Note 3 - Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue	$ 1,089	$ 2,563	$ 3,146	$ 4,623
UNITED STATES
Revenue	188	181	527	578
Non-US [Member]
Revenue	901	2,382	2,619	4,045
Systems [Member]
Revenue	0	1,227	0	1,228
Systems [Member] | UNITED STATES
Revenue	0	0	0	0
Systems [Member] | Non-US [Member]
Revenue	0	1,227	0	1,228
Instruments and Accessories [Member]
Revenue	301	737	892	1,337
Instruments and Accessories [Member] | UNITED STATES
Revenue	71	60	169	142
Instruments and Accessories [Member] | Non-US [Member]
Revenue	230	677	723	1,195
Service [Member]
Revenue	295	335	779	1,067
Service [Member] | UNITED STATES
Revenue	77	75	228	225
Service [Member] | Non-US [Member]
Revenue	218	260	551	842
Lease [Member]
Revenue	493	264	1,475	991
Lease [Member] | UNITED STATES
Revenue	40	46	130	211
Lease [Member] | Non-US [Member]
Revenue	$ 453	$ 218	$ 1,345	$ 780