Note 11 - Segment and Geographic Information - Summary of Current Segments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 28, 2024	Dec. 30, 2023	Dec. 31, 2022
Net sales		$ 401,779	$ 636,322	$ 812,775
Cost of sales (1)	[1]	221,485	333,454	429,449
Research and development		84,797	88,571	92,589
Amortization of purchased intangible assets		39,087	36,355	33,185
Share-based compensation of continuing operations		20,740	17,237	14,918
Income (loss) before taxes		(64,946)	45,816	126,715
Semiconductor Test & Inspection Segment [Member]
Net sales		401,779	636,322	812,775
Cost of sales (1)	[2]	220,436	332,609	428,803
Research and development		81,231	85,178	89,489
Selling		51,584	61,056	60,006
General and administrative		60,328	58,196	60,212
Amortization of purchased intangible assets		39,087	36,355	33,185
Share-based compensation of continuing operations		20,740	17,237	14,918
Other segment items	[2]	(6,681)	(125)	(553)
Income (loss) before taxes		$ (64,946)	$ 45,816	$ 126,715

[1] Excludes amortization of $30,008, $28,418, and $26,023 for the years ended December 28, 2024, December 30, 2023, and December 31, 2022, respectively.

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