Angle detecting apparatus for detecting angle of inclination of scanning mirror provided on michelson interferometer

摘要

A laser beam from a laser beam oscillator is guided to an incidence light path of a beam splitter of a Michelson interferometer by means of a first guide mirror, reflected by a fixed mirror and a scanning mirror of the Michelson interferometer, and returned to the beam splitter, thus obtaining an interference light beam. The interference laser beam is guided to first and second laser beam detectors by means of a second guide mirror to detect variations in intensity of the interference laser beam. On the basis of the variations in intensity of the interference laser beam, an angle of inclination ( theta ) of the scanning mirror is measured.