Note 10 - Segment and Geographic Information - Summary of Current Segments (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 28, 2025	Jun. 29, 2024	Jun. 28, 2025	Jun. 29, 2024
Net sales		$ 107,680	$ 104,701	$ 204,477	$ 212,315
Cost of sales	[1]	60,571	57,779	115,051	116,144
Research and development		23,188	21,342	46,340	43,678
Amortization of purchased intangible assets		10,081	9,748	19,933	19,543
Stock-based compensation		5,675	5,583	11,905	10,211
Loss before taxes		(14,831)	(14,483)	(40,797)	(30,818)
Semiconductor Test & Inspection Segment [Member]
Net sales		107,680	104,701	204,477	212,315
Cost of sales		60,173	57,517	114,327	115,655
Research and development		21,674	20,341	43,607	41,843
Selling		13,320	13,049	26,445	27,525
General & administrative		12,783	14,749	24,984	31,788
Amortization of purchased intangible assets		10,081	9,748	19,933	19,543
Stock-based compensation		5,675	5,583	11,905	10,211
Other segment items (1)	[2]	(1,195)	(1,803)	4,073	(3,432)
Loss before taxes		$ (14,831)	$ (14,483)	$ (40,797)	$ (30,818)

[1] Excludes amortization of purchased intangibles of $7,739 and $7,486 for the three months ended June 28, 2025, and June 29, 2024, respectively, and $15,298 and $15,008 for the six months ended June 28, 2025, and June 29, 2024, respectively.

[2] Other segment items include restructuring charges as well as miscellaneous non-operating items.