Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 25, 2017
Net sales	$ 95,150	$ 81,097
Cost and expenses:
Cost of sales	55,599	48,841
Research and development	11,775	9,776
Selling, general and administrative	17,763	14,460
	85,137	73,077
Income from operations	10,013	8,020
Interest income	236	101
Income from continuing operations before taxes	10,249	8,121
Income tax provision	2,127	1,358
Income from continuing operations	8,122	6,763
Income from discontinued operations
Net income	$ 8,122	$ 6,763
Basic:
Income from continuing operations (in dollars per share)	$ 0.28	$ 0.25
Income from discontinued operations (in dollars per share)
Net income (in dollars per share)	0.28	0.25
Diluted:
Income from continuing operations (in dollars per share)	0.28	0.24
Income from discontinued operations (in dollars per share)
Net income (in dollars per share)	$ 0.28	$ 0.24
Weighted average shares used in computing income per share:
Basic (in shares)	28,602	26,978
Diluted (in shares)	29,531	28,252
Cash dividends declared per share (in dollars per share)	$ 0.06	$ 0.06