Device for measurement of the torsional angular deviation of a loaded rotating or static shaft

摘要

A torsional angular deviation measuring device comprising a first diffraction grating which is placed at one end of a shaft and a second diffraction grating placed at the other end or at least some distance from the first end. A beam of light from a light source is then passed through the first diffraction grating generating zeroth order and other order beams. The beams are thence passed through collimating optics and then through the second diffraction grating. The beams from the second diffraction grating are sensed by split photodiodes and the amount of angular deviation is then measured by comparing the phases of pulse trains generated from the different photodiodes with one another.