Information for Each Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Jan. 02, 2016	Oct. 03, 2015	Jul. 04, 2015	Apr. 04, 2015	Dec. 31, 2016	Jan. 02, 2016	Jan. 03, 2015
Segment Reporting Information [Line Items]
Total segment net revenues	$ 28,982	$ 22,559	$ 14,918	$ 13,664	$ 16,398	$ 18,418	$ 20,458	$ 19,885	$ 80,124	$ 75,160	$ 65,550
Operating loss									(7,563)	(8,738)	(19,354)
Interest income									195	179	179
Other income and expense, net									178	(52)	158
Loss before income taxes									(7,190)	(8,611)	(19,017)
Thin-film Equipment Segment
Segment Reporting Information [Line Items]
Total segment net revenues									45,253	39,622	25,290
Photonics
Segment Reporting Information [Line Items]
Total segment net revenues									34,871	35,538	40,260
Operating Segments
Segment Reporting Information [Line Items]
Operating loss									(2,496)	(4,139)	(13,076)
Operating Segments | Thin-film Equipment Segment
Segment Reporting Information [Line Items]
Operating loss									(8,309)	(9,345)	(22,008)
Operating Segments | Photonics
Segment Reporting Information [Line Items]
Operating loss									5,813	5,206	8,932
Unallocated Amount to Segment
Segment Reporting Information [Line Items]
Unallocated costs									$ (5,067)	$ (4,599)	$ (6,278)