Amortizable Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	Jun. 28, 2013	Dec. 28, 2012
Amortized intangible assets:
Amortizable intangible assets, Gross Carrying Amount	$ 13,301	$ 13,787
Amortizable intangible assets, Accumulated Amortization	(11,612)	(11,645)
Amortizable intangible assets, Net	1,689	2,142
Patents and Licenses [Member]
Amortized intangible assets:
Amortizable intangible assets, Gross Carrying Amount	10,685	10,786
Amortizable intangible assets, Accumulated Amortization	(9,961)	(9,875)
Amortizable intangible assets, Net	724	911
Customer Relationships [Member]
Amortized intangible assets:
Amortizable intangible assets, Gross Carrying Amount	1,600	1,835
Amortizable intangible assets, Accumulated Amortization	(880)	(917)
Amortizable intangible assets, Net	720	918
Developed technology [Member]
Amortized intangible assets:
Amortizable intangible assets, Gross Carrying Amount	1,016	1,166
Amortizable intangible assets, Accumulated Amortization	(771)	(853)
Amortizable intangible assets, Net	$ 245	$ 313