Patent ID: 9109869
Filing Date: 2015-08-18
Classification: G01B,G01J

Abstract:
1. An interferometer, comprising: a measurement optical system in which measurement light from a measurement light source is split by a beam splitter into light beams, which are guided to a movable mirror and to a stationary mirror, respectively, and the light beam reflected off the movable mirror and the light beam reflected off the stationary mirror are combined by the beam splitter into measurement interference light, which is guided to a measurement light photodetector; and a reference optical system in which reference light from a reference light source is split by the beam splitter into light beams, which are guided to the movable mirror and to the stationary mirror, respectively, and the light beam reflected off the movable mirror and the light beam reflected off the stationary mirror are combined by the beam splitter into reference interference light, which is guided to a reference light photodetector, the interferometer performing measurement of the measurement interference light while, based on a detection result of the reference light photodetector, detecting a position of the movable mirror, wherein