Revenue, Gross Profit, Gross Profit Margin and Operating Income (Loss) by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 02, 2021	Apr. 03, 2020
Segment Reporting Information [Line Items]
Revenue	$ 162,584	$ 155,468
Gross Profit	$ 68,740	$ 64,445
Gross profit margin percentage	42.30%	41.50%
Operating Income (Loss)	$ 11,099	$ 13,250
Operating Segments | Photonics
Segment Reporting Information [Line Items]
Revenue	58,493	55,140
Gross Profit	$ 28,109	$ 24,661
Gross profit margin percentage	48.10%	44.70%
Operating Income (Loss)	$ 12,395	$ 8,915
Operating Segments | Vision
Segment Reporting Information [Line Items]
Revenue	67,636	69,008
Gross Profit	$ 26,926	$ 26,575
Gross profit margin percentage	39.80%	38.50%
Operating Income (Loss)	$ 3,366	$ 5,634
Operating Segments | Precision Motion
Segment Reporting Information [Line Items]
Revenue	36,455	31,320
Gross Profit	$ 16,077	$ 13,908
Gross profit margin percentage	44.10%	44.40%
Operating Income (Loss)	$ 7,446	$ 6,538
Unallocated Corporate and Shared Services
Segment Reporting Information [Line Items]
Gross Profit	(2,372)	(699)
Operating Income (Loss)	$ (12,108)	$ (7,837)