Information Concerning Product Lines, Geographic Information and Revenue Concentration - Schedule of Revenue by Shipment Destination (Details) - USD ($) $ in Thousands		3 Months Ended
	Mar. 31, 2019	Mar. 31, 2019	Apr. 01, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 3,194	$ 3,194	$ 2,764
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	1,431		921
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	1,163		1,565
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 600		278
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue		$ 953	$ 136
China | Total Revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Percentage of total revenue		30.00%	5.00%
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue		$ 434	$ 396
Japan | Total Revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Percentage of total revenue		14.00%	14.00%
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue		$ 1,100	$ 1,500
United States | Total Revenue
Revenues from External Customers and Long-Lived Assets [Line Items]
Percentage of total revenue		36.00%	56.00%