Displacement detection apparatus and drive control apparatus using the same

摘要

An apparatus for obtaining displacement information relative to a member (SC) is disclosed. The apparatus includes a light source (L1) for illuminating a phase type diffraction grating (GT1) on the member (SC), an amplitude type diffraction grating (GT2) arranged at the position where interference fringes are generated immediately after emerging of diffracted light from the phase type diffraction grating (GT1) illuminated by the light source (L1), and a light-receiving element (PD) for receiving light emerging from the amplitude type diffraction grating (GT2). The light-receiving element (PD) generates a periodic signal as displacement information upon relative movement of the member (SC).