Patent ID: 6914682

Claim:
An interferometer comprising: a first light flux split optical system for splitting a laser light flux having a plurality of wavelengths into a measurement light flux illuminating an object to be measured and a reference light flux illuminating a reference surface; a multiplexing optical system for multiplexing the measurement light flux reflected by the object to be measured and the reference light flux reflected by the reference surface so as to obtain an interference signal; a second light flux split optical system for splitting a light flux multiplexed by the multiplexing optical system into plural light fluxes; a wavelength selecting optical system for extracting light fluxes, each of which has a wavelength different from each other light flux, from the plural light fluxes obtained by the second light flux split optical system; and photoelectric sensors, each of which (i) receives a respective light flux from the light fluxes selected by the wavelength selecting optical system, and (ii) outputs a signal which relates to the received, respective light flux.