Patent ID: 6229619
Filing Date: 2001-05-08
Classification: G01B

Abstract:
A method for compensating for measurement error due to refractive index variations in a measurement environment, said method comprising the steps of:providing a first source of radiation and a second source of radiation, said first source of radiation and said second source of radiation being separated by a first predetermined distance;irradiating a first target location with radiation from said first source of radiation through said refractive index variations in said measurement environment;irradiating a second target location with radiation from said second source of radiation through said refractive index variations in said measurement environment, said second target location separated from said first target location by a second predetermined distance;combining said radiation from said first and second target locations to generate optical interference at a third target location; anddetecting radiation at said third target location to generate a signal having substantially reduced measurement error due to said refractive index variations in said measurement environment.