Patent attributes
Position detection apparatus comprises: an incident unit that forms a parallel beam from a light beam of a light source and supplies the parallel beam to a beam splitter in a way that the separated beams, obtained from the parallel beam by the beam splitter, are respectively incident upon the reference surface and the measurement target surface at an angle; and a reflection unit that reflects the separated beams, which have been reflected by the reference surface and the measurement target surface and integrated to a light path by the beam splitter, to be supplied to the beam splitter as a parallel beam along the light path, and generates a signal corresponding to a phase difference of the separated beams by interfering a light beam that has been supplied from the reflection unit, separated by the beam splitter, reflected by the reference surface and the measurement target surface, and integrated again to a light path by the beam splitter.
