Segment and Geographic Information - Information for Each Reportable Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018
Segment Reporting Information [Line Items]
Total segment net revenues	$ 108,885	$ 95,114
Operating income (loss)	3,925	(4,217)
Interest income	574	516
Other income (expense), net	8	106
Income (loss) before income taxes	4,507	(3,595)
TFE
Segment Reporting Information [Line Items]
Total segment net revenues	73,678	69,348
Photonics
Segment Reporting Information [Line Items]
Total segment net revenues	35,207	25,766
Operating Segments
Segment Reporting Information [Line Items]
Operating income (loss)	8,181	(895)
Operating Segments | TFE
Segment Reporting Information [Line Items]
Operating income (loss)	1,747	(1,335)
Operating Segments | Photonics
Segment Reporting Information [Line Items]
Operating income (loss)	6,434	440
Unallocated Amount to Segment
Segment Reporting Information [Line Items]
Unallocated costs	$ (4,256)	$ (3,322)