| 摘要 |
PROBLEM TO BE SOLVED: To prevent an optical recording medium from being forged by an efficient and highly reliable authenticity judging method when judging authenticity of the optical recording medium. SOLUTION: An optical recording medium 1 provided with a computer hologram (CGH) 3 arranged in the peripheral part of a rainbow hologram 2, and a method for judging authenticity of the optical recording medium comprises making while light and monochromatic light incident on the rainbow hologram 2 and the computer hologram 3, respectively; switching between reflected light from the rainbow hologram 2 and the computer hologram 3 to receive the light reflected from either of the holograms by an imaging device 23; and judging the authenticity of the optical recording medium 1 from the picked up image data.
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