Revenue - Primary Geography Markets (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Total net revenues	$ 24,827	$ 17,974
Products Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Total net revenues	19,506	13,218
Products and Services Transferred Over Time
Disaggregation of Revenue [Line Items]
Total net revenues	5,321	4,756
United States
Disaggregation of Revenue [Line Items]
Total net revenues	5,877	6,673
Asia
Disaggregation of Revenue [Line Items]
Total net revenues	18,784	10,878
Europe
Disaggregation of Revenue [Line Items]
Total net revenues	166	293
Rest of World
Disaggregation of Revenue [Line Items]
Total net revenues		130
TFE
Disaggregation of Revenue [Line Items]
Total net revenues	18,945	12,789
TFE | Products Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Total net revenues	18,945	12,789
TFE | United States
Disaggregation of Revenue [Line Items]
Total net revenues	161	1,911
TFE | Asia
Disaggregation of Revenue [Line Items]
Total net revenues	18,784	10,878
Photonics
Disaggregation of Revenue [Line Items]
Total net revenues	5,882	5,185
Photonics | Products Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Total net revenues	561	429
Photonics | Products and Services Transferred Over Time
Disaggregation of Revenue [Line Items]
Total net revenues	5,321	4,756
Photonics | United States
Disaggregation of Revenue [Line Items]
Total net revenues	5,716	4,762
Photonics | Asia
Disaggregation of Revenue [Line Items]
Total net revenues
Photonics | Europe
Disaggregation of Revenue [Line Items]
Total net revenues	166	293
Photonics | Rest of World
Disaggregation of Revenue [Line Items]
Total net revenues		$ 130