Consolidated Statements Of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Consolidated Statements Of Operations [Abstract]
Sales	$ 56,233	$ 50,696	$ 99,514	$ 93,797
Cost of sales	31,173	29,012	53,796	53,020
Gross profit	25,060	21,684	45,718	40,777
Operating expenses:
Selling, general and administrative	4,911	5,308	9,646	9,750
Research and development	3,509	3,225	6,398	6,165
Bad debt expense	168	103	604	33
Total operating expenses	8,588	8,636	16,648	15,948
Gain on disposal of equipment				16
Income from operations	16,472	13,048	29,070	24,845
Other income (expense):
Interest expense	(43)		(43)	(43)
Interest income	176	67	443	129
Foreign exchange gains (losses)	171	(94)	293	46
Other, net	47	(17)	(8)	(37)
Total other income (expense), net	351	(44)	685	95
Income before income taxes	16,823	13,004	29,755	24,940
Income tax expense	5,392	4,302	9,639	8,025
Net income	$ 11,431	$ 8,702	$ 20,116	$ 16,915
Basic earnings per share	$ 1.80	$ 1.41	$ 3.16	$ 2.75
Diluted earnings per share	$ 1.78	$ 1.38	$ 3.13	$ 2.70
Weighted average shares outstanding-Basic	6,363,146	6,166,290	6,357,678	6,142,197
Weighted average shares outstanding-Diluted	6,430,390	6,297,254	6,419,780	6,265,181