OPTICAL ENCODER

摘要

An optical encoder comprises a light source, a first lattice consisting of an amplitude lattice having a first lattice pitch P1 and performing spatial amplitude modulation of light from the light source, a second lattice consisting of a phase lattice having a second lattice pitch P2 and performing spatial phase modulation of light from the first lattice, a third lattice consisting of an amplitude lattice having a third lattice pitch P3 and performing spatial amplitude modulation of light from the second lattice, and a light-receiving element for receiving light from the third lattice. The optical encoder detects relative movements among the lattices. With such an arrangement, the OTF from the light source to the light-receiving element is enhanced and utilization efficiency of light can be improved remarkably.