Operating Income (Loss) from Continuing Operations by Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2016	Jul. 03, 2015	Jul. 01, 2016	Jul. 03, 2015
Operating Income (Loss) from Continuing Operations
Operating Income (Loss) from Continuing Operations	$ 7,598	$ 10,315	$ 10,185	$ 15,712
Laser Products
Operating Income (Loss) from Continuing Operations
Operating Income (Loss) from Continuing Operations	9,663	10,046	16,519	18,441
Vision Technologies
Operating Income (Loss) from Continuing Operations
Operating Income (Loss) from Continuing Operations	(2,700)	(14)	(6,471)	(668)
Precision Motion
Operating Income (Loss) from Continuing Operations
Operating Income (Loss) from Continuing Operations	5,178	5,803	10,413	9,940
Unallocated Corporate and Shared Services
Operating Income (Loss) from Continuing Operations
Operating Income (Loss) from Continuing Operations	$ (4,543)	$ (5,520)	$ (10,276)	$ (12,001)