Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Rate	Jun. 30, 2013 Rate
Segment Reporting Information [Line Items]
Revenues	$ 43,018	$ 46,059	$ 84,667	$ 87,709
Concentration Risk, Percentage			11.10%	10.80%
Inspection Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	22,852	26,829	40,853	51,708
Metrology Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	4,652	5,869	10,401	6,157
Lithography Revenue [Domain]
Segment Reporting Information [Line Items]
Revenues	0	0	3,657	3,700
Data Analysis & Review [Member]
Segment Reporting Information [Line Items]
Revenues	6,956	4,856	12,930	9,013
Sales Revenue, Goods, Net [Member]
Segment Reporting Information [Line Items]
Revenues	5,072	5,255	10,112	10,801
Sales Revenue, Services, Net [Member]
Segment Reporting Information [Line Items]
Revenues	3,486	3,250	6,714	6,330
Sales Revenue, Segment [Member]
Segment Reporting Information [Line Items]
Revenues	$ 43,018	$ 46,059	$ 84,667	$ 87,709
Sales [Member] | Percentage of Inspection Revenues [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	53.00%	58.00%	48.00%	59.00%
Sales [Member] | Percentage of Metrology Revenue [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	11.00%	13.00%	12.00%	7.00%
Sales [Member] | Percentage of Lithography Revenue [Member] [Domain]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	0.00%	0.00%	5.00%	4.00%
Sales [Member] | Percentage of Data Analysis & Review [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	16.00%	11.00%	15.00%	10.00%
Sales [Member] | Percentage of Parts [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	12.00%	11.00%	12.00%	13.00%
Sales [Member] | Percentage of Service [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	8.00%	7.00%	8.00%	7.00%
Sales [Member] | Percentage of Total Revenue [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%