Method for validation of a hologram and reader for carrying out this method

摘要

The method involves illuminating the hologram (1) with a reconstruction beam (2). The image of the first order diffraction beam of the wave field at the hologram is formed on a first light sensitive element, esp. a CCD target (5), and brought into interference with a first reference beam (7). The image of the zero order diffraction beam (4) is formed on a second light sensitive element (6) and brought into interference with a second reference beam (10). The intensity distributions on both light sensitive elements are correlated for at least two phase relations between the reconstruction beam and each reference beam to produce a correlation intensity distribution for each diffraction order. The correlation intensity distributions for each diffraction order are correlated, especially subtracted by pixel.