STOCK-BASED COMPENSATION - Stock-based Compensation (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 399,000	$ 334,000	$ 1,085,000	$ 1,057,000
Cost of goods sold
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	12,000	16,000	23,000	42,000
Research, development and engineering
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	47,000	53,000	135,000	198,000
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	340,000	265,000	927,000	817,000
Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	244,000	293,000	740,000	959,000
Unrecognized stock-based compensation, related to stock options	1,500,000		1,500,000
Weighted average recognition period for stock-based compensation			2 years 6 months
Restricted stock units
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	143,000	36,000	309,000	83,000
Unrecognized stock-based compensation, related to stock options	1,400,000		1,400,000
Weighted average recognition period for stock-based compensation			3 years
Employee stock purchase plan
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation	$ 12,000	$ 5,000	$ 36,000	$ 15,000