PRINTED MATERIAL WITH OPTICAL DIFFRACTION IMAGE AND DEVICE FOR JUDGING AUTHENTICITY OF THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a hologram which has complicated contents and makes forgery more difficult, a printed product which uses the hologram and a device to judge the authenticity of the printed product. SOLUTION: The optical diffraction image is obtained by forming at least one visible pattern and two or more invisible patterns giving different forms from each other on a plane in one region. The invisible patterns contain at least one pair of such patterns that the irradiation angles of reproducing light to reproduce the patterns differ by 90 deg. from each other.