Note 1 - Summary of Significant Accounting Policies - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 25, 2021	Dec. 26, 2020
Net sales	$ 812,775	$ 887,214	$ 636,007
Semiconductor Test and Inspection [Member]
Net sales		860,454	585,240
PCB Test [Member]
Net sales		26,760	50,767
Systems [Member] | Semiconductor Test and Inspection [Member]
Net sales	474,655	541,589	317,821
Systems [Member] | PCB Test [Member]
Net sales	0	17,831	33,293
Non-systems [Member] | Semiconductor Test and Inspection [Member]
Net sales	338,120	318,865	267,419
Non-systems [Member] | PCB Test [Member]
Net sales	$ 0	$ 8,929	$ 17,474