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	6 Months Ended
	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Customers individually accounting for more than 10% of net sales	1	1	1
One Customer [Member]
Percentage of net sales	12.00%	13.00%	12.00%