Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Consolidated Statements of Operations [Abstract]
Sales	$ 55,201	$ 46,368	$ 154,715	$ 140,165
Cost of sales	32,238	25,812	86,034	78,832
Gross profit	22,963	20,556	68,681	61,333
Operating expenses:
Selling, general and administrative	4,838	4,114	14,484	13,864
Research and development	2,800	2,820	9,198	8,985
Bad debt expense (recovery)	(279)	112	325	145
Total operating expenses	7,359	7,046	24,007	22,994
Gain (loss) on disposal of equipment	(3)	1	(3)	17
Income from operations	15,601	13,511	44,671	38,356
Other income (expense):
Interest expense	(76)		(119)	(43)
Interest income	118	37	561	166
Foreign exchange gains (losses)	(9)	(10)	284	36
Other, net	(47)	(2)	(55)	(39)
Total other income (expense), net	(14)	25	671	120
Income before income taxes	15,587	13,536	45,342	38,476
Income tax expense	4,851	4,329	14,491	12,354
Net income	$ 10,736	$ 9,207	$ 30,851	$ 26,122
Basic earnings per share	$ 1.68	$ 1.47	$ 4.85	$ 4.23
Diluted earnings per share	$ 1.67	$ 1.44	$ 4.80	$ 4.15
Weighted average shares outstanding-Basic	6,374,083	6,257,336	6,363,126	6,180,576
Weighted average shares outstanding-Diluted	6,441,224	6,375,156	6,426,185	6,293,804