Note 1 - Summary of Significant Accounting Policies - Customer Concentration (Details) - Revenue Benchmark [Member] - Customer Concentration Risk [Member] - Semiconductor Test and Inspection [Member]	3 Months Ended	9 Months Ended
	Sep. 25, 2021	Sep. 25, 2021	Sep. 26, 2020
Customers individually accounting for more than 10% of net sales	2	1	1
Two Customers [Member]
Percentage of net sales	32.00%
One Customer [Member]
Percentage of net sales		14.00%	11.00%