Patent ID: 9062957
Filing Date: 2015-06-23
Classification: G01B

Abstract:
1. A multi-wavelength interferometer using at least two light fluxes each having a different wavelength, the multi-wavelength interferometer comprising: a beam splitter configured to split the light fluxes into a reference beam and a measurement beam; a frequency shifter configured to shift a frequency of the reference beam or a frequency of the measurement beam or to shift the frequencies of the reference beam and the measurement beam to make the frequencies of the reference beam and the measurement beam different from each other; an optical system configured to cause the measurement beam to be incident on a measurement surface and to cause the measurement beam reflected from the measurement surface to interfere with the reference beam to obtain interference light, the frequencies of the reference beam and the measurement beam being different from each other by the frequency shifter; a wavefront dividing unit configured to divide a wavefront of the interference light into wavefronts of a plurality of light beams; and a detection unit configured to detect the plurality of light beams divided by the wavefront dividing unit for each wavelength.