Revenue - Primary Geography Markets (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Disaggregation of Revenue [Line Items]
Total net revenues	$ 28,842	$ 22,314	$ 47,682	$ 47,141
Products Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Total net revenues	17,240	14,074	25,632	33,580
Products and Services Transferred Over Time
Disaggregation of Revenue [Line Items]
Total net revenues	11,602	8,240	22,050	13,561
United States
Disaggregation of Revenue [Line Items]
Total net revenues	12,438	9,167	23,813	15,044
Asia
Disaggregation of Revenue [Line Items]
Total net revenues	16,282	12,908	23,725	31,692
Europe
Disaggregation of Revenue [Line Items]
Total net revenues	122	239	144	405
TFE
Disaggregation of Revenue [Line Items]
Total net revenues	16,595	13,264	24,557	32,209
TFE | Products Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Total net revenues	16,595	13,264	24,557	32,209
TFE | United States
Disaggregation of Revenue [Line Items]
Total net revenues	313	356	832	517
TFE | Asia
Disaggregation of Revenue [Line Items]
Total net revenues	16,282	12,908	23,725	31,692
Photonics
Disaggregation of Revenue [Line Items]
Total net revenues	12,247	9,050	23,125	14,932
Photonics | Products Transferred at a Point in Time
Disaggregation of Revenue [Line Items]
Total net revenues	645	810	1,075	1,371
Photonics | Products and Services Transferred Over Time
Disaggregation of Revenue [Line Items]
Total net revenues	11,602	8,240	22,050	13,561
Photonics | United States
Disaggregation of Revenue [Line Items]
Total net revenues	12,125	8,811	22,981	14,527
Photonics | Asia
Disaggregation of Revenue [Line Items]
Total net revenues
Photonics | Europe
Disaggregation of Revenue [Line Items]
Total net revenues	$ 122	$ 239	$ 144	$ 405