CONSOLIDATED STATEMENTS OF OPERATIONS (in thousands, except per share amounts) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net sales	$ 6,533	$ 9,596	$ 21,367	$ 25,955
Cost of goods sold	2,415	3,639	8,584	10,629
Gross margin	4,118	5,957	12,783	15,326
Operating expenses:
Research and development	1,826	1,814	5,550	5,130
Selling, general and administrative	1,888	2,319	6,239	6,300
Total operating expenses	3,714	4,133	11,789	11,430
Operating income	404	1,824	994	3,896
Non-operating income (expense):
Interest income	10	6	26	19
Gain on sale of assets	0	72	4	363
Foreign currency transaction gain (loss)	108	(66)	201	(158)
Total non-operating income	118	12	231	224
Income before income taxes	522	1,836	1,225	4,120
Income tax (expense)	(180)	(108)	(267)	(207)
Net income	$ 342	$ 1,728	$ 958	$ 3,913
Basic earnings per share	$ 0.04	$ 0.21	$ 0.11	$ 0.48
Diluted earnings per share	$ 0.04	$ 0.20	$ 0.11	$ 0.47
Weighted-average basic shares	8,439	8,201	8,361	8,112
Weighted-average diluted shares	8,507	8,467	8,516	8,400