Segment Reporting and Geographic Information (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Segment Reporting Information [Line Items]
Segment Reporting, Disclosure of Major Customers	.307	.043
Inspection Revenue [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	22,856,000	23,103,000
Percentage of Inspection Revenues [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	0.50	0.46
Metrology Revenue [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	10,237,000	12,182,000
Percentage of Metrology Revenue [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	0.22	0.24
Data Analysis & Review [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	4,547,000	6,147,000
Percentage of Data Analysis & Review [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	0.10	0.12
Sales Revenue, Goods, Net [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	5,504,000	6,240,000
Percentage of Parts [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	0.12	0.12
Sales Revenue, Services, Net [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	2,565,000	2,927,000
Percentage of Service [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	0.06	0.06
Sales [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	45,709,000	50,599,000
Percentage of Total Revenue [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Revenue for Reportable Segment	1.00	1.00
UNITED STATES
Segment Reporting Information [Line Items]
Segment Reporting, General Information	9355	12575
Taiwan [Domain]
Segment Reporting Information [Line Items]
Segment Reporting, General Information	8665	10148
JAPAN
Segment Reporting Information [Line Items]
Segment Reporting, General Information	1393	3877
CHINA
Segment Reporting Information [Line Items]
Segment Reporting, General Information	1913	6465
South Korea [Domain]
Segment Reporting Information [Line Items]
Segment Reporting, General Information	14492	5552
Other Asia [Member]
Segment Reporting Information [Line Items]
Segment Reporting, General Information	5104	2887
Austria [Domain]
Segment Reporting Information [Line Items]
Segment Reporting, General Information	2598	3001
GERMANY
Segment Reporting Information [Line Items]
Segment Reporting, General Information	373	3535
Segment, Geographical, Groups of Countries, Group Two [Member]
Segment Reporting Information [Line Items]
Segment Reporting, General Information	1816	2559
Sales [Member]
Segment Reporting Information [Line Items]
Segment Reporting, General Information	45709	50599
Major Customers Two [Domain]
Segment Reporting Information [Line Items]
Segment Reporting, Disclosure of Major Customers	.104	.124
Major Customer Three [Domain]
Segment Reporting Information [Line Items]
Segment Reporting, Disclosure of Major Customers	.06	.106