METHOD FOR POSITION AND/OR ANGLE MEASUREMENT BY MEANS OF GRATINGS

摘要

The present invention relates to an optical measurement device, comprising first phase grating (G1) and second phase grating (G2), a light source (L), and at least two optical detectors. The first phase grating (G1) is arranged to be reproduced on said second phase grating (G2) upon illumination with the light source (L), which reproduction is coherently achieved, so that periods of the image of the first phase grating (G1) and the second phase grating (G2) are in an integral relationship with respect to one another, and so that the grating lines of the image of one grating and the other grating are parallel. A relative positional displacement between the image of one phase grating on the other phase grating is registered by said at least two optical detectors.