Geographic and Product Data (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 29, 2013	Mar. 30, 2012
Net sales	$ 18,001	$ 15,509
United States [Member]
Net sales	3,240	3,174
Japan [Member]
Net sales	4,739	3,857
Korea [Member]
Net sales	2,035	1,903
China [Member]
Net sales	2,071	2,106
Spain [Member]
Net sales	1,291	510
Others [Member]
Net sales	$ 4,625	$ 3,959