Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Statement of Cash Flows [Abstract]
Net loss	$ (10,757)	$ (18,619)
Adjustments to reconcile net loss to net cash used in operations:
Depreciation	727	1,142
Amortization of intangible assets	118	138
Gain on disposal of property and equipment	(35)	(47)
Realizeld loss on sale of short-term investments	0	32
Non-cash stock-based compensation expense	996	1,730
Change in warrant liability	(397)	0
Realized gain on exchange of warrants	(18)	0
Inventory write-downs		303
Non-cash deferred rent	(16)	(118)
Change in:
Accounts receivable, net	978	(516)
Costs and estimated earnings in excess of billings on uncompleted contracts	0	58
Inventory	166	2,538
Other current assets	789	183
Other assets	4	12
Accounts payable	(1,413)	(3,413)
Accrued liabilities	(896)	(1,095)
Deferred revenue	(609)	0
Billings in excess of costs and estimated earnings on uncompleted contracts	111	(70)
Net cash used in operating activities	(9,949)	(16,951)
Cash flows from investing activities
Sales of investment securities	0	11
Decrease in restricted cash	1	350
Proceeds on sale of property and equipment	35	47
Purchases of property and equipment	(273)	(478)
Net cash used in investing activities	(237)	(70)
Cash flows from financing activities
Principal payments under capital leases and long-term debt	(106)	(100)
Net proceeds from issuance of common stock and warrants	11,763	14,789
Net cash provided by (used in) financing activities	11,657	14,689
Net increase (decrease) in cash and cash equivalents	1,471	(2,332)
Cash and cash equivalents, at beginning of period	6,850	13,075
Cash and cash equivalents, at end of period	8,321	10,743
Supplemental disclosure of cash flow information
Cash paid for interest	10	24
Supplemental schedule of non-cash investing and financing activities
Other non-cash additions to property and equipment	431	11
Issuance of common stock for exchange of warrants	$ 207	$ 0