JP2004077896A - Hologram recording medium and hologram recording medium reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hologram recording medium of inexpensive and simple construction capable of easily and speedily performing alignment of incident light. <P>SOLUTION: The hologram recording medium 3 which has a structure of laminating a plurality of slab optical waveguides where diffraction factors or scattering factors are recorded, and forms an image of guided light generated by making read light incident to the waveguide by diffracting or scattering the guided light by the diffraction factors or scattering factors on a predetermined image-forming plane as a hologram image, and an azimuth of the read light to the optical waveguide α of one of the layers adjacent to each other in the plurality of slab optical waveguides and an azimuth of the read light to the optical waveguide β of the other layer have an angle difference, and when the read light to the optical waveguide α of one of the layers is made incident to the optical waveguides α, β of both of the adjacent layers, this angle difference is an angle at which a ratio of the brightness of an image formed from the optical waveguide α of the one of the layers to that of an image formed from the optical waveguide β of the other layer takes a predetermined value or larger. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hologram recording medium having a structure in which a large amount of information is recorded and a slab-type optical waveguide that enables the information to be easily read is stacked, and a hologram recording medium reproducing apparatus.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in various fields including mobile computing, a demand for a memory that is compact, easy to carry, and has a large capacity has rapidly increased.
As one method for realizing a large-capacity memory at low cost, a planar optical waveguide type multiplex optical memory in which recording information as shown in FIG. 5 is embedded in a slab optical waveguide and the optical waveguides are stacked has been proposed.
[0003]
In this method, a hologram recording medium (multiple optical memory) 3 forms a multilayer optical waveguide by alternately laminating a core layer and a cladding layer, and information is recorded in each optical waveguide as a scattering factor.
Reproduction of information is performed by precisely entering the incident light 2 emitted from the light source 1 only at the incident position 31 of the optical waveguide to be reproduced, and capturing the reproduced image 4A generated by the image sensor 5.
[0004]
[Problems to be solved by the invention]
As described above, the optical memory using the laminated waveguide can increase the capacity and is promising as a memory in the future. However, as shown in FIG. 5, the alignment of the incident light on the hologram recording medium 3 is incomplete, If the light is partially coupled not only to the incident position 31 of the target optical waveguide but also to the incident position 32 of the adjacent optical waveguide, information recorded in the adjacent layer is simultaneously reproduced as crosstalk 4B. There was a problem.
[0005]
Therefore, in order to read out information without error, precise positioning and focusing of incident light in the hologram reproducing optical system are required. On the other hand, a fast and simple focusing method has not been devised, and it is difficult to design a device. In the way.
Also, when reproducing hologram-recorded information, it is necessary to increase the distance between adjacent waveguides in order to eliminate the need for precise position control of incident light with respect to the hologram recording medium. Has been limited, which has hindered the increase in storage capacity.
[0006]
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an inexpensive and easy-to-configure hologram recording medium and a hologram recording medium reproducing apparatus that can easily and quickly align incident light. Aim.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 has a structure in which a plurality of slab type optical waveguides on which a diffraction factor or a scattering factor is recorded are stacked, and a readout light is incident on the optical waveguide. A hologram recording medium for diffracting or scattering the generated guided light by the diffraction factor or the scattering factor to form a hologram image on a predetermined image plane, wherein one of the plurality of slab-type optical waveguides is adjacent to one another. And the azimuth of the read light with respect to the optical waveguide of the other layer and the azimuth of the read light with respect to the optical waveguide of the other layer have an angle difference, the angle difference, the read light with respect to the optical waveguide of the one layer both the adjacent When simultaneously incident on the optical waveguides of the other layer, the ratio between the brightness of the image generated from the optical waveguide of the one layer and the brightness of the image generated from the optical waveguide of the other layer is a predetermined value. Characterized in that an angle becomes greater.
[0008]
According to a second aspect of the present invention, in the hologram recording medium according to the first aspect, the angle difference is 90 degrees.
[0009]
Further, the invention according to claim 3 has a structure in which a plurality of slab-type optical waveguides on which a diffraction factor or a scattering factor is recorded are laminated, and a guided light generated by irradiating readout light to the optical waveguide is generated. A hologram recording medium that forms a hologram image on a predetermined image plane by being diffracted or scattered by the diffraction factor or the scattering factor, wherein read light for an optical waveguide of one of adjacent layers in the plurality of slab-type optical waveguides is provided. The azimuth angle and the azimuth angle of the read light with respect to the optical waveguide of the other layer have an angle difference, the angle difference, the read light with respect to the optical waveguide of the one layer to the optical waveguide of both adjacent layers. The angle at which the ratio of the brightness of the image generated from the optical waveguide of the one layer to the brightness of the image generated from the optical waveguide of the other layer is equal to or greater than a predetermined value when the light is simultaneously incident. A hologram recording medium reproducing apparatus for reproducing information recorded on a hologram recording medium, comprising: a mechanism capable of making a plurality of reading lights having azimuth angles having the angle difference incident on the hologram recording medium. .
[0010]
According to a fourth aspect of the present invention, in the hologram recording medium reproducing apparatus according to the third aspect, the angle difference is 90 degrees.
[0011]
According to a fifth aspect of the present invention, in the hologram recording medium reproducing apparatus according to any one of the third and fourth aspects, the interval between the incident positions of the plurality of reading lights in the hologram recording medium stacking direction is the same as that of the hologram recording medium. It is characterized by being an odd multiple of the optical waveguide lamination interval of the medium.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a configuration of a hologram recording medium according to an embodiment of the present invention. The hologram recording medium according to the embodiment of the present invention has a structure in which a plurality of slab-type optical waveguides on which a diffraction factor or a scattering factor is recorded are stacked, and a readout light is generated by being incident on the optical waveguide. A hologram recording medium in which wave light is diffracted or scattered by the diffraction factor or the scattering factor to form a hologram image on a predetermined image plane.
[0013]
In the hologram recording medium 3 according to the present embodiment, the azimuth angle (incident direction) of the read light with respect to the optical waveguide α of one adjacent layer in the plurality of slab-type optical waveguides and the read light with respect to the optical waveguide β of the other layer are different. The azimuth has an angle difference.
This difference in angle is caused by the brightness of an image generated from the optical waveguide α of the one layer when the reading light for the optical waveguide α of the one layer is simultaneously incident on the optical waveguides α and β of the two adjacent layers. The angle at which the ratio with the brightness of the image generated from the optical waveguide β of the other layer becomes a predetermined value or more, for example, 90 degrees.
[0014]
In the conventional hologram recording medium shown in FIG. 5, hologram recording is performed on all optical waveguides so that a reproduced image is formed with respect to readout light in the same direction.
On the other hand, in the hologram recording medium 3 according to the embodiment of the present invention, in the adjacent optical waveguides α and β, the azimuths of the readout light necessary for reproduction are orthogonal to each other or similar thereto. Information is recorded on the hologram.
In hologram recording, the readout light is distorted and the intensity of the readout light is reduced with respect to the readout light other than the recorded or calculated direction, and the readout light is reduced as the design direction and the readout light direction approach the orthogonal state. Is no longer generated.
[0015]
Therefore, even if the incident light 2α in the direction from which information can be read from a certain optical waveguide α is incident and coupled to the adjacent optical waveguide β, the information recorded in the optical waveguide β is not reproduced by this guided light, or Even if reproduced, the output is almost negligible.
[0016]
FIG. 2 shows the principle of reproducing information from the hologram recording medium according to the present invention. In the figure, the incident light 2 emitted from the light source 1 is positioned at the incident end 31 of the optical waveguide A in the hologram recording medium 3 to be reproduced, and the incident light is coupled to the optical waveguide A. Since the incident light 2 has a certain degree of spread, a part of the incident light is also coupled to the adjacent optical waveguide B and guided.
In the conventional hologram recording medium, as shown in FIG. 5, the information recorded in the optical waveguide B is reproduced at the same time, and the target information in the optical waveguide A cannot be read accurately.
[0017]
On the other hand, in the hologram recording medium according to the present invention, as described with reference to FIG. 2, even if the incident light is coupled to the optical waveguide adjacent to the target optical waveguide, the information of the adjacent optical waveguide is not changed. Since the information is not reproduced, only the information recorded in the target optical waveguide A can be accurately read without crosstalk.
3 and 4 show a schematic configuration of a hologram recording medium and a hologram recording medium reproducing device according to an embodiment of the present invention.
[0018]
The hologram recording medium reproducing apparatus according to the present embodiment has a structure in which a plurality of slab-type optical waveguides on which a diffraction factor or a scattering factor is recorded are stacked, and guided light generated by irradiating readout light to the optical waveguide. A hologram recording medium that forms a hologram image on a predetermined image plane by diffracting or scattering the light by the diffraction factor or the scattering factor, and reading out one of the adjacent slab type optical waveguides from the optical waveguide. The azimuth angle of the light and the azimuth angle of the read light with respect to the optical waveguide of the other layer have an angle difference, and the angular difference is the optical waveguide of the two adjacent layers that outputs the read light with respect to the optical waveguide of the one layer. At the same time, the ratio of the brightness of the image generated from the optical waveguide of the one layer to the brightness of the image generated from the optical waveguide of the other layer is equal to or less than a predetermined value. A hologram recording medium reproducing apparatus for reproducing information recorded on the hologram recording medium is an angle the azimuth has a plurality of read-out light for a possible incident on the hologram recording medium mechanism having the angular difference.
The angle difference is, for example, 90 degrees.
[0019]
In these drawings, the hologram recording medium 3 is configured so that reading light can be incident on the hologram recording medium 3 from directions orthogonal to each other. FIG. 3 shows an example of reading data of the optical waveguide α of the odd-numbered layer, and FIG. 4 shows an example of reading data of the optical waveguide β of the even-numbered layer.
[0020]
The light source 1α is used to read data from the optical waveguide α group of the odd-numbered layer, and the light source 1β is used to read data from the optical waveguide β group of the even-numbered layer. The reproduced image 4β is captured by the image sensor 5 to obtain data.
As described above, in the hologram recording medium and the hologram recording medium reproducing apparatus according to the embodiment of the present invention, when data is read from a certain layer, information in an adjacent layer is not read. The accuracy of the incident light positioning may be low, and the apparatus can be simplified.
[0021]
Further, when the same positioning accuracy as that of the related art can be realized, the interval between adjacent optical waveguides can be reduced, and the number of stacked optical waveguides can be increased, so that the recording capacity of the hologram recording medium can be easily increased. It is possible to increase.
In this embodiment, an example in which there are two reading light sources is shown. However, one light source is used to guide light by an optical system including a mirror, a prism, a waveguide, and the like, and the reading light is applied to the hologram recording medium in directions orthogonal to each other. You may comprise so that it may be made incident on an adjacent optical waveguide.
[0022]
Also, by setting the interval between these orthogonal lights to be an odd multiple of the interval between the optical waveguides, once the incident light is positioned, the data recorded on both adjacent layers can be separated by simply switching the direction of the read light. And the data access speed can be improved.
In the present embodiment, the angles formed by the two readout lights are orthogonal, but it goes without saying that there is no problem even if crosstalk occurs without any problem in data decoding.
Therefore, the angle difference between the azimuths of the two readout lights does not need to be 90 degrees, but may be any angle close to 90 degrees.
Needless to say, the number of incident read lights does not necessarily need to be two.
[0023]
【The invention's effect】
As described above, according to the hologram recording medium according to the present invention, the hologram recording medium has a structure in which a plurality of slab-type optical waveguides on which a diffraction factor or a scattering factor is recorded are stacked, and a readout light is incident on the optical waveguide. A hologram recording medium that forms a hologram image on a predetermined imaging surface by diffracting or scattering the generated guided light by the diffraction factor or the scattering factor, and one of the slab type optical waveguides adjacent to the hologram recording medium. The azimuth angle of the read light with respect to the optical waveguide of the layer and the azimuth angle of the read light with respect to the optical waveguide of the other layer have an angle difference, and the angle difference causes the read light with respect to the optical waveguide of the one layer to be adjacent to the optical waveguide of the one layer. When simultaneously incident on the optical waveguides of both layers, the brightness of the image generated from the optical waveguide of the one layer and the brightness of the image generated from the optical waveguide of the other layer are reduced. Since the ratio is set to an angle equal to or greater than a predetermined value, it is possible to eliminate the crosstalk due to the adjacent layers at the time of reproduction, therefore, simple and high-speed data read can be large-capacity recording medium is obtained.
[0024]
Further, according to the hologram recording medium reproducing apparatus according to the present invention, the hologram recording medium reproducing apparatus has a structure in which a plurality of slab type optical waveguides in which a diffraction factor or a scattering factor is recorded are stacked, and a readout light is caused to enter the optical waveguide. A hologram recording medium that diffracts or scatters the guided light by the diffraction factor or the scattering factor to form an image on a predetermined image plane as a hologram image, wherein the optical waveguide of one of the adjacent layers in the plurality of slab-type optical waveguides is provided. The azimuth of the read light with respect to the optical waveguide and the azimuth of the read light with respect to the optical waveguide of the other layer have an angle difference, and the angular difference causes the read light with respect to the optical waveguide of the one layer to be reflected by the two adjacent layers. The ratio of the brightness of the image generated from the optical waveguide of the one layer to the brightness of the image generated from the optical waveguide of the other layer when simultaneously entering the optical waveguide of A hologram recording medium reproducing apparatus that reproduces information recorded on a hologram recording medium having an angle equal to or greater than a predetermined value, wherein a mechanism capable of causing a plurality of readout lights having azimuth angles having the angle difference to be incident on the hologram recording medium. As a result, it is possible to eliminate crosstalk caused by an adjacent layer during reproduction, and therefore, simple and high-speed data reading becomes possible.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the principle of reading a hologram recording medium according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a hologram recording medium and a reproducing apparatus showing a principle of reproducing information from the hologram recording medium according to the embodiment of the present invention.
FIG. 3 is a schematic diagram illustrating an embodiment of a hologram recording medium and a reproducing apparatus according to the embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating a hologram recording medium and a reproducing apparatus according to an embodiment of the present invention.
FIG. 5 is a schematic diagram showing a configuration of a conventional waveguide type optical memory medium and a reproducing apparatus.
[Explanation of symbols]
A: target waveguide, B: adjacent waveguide, α: waveguide group of odd layer, β: waveguide group of even layer, 1: laser light source, 1α: light source for reading odd layer, 1β: Light source for reading even-numbered layers, 2: incident light, 2α: incident light in the direction of reading waveguide group α, 3: hologram recording medium, 31: target incident position, 32: incident position of adjacent layer, 4A: target Reproduction light, 4B: crosstalk from an adjacent layer, 4α: reproduction light from an odd layer, 4β: reproduction light from an even layer, 5: image sensor

Claims (5)

It has a structure in which a plurality of slab-type optical waveguides in which a diffraction factor or a scattering factor is recorded are laminated, and a guided light generated by irradiating readout light to the optical waveguide is diffracted or scattered by the diffraction factor or the scattering factor. A hologram recording medium for forming an image as a hologram image on a predetermined image plane,
In the plurality of slab-type optical waveguides, the azimuth of read light with respect to the optical waveguide of one adjacent layer and the azimuth of read light with respect to the optical waveguide of the other layer have an angle difference,
The angle difference is such that, when reading light for the optical waveguide of the one layer is simultaneously incident on the optical waveguides of the two adjacent layers, the brightness of an image generated from the optical waveguide of the one layer and the brightness of the other layer are reduced. A hologram recording medium, wherein the angle is such that the ratio of the brightness of an image generated from the optical waveguide to a predetermined value or more. The hologram recording medium according to claim 1, wherein the angle difference is 90 degrees. It has a structure in which a plurality of slab-type optical waveguides in which a diffraction factor or a scattering factor is recorded are laminated, and a guided light generated by irradiating readout light to the optical waveguide is diffracted or scattered by the diffraction factor or the scattering factor. A hologram recording medium for forming an image as a hologram image on a predetermined image plane,
In the plurality of slab-type optical waveguides, the azimuth of read light with respect to the optical waveguide of one adjacent layer and the azimuth of read light with respect to the optical waveguide of the other layer have an angle difference,
The angle difference is such that, when reading light for the optical waveguide of the one layer is simultaneously incident on the optical waveguides of the two adjacent layers, the brightness of an image generated from the optical waveguide of the one layer and the brightness of the other layer are reduced. A hologram recording medium reproducing device that reproduces information recorded on a hologram recording medium at an angle at which a ratio with the brightness of an image generated from the optical waveguide is equal to or more than a predetermined value,
An apparatus for reproducing a hologram recording medium, comprising: a mechanism capable of causing a plurality of readout lights having azimuths having the angle difference to enter the hologram recording medium. The hologram recording medium reproducing device according to claim 3, wherein the angle difference is 90 degrees. 5. The hologram recording according to claim 3, wherein an interval between the incident positions of the plurality of reading lights in the hologram recording medium lamination direction is an odd multiple of an optical waveguide lamination interval of the hologram recording medium. Media playback device.

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