Condensed Consolidated Statements of Operations (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue:
Product revenue	$ 16,283	$ 18,658	$ 34,408	$ 34,665
Service revenue	3,442	2,926	6,492	5,801
Total revenue	19,725	21,584	40,900	40,466
Cost of Revenue:
Cost of product	8,666	10,285	17,935	17,880
Cost of services	902	1,228	2,104	2,712
Total cost of revenue	9,568	11,513	20,039	20,592
Gross profit	10,157	10,071	20,861	19,874
Operating expenses:
Product development and engineering	4,610	5,125	9,338	10,469
Selling, general and administrative	7,455	7,007	14,223	15,024
Total operating expenses	12,065	12,132	23,561	25,493
Operating loss	(1,908)	(2,061)	(2,700)	(5,619)
Other income (expense), net	(155)	74	(358)	(203)
Loss before provision for income taxes	(2,063)	(1,987)	(3,058)	(5,822)
Provision for income taxes	34	36	80	97
Net loss	$ (2,097)	$ (2,023)	$ (3,138)	$ (5,919)
Net loss per share — basic (usd per share)	$ (0.31)	$ (0.29)	$ (0.46)	$ (0.84)
Net loss per share — diluted (usd per share)	$ (0.31)	$ (0.29)	$ (0.46)	$ (0.84)
Weighted average number of shares:
Basic (shares)	6,786	7,092	6,784	7,042
Diluted (shares)	6,786	7,092	6,784	7,042