Note 1 - Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 25, 2021

Notes Tables

Schedule of Inventory, Current [Table Text Block]

	September 25,		December 26,
	2021		2020
Raw materials and purchased parts	$	91,935	$	83,755
Work in process		44,952		44,315
Finished goods		20,625		14,430
Total inventories	$	157,512	$	142,500

Property, Plant and Equipment [Table Text Block]

	September 25,			December 26,
	2021			2020
Land and land improvements	$	7,875		$	8,141
Buildings and building improvements		26,749			41,153
Machinery and equipment		78,816			65,342
		113,440			114,636
Less accumulated depreciation and amortization		(48,282	)		(47,720	)
Property, plant and equipment, net	$	65,158		$	66,916

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

	Three Months Ended						Nine Months Ended
	September 25,			September 26,			September 25,			September 26,
	2021			2020			2021			2020
Cost of sales	$	239		$	218		$	692		$	641
Research and development		889			782			2,433			2,443
Selling, general and administrative		2,586			2,299			7,618			7,229
Total share-based compensation		3,714			3,299			10,743			10,313
Income tax benefit		(155	)		(215	)		(569	)		(610	)
Total share-based compensation, net	$	3,559		$	3,084		$	10,174		$	9,703

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

	Three Months Ended				Nine Months Ended
	September 25,		September 26,		September 25,		September 26,
	2021		2020		2021		2020
Weighted average common shares		48,666		41,947		46,992		41,764
Effect of dilutive securities		791		-		1,145		-
		49,457		41,947		48,137		41,764

Disaggregation of Revenue [Table Text Block]

	Three Months Ended				Nine Months Ended
Disaggregated Net Sales	September 25, 2021		September 26, 2020		September 25, 2021		September 26, 2020
Systems:
Semiconductor Test & Inspection	$	146,010	$	70,360	$	433,830	$	214,910
PCB Test		-		8,990		17,831		23,939
Non-systems:
Semiconductor Test & Inspection		79,053		66,865		234,764		181,756
PCB Test		-		4,432		8,929		13,047
Total net sales	$	225,063	$	150,647	$	695,354	$	433,652

	Three Months Ended				Nine Months Ended
Disaggregated Net Sales	September 25, 2021		September 26, 2020		September 25, 2021		September 26, 2020
China	$	60,205	$	30,423	$	171,653	$	92,367
Philippines		49,382		11,860		119,669		35,170
Taiwan		15,006		22,689		74,392		59,060
Malaysia		21,086		11,435		63,481		38,451
United States		15,498		32,111		57,435		71,739
Rest of the World		63,886		42,129		208,724		136,865
Total net sales	$	225,063	$	150,647	$	695,354	$	433,652

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

	Three Months Ended					Nine Months Ended
	September 25,			September 26,		September 25,			September 26,
	2021			2020		2021			2020
Semiconductor Test & Inspection
Customers individually accounting for more than 10% of net sales		two			*	one				one
Percentage of net sales		32	%		*		14	%		11	%
PCB Test
Customers individually accounting for more than 10% of net sales		N/A			*		*			*
Percentage of net sales		N/A			*		*			*