| 摘要 |
An optical recording medium has a recording layer formed of a plurality of reflection hologram layers. A spacer layer is interposed between the respective reflection hologram layers. The reflection hologram layer is made of a material having a thermal threshold value which allows, when being irradiated with a recording laser beam, local absorbed heat to vary hologram diffraction conditions at a focal position, and allows the hologram to be retained at non-focal positions. The spacer layer is made of a material which is insensitive to a laser beam of a recording wavelength and which has a smaller extinction coefficient than that of the reflection hologram layer.
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