| 摘要 |
<p>An information storage medium (1) has a base portion (2) and a code storage portion (3). The code storage portion (3) is disposed on the base portion (2) and contains an infrared absorber which absorbs substantially only infrared rays within a narrow wavelength band. If a real information storage medium (1) is produced like that, subject mediums (1, 11) are judged real or not by a method including the steps of emitting rays to the subject medium (1, 11) , receiving rays reflected from the subject medium (1, 11), detecting a first reflectance at the peak absorption wavelength ( lambda 0) and a second reflectance at a comparison wavelength ( lambda 1) near the peak wavelength ( lambda 0), and judging if the subject medium (1, 11) is real or not. The rays at the comparison wavelength ( lambda 1) are not very much absorbed by the absorber. <IMAGE> <IMAGE></p> |
