STOCK-BASED COMPENSATION - Stock-based Compensation (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 29, 2014	Jun. 30, 2013	Jun. 29, 2014	Jun. 30, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 387,000	$ 346,000	$ 685,000	$ 723,000
Cost of goods sold
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	8,000	9,000	11,000	26,000
Research, development and engineering
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	47,000	70,000	87,000	145,000
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	332,000	267,000	587,000	552,000
Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	249,000	309,000	496,000	666,000
Unrecognized stock-based compensation, related to stock options	1,700,000		1,700,000
Weighted average recognition period for stock-based compensation			2 years 7 months 6 days
Restricted stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	126,000	32,000	165,000	47,000
Unrecognized stock-based compensation, related to stock options	1,400,000		1,400,000
Weighted average recognition period for stock-based compensation			3 years 3 months 18 days
Employee stock purchase plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 12,000	$ 5,000	$ 24,000	$ 10,000