Patent ID: 6885457
Filing Date: 2005-04-26
Classification: G01D

Abstract:
1. A rotary position measuring system in accordance with the interferential operating principle, comprising: a housing; a scanning unit connected with the housing and comprising a light source that emits beams of light and a detector element; a reflection scanning graduation structure arranged directly on the housing opposite the scanning unit; a graduated disk that is connected with a rotatable shaft and comprising a radial transmission measuring graduation structure, wherein the graduated disk is arranged so it is rotatable around an axis of symmetry in the housing so that the measuring graduation structure is located between the scanning unit and the scanning graduation structure; and wherein the beams of light emitted by the light source first reach the measuring graduation structure where they are transmitted via a graduation of the measuring graduation structure a first time and split into a first set of diffracted partial beams of different orders, the diffracted partial beams impinge on the scanning graduation structure, where under reflection a second set of diffracted partial beams of different orders results and a back-reflection of the second set of diffracted partial beams in the direction toward the measuring graduation structure results, so that in effect the beams of light emitted by the light source are transmitted a second time through the same graduation of the measuring graduation structure, subsequent to the first time, wherein the beams of light transmitted the second time are directed along a direction that is opposite to a direction of transmission of the beams of light transmitted the first time and where the second set of diffracted partial beams interfere with one another and the detection of interfering partial beams takes place by the detector element.