CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 27, 2014	Sep. 28, 2013	Sep. 27, 2014	Sep. 28, 2013
Income Statement [Abstract]
Net sales	$ 94,441	$ 55,977	$ 237,155	$ 170,438
Cost and expenses:
Cost of sales	61,265	43,293	156,295	124,298
Research and development	9,679	11,136	30,419	35,201
Selling, general and administrative	14,089	13,966	43,412	41,389
Total cost and expenses	85,033	68,395	230,126	200,888
Income (loss) from operations	9,408	(12,418)	7,029	(30,450)
Interest and other, net	6	16	25	42
Income (loss) from continuing operations before taxes	9,414	(12,402)	7,054	(30,408)
Income tax provision (benefit)	2,493	(1,289)	2,556	(2,726)
Income (loss) from continuing operations	6,921	(11,113)	4,498	(27,682)
Income from discontinued operations, net of tax	598	293	3,836	714
Net income (loss)	$ 7,519	$ (10,820)	$ 8,334	$ (26,968)
Basic:
Income (loss) from continuing operations	$ 0.28	$ (0.44)	$ 0.18	$ (1.12)
Income from discontinued operations, net of tax	$ 0.02	$ 0.01	$ 0.15	$ 0.03
Net income (loss)	$ 0.30	$ (0.43)	$ 0.33	$ (1.09)
Diluted:
Income (loss) from continuing operations	$ 0.27	$ (0.44)	$ 0.17	$ (1.12)
Income from discontinued operations, net of tax	$ 0.02	$ 0.01	$ 0.15	$ 0.03
Net income (loss)	$ 0.29	$ (0.43)	$ 0.32	$ (1.09)
Weighted average shares used in computing income (loss) per share:
Basic	25,481	24,929	25,309	24,801
Diluted	26,174	24,929	25,698	24,801
Cash dividends declared per share	$ 0.06	$ 0.06	$ 0.18	$ 0.18