Note 3 - Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenue	$ 994	$ 1,102	$ 2,060	$ 3,185
UNITED STATES
Revenue	144	274	395	527
Non-US [Member]
Revenue	850	828	1,665	2,658
Systems [Member]
Revenue	0	0	0	924
Systems [Member] | UNITED STATES
Revenue	0	0	0	3
Systems [Member] | Non-US [Member]
Revenue	0	0	0	921
Instruments and Accessories [Member]
Revenue	254	363	601	802
Instruments and Accessories [Member] | UNITED STATES
Revenue	18	79	82	141
Instruments and Accessories [Member] | Non-US [Member]
Revenue	236	284	519	661
Service [Member]
Revenue	424	406	732	785
Service [Member] | UNITED STATES
Revenue	75	104	149	202
Service [Member] | Non-US [Member]
Revenue	349	302	583	583
Lease [Member]
Revenue	316	333	727	674
Lease [Member] | UNITED STATES
Revenue	51	91	164	181
Lease [Member] | Non-US [Member]
Revenue	$ 265	$ 242	$ 563	$ 493