STOCK-BASED COMPENSATION - Stock-based Compensation (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jul. 01, 2012	Jun. 30, 2013	Jul. 01, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 346,000	$ 352,000	$ 723,000	$ 757,000
Cost of Sales
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	9,000	17,000	26,000	32,000
Research, Development and Engineering
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	70,000	74,000	145,000	147,000
Selling, General and Administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	267,000	261,000	552,000	578,000
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	309,000	343,000	666,000	732,000
Unrecognized stock-based compensation, related to stock options	2,100,000		2,100,000
Weighted average recognition period for stock-based compensation			2 years 2 months 13 days
Restricted Stock Units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	32,000	4,000	47,000	15,000
Unrecognized stock-based compensation, related to stock options	400,000		400,000
Weighted average recognition period for stock-based compensation			3 years 7 months 9 days
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	$ 10,000