Note 13 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Net revenues	$ 32,558	$ 29,571	$ 64,477	$ 53,652
Earnings before income tax expense	3,365	2,570	6,759	3,225
Earnings before income tax expense	3,365	2,570	6,759	3,225
Acquired intangible amortization	(523)	(765)	(1,067)	(1,547)
Interest expense	176	141	358	278
Other income (expense)	197	(17)	255	(27)
Operating Segments [Member]
Net revenues	32,558	29,571	64,477	53,652
Earnings before income tax expense	6,176	5,832	12,443	9,251
Earnings before income tax expense	6,176	5,832	12,443	9,251
Operating Segments [Member] | Electronic Test [Member]
Net revenues	10,993	9,797	21,364	18,575
Earnings before income tax expense	2,641	2,193	5,219	4,080
Earnings before income tax expense	2,641	2,193	5,219	4,080
Operating Segments [Member] | Environmental Technologies [Member]
Net revenues	8,136	7,507	16,178	14,500
Earnings before income tax expense	943	1,070	1,956	1,872
Earnings before income tax expense	943	1,070	1,956	1,872
Operating Segments [Member] | Process Technologies [Member]
Net revenues	13,429	12,267	26,935	20,577
Earnings before income tax expense	2,592	2,569	5,268	3,299
Earnings before income tax expense	2,592	2,569	5,268	3,299
Corporate, Non-Segment [Member]
Earnings before income tax expense	(2,309)	(2,339)	(4,514)	(4,174)
Earnings before income tax expense	$ (2,309)	$ (2,339)	$ (4,514)	$ (4,174)