CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Net sales and contract revenues:
Net product sales and contract revenues	$ 21,280	$ 25,709
Net service revenues	21,804	21,635
Total net sales and contract revenues	43,084	47,344
Cost of sales and contracts:
Cost of product sales and contracts	12,553	15,124
Cost of service revenues	11,384	10,747
Total cost of sales and contracts	23,937	25,871
Gross profit	19,147	21,473
Expenses:
Selling, general and administrative expenses	7,409	7,998
Research and development costs	4,414	7,115
Total operating expenses	11,823	15,113
Operating income	7,324	6,360
Other income (expense):
Interest and investment income	94	207
Interest expense	(15)	(20)
Other, net	(87)	(180)
Total other income (expense)	(8)	7
Income before provision for income taxes	7,316	6,367
Provision for income taxes	2,451	2,165
Net income	4,865	4,202
Other comprehensive loss:
Unrealized loss on available for sale securities (net of tax)	(26)	(36)
Comprehensive income	$ 4,839	$ 4,166
Income per share - Basic (in dollars per share)	$ 0.62	$ 0.47
Income per share - Diluted (in dollars per share)	$ 0.62	$ 0.47
Weighted average shares - Basic (in shares)	7,842	8,853
Weighted average shares - Diluted (in shares)	7,882	8,905