CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data	3 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Net sales and contract revenues:
Net product sales and contract revenues	$ 29,049	$ 32,474
Net service revenues	22,054	21,169
Total net sales and contract revenues	51,103	53,643
Cost of sales and contracts:
Cost of product sales and contracts	15,221	18,790
Cost of service revenues	11,980	11,041
Total cost of sales and contracts	27,201	29,831
Gross profit	23,902	23,812
Expenses:
Selling, general and administrative expenses	9,258	9,813
Research and development costs	6,077	5,010
Total operating expenses	15,335	14,823
Operating income	8,567	8,989
Other income (expense):
Interest and investment income	166	228
Interest expense	(25)	(30)
Other, net	(82)	1,196
Total other income	59	1,394
Income before provision for income taxes	8,626	10,383
Provision for income taxes	2,933	3,582
Net income	$ 5,693	$ 6,801
Income per share - Basic (in dollars per share)	$ 0.62	$ 0.75
Income per share - Diluted (in dollars per share)	$ 0.61	$ 0.74
Weighted average shares - Basic (in shares)	9,193	9,021
Weighted average shares - Diluted (in shares)	9,337	9,219
Dividends declared per share (in dollars per share)	$ 0.30	$ 0.30