Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net loss	$ (15,591)	$ (11,605)
Adjustments to reconcile net loss to net cash used in operations:
Depreciation	852	172
Amortization of intangible assets	58	58
Share-based compensation expense	539	703
Inventory write-downs	4	37
Other non-cash adjustments	(23)	(31)
Change in:
Accounts receivable, net	(2,657)	(604)
Costs and estimated earnings in excess of billings on uncompleted contracts	680	0
Inventory	32	(1,438)
Other current and non-current assets	(293)	(3,289)
Accounts payable	(1,215)	(277)
Accrued liabilities	283	956
Deferred revenue	5,000	0
Billings in excess of costs and estimated earnings on uncompleted contracts	441	3,284
Other currrent liabilities	(79)	9,892
Other long-term liabilities	(284)	(17)
Net cash used in operating activities	(12,253)	(2,159)
Cash flows from investing activities
Purchases of property and equipment	(502)	(2,000)
Net cash used in investing activities	(502)	(2,000)
Cash flows from financing activities
Net proceeds from issuance of common stock and warrants	16,782	6,764
Net cash provided by financing activities	16,782	6,764
Change in cash and cash equivalents	4,027	2,605
Cash, cash equivalents and restricted cash at beginning of period	17,401	15,574
Cash, cash equivalents and restricted cash at end of period	21,428	18,179
Supplemental schedule of non-cash investing and financing activities
Non-cash additions to property and equipment	$ 386	$ 285