Stock-Based Compensation (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Sep. 29, 2012	Oct. 01, 2011
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	$ 1,482	$ 970	$ 4,535	$ 2,746
Cost of Products [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	50	45	128	111
Cost of Service [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	62	51	195	146
Research and development [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	289	221	952	589
Selling [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	451	264	1,374	790
General and administrative [Member]
Stock-based compensation expense for all share-based payment awards
Total stock-based compensation expense	$ 630	$ 389	$ 1,886	$ 1,110