Note 11 - Business Segment, Geographic and Concentration Risk Information - Sales by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jul. 01, 2016	Jun. 30, 2017	Jul. 01, 2016
Sales revenue, net	$ 7,223	$ 2,554	$ 12,263	$ 4,616
UNITED STATES
Sales revenue, net	5,601	1,163	9,371	1,827
SWITZERLAND
Sales revenue, net	586	724	1,059	1,270
GERMANY
Sales revenue, net	523	309	874	865
Rest of World [Member]
Sales revenue, net	$ 513	$ 358	$ 959	$ 654