Revenue, Gross Profit and Gross Profit Margin by Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 03, 2015	Jun. 27, 2014	Jul. 03, 2015	Jun. 27, 2014
Segment Reporting Information [Line Items]
Revenue	$ 96,494	$ 96,905	$ 191,108	$ 176,038
Gross Profit	$ 41,345	$ 38,651	$ 81,351	$ 70,756
Gross profit margin percentage	42.80%	39.90%	42.60%	40.20%
Laser Products
Segment Reporting Information [Line Items]
Revenue	$ 42,190	$ 43,828	$ 87,145	$ 85,688
Gross Profit	$ 18,950	$ 17,155	$ 38,325	$ 34,168
Gross profit margin percentage	44.90%	39.10%	44.00%	39.90%
Vision Technologies
Segment Reporting Information [Line Items]
Revenue	$ 31,216	$ 34,791	$ 62,327	$ 57,158
Gross Profit	$ 12,158	$ 13,838	$ 24,671	$ 22,727
Gross profit margin percentage	38.90%	39.80%	39.60%	39.80%
Precision Motion
Segment Reporting Information [Line Items]
Revenue	$ 23,088	$ 18,286	$ 41,636	$ 33,192
Gross Profit	$ 10,611	$ 7,949	$ 19,076	$ 14,365
Gross profit margin percentage	46.00%	43.50%	45.80%	43.30%
Unallocated Corporate and Shared Services
Segment Reporting Information [Line Items]
Gross Profit	$ (374)	$ (291)	$ (721)	$ (504)