Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS PROVIDED BY (USED IN) OPERATING ACTIVITIES:
Net loss	$ (1,379)	$ (1,261)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	119	110
Reduction in allowance for doubtful accounts	0	(7)
Increase in accrued investment income	(44)	(16)
Stock-based compensation	444	467
Gain on liquidation of joint venture	(424)	0
Change in operating assets and liabilities:
Accounts receivable	(270)	(224)
Inventories	(315)	54
Deferred cost of revenues	48	(159)
Other current assets	65	(124)
Accounts payable	290	42
Accrued liabilities	135	(545)
Deferred revenues	(3)	185
Deferred rent	(19)	(18)
Net cash used in operating activities	(1,353)	(1,496)
CASH FLOWS PROVIDED BY (USED IN) INVESTING ACTIVITIES:
Purchases of available‑for‑sale short‑term investments	(5,948)	(5,979)
Proceeds from maturities and sales of available‑for‑sale short‑term investments	6,000	6,000
Change in other long‑term assets	9	11
Capital expenditures	(87)	(16)
Net cash provided by (used in) investing activities	(26)	16
CASH FLOWS PROVIDED BY (USED IN) FINANCING ACTIVITIES:
Repurchase of common stock from employees for payment of taxes on vesting of restricted stock units and upon exercise of stock options	(66)	(17)
Net cash used in financing activities	(66)	(17)
EFFECT OF EXCHANGE RATE CHANGES ON CASH	30	19
NET CHANGE IN CASH AND CASH EQUIVALENTS	(1,415)	(1,478)
CASH AND CASH EQUIVALENTS:
Beginning of period	7,261	9,803
End of period	5,846	8,325
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for income taxes	$ 35	$ 37