Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 28, 2014	Jun. 29, 2013	Jun. 28, 2014	Jun. 29, 2013
Income Statement [Abstract]
Net sales	$ 196,517	$ 213,725	$ 589,295	$ 596,985
Cost of sales	122,256	130,461	356,823	359,755
Gross profit	74,261	83,264	232,472	237,230
Operating expenses:
Research and development	19,046	21,782	60,396	61,229
Selling, general and administrative	37,226	38,748	116,413	113,076
Amortization of intangible assets	841	1,290	2,691	4,086
Total operating expenses	57,113	61,820	179,500	178,391
Income from operations	17,148	21,444	52,972	58,839
Other income (expense):
Interest and dividend income	201	48	318	161
Interest expense	(9)	(37)	(40)	(60)
Other—net	(415)	(964)	319	(1,196)
Total other income (expense), net	(223)	(953)	597	(1,095)
Income before income taxes	16,925	20,491	53,569	57,744
Provision for income taxes	3,926	3,806	13,560	11,904
Net income	$ 12,999	$ 16,685	$ 40,009	$ 45,840
Net income per share:
Basic	$ 0.52	$ 0.69	$ 1.62	$ 1.91
Diluted	$ 0.52	$ 0.68	$ 1.60	$ 1.87
Shares used in computation:
Basic	24,837	24,310	24,720	24,055
Diluted	25,115	24,690	25,025	24,462