METHOD FOR INSPECTING TRUTH OF HOLOGRAM AND READING DEVICE USED FOR EXECUTING IT

摘要

PROBLEM TO BE SOLVED: To provide a method for easily judging whether a hologram being attached to a projecting or recessed base is true or not. SOLUTION: A restoration beam 2 is applied to a hologram 1 to be inspected. The image of a primary diffraction beam 3 of a wave field being generated at the hologram 1 is formed on a first light-sensitive element, especially a CCD target 5, and at the same time is allowed to interfere with a first reference beam 10. Intensity distributions being generated at the mutually different light- sensitive elements 5 and 6 are mutually correlated regarding at least two phase relationships between the restoration beam 2 and mutually different reference beams 7 and 10, thus obtaining a correlated intensity distribution for the related diffraction order. The correlation intensity distributions that are determined for the related diffraction order are mutually correlated, and a subtraction is made for each pixel one another.