Revenue (Tables)

3 Months Ended

Mar. 28, 2020

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue from Contracts with Customers

The following tables represent a disaggregation of revenue from contracts with customers for the three months ended March 28, 2020 and March 30, 2019 along with the reportable segment for each category.

Major Products and Service Lines

TFE	Three Months Ended March 28, 2020								Three Months Ended March 30, 2019
	(In thousands)
	HDD		DCP		PV		Total		HDD		DCP		PV		Total
Systems, upgrades and spare parts	$	6,361	$	—	$	208	$	6,569	$	11,050	$	—	$	6,373	$	17,423
Field service		1,393		—		—		1,393		1,522		—		—		1,522
Total TFE net revenues	$	7,754	$	—	$	208	$	7,962	$	12,572	$	—	$	6,373	$	18,945

	Three Months Ended
Photonics	March 28, 2020		March 30, 2019
	(In thousands)
Products:
Military products	$	5,365	$	1,813
Commercial products		79		318
Repair and other services		430		561
Total Photonics product net revenues		5,874		2,692
Technology development:
Firm Fixed Price (“FFP”)		4,430		1,692
Cost Plus Fixed Fee (“CPFF”)		574		1,496
Time and materials		—		2
Total technology development net revenues		5,004		3,190
Total Photonics net revenues	$	10,878	$	5,882

Primary Geographical Markets

	Three Months Ended
	March 28, 2020						March 30, 2019
	(In thousands)
	TFE		Photonics		Total		TFE		Photonics		Total
United States	$	519	$	10,856	$	11,375	$	161	$	5,716	$	5,877
Asia		7,443		—		7,443		18,784		—		18,784
Europe		—		22		22		—		166		166
Total net revenues	$	7,962	$	10,878	$	18,840	$	18,945	$	5,882	$	24,827

Timing of Revenue Recognition

	Three Months Ended
	March 28, 2020						March 30, 2019
	(In thousands)
	TFE		Photonics		Total		TFE		Photonics		Total
Products transferred at a point in time	$	7,962	$	430	$	8,392	$	18,945	$	561	$	19,506
Products and services transferred over time		—		10,448		10,448		—		5,321		5,321
	$	7,962	$	10,878	$	18,840	$	18,945	$	5,882	$	24,827

Changes in Contract Assets and Contract Liabilities

The following table reflects the changes in our contract assets, which we classify as accounts receivable, unbilled or retainage, and our contract liabilities, which we classify as deferred revenue and customer advances, for the three months ended March 28 2020.

	March 28, 2020		December 28, 2019		Three Months Change
	(In thousands)
TFE:
Contract assets:
Accounts receivable, unbilled	$	—	$	760	$	(760	)
Contract liabilities:
Deferred revenue	$	486	$	320	$	166
Customer advances		4,696		4,007		689
	$	5,182	$	4,327	$	855
Photonics:
Contract assets:
Accounts receivable, unbilled	$	6,187	$	3,210	$	2,977
Retainage		103		99		4
	$	6,290	$	3,309	$	2,981