Revenue Concentrations, Significant Customers, and Geographic Areas (Summary Of Revenue By Product Line) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Concentration Risk [Line Items]
Revenues	$ 12,391	$ 16,683	$ 42,411	$ 46,657
High Precision 3D and 2D Sensors [Member]
Concentration Risk [Line Items]
Revenues	3,170	5,388	8,923	15,696
Semiconductor Sensors [Member]
Concentration Risk [Line Items]
Revenues	3,676	3,463	10,934	10,564
Inspection and Metrology Systems [Member]
Concentration Risk [Line Items]
Revenues	$ 5,545	$ 7,832	$ 22,554	$ 20,397