Patent ID: 6122058
Filing Date: 2000-09-19
Classification: G01B

Abstract:
An interferometer system having at least one measuring axis, comprising:a measuring mirror;a reference mirror;a radiation source that provides a first coherent monochromatic beam having a first wavelength and a second coherent monochromatic beam having a second wavelength, the wavelength of the second beam being larger than the wavelength of the first beam by a factor of N, where N is an odd integer;a beam splitter having a quarter wavelength dependency that splits the first beam into a first measuring beam and a first reference beam and that guides the first measuring beam along a measuring path to said measuring mirror and that guides the first reference beam along a reference path to said reference mirror;said beam splitter splitting the second beam into a second measuring beam and a second reference beam, said beam splitter guiding the second measuring beam along the measuring path to the measuring mirror and guiding the second reference beam along the reference path to the reference mirror;a first displacement detector that detects a displacement of the measuring mirror based on an interference pattern formed by the first measuring beam reflected from the measuring mirror and the fist reference beam reflected from the reference mirror; anda second displacement detector that detects disturbances in the medium in which the first measuring beam propagates based on the first measuring beam and the second coherent monochromatic beam reflected by the measuring mirror.