| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical recording medium which is hardly forged and which has brilliant appearance and high quality by forming the medium of an assembly of recording pits which generate phase difference to constitute visible information so that the information can be visually recognized by the reflection of diffracted light due to the phase difference. SOLUTION: Visible information consisting of an assembly of recording pits is arranged in the optical recording region of an optical card. The visible information consists of recording pits 13 which generate phase difference. As for the method to produce the phase difference, for example, a method to change the inner form of the recording pits or a method to change the refractive index of the recording pits can be used. By forming the visible information from the assembly of recording pits 13 which generate phase difference, the reflected light is diffracted to make the visible information visually recognized. The visible information causes changes in the quantity of the reflected light by the interference of the diffracted light depending on the viewing angle for the optical card so that the information is visually recognized as a glaring visible information and that visible information with high quality can be obtained. |
