CONSOLIDATED STATEMENTS OF OPERATIONS (in thousands, except per share amounts) (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Net sales	$ 6,058	$ 7,629
Cost of goods sold	2,373	3,213
Gross margin	3,685	4,416
Operating expenses:
Research and development	1,681	1,879
Selling, general and administrative	1,975	2,193
Total operating expenses	3,656	4,072
Operating income	29	344
Non-operating income (expense):
Interest income	12	7
Gain on sale of assets	60	0
Foreign currency transaction gain (loss)	(104)	(176)
Total non-operating income	(32)	(169)
Income (loss) before income taxes	(3)	175
Income tax (expense) benefit	29	(45)
Net income	$ 26	$ 130
Basic earnings per share	$ 0.00	$ 0.02
Diluted earnings per share	$ 0.00	$ 0.02
Weighted-average basic shares	8,303	8,287
Weighted-average diluted shares	8,417	8,542