,511	16,882	50,926	47,362
	79,385	83,233	250,541	238,532
Income from operations	6,779	10,418	30,590	30,082
Interest income	326	174	880	417
Income from continuing operations before taxes	7,105	10,592	31,470	30,499
Income tax provision	2,302	1,837	6,897	4,273
Income from continuing operations	4,803	8,755	24,573	26,226
Loss from discontinued operations				(278)
Net income	$ 4,803	$ 8,755	$ 24,573	$ 25,948
Basic:
Income from continuing operations (in dollars per share)	$ 0.17	$ 0.31	$ 0.85	$ 0.95
Loss from discontinued operations (in dollars per share)				(0.01)
Net income (in dollars per share)	0.17	0.31	0.85	0.94
Diluted:
Income from continuing operations (in dollars per share)	0.16	0.30	0.83	0.92
Loss from discontinued operations (in dollars per share)				(0.01)
Net income (in dollars per share)	$ 0.16	$ 0.30	$ 0.83	$ 0.91
Weighted average shares used in computing income (loss) per share:
Basic (in shares)	28,948	28,155	28,814	27,614
Diluted (in shares)	29,770	29,105	29,650	28,640
Cash dividends declared per share (in dollars per share)	$ 0.06	$ 0.06	$ 0.18	$ 0.18