Depreciation and Amortization 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
Depreciation and Amortization
Depreciation and amortization	$ 4,938	$ 4,623	$ 10,769	$ 9,385
Laser Products
Depreciation and Amortization
Depreciation and amortization	1,759	1,397	3,303	2,979
Vision Technologies
Depreciation and Amortization
Depreciation and amortization	2,301	2,082	5,401	4,340
Precision Motion
Depreciation and Amortization
Depreciation and amortization	628	689	1,242	1,162
Unallocated Corporate and Shared Services
Depreciation and Amortization
Depreciation and amortization	$ 250	$ 455	$ 823	$ 904