Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Operating activities:
Net loss			$ (742)	$ (1,817)
Reconciliation of net loss to net cash used in operating activities:
Depreciation and amortization			1,211	1,075
Stock-based compensation expense	$ 503	$ 504	1,069	845
Deferred tax liability			300
Changes in operating assets and liabilities:
Accounts receivable			(6,188)	(145)
Inventories			46	409
Prepaid expenses and other current assets			487	(240)
Accounts payable			2,915	(805)
Accrued expenses and other			1,898	(335)
Deferred rent			(23)	(18)
Deferred revenue			469	1,522
Net cash provided by operating activities			1,442	491
Investing activities:
Purchases of property and equipment			(3,092)	(1,404)
Net cash used in investing activities			(3,092)	(1,404)
Financing activities:
Proceeds from sale of common stock / exercise of options			1,407
Proceeds from loan facility				954
Proceeds from equipment loans				1,501
Principal payments on debt			(274)	(1,143)
Payments to satisfy employee taxes due on vesting of restricted awards			(60)
Dividends paid				(7)
Net cash provided by financing activities			1,073	1,305
Effect of exchange rate changes on cash and cash equivalents			(43)	78
Net (decrease) increase in cash and cash equivalents			(620)	470
Cash and cash equivalents, beginning of period			21,446	20,994	$ 20,994
Cash and cash equivalents, end of period	$ 20,826	21,464	20,826	21,464	21,446
Supplemental cash flow information
Cash paid for interest			75	50
Supplemental noncash information
Purchases of equipment through accounts payable and accrued expenses			$ 470	327
Series C Preferred Stock [Member]
Supplemental noncash information
Excess of carrying value of Series C Preferred Stock over redemption value		$ 459		459	$ 500
Redemption of Series C Preferred Stock and dividend included in accounts payable				$ 98