Details of Certain Financial Statement Components and Supplemental Disclosures of Cash Flow Information and Non-Cash Activities - Balance Sheet Data (Detail) (USD $)	6 Months Ended
	Jun. 29, 2013	Jun. 30, 2012	Dec. 31, 2012
Accounts receivable:
Accounts receivable-trade	$ 234,000		$ 57,000
U.S. government accounts receivable-billed			67,000
Less: allowance for doubtful accounts	(2,000)		(2,000)
Accounts receivable, net	232,000		122,000
Inventories:
Raw materials	1,062,000		1,031,000
Reserve for raw materials	(1,028,000)		(1,031,000)
Work-in-process	336,000		335,000
Reserve for work-in process	(328,000)		(314,000)
Finished goods	261,000		676,000
Reserve for finished goods	(196,000)		(646,000)
Inventories, net	107,000		51,000
Property and Equipment:
Property and Equipment, Gross	25,862,000		25,687,000
Less: accumulated depreciation and amortization	(19,994,000)		(19,445,000)
Property and Equipment, Net	5,868,000		6,242,000
Patents, Licenses and Purchased Technology:
Less accumulated amortization	(2,400,000)		(2,367,000)
Net Patents, Licenses and Purchased Technology	806,000		889,000
Accrued Expenses and Other Long Term Liabilities:
Accrued Expenses and Other Long Term Liabilities	1,234,000		1,134,000
Less current portion	(687,000)		(460,000)
Long term portion	547,000		674,000
Warranty Reserve Activity:
Beginning balance	227,000	225,000
Additions	2,000	19,000
Deductions	(44,000)	(50,000)
Ending balance	185,000	194,000
Salaries Payable [Member]
Accrued Expenses and Other Long Term Liabilities:
Accrued Expenses and Other Long Term Liabilities	77,000		81,000
Compensated Absences [Member]
Accrued Expenses and Other Long Term Liabilities:
Accrued Expenses and Other Long Term Liabilities	250,000		215,000
Compensation Related [Member]
Accrued Expenses and Other Long Term Liabilities:
Accrued Expenses and Other Long Term Liabilities	48,000		47,000
Warranty Reserve [Member]
Accrued Expenses and Other Long Term Liabilities:
Accrued Expenses and Other Long Term Liabilities	185,000		227,000
Deferred Rent [Member]
Accrued Expenses and Other Long Term Liabilities:
Accrued Expenses and Other Long Term Liabilities	460,000		470,000
Other [Member]
Accrued Expenses and Other Long Term Liabilities:
Accrued Expenses and Other Long Term Liabilities	214,000		94,000
Equipment [Member]
Property and Equipment:
Property and Equipment, Gross	18,078,000		18,625,000
Leasehold Improvements [Member]
Property and Equipment:
Property and Equipment, Gross	7,397,000		6,675,000
Furniture and Fixtures [Member]
Property and Equipment:
Property and Equipment, Gross	387,000		387,000
Patents [Member]
Patents, Licenses and Purchased Technology:
Patents pending	403,000		517,000
Patents issued	1,097,000		1,033,000
Less accumulated amortization	(694,000)		(661,000)
Total	403,000		372,000
Purchased Technology [Member]
Patents, Licenses and Purchased Technology:
Purchased technology	1,706,000		1,706,000
Less accumulated amortization	(1,706,000)		(1,706,000)
Total