Note 3 - Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenue	$ 2,563	$ 2,571	$ 4,623	$ 5,756
UNITED STATES
Revenue	181	243	578	770
Non-US [Member]
Revenue	2,382	2,328	4,045	4,986
Systems [Member]
Revenue	1,227	1,129	1,228	2,050
Systems [Member] | UNITED STATES
Revenue	0	0	0	0
Systems [Member] | Non-US [Member]
Revenue	1,227	1,129	1,228	2,050
Instruments and Accessories [Member]
Revenue	737	793	1,337	1,601
Instruments and Accessories [Member] | UNITED STATES
Revenue	60	60	142	204
Instruments and Accessories [Member] | Non-US [Member]
Revenue	677	733	1,195	1,397
Service [Member]
Revenue	335	395	1,067	1,180
Service [Member] | UNITED STATES
Revenue	75	105	225	307
Service [Member] | Non-US [Member]
Revenue	260	290	842	873
Lease [Member]
Revenue	264	254	991	925
Lease [Member] | UNITED STATES
Revenue	46	78	211	259
Lease [Member] | Non-US [Member]
Revenue	$ 218	$ 176	$ 780	$ 666