STOCK-BASED COMPENSATION - Stock-based Compensation (Details) (USD $)	3 Months Ended		6 Months Ended
	Jul. 01, 2012	Jul. 03, 2011	Jul. 01, 2012	Jul. 03, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 352,000	$ 675,000	$ 757,000	$ 1,403,000
Cost of Sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	17,000	22,000	32,000	56,000
Research, Development and Engineering
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	74,000	115,000	147,000	241,000
Selling, General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	261,000	538,000	578,000	1,106,000
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	343,000	640,000	732,000	1,320,000
Unrecognized stock-based compensation, related to stock options	3,100,000		3,100,000
Weighted average recognition period for stock-based compensation			2 years 10 months 24 days
Restricted Stock Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	4,000	30,000	15,000	68,000
Employee Stock Purchase Plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 5,000	$ 5,000	$ 10,000	$ 15,000