Note 1 - Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 24, 2022

Notes Tables

Schedule of Inventory, Current [Table Text Block]

	September 24,		December 25,
	2022		2021
Raw materials and purchased parts	$	98,440	$	92,798
Work in process		41,352		40,732
Finished goods		25,452		27,523
Total inventories	$	165,244	$	161,053

Property, Plant and Equipment [Table Text Block]

	September 24,			December 25,
	2022			2021
Land and land improvements	$	6,439		$	7,703
Buildings and building improvements		29,479			31,711
Machinery and equipment		100,911			95,542
		136,829			134,956
Less accumulated depreciation and amortization		(75,040	)		(70,999	)
Property, plant and equipment, net	$	61,789		$	63,957

Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Months Ended						Nine Months Ended
	September 24,			September 25,			September 24,			September 25,
	2022			2021			2022			2021
Cost of sales	$	161		$	239		$	478		$	692
Research and development		755			889			2,333			2,433
Selling, general and administrative		2,824			2,586			8,284			7,618
Total share-based compensation		3,740			3,714			11,095			10,743
Income tax benefit		(770	)		(155	)		(3,232	)		(569	)
Total share-based compensation, net	$	2,970		$	3,559		$	7,863		$	10,174

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Three Months Ended				Nine Months Ended
	September 24,		September 25,		September 24,		September 25,
	2022		2021		2022		2021
Weighted average common shares		47,984		48,666		48,412		46,992
Effect of dilutive securities		542		791		596		1,145
		48,526		49,457		49,008		48,137

Disaggregation of Revenue [Table Text Block]

	Three Months Ended				Nine Months Ended
Disaggregated Net Sales	September 24, 2022		September 25, 2021		September 24, 2022		September 25, 2021
Systems:
Semiconductor Test & Inspection	$	120,672	$	146,010	$	369,972	$	433,830
PCB Test		-		-		-		17,831
Non-systems:
Semiconductor Test & Inspection		86,015		79,053		251,698		234,764
PCB Test		-		-		-		8,929
Total net sales	$	206,687	$	225,063	$	621,670	$	695,354

	Three Months Ended				Nine Months Ended
Disaggregated Net Sales	September 24, 2022		September 25, 2021		September 24, 2022		September 25, 2021
China	$	31,477	$	60,205	$	116,715	$	171,653
Philippines		38,852		49,382		84,799		119,669
Malaysia		24,060		21,086		73,033		63,481
United States		19,510		15,498		62,826		57,435
Taiwan		11,243		15,006		46,620		74,392
Rest of the World		81,545		63,886		237,677		208,724
Total net sales	$	206,687	$	225,063	$	621,670	$	695,354

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

	Three Months Ended		Nine Months Ended
	September 24,	September 25,	September 24,	September 25,
	2022	2021	2022	2021
Semiconductor Test & Inspection
Customers individually accounting for more than 10% of net sales	one	two	*	one
Percentage of net sales	13%	32%	*	14%
PCB Test
Customers individually accounting for more than 10% of net sales	N/A	N/A	N/A	*
Percentage of net sales	N/A	N/A	N/A	*