Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Rate	Sep. 30, 2013 Rate
Segment Reporting Information [Line Items]
Revenues	$ 46,960	$ 44,044	$ 131,627	$ 131,753
Concentration Risk, Percentage			7.40%	13.00%
Inspection Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	23,134	21,734	63,987	73,441
Metrology Revenue [Member]
Segment Reporting Information [Line Items]
Revenues	2,692	5,470	13,093	11,627
Lithography Revenue [Domain]
Segment Reporting Information [Line Items]
Revenues	7,304	3,618	10,961	7,318
Data Analysis & Review [Member]
Segment Reporting Information [Line Items]
Revenues	5,463	4,724	18,393	13,737
Sales Revenue, Goods, Net [Member]
Segment Reporting Information [Line Items]
Revenues	4,939	5,235	15,051	16,036
Sales Revenue, Services, Net [Member]
Segment Reporting Information [Line Items]
Revenues	3,428	3,263	10,142	9,594
Sales Revenue, Segment [Member]
Segment Reporting Information [Line Items]
Revenues	$ 46,960	$ 44,044	$ 131,627	$ 131,753
Sales [Member] | Percentage of Inspection Revenues [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	49.00%	49.00%	49.00%	55.00%
Sales [Member] | Percentage of Metrology Revenue [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	6.00%	12.00%	10.00%	9.00%
Sales [Member] | Percentage of Lithography Revenue [Member] [Domain]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	16.00%	8.00%	8.00%	6.00%
Sales [Member] | Percentage of Data Analysis & Review [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	12.00%	11.00%	14.00%	10.00%
Sales [Member] | Percentage of Parts [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	10.00%	12.00%	11.00%	13.00%
Sales [Member] | Percentage of Service [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	7.00%	8.00%	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%