Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities
Net loss	$ (11,141)	$ (7,032)
Adjustments to reconcile net loss to net cash used in operations:
Depreciation	172	396
Amortization of intangible assets	58	64
Share-based compensation expense	703	674
Inventory write-downs	37	171
Other non-cash adjustments	(31)	62
Change in:
Accounts receivable, net	(560)	(400)
Inventory	(1,481)	(427)
Other current and non-current assets	(3,471)	12
Accounts payable	(277)	362
Accrued liabilities	954	(150)
Deferred revenue	(496)	(713)
Billings in excess of costs and estimated earnings on uncompleted contracts	3,499	0
Other currrent liabilities	9,892	(117)
Other long-term liabilities	(17)	0
Net cash used in operating activities	(2,159)	(7,098)
Cash flows from investing activities
Purchases of property and equipment	(2,000)	(193)
Net cash used in investing activities	(2,000)	(193)
Cash flows from financing activities
Net proceeds from issuance of common stock and warrants	6,764	6,594
Net cash provided by financing activities	6,764	6,594
Change in cash and cash equivalents	2,605	(697)
Cash and cash equivalents, at beginning of period	15,139	7,888
Cash and cash equivalents, at end of period	17,744	7,191
Supplemental schedule of non-cash investing and financing activities
Non-cash additions to property and equipment	$ 285	$ 116