Patent ID: 7542185
Filing Date: 2009-06-02
Classification: G03H,G11B

Abstract:
1. A holographic record erasing method, comprising projecting an object beam for erasing and a reference beam for erasing onto a crosstalk layer and forming a crosstalk hologram in the crosstalk layer in a superimposed manner with respect to data holograms multiplex-recorded in a recording layer of a holographic recording medium, the crosstalk layer being provided substantially adjacent to the recording layer, being formed of one of a photopolymer, a dichroic holographic material and a photorefractive material, the photopolymer develops photosensitivity through a polymerization initiator having an absorption edge at a wavelength shorter than those of an object beam and a reference beam, the photosensitivity in the dichroic holographic material can be turned ON-OFF by the presence or absence of a gate beam, and the photorefractive material exhibits photosensitivity only under the presence of an electrostatic field and being set to exhibit no sensitivity or very low sensitivity to interference fringes of the object beam and the reference beam at the time of data hologram recording in the recording layer, wherein: data holograms are angle-multiplex-recorded; and the reference beam for erasing has a beam diameter upon the projection onto the holographic recording medium 2 to 10 times the diameter of a beam which is projected onto the holographic recording medium at the time of data hologram recording.