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1. WO2009075424 - SUPPORT DE STOCKAGE DE DONNÉES HOLOGRAPHIQUES ET APPAREIL ET PROCÉDÉ D'ENREGISTREMENT/DE REPRODUCTION DE DONNÉES HOLOGRAPHIQUES VERS/DEPUIS LEDIT SUPPORT

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

Claims
[1] A holographic data storage medium comprising:
a substrate;
a holographic recording layer disposed on the substrate; and
a cover layer covering the holographic recording layer,
wherein the holographic recording layer comprises:
a data recording region including a plurality of data layers to which data is
recorded, the data recording region in which interference fringes due to first and second beams are formed in different data layers in a depth wise direction; and
a layer discrimination region for providing discrimination between the data
layers.
[2] The medium of claim 1, wherein the layer discrimination region of the
holographic recording layer includes a plurality of reflection layers, which are
stacked on the substrate and correspond to the data layers, respectively.
[3] The medium of claim 1, wherein the layer discrimination region of the
holographic recording layer includes a plurality of reflection layers, which are
stepped in a staircase shape and correspond to the data layers, respectively.
[4] The medium of claim 2, wherein each of the reflection layers stores layer discrimination data of the corresponding data layer.
[5] The medium of claim 1, wherein the holographic recording layer has a disk
shape, and the layer discrimination region is disposed near an inner circumferential area or an outer circumferential area of the disk-shaped holographic
recording layer.
[6] The medium of claim 1, wherein the data recording region of the holographic
recording layer is formed of a photosensitive material selected from one of a
photo-polymer and a thermoplastic resin.
[7] The medium of claim 1, wherein data recorded to each of the interference fringes is recording in units of a single bit.
[8] The medium of claim 1, wherein the medium is a transmissive-type in which the substrate and the cover layer are formed of a transparent material, which
transmits the first and second beams, such that the first and second beams are
incident to both sides of the holographic recording layer disposed between the
substrate and the cover layer.
[9] The medium of claim 1, wherein the medium is a reflective-type in which a re- flection layer is interposed between the substrate and the holographic recording
layer such that the first and second beams are incident to the holographic
recording layer through the cover layer.
[10] The medium of claim 9, wherein:
the first and second beams are polarized beams that intersect each other,
the reflection layer is a polarization- selective reflection layer that reflects the
first beam and transmits the second beam.
[11] The medium of claim 10, wherein the reflection layer is formed of a cholesteric liquid crystal (CLC) material.
[12] The medium of claim 11, wherein the reflection layer is a liquid crystal (LC)
film that is in a liquid state or cured.
[13] The medium of claim 11, wherein the reflection layer includes a single liquid
crystal (LC) layer or a plurality of LC layers with different LC-molecule helical periods.
[14] The medium of claim 9, further comprising a servo layer for recording servo data disposed between the substrate and the reflection layer, between the reflection
layer and the holographic recording layer, in the holographic recording layer, or between the holographic recording layer and the cover layer.
[15] The medium of claim 9, wherein servo data is recorded in the reflection layer.
[16] The medium of claim 1, further comprising a space layer disposed between the
reflection layer and the holographic recording layer.
[17] A holographic data recording/reproducing apparatus for reproducing data from a holographic data storage medium comprising:
an optical pickup unit to irradiate light to the holographic data storage medium
comprising a holographic recording layer including a data recording region with a plurality of data layers to which data is recorded, in which interference fringes are formed in different data layers in a depthwise direction, and a layer discrimination region for providing discrimination between the data layers; and
a controller to control the optical pickup unit for irradiating light to the layer discrimination region to read layer discrimination data stored in the layer discrimination region of the holographic recording layer, and for recording data or reading recorded data on/from different data layers of the holographic data
storage medium based on the layer discrimination data.
[18] The apparatus of claim 17, wherein the optical pickup unit comprises:
a light source for emitting light;

an object lens optical system for irradiating light to the layer discrimination
region and receiving reflected light; and
a focus control unit for controlling a focus of the light to be in a data layer to/
from which data is recorded/read, based on the layer discrimination data.
[19] The apparatus of claim 18, wherein the object lens optical system reads the layer discrimination data from the layer discrimination region, moves to the data
recording region based on the layer discrimination data, and records data or reads recorded data on/from the holographic data storage medium.
[20] The apparatus of claim 18, wherein the object lens optical system comprises:
a layer discrimination optical system for reading the layer discrimination data
from the layer discrimination region; and
a data recording optical system for recording data in the data recording region or reading recorded data from the data recording region,
wherein the layer discrimination optical system and the data recording optical
system have the same focal height on the holographic data storage medium so
that the data recording optical system is recording data to a data layer of a
plurality of data layers or reading recorded data from the data layer, the data
layer having the same height as a focal position of the layer discrimination
optical system.
[21] The apparatus of claim 18, wherein the light irradiated to the layer discrimination region of the holographic data storage medium is the first beam or the second
beam.
[22] The apparatus of claim 18, further comprising a servo optical system for tracking a recording position in the holographic data storage medium.
[23] The apparatus of claim 22, wherein the light irradiated to the layer discrimination region of the holographic data storage medium is a servo beam emitted by the
servo optical system.
[24] The apparatus of claim 18, wherein the focus control unit is one of a beam
expander and a liquid crystal (LC) lens.
[25] The apparatus of claim 18, wherein data recorded to the interference fringe is
recorded in units of a single bit.
[26] A method of recording/reproducing holographic data, the method comprising: irradiating light to a holographic data storage medium comprising a holographic
recording layer including a data recording region with a plurality of data layers to which data is recorded, in which interference fringes are formed in different data layers in a depthwise direction, and a layer discrimination region for
providing discrimination between the data layers, so as to read layer discrimination data stored in the layer discrimination region of the holographic
recording layer; and
recording data on or reading recorded data from different data layers based on
layer discrimination data stored in the layer discrimination region of the
holographic recording layer.
[27] The method of claim 26, which comprises:
locating an optical pickup unit over the layer discrimination region and controlling a focal position of the optical pickup unit to have the same height as the data layer for recording data or reading recorded data while reading layer discrimination data using the optical pickup unit; and
moving the optical pickup unit to the data recording region, while maintaining
the focal position of the optical pickup unit to record data in the data layer for
recording data or read the recorded data from the data layer.
[28] The method of claim 26, which comprises:
locating a layer discrimination optical system of an optical pickup unit over the layer discrimination region and controlling a focal position of a data recording
optical system of the optical pickup unit to have the same height as the data layer for recording data or reading recorded data while reading layer discrimination
data using the layer discrimination optical system; and
recording data in the data layer for recording data or reading the recorded data
from the data layer, while locating the layer discrimination optical system of the optical pickup unit over the layer discrimination region.
[29] The method of claim 26, wherein the data is recorded by a single-bit in a focus of the data layer.