A rotary position measuring system having a housing connected with a scanning
unit
having 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 is connected with a rotatable shaft and has 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.
The beams of light emitted by the light source first reach the measuring graduation
structure where they are split into a first set of diffracted partial beams of
different orders and the diffracted partial beams impinge on the scanning graduation
structure. 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, 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.
