Equity and Stock Based Compensation Plans (Tables)

6 Months Ended

Jun. 28, 2014

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

The fair value of each option award is estimated on the date of grant using the Black-Scholes valuation model and the assumptions noted in the following table. The expected life of options granted was calculated using the simplified method. The risk-free rate is based on the U.S. Treasury rates in effect during the corresponding period of grant. The expected volatility is based on the historical volatility of the Company's stock price. The dividend yield reflects that the Company has not paid any cash dividends since inception and does not intend to pay any cash dividends in the foreseeable future.



	Three Months Ended				Six Months Ended
	June 28, 2014		June 29, 2013		June 28, 2014		June 29, 2013
Stock Options
Expected life	4.6 years		4.6 years		4.6 years		4.5 years
Expected volatility	52.00	%	68.90	%	54.86	%	72.32	%
Risk-free interest rate	1.56	%	1.02	%	1.54	%	0.90	%
Dividends	—		—		—		—
Employee Stock Purchase Plan
Expected life	0.5 years		0.5 years		0.5 years		0.5 years
Expected volatility	32.60	%	25.94	%	32.60	%	27.61	%
Risk-free interest rate	1.00	%	0.10	%	1.00	%	0.11	%
Dividends	—		—		—		—

Stock-based compensation expense for all share-based payment awards

Stock-based compensation expense for all share-based payment awards made to the Company’s employees and directors pursuant to the employee stock option and employee stock purchase plans by function was as follows (in thousands):



	Three Months Ended				Six Months Ended
	June 28, 2014		June 29, 2013		June 28, 2014		June 29, 2013
Cost of products	$	68	$	53	$	129	$	98
Cost of service	89		71		174		130
Research and development	296		362		636		679
Selling	437		501		863		941
General and administrative	886		764		1,608		1,360
Total stock-based compensation expense	$	1,776	$	1,751	$	3,410	$	3,208

Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock option plans activity

A summary of activity under the Company’s stock option plans during the six months ended June 28, 2014 is as follows:



	Number of Shares Outstanding (Options)		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value (in Thousands)
Options:
Outstanding at December 28, 2013	1,909,039		$	13.22	4.02	$	10,341
Exercised	(327,466	)	$	10.39
Granted	74,300		$	17.56
Cancelled	(70,688	)	$	15.42
Outstanding at June 28, 2014	1,585,185		$	13.91	3.96	$	7,139
Exercisable at June 28, 2014	1,028,377		$	12.73	3.17	$	5,840

Restricted Stock Units (RSUs) [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock option plans activity

A summary of activity for RSUs during the six months ended June 28, 2014, is as follows:



	Number of RSUs		Weighted Average Fair Value
Outstanding RSUs at December 28, 2013	334,444		$	18.61
Granted	385,385		$	17.65
Released	(134,858	)	$	17.91
Cancelled	(15,246	)	$	17.51
Outstanding RSUs at June 28, 2014	569,725		$	18.37