Stock Based Compensation Expense (Detail) (USD $)	3 Months Ended		6 Months Ended
	Sep. 28, 2012	Sep. 30, 2011	Sep. 28, 2012	Sep. 30, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation expense	$ 49,000	$ 209,000	$ 78,000	$ 245,000
Cost of Products Sold
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation expense	4,000	25,000	7,000	29,000
Research, development & engineering expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation expense	16,000	73,000	23,000	86,000
General and Administrative expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation expense	24,000	100,000	41,000	116,000
Sales and Marketing expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock based compensation expense	$ 5,000	$ 11,000	$ 7,000	$ 14,000