Apparatus for reducing Moire effects in optical identification of structural elements esp. encoded information using pseudo periodicity length and detection periodicity length

摘要

The apparatus has imaging means and detection means (3) with several components (3a) having at least a detection periodicity length in one direction. An optical element can be brought into the beam path between an object and the detection means. An image is formed of optically identifiable structural elements (2) on the object, having a structural element periodicity length. The optical element causes distortion of the image periodicity length to a pseudo periodicity length so that the ratio of pseudo length to detection length is location dependent. Independent claims also cover a digital leveller having such an apparatus.