Segment Reporting - Assets for Each Reportable Segment (Detail) - USD ($) $ in Thousands	Jul. 03, 2021	Jan. 02, 2021
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets	$ 113,069	$ 127,238
Cash, cash equivalents and investments	53,340	49,568
Restricted cash	787	787
Deferred income taxes	5,537	5,335
Other current assets	1,083	1,093
Common property, plant and equipment	1,206	1,443
Common operating lease right-of-use assets	1,381	1,603
Other assets	164	151
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets	49,571	67,258
Operating Segments | TFE
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets	31,734	44,335
Operating Segments | Photonics
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets	$ 17,837	$ 22,923