Abstract: A photorefractive material provides a high photosensitivity without reduction. The material comprises a single crystal of terbium (Tb)-doped niobate or tantalate. The single crystal is a single crystal of lithium niobate (LiNbO3) whose molar fraction of [Li2O]/([Li2O]+[Nb2O5]) lies in a range of 0.482 to 0.505, or a single crystal of lithium tantalate (LiTaO3) whose molar fraction of [Li2O]/([Li2O]+[Ta2O5]) lies in a range of 0.482 to 0.505. The amount of terbium added in the photorefractive material ranges from 10 weight ppm to 1000 weight ppm.
Type:
Grant
Filed:
June 21, 2000
Date of Patent:
December 30, 2003
Assignees:
Director General of National Institute for Research in
Inorganic Materials, Pioneer Corporation
Abstract: A hologram recording apparatus is capable of directing interferable signal light and reference light into a hologram recording medium to record an information signal carried by the signal light. The hologram recording medium is sensitive to a first light at a first wavelength in an ultraviolet or short-wavelength visible light band to develop light induced absorption. The apparatus includes a light source for irradiating the hologram recording medium with the first light, and a laser light source for irradiating the hologram recording medium with signal light and reference light at a second wavelength longer than the first wavelength after the first light is irradiated.
Type:
Grant
Filed:
August 2, 2000
Date of Patent:
March 18, 2003
Assignees:
Director General of National Institute for Research in
Inorganic Materials, Science and Technology Agent, Japan, Pioneer Corporation
Abstract: A two-color holographic recording apparatus reduces error signals possibly included in reproduced digital data signals. The two-color holographic recording apparatus has first, second and third light shutters for passing or blocking gate light, signal light and reference light incident on a recording medium respectively, and a controller for controlling the respective states of the first, second and third light shutters.
Type:
Grant
Filed:
June 21, 2000
Date of Patent:
October 29, 2002
Assignees:
Director General of National Institute for Research in
Inorganic Materials, Science and Technology Agent, Pioneer Corporation
Abstract: A two-color hologram recording/reproducing apparatus is capable of directing interferable signal light and reference light into a hologram recording medium to record an information signal carried by the signal light. The hologram recording medium is sensitive to a first light at a first wavelength in an ultraviolet or short-wavelength visible light band to develop light induced absorption. The apparatus includes a light source for irradiating the hologram recording medium with the first light, a laser light source for irradiating the hologram recording medium with signal light and reference light at a second wavelength longer than the first wavelength after the first light is irradiated, and a gate light source for directing gate light at a third wavelength into the hologram recording medium.
Type:
Grant
Filed:
August 2, 2000
Date of Patent:
April 16, 2002
Assignees:
Director General of National Institute for Research in
Inorganic Materials, Science and Technology Agent, Japan, Pioneer Corporation