Stockholders' Equity and Stock-Based Compensation (Tables)

6 Months Ended

Jun. 27, 2015

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock options valuation assumptions

	Three Months Ended		Six Months Ended
	June 27, 2015	June 28, 2014	June 27, 2015	June 28, 2014
Stock Options:
Expected life	—	4.6 years	—	4.6 years
Volatility	—	52.0%	—	54.9%
Risk free interest rate	—	1.56%	—	1.54%
Dividends	—	—	—	—
Employee Stock Purchase Plan:
Expected life	0.5 years	0.5 years	0.5 years	0.5 years
Volatility	37.2%	32.6%	37.2%	32.6%
Risk free interest rate	0.11%	1.00%	0.11%	1.00%
Dividends	—	—	—	—

Employee stock purchase plan valuation assumptions

	Three Months Ended		Six Months Ended
	June 27, 2015	June 28, 2014	June 27, 2015	June 28, 2014
Stock Options:
Expected life	—	4.6 years	—	4.6 years
Volatility	—	52.0%	—	54.9%
Risk free interest rate	—	1.56%	—	1.54%
Dividends	—	—	—	—
Employee Stock Purchase Plan:
Expected life	0.5 years	0.5 years	0.5 years	0.5 years
Volatility	37.2%	32.6%	37.2%	32.6%
Risk free interest rate	0.11%	1.00%	0.11%	1.00%
Dividends	—	—	—	—

Stock option plans activity

A summary of activity of stock options during the six months ended June 27, 2015 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 27, 2014	1,382,993		$	13.92	3.41	$	4,108
Exercised	(152,882	)	10.82
Cancelled	(30,790	)	16.08
Outstanding at June 27, 2015	1,199,321		$	14.27	2.90	$	3,227
Exercisable at June 27, 2015	997,952		$	13.86	2.48	$	3,062

Summary of activity for RSUs

A summary of activity for RSUs is as follows:

RSUs	Number of RSUs		Weighted Average Fair Value
Outstanding RSUs as of December 27, 2014	563,337		$	17.90
Granted	365,539		16.04
Released	(203,429	)	17.01
Cancelled	(47,592	)	17.31
Outstanding RSUs as of June 27, 2015	677,855		$	17.21

PSUs valuation assumptions

The assumptions for the valuation of PSUs are summarized as follows:

	2015 Award
Number of PSUs granted and outstanding as of June 27, 2015	40,000
Grant Date Fair Value Per Share	$	18.35
Weighted-average assumptions/inputs:
Expected Dividend	—
Range of risk-free interest rates	0.25%-1.1%
Range of expected volatilities for peer group	23%-65%

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 were as follows (in thousands):

	For the Three Months Ended				For the Six Months Ended
	June 27, 2015		June 28, 2014		June 27, 2015		June 28, 2014
Cost of products	$	60	$	68	$	132	$	129
Cost of service	45		89		91		174
Research and development	215		296		496		636
Selling	393		437		892		863
General and administrative	698		886		1,371		1,608
Total stock-based compensation expense	$	1,411	$	1,776	$	2,982	$	3,410