| 摘要 |
PURPOSE:To surely identify whether an information recording medium is genuine or not by viewing by forming a hologram on a substrate. CONSTITUTION:An optical disk is formed of a transparent substrate 6 consisting of glass, etc., information bits 7 formed on this substrate 6, a reflection layer 8, a protective layer 9, etc. The hologram 5 is formed as plural pieces of ruggedness of a depth smaller than the depth of the bits 7 on the substrate 6 of the non-information region 3 of this disk 1. The hologram 5 is not read by coherent light for reading the bit 7 information and is not reproduced. Then, whether the optical disk, etc., are genuine or not is always identified when the hologram 5 image is viewed, unlike the case of sticking a peelable hologram to the disk. |
