Displacement measurement system

摘要

A displacement measurement apparatus includes a light source, a splitter grating, a measurement grating, and first a second detector arrays. The splitter grating splits a light beam into first and second measurement channels that each illuminates the measurement grating. The first and second measurement channels split into 0th and 1st order diffraction products at the measurement grating in a first pass and recombine at the measurement grating in a second pass before being measured at the first and second detector arrays.