Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities
Net loss	$ (7,032)	$ (6,731)
Adjustments to reconcile net loss to net cash provided by (used in) operations:
Depreciation	396	180
Amortization of intangible assets	64	64
Share-based compensation expense	674	424
Inventory write-downs	171	287
Other non-cash adjustments	62	(31)
Change in:
Accounts receivable, net	(400)	(651)
Inventory	(427)	(519)
Other current and non-current assets	12	(30)
Accounts payable	362	248
Accrued liabilities	(267)	508
Deferred revenue	(713)	7,937
Billings in excess of costs and estimated earnings on uncompleted contracts	0	(225)
Net cash provided by (used in) operating activities	(7,098)	1,461
Cash flows from investing activities
Purchases of property and equipment	(193)	(719)
Net cash used in investing activities	(193)	(719)
Cash flows from financing activities
Net proceeds from issuance of common stock and warrants	6,594	5,994
Net cash provided by financing activities	6,594	5,994
Change in cash and cash equivalents	(697)	6,736
Cash and cash equivalents, at beginning of period	7,888	8,336
Cash and cash equivalents, at end of period	7,191	15,085
Supplemental schedule of non-cash investing and financing activities
Non-cash additions to property and equipment	$ 116	$ 187