Segment Data (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 27, 2013	Jul. 28, 2012
Segment Data
Intersegment sales	$ 0
Revenue:
Total revenue	44,117	58,677
Cost of sales:
Total cost of sales	31,572	39,172
Gross margin:
Gross margin	12,545	19,505
Selling, general and administrative	12,459	13,621
Research and development	7,190	8,136
Loss from operations	(7,104)	(2,252)
Other income (expense):
Interest income	205	172
Other expense	(3,394)
Loss before income taxes	(10,293)	(2,080)
UAS
Revenue:
Total revenue	35,211	48,806
Cost of sales:
Total cost of sales	24,599	32,756
Gross margin:
Gross margin	10,612	16,050
EES
Revenue:
Total revenue	8,906	9,871
Cost of sales:
Total cost of sales	6,973	6,416
Gross margin:
Gross margin	1,933	3,455
Unallocated to segment
Gross margin:
Selling, general and administrative	12,459	13,621
Research and development	7,190	8,136
Other income (expense):
Interest income	205	172
Other expense	$ (3,394)