HOLOGRAPHIC RECORDING MEDIUM, HOLOGRAPHIC RECORDING/ERASING METHOD AND HOLOGRAPHIC RECORDING/REPRODUCING APPARATUS

摘要

A holographic recording/erasing method and a holographic recording/reproducing apparatus in both of which data reproduction is made impossible without projecting a high-energy erasing beam onto a holographic recording medium or without physical destruction. A holographic recording medium (16) used for a holographic recording/reproducing apparatus (10) comprises a recording layer (17) composed of two separated recording layers (17A, 17B), between which a crosstalk layer (17C) is provided. Even after multiplex recording of a data hologram (24) in the recording layer is ended, the crosstalk layer (17C) still has a photosensitivity. An erasing object light beam (IOb) having a large diameter and an erasing reference light beam (IRe) are directed to the crosstalk layer (17C), thereby forming a crosstalk hologram (26) of low selectivity. When a reproducing light beam is applied to the data hologram (24), diffracted light is infallibly produced also from the crosstalk hologram (26).