Brinks Hofer Gilson & Lione
Photo-electric position measuring system having a scanning grating with transverse graduations
 A scanning grating is provided in a photo-electric position measuring system and the scanning grating includes several grating areas. Each one of these grating areas has a transverse grating with a graduation period. The transverse gratings of the grating areas are disposed offset by TT/4 perpendicularly to the measuring direction, i.e., in the Y direction, with respect to each other. The partial light beams diffracted at the scanning grating in the +1st and -1st order lead to an intensity modulation at a defined scanning distance Z1. An amplitude grating is provided at the location of this intensity modulation, so that by means of downstream disposed photo-detectors a scanning signal is generated by the +1st diffraction order and a scanning signal, which is phase-shifted by 180.degree. with respect to the first, is generated by the -1st diffraction order. 
Dr. Johannes Heidenhain GmbH
Wolfgang
Holzapfel