Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities
Net loss	$ (3,556)	$ (3,962)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation	187	83
Amortization of intangible assets	32	32
Non-cash share-based compensation expense	300	190
Inventory write-downs	122	139
Other non-cash adjustments	1	(15)
Change in:
Accounts receivable, net	691	191
Inventory	(166)	(455)
Other current and non-current assets	48	(46)
Accounts payable	141	381
Accrued liabilities	383	207
Deferred revenue	(1,165)	8,126
Billings on uncompleted contracts in excess of related costs	0	179
Net cash provided by (used in) operating activities	(2,982)	5,050
Cash flows from investing activities
Purchases of property and equipment	(82)	(69)
Net cash used in investing activities	(82)	(69)
Cash flows from financing activities
Net proceeds from issuance of common stock and warrants	6,385	3,355
Net cash provided by financing activities	6,385	3,355
Change in cash and cash equivalents	3,321	8,336
Cash and cash equivalents, at beginning of period	7,888	8,349
Cash and cash equivalents, at end of period	11,209	16,685
Supplemental schedule of non-cash investing and financing activities
Non-cash additions to property and equipment	$ 154	$ 246