JP2005265978A - Holographic recording medium and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holographic recording medium from which a plurality of holograms can be simultaneously reproduced by irradiation with a plurality of laser diodes and a method for manufacturing the same. <P>SOLUTION: The holographic recording system 10 comprises a plurality of hologram cells 12 arranged in a two-dimensional array, making an X-axis direction as a row and a Y-axis direction as a column. The respective hologram cells 12 are formed by irradiating the cells with signal light from the Y-axis direction and reference light from a Z-axis direction to form holograms on a recording layer 18. In reproducing, the diffracted light in the Y-axis direction by as many as the number of the rows can be obtained when one hologram cell is irradiated by each of the respective rows with the reference light for reproduction simultaneously from the laser diodes. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a holographic recording medium and a manufacturing method thereof.

  One storage technology that can store large amounts of digital information is holographic memory.

  This holographic memory is excellent in that it has a high speed and a large capacity, but there is a problem that the holographic memory system is large and expensive.

  This is because the laser light used at the time of recording requires coherence and wavelength stability, so that the laser light source becomes large and expensive (for example, Patent Document 1).

Japanese Patent Laid-Open No. 2002-207412

  In the holographic memory system as described above, since the laser light sources are large and expensive, it is difficult to provide a plurality of the laser light sources. Therefore, the holographic memories are sequentially formed by the laser light from a single light source. Irradiation causes information to be reproduced, and the reproduction data rate is limited.

  The present invention has been made in view of the above problems, and can use a plurality of inexpensive laser diodes to simultaneously irradiate hologram cells at a plurality of locations to reproduce information, thereby greatly improving the reproduction data rate. It is an object of the present invention to provide a holographic recording medium and a manufacturing method thereof.

  As a result of earnest research, the inventor has hologram cells arranged in a two-dimensional array in which the X-axis direction is a row and the Y-axis direction is a column, and each hologram cell has a signal light, a Z-axis direction from the Y-axis direction. From a plurality of laser diodes arranged in a similar two-dimensional array to a holographic recording medium in which a hologram is formed by irradiating a reference beam from 1 to the Z-axis direction for each row In addition, it has been found that the reproduction data rate can be greatly improved by simultaneously reproducing information from a plurality of image sensors by simultaneously irradiating reproduction reference light.

  That is, the following object can be achieved by the present invention described below.

  (1) A plurality of hologram cells arranged in a two-dimensional array with the X-axis direction as rows and the Y-axis direction as columns, and each hologram cell receives reproduction reference light from one of the X-axis direction and the Z-axis direction. A hologram is formed so that diffracted light is generated in the Y-axis direction when irradiated, and is configured to transmit diffraction light from a hologram cell adjacent in the Y-axis direction. Graphic recording medium.

  (2) The hologram cell has a recording layer, and the recording layer is formed along the X-axis direction and has a planar shape that forms an angle of about 45 ° with respect to the Y-axis direction and the Z-axis direction. The holographic recording medium according to (1), characterized in that:

  (3) The hologram cell has a recording layer, and the recording layer is formed along the Z-axis direction and has a planar shape that forms an angle of about 45 ° with respect to the X-axis direction and the Y-axis direction. The holographic recording medium according to (1), characterized in that:

  (4) The hologram cell has a hexahedral shape and includes a pair of triangular prism-shaped substrates having a right-angled triangle cross-section and the recording layer, and the pair of substrates is a right-angled triangle. The holographic recording medium according to (2) or (3), wherein the oblique sides are arranged to face each other, and the recording layer is formed between inclined surfaces including the opposite oblique sides.

  (5) A plurality of quadrangular prism substrates having a parallelogram cross-section with apex angles of about 45 ° and about 135 °, and the recording layer, and the quadrangular prism substrate includes the parallel four sides. The holographic recording medium according to (2) or (3), wherein a pair of planes parallel to each other are arranged so as to overlap each other, and the recording layer is arranged between the overlapping planes.

  (6) Recording on both end faces of a coupling body having two triangular prism substrates each having a right-angled isosceles triangle and the plurality of quadrangular prism substrates coupled so that the recording layers are parallel to each other. (3) The triangular prism substrate is attached so that a layer is sandwiched between a slope including a hypotenuse of the right isosceles triangle and a plane of the rectangular prism substrate. Holographic recording medium.

  (7) The substrate has a right isosceles triangle shape in cross section, and an axial length of the triangular prism is equal to a length of two orthogonal sides in the right angle isosceles triangle. The holographic recording medium according to (4).

  (8) The entire structure has a hexahedron shape, and a pair of end faces of the hexahedron are configured by both end faces in the length direction of the quadrangular prism substrate. (5) and (6) Holographic recording medium.

  (9) The holographic recording medium according to any one of (1) to (8), wherein information is holographically recorded in advance in each of the hologram cells and then assembled together.

  (10) It has an antireflection coating layer provided at least on the outer periphery of the holographic recording medium at the portion where the light beam passes during recording and reproduction. Holographic recording medium.

  (11) A step of forming a recording layer made of a holographic recording material on a slope of a first substrate having a substantially right isosceles triangle and a triangular prism shape, and a second shape having the same shape as the first substrate. Attaching the substrate so that the inclined surface sandwiches the recording layer between the inclined surface of the first substrate and forming a hexahedral hologram cell; and the recording layer includes a plurality of hologram cells. A method for producing a holographic recording medium, comprising the steps of:

  (12) The lengths of the first and second substrates are equal to the lengths of two orthogonal sides in a right-angled isosceles triangle, and are joined so that the hologram cells form a cube. (11) The manufacturing method of the holographic recording medium as described in (11).

  (13) The lengths of the first and second triangular prism substrates and the recording layer are made equal to the length of one side of the holographic recording medium, and the pair of end faces of the holographic recording medium The method for producing a holographic recording medium according to (11), characterized by comprising both end faces in the axial direction of the second substrate.

  (14) a step of forming a recording layer made of a holographic recording material on the inclined surface of the first triangular prism substrate having a substantially right-angled isosceles triangle, and the apex angles are about 45 ° and about 135 °; A first quadrangular prism substrate having a parallelogram-shaped cross section having a pair of planes having a length equal to the hypotenuse of an isosceles triangle is interposed between one plane of the pair of planes and the inclined surface. A step of mounting so as to sandwich, a step of forming a second recording layer made of a holographic recording material on the other plane of the pair of planes, and a second quadrangular prism having the same shape as the first quadrangular prism substrate Mounting the substrate so that the second recording layer is sandwiched between the one plane and the other plane of the first quadrangular prism substrate, and forming the recording layer and the quadrangular prism in the same manner as described above. Repeated board mounting, Nth square pillar Attaching a substrate and forming a recording layer; and a second triangular prism substrate having the same shape as the first triangular prism substrate so as to sandwich the Nth recording layer with the Nth quadrangular prism substrate And a method for manufacturing a holographic recording medium.

  (15) The lengths of the first and second triangular prism substrates and the first to Nth quadrangular prism substrates in the axial direction are made equal to the length of one side of the holographic recording medium, and The method of manufacturing a holographic recording medium according to (14), wherein the two triangular prism substrates and the first to Nth rectangular prism substrates are assembled so that both ends in the axial direction form a pair of end faces.

  (16) The hologram according to any one of (10) to (15), further including a step of forming a hologram by holographic recording of information on the recording layer every time the recording layer is formed. A method of manufacturing a graphic recording medium.

  In the present invention, since the holographic recording medium is configured by the hologram cells arranged in a two-dimensional array, a plurality of information is simultaneously reproduced by arranging inexpensive laser diodes in the array and irradiating the hologram cells simultaneously. Therefore, the reproduction data rate can be greatly improved without using expensive equipment.

  The recording medium has a hexahedral shape composed of a plurality of hologram cells arranged in a two-dimensional array with the X-axis direction as a row and the Y-axis direction as a column. Each hologram cell has a reproduction reference from the Z-axis direction. A hologram is formed so that diffracted light is generated in the Y-axis direction when irradiated with light. In the hologram cell, two triangular prismatic substrates having a right isosceles triangle are arranged so that the hypotenuses in the right triangle face each other, and a recording layer made of a holographic recording material is formed therebetween. .

  Hereinafter, a holographic recording medium 10 according to Embodiment 1 of the present invention will be described with reference to FIG.

  This holographic recording medium 10 is composed of a plurality of hologram cells 12 arranged in a two-dimensional array of A rows to D rows and 1 column to 8 columns, with the X axis direction as the row and the Y axis direction as the column. Yes.

  As shown in an enlarged view in FIG. 2, the hologram cell 12 has a cubic shape and is sandwiched between a pair of triangular pillars 14 and 16 having an isosceles right triangle and a cross section. And a recording layer 18. More specifically, the pair of substrates 14 and 16 are arranged so that the oblique sides of the right triangle are opposed to each other, and the recording layer 18 is formed between the inclined surfaces 14A and 16A including the opposite oblique sides. The slope 14A of the substrate 14, the slope 16A of the substrate 16, and the recording layer 18 are integrally bonded with an adhesive or the like, respectively.

  The substrates 14 and 16 are made of a light transmissive resin such as polycarbonate, and the recording layer 18 is formed by applying a holographic recording material such as a photopolymer between spacers 20, for example.

  As described above, the hologram cell 12 provided with the recording layer 18 is arranged in a two-dimensional array as described above so that the recording layer 18 is parallel, and is bonded and fixed to each other. A graphic recording medium 10 is configured. Each hologram cell 12 is configured to transmit diffraction light from the hologram cell 12 adjacent in the Y-axis direction.

  Here, before the hologram cells 12 are arranged in a two-dimensional array and bonded and integrated with the recording layer 18 in each hologram cell 12, as shown in FIG. The signal light Si to which page data is given by a spatial light modulator (not shown) is simultaneously irradiated from the Y-axis direction and the reference light Re from the Z-axis direction so as to intersect the recording layer 18 at an angle of about 45 °. Then, a hologram is formed in advance. In this case, angle multiplex recording may be performed by modulating the incident angle of the reference light, or shift multiplex recording may be performed by shifting the reference light into a spherical wave and shifting in the Y-axis direction and / or the X-axis direction.

  In this manner, by irradiating the target hologram cell 12 with the reproduction reference light from the Z-axis direction, diffracted light holding information to be reproduced in the direction of the signal light Si (Y-axis direction) is obtained. Can do.

  Further, when one hologram cell 12 is simultaneously irradiated with reproduction reference light from the Z-axis direction for each of rows A to D of the holographic recording medium 10, diffracted light can be obtained from the ends of the rows. . That is, diffracted light can be simultaneously obtained from the four hologram cells 12 and the recorded information can be reproduced.

  Reference numeral 22 in FIG. 1 denotes an AR (antireflection) coat layer. The AR coating layer 22 covers the hologram cell 12 and prevents a good reproduction operation from being hindered by unnecessary scattered light and an unnecessary diffraction grating from being formed. In this case, at least a portion of the hologram cell 12 through which the recording light beam and the reproduction light beam pass may be covered, or the entire hologram cell 12 may be covered. Further, the AR coating layer 22 may be formed on the whole without providing the AR coating layer for each hologram cell 12.

  Each of the hologram cells 12 has a cubic shape, but the present invention is not limited to this, and the same length as when a plurality of hologram cells 12 are connected as in the second embodiment shown in FIG. The hologram stick 24 may be used.

  This hologram stick 24 is composed of triangular prism-shaped substrates 26 and 28 and a recording layer 27 between them, which are preferably made equal to the length of the completed holographic recording medium 11 in the X-axis direction. As a result, both end surfaces in the X-axis direction of the holographic recording medium 11 are formed by the longitudinal end surfaces 24A and 24B of the hologram stick 24. Here, there is no boundary between the hologram cells 12, but in the hologram stick 24, recording or reproduction is performed for each column virtually partitioned by a two-dot chain line in FIG.

  Next, a holographic recording medium 30 according to Embodiment 3 of the present invention shown in FIG. 5 will be described.

  The holographic recording medium 30 is formed by adhering and fixing seven quadratic prism substrates 32 and two triangular prism substrates 34 with a recording layer 36 interposed therebetween.

  The quadrangular prism substrate 32 has a parallelogram shape with cross sections having apex angles of about 45 ° and about 135 °, and the triangular prism substrate 34 has a right angled isosceles triangle shape. The recording layer 36 is formed between a pair of parallel planes of each quadrangular prism substrate 32 and between one of these planes 32A and 32B and a slope 34A corresponding to a hypotenuse of a right triangle in the triangular prism substrate 34. It is sandwiched and formed integrally. The length of the quadrangular prism substrate 32, the triangular prism substrate 34, and the recording layer 36 in the X-axis direction is equal to the length of the holographic recording medium 30 in the X-axis direction. Both end surfaces in the direction are constituted by both end surfaces 33A, 33B, 35A, and 35B in the X-axis direction of the quadrangular prism substrate 32 and the triangular prism substrate 34. Reference numeral 38 in FIG. 5 indicates an AR coating layer.

  Next, a holographic recording medium 40 according to Embodiment 4 of the present invention shown in FIG. 6 will be described.

  The holographic recording medium 40 has the same size as the holographic recording medium 10 and is not clearly partitioned here using, for example, an integral photorefractive crystal such as LiNbO 3. Similar to the holographic recording medium 10, eight hologram cells 42 of A rows to D rows and 1 column to 8 columns are configured.

  Next, a process for manufacturing the hologram cell 12 of the first embodiment will be described with reference to FIG.

  First, the spacer 20 is attached to the inclined surface 14A of the triangular prism-shaped substrate 14, and a holographic recording material such as a photopolymer is applied to the inside thereof to form the recording layer 18 (see FIG. 7A).

  Next, as shown in FIG. 7B, the other substrate 16 is bonded and integrally fixed by the inclined surface 16A so as to sandwich the recording layer 18 together with the inclined surface 14A of the substrate 14.

  Further, as shown in FIG. 7C, an AR coating layer 22 is formed on the entire hologram cell 12 having a cubic shape.

  In this state, signal light is irradiated from the Y-axis direction and reference light is irradiated from the Z-axis direction, and predetermined information is recorded on the recording layer 18 as a hologram.

  As shown in FIG. 7D, the hologram cell 12 formed in this way and having the hologram recorded is sequentially two-dimensionally in the X-axis direction and the Y-axis direction so that the recording layers 18 are parallel to each other. The holographic recording medium 10 is formed by bonding and fixing in an array.

  Next, the manufacturing process of the holographic recording medium 30 will be described with reference to FIG.

  First, as shown in FIG. 8A, the triangular prism substrate 34 is set so that the inclined surface 34A faces upward, and the first recording layer 36A is formed thereon by coating. Next, as shown in FIG. 8B, the first quadrangular prism substrate 33A is orthogonal to the regular triangle so that the first recording layer 36A is sandwiched between the flat surface 32A and the inclined surface 34A. The other side of the parallelogram is overlapped and bonded and fixed so that the other plane of the parallelogram is continuous.

  Next, as shown in FIG. 8C, the second recording layer 36B is applied and formed, and the second quadrangular prism substrate 33B is overlaid on the second recording layer 36B as described above (FIG. 8C). (See (D)), such a process is repeated up to the seventh quadrangular prism substrate 33G and the eighth recording layer 36H, and the final eighth recording layer 36H is shown in FIG. 8E. Then, the triangular prism substrate 34 is bonded and fixed so that the inclined surface 34A sandwiches the eighth recording layer 36H.

  If necessary, the AR coating layer 38 is formed, and the manufacture of the holographic recording medium 30 is completed.

  In the first to third embodiments, the recording layer is configured such that diffracted light is generated in the Y-axis direction by the reproduction reference light from the Z-axis direction. The holographic recording medium 50 shown in FIG. As in the hologram cell 52 in FIG. 5, diffracted light may be generated in the Y-axis direction with respect to the reproduction reference light from the X-axis direction. In this case, the recording layer 54 is formed at about 45 ° with respect to the X-axis direction and the Y-axis direction.

  When reproducing the information recorded in the hologram, when reproducing reference light is irradiated to the hologram cells 52 in the same column from the X-axis direction, diffraction light is simultaneously generated from the hologram cells 52 in the same column in each row.

  In each of Examples 1 to 3 and 7, the recording layer is formed at about 45 ° with respect to the Y-axis direction and the Z-axis direction, or the X-axis direction and the Y-axis direction. However, it is only necessary that the diffracted light is generated in the Y-axis direction by the incidence of the reproduction reference light from the Z-axis direction or the X-axis direction. Therefore, the angle of the recording layer is particularly limited. It is not something.

  However, if the recording layer is about 45 ° with respect to the Y-axis direction and the Z-axis direction or the X-axis direction and the Y-axis direction as described above, the manufacturing is easy, and the signal light at the time of recording There is an advantage that optical interference with the reference light is easily generated.

  Further, in the above embodiment, the hologram cells are arranged in a total of 32 two-dimensional arrays of A rows to D rows and 1 column to 8 columns, but the present invention is not limited to this, The hologram cells are not limited in number in the X-axis direction and the Y-axis direction, and may be arranged in a two-dimensional array.

1 is a perspective view schematically showing a holographic recording medium according to Embodiment 1 of the present invention. Perspective view schematically showing a single hologram cell constituting the holographic recording medium Front view schematically showing a state of forming a hologram in the hologram cell The perspective view which shows typically the hologram stick which comprises the holographic recording medium which concerns on Example 2 of this invention. The perspective view which shows typically the holographic recording medium which concerns on Example 3 of this invention. The perspective view which shows typically the holographic recording medium which concerns on Example 4 of this invention. FIG. 3 is a perspective view schematically showing a process of manufacturing a hologram cell according to the first embodiment. Front view schematically showing a process of manufacturing a holographic recording medium according to Example 7. FIG. 6 is a perspective view schematically showing a hologram cell according to Example 4.

Explanation of symbols

10, 11, 30, 40, 50 ... Holographic recording medium 12, 42, 52 ... Hologram cell 14, 16, 26, 28 ... Substrate 14A, 16A ... Slope 18, 27, 36, 54 ... Recording layer 20 ... Spacer 22 , 38... AR (antireflection) coating layer 24... Hologram stick 32... Square prism substrate 34... Square prism substrate 32 A, 32 B. Quadratic prism substrate 34A ... slope 36A ... first recording layer 36B ... second recording layer 36H ... eighth recording layer

Claims (16)

  A plurality of hologram cells arranged in a two-dimensional array with the X-axis direction as rows and the Y-axis direction as columns, and each hologram cell is irradiated with reproduction reference light from one of the X-axis direction and the Z-axis direction Holographic recording medium, wherein a hologram is formed so that diffracted light is generated in the Y-axis direction, and diffraction light from a hologram cell adjacent in the Y-axis direction is transmitted. . In claim 1,
The hologram cell has a recording layer, and the recording layer is formed along the X-axis direction and has a planar shape that forms an angle of about 45 ° with respect to the Y-axis direction and the Z-axis direction. Holographic recording medium. In claim 1,
The hologram cell has a recording layer, and the recording layer is formed along the Z-axis direction and has a planar shape that forms an angle of about 45 ° with respect to the X-axis direction and the Y-axis direction. Holographic recording medium. In claim 2 or 3,
The hologram cell has a hexahedral shape, and has a pair of triangular prism-shaped substrates whose cross section is a right triangle, and the recording layer,
2. The holographic recording medium according to claim 1, wherein the pair of substrates are arranged such that oblique sides of a right triangle are opposed to each other, and the recording layer is formed between inclined surfaces including the opposed oblique sides. In claim 2 or 3,
A plurality of quadrangular prism substrates having a parallelogram cross-section with apex angles of about 45 ° and about 135 °, and the recording layer;
The holographic recording medium, wherein the quadrangular prism substrate is disposed so that a pair of parallel planes of the parallelogram are sequentially overlapped, and the recording layer is disposed between the overlapping planes. In claim 5,
A recording layer on both end faces of a coupling body, which has two triangular prism substrates each having a right-angled isosceles triangle and is connected so that the recording layers are parallel to each other. A holographic recording medium, wherein the triangular prism substrate is attached so as to be sandwiched between an inclined surface including an oblique side of the right-angled isosceles triangle and a plane of the rectangular prism substrate. In claim 4,
The substrate has a rectangular isosceles triangle shape in cross section, and the axial length of the triangular prism is equal to the length of two orthogonal sides in the right angled isosceles triangle. recoding media. In claims 5 and 6,
A holographic recording medium having a hexahedral shape as a whole, and a pair of end faces of the hexahedron formed by both end faces in the length direction of the quadrangular prism substrate. In any one of Claims 1 thru | or 8.
A holographic recording medium, wherein information is holographically recorded in advance in each of the hologram cells and then assembled integrally. In any one of Claims 1 thru | or 9,
A holographic recording medium comprising an antireflection coating layer provided at least at a portion where a light beam passes during recording and reproduction on the outer periphery of the holographic recording medium. Forming a recording layer made of a holographic recording material on the inclined surface of the first substrate having a substantially isosceles right triangle and a triangular prism shape in cross section;
A step of attaching a second substrate having the same shape as the first substrate so that the inclined surface sandwiches the recording layer between the inclined surface of the first substrate and forming a hexahedral hologram cell. When,
Arranging a plurality of the hologram cells so that the recording layers are parallel and integrated;
A method for producing a holographic recording medium comprising: In claim 11,
The length of the first and second substrates is equal to the length of two orthogonal sides in a right-angled isosceles triangle, and these are joined so that the hologram cells form a cube. A method of manufacturing a graphic recording medium. In claim 11,
The lengths of the first and second substrates and the recording layer are made equal to the length of one side of the holographic recording medium, and a pair of end faces of the holographic recording medium are formed on the first and second substrates. A method for producing a holographic recording medium, comprising both end faces in the axial direction. Forming a recording layer made of a holographic recording material on the slope of the first triangular prism substrate having a substantially right-angled isosceles triangle section;
A first quadrangular prism substrate having a parallelogram having a vertical angle of about 45 ° and about 135 ° and having a pair of planes having a length equal to the hypotenuse of the right-angled isosceles triangle is selected from the pair of planes. Attaching the recording layer so as to sandwich the recording layer between one plane and the slope;
Forming a second recording layer made of a holographic recording material on the other of the pair of planes;
A second quadrangular prism substrate having the same shape as the first quadrangular prism substrate is attached so that the second recording layer is sandwiched between one plane of the first quadrangular prism substrate and the other plane of the first quadrangular prism substrate. Process,
In the same manner as described above, the steps of repeatedly forming the recording layer and attaching the quadrangular prism substrate, attaching the Nth quadrangular prism substrate, and forming the recording layer;
Attaching a second triangular prism substrate having the same shape as the first triangular prism substrate so as to sandwich the Nth recording layer with the Nth rectangular prism substrate;
A method for producing a holographic recording medium comprising: In claim 14,
The lengths of the first and second triangular prism substrates and the first to Nth quadrangular prism substrates in the axial direction are made equal to the length of one side of the holographic recording medium, so that the first and second 3 A method for producing a holographic recording medium, comprising assembling a prism substrate and first to Nth rectangular column substrates so that both ends in an axial direction form a pair of end faces. In any of claims 11 to 15,
A method for producing a holographic recording medium, comprising the step of forming a hologram by holographic recording of information on the recording layer each time the recording layer is formed.

Images