STOCKHOLDERS' EQUITY AND STOCK-BASED COMPENSATION - Expense Related to Employee Stock Options and Nonvested Restricted Common Stock Awards (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jun. 25, 2016	Jul. 01, 2017	Jun. 25, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 676,023	$ 894,599	$ 1,968,128	$ 951,053
Cost of product revenues
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	159,081	147,403	263,174	289,937
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	194,655	131,953	413,213	248,848
Selling, general and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 322,287	$ 615,243	$ 1,291,741	$ 412,268