Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Sales:
Net sales	$ 42,984	$ 41,112	$ 128,639	$ 114,606
Costs and expenses:
Research and development	4,335	3,548	13,407	11,701
Sales, marketing and support	7,429	6,931	22,912	22,426
General and administrative	6,666	5,839	22,514	18,006
Total costs and expenses	46,213	41,615	141,277	126,193
Loss from operations	(3,229)	(503)	(12,638)	(11,587)
Interest income	218	229	673	759
Interest expense	20	2	52	9
Other income (expense), net	7,065	(370)	6,275	971
Income (loss) before income tax expense (benefit)	4,034	(646)	(5,742)	(9,866)
Income tax expense (benefit)	16	(109)	(59)	437
Net income (loss)	$ 4,018	$ (537)	$ (5,683)	$ (10,303)
Net income (loss) per common share
Basic (in USD per share)	$ 0.22	$ (0.03)	$ (0.31)	$ (0.58)
Diluted (in USD per share)	$ 0.22	$ (0.03)	$ (0.31)	$ (0.58)
Weighted average number of common shares outstanding:
Basic (in shares)	18,341,000	17,723,000	18,152,000	17,634,000
Diluted (in shares)	18,566,000	17,723,000	18,152,000	17,634,000
Product
Sales:
Net sales	$ 15,239	$ 16,650	$ 50,940	$ 43,693
Costs and expenses:
Costs of sales	10,945	10,422	34,059	29,612
Service
Sales:
Net sales	27,745	24,462	77,699	70,913
Costs and expenses:
Costs of sales	$ 16,838	$ 14,875	$ 48,385	$ 44,448