Note 3 - Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Revenue	$ 976	$ 1,066
UNITED STATES
Revenue	206	251
Non-US [Member]
Revenue	770	815
Systems [Member]
Revenue	0	0
Systems [Member] | UNITED STATES
Revenue	0	0
Systems [Member] | Non-US [Member]
Revenue	0	0
Instruments and Accessories [Member]
Revenue	293	347
Instruments and Accessories [Member] | UNITED STATES
Revenue	60	64
Instruments and Accessories [Member] | Non-US [Member]
Revenue	233	283
Service [Member]
Revenue	195	308
Service [Member] | UNITED STATES
Revenue	75	74
Service [Member] | Non-US [Member]
Revenue	120	234
Lease [Member]
Revenue	488	411
Lease [Member] | UNITED STATES
Revenue	71	113
Lease [Member] | Non-US [Member]
Revenue	$ 417	$ 298