A device for positioning encoding of a rotating shaft in which a polygonal mirror having a number of facets is mounted to the shaft and a light beam is directed towards the facets. The facets of the polygonal mirror reflect the light beam such that a light spot is created on a linear array detector....http://www.google.fr/patents/US5329121?utm_source=gb-gplus-shareBrevet US5329121 - Rotary encoding device with polygonal reflector and centroid detection
Rotary encoding device with polygonal reflector and centroid detection
