JP4094372B2 - Hologram recording / reproducing method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hologram recording / reproducing method and apparatus suitable for high-density recording.
[0002]
[Prior art]
Hologram recording is attracting attention as a next-generation powerful recording method capable of recording information with high density because it can record a large amount of information on a single medium.
As a specific method of performing multiplex recording in hologram recording, angle multiplexing by so-called volume hologram (reference: JFHeanue et al., “Volume Holographic Storage and Retrieval of Digital Data”, Science, Vol.265, pp.749- 752, 1994).
[0003]
FIG. 38 shows an example of a conventional volume hologram recording / reproducing method. In the figure, 400 is a hologram medium made of an optical recording material, 6 is object light, 71 is reference light, and 7 is reproduction light. The reference beam 71 and the object beam 6 have the same wavelength, which is the wavelength to which the hologram medium 400 is exposed.
In FIG. 38, when recording is performed, the object light 6 to which information to be recorded on the medium 400 is added and the reference light 71 having a certain characteristic wavefront are simultaneously irradiated. Thereby, the interference fringes formed by the object light 6 and the reference light 71 are recorded on the medium 400. That is, the information given to the object light 6 is recorded as a hologram.
[0004]
When reproduction is performed, the recording medium 400 is irradiated with reference light 71 having a wavefront equal to that used during recording. Accordingly, the reference light 71 is diffracted by the interference fringes recorded on the medium 400, and this diffracted light is obtained as the reproduction light 7. At this time, since the wavefront of the reproduction light 7 is a reproduction of the wavefront of the object light 6 at the time of recording, the information given to the object light 6 can also be reproduced from the reproduction light 7.
Here, for example, when a plane wave is used as the reference light 71 and recording is performed a plurality of times while changing the angle of incidence on the medium 400, the interference fringes formed by the object light 6 and the reference light 71 are the reference light 71. The information is recorded on the medium 400 as independent ones depending on the incident angle. That is, angle multiplex recording is realized.
[0005]
At the time of reproduction, the reference light 71 is incident on the medium 400 at the same incident angle as that at the time of recording, so that only one reproduction light 7 corresponding to the incident angle is obtained. Thereby, it is possible to reproduce only the desired information out of the multiplex recording.
Hologram recording has a very high angular resolution and is recorded as independent information even with a slight difference in incident angle, so that high multiplexing is possible and high-density recording is realized.
[0006]
[Problems to be solved by the invention]
However, in the case of angle multiplex recording by the method of FIG. 38, it is necessary to control the incident angle of the reference beam 71 with respect to the medium 400 at the time of recording and reproduction with high accuracy. In the method in which 71 is incident from the outside of the medium 400, the accuracy of the drive unit of the optical system such as a mirror must be made sufficiently high, resulting in a problem that the mechanism becomes large and expensive.
[0007]
The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to provide a hologram recording / reproducing method and apparatus suitable for high-density recording that do not require high-precision control of the incident angle of reference light and the like. It is said.
[0008]
[Means for Solving the Problems]
  Therefore, in the present invention, at least one core layer that guides light by being sandwiched between lower refractive index portions and the boundary between the core layer and the lower refractive index portion or provided in the core layer is provided. A hologram is formed on a hologram medium having an optical waveguide having at least one diffraction grating layer, and at least one recording layer arranged outside the optical waveguide so that reference light can enter through the optical waveguide. A method of recording,
  As each layer of the optical waveguide of the hologram medium is laminated from below to above, object light is incident from either above or below the hologram medium,
The reference light is incident from either above or below the hologram medium,
A method for holographically recording information on the recording layer with the object beam and the reference beam,
  The object light is collected and incident on at least one small area in the recording layer,
  Provided is a hologram recording method in which the reference light is incident so that the small region is irradiated.
[0009]
  When excitation light is required for recording the hologram medium, the hologram mediumthe body'sExcitation light can be incident on the recording layer so that the small area is irradiated from either the upper side or the lower side..
  Alternatively, excitation light is incident on the core layer from the end face of any of the core layers, and the excitation light is diffracted by the diffraction grating layer corresponding to the incident core layer, and the small region of the recording layer is irradiated. The excitation light may be incident on the recording layer by the diffracted light irradiated as described above.
  Moreover, you may irradiate the other object light which shifted the irradiation position so that the irradiation area and irradiation area of the said object light may overlap partially.
[0010]
  The present invention is also a method for reproducing a hologram recorded on a recording layer of a similar hologram medium,
  Information is recorded in at least one small area in the recording layer,
  Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, the hologram is reproduced by entering reference light from either above or below the hologram medium,
  Provided is a hologram reproducing method for partially shielding the reproducing light so that the reproducing light emitted from the recording layer is concentratedly emitted from the small area.
[0011]
  The present invention is also a method for reproducing a hologram recorded on a recording layer of a similar hologram medium,
  Information is recorded in at least one small area in the recording layer,
  Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, reference light is incident from either above or below the hologram medium to reproduce the hologram, and the reference light is recorded on the recording medium. Provided is a hologram reproduction method for selectively irradiating reproduction light emitted from a layer so as to be intensively emitted from the small region.
[0012]
  The present invention is also a method for reproducing a hologram recorded on a recording layer of a similar hologram medium,
  A plurality of information is recorded in a multiplexed manner in at least one small region in the recording layer of the hologram medium,
  Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, the hologram is reproduced by entering reference light from either above or below the hologram medium,
  A hologram reproduction method is provided that blocks reproduction light corresponding to other information so that any one of the plurality of information is selectively reproduced.
[0013]
  The present invention is also an apparatus for recording a hologram on a similar hologram medium,
  A light source that emits light;
  A light branching unit for branching the light emitted from the light source into a first light and a second light;
  Assuming that each layer of the optical waveguide of the hologram medium is laminated from the bottom to the top, the object light incident on the object light obtained by spatially modulating the first light from either above or below the hologram medium And
  A reference light incident part that enters the second light as reference light from either above or below the hologram medium,
  Information is recorded on the recording layer by the object beam and the reference beam,
  The object light incident part has a condensing incident part that condenses and enters the object light into at least one small region in the recording layer of the hologram medium,
  The reference light incident section provides a hologram recording apparatus that makes the reference light incident so that the small area is irradiated.
[0014]
  When excitation light is required for recording on the hologram medium, an excitation light incident portion that makes the excitation light incident on the recording layer so as to irradiate the small area from either above or below the hologram medium is provided. You may make it have further.
  Alternatively, excitation light is incident on the core layer from the end face of any of the core layers, and the excitation light is diffracted by the diffraction grating layer corresponding to the incident core layer, and the small region of the recording layer is irradiated. An excitation light incident portion that makes excitation light incident on the recording layer by the diffracted light irradiated as described above may be further included.
  As a typical example, the condensing incident part includes an imaging optical system using a lens.
  The condensing incident part may include a spatial light phase modulator, and the spatial light phase modulator may include a transparent dielectric plate or a liquid crystal panel.
[0015]
  The present invention is also an apparatus for reproducing a hologram recorded on a recording layer of a similar hologram medium,
  A light source that emits light;
  Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, at least part of the light emitted from the light source is incident as reference light from either above or below the hologram medium A light incident part,
  The hologram-recorded information is detected as reproduction light by the reference light,
  Information is recorded in at least one small area in the recording layer of the hologram medium,
  Provided is a hologram reproducing apparatus having a spatial light selector that partially shields the reproducing light emitted from the recording layer so as to be emitted intensively from the small area.
[0016]
  The present invention is also an apparatus for reproducing a hologram recorded on a recording layer of a similar hologram medium,
  A light source that emits light;
  A light branching portion for branching at least part of the light emitted from the light source into first light and second light;
  A first reference light incident part that enters the first light as reference light from an end face of any one of the core layers;
  Assuming that each layer of the optical waveguide of the hologram medium is laminated from the bottom to the top, a second reference light incident section that enters the second light as reference light from either the top or the bottom of the hologram medium When,
  A light-shielding portion that activates one of the first and second reference light incident portions by blocking any one of the first and second lights,
  When the first reference light incident part is validated, the reference light incident from the first reference light incident part is diffracted by the diffraction grating layer corresponding to the incident core layer and irradiated to the recording layer. When the information recorded in the hologram is detected as reproduction light by the diffracted light and the second reference light incident part is validated, the information is obtained by the reference light incident from the second reference light incident part. Is detected as reproduction light,
  Information is recorded in at least one small area in the recording layer of the hologram medium,
  Provided is a hologram reproducing apparatus having a spatial light selector that partially shields the reproducing light emitted from the recording layer so as to be emitted intensively from the small area.
[0017]
  The present invention is also an apparatus for reproducing a hologram recorded on a recording layer of a similar hologram medium,
  A light source that emits light;
  Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, at least part of the light emitted from the light source is incident as reference light from either above or below the hologram medium A light incident part,
  The hologram-recorded information is detected as reproduction light by the reference light,
  Information is recorded in at least one small area in the recording layer of the hologram medium,
  The reference light incident section provides a hologram reproducing apparatus that selectively irradiates the reference light so that the reproduced light emitted from the recording layer is emitted from the small area in a concentrated manner.
[0018]
  The present invention is also an apparatus for reproducing a hologram recorded on a recording layer of a similar hologram medium,
  A light source that emits light;
  A light branching portion for branching at least part of the light emitted from the light source into first light and second light;
  A first reference light incident part that enters the first light as reference light from an end face of any one of the core layers;
  Assuming that each layer of the optical waveguide of the hologram medium is laminated from the bottom to the top, a second reference light incident section that enters the second light as reference light from either the top or the bottom of the hologram medium When,
  A light-shielding portion that activates one of the first and second reference light incident portions by blocking any one of the first and second lights,
  When the first reference light incident part is validated, the reference light incident from the first reference light incident part is diffracted by the diffraction grating layer corresponding to the incident core layer and irradiated to the recording layer. When the information recorded in the hologram is detected as reproduction light by the diffracted light and the second reference light incident part is validated, the information is obtained by the reference light incident from the second reference light incident part. Is detected as reproduction light,
  Information is recorded in at least one small area in the recording layer of the hologram medium,
  The second reference light incident section provides a hologram reproducing apparatus that selectively irradiates the reference light so that the reproduction light emitted from the recording layer is emitted intensively from the small area.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. Corresponding portions are denoted by the same reference numerals in the drawings of the respective embodiments, and the description thereof is omitted or simplified.
[0026]
<First Embodiment>
1 to 3 show a hologram recording method as a first embodiment of the present invention.
In these figures, 130 is a hologram medium, 131 is an area divided into a plurality of mediums 130, 132 is an area for recording and reproducing, 133 is a set of areas for recording and reproducing information of one of the areas 131, Reference numerals 1 and 2 denote a core layer and a clad layer for forming an optical waveguide (or a planar waveguide), respectively, 3 denotes a diffraction grating layer formed at the interface between the core layer 1 and the clad layer 2, and 4 denotes the optical waveguide. A recording layer made of an optical recording material disposed on the upper surface, 6 is object light to which information to be recorded, which is first light, is applied, and 71 is reference light, which is second light.
[0027]
First, the hologram recording method of this embodiment will be described with reference to FIGS. 1A (top view) and B (cross-sectional view taken along the line “a-b” in FIG. 1A).
In this embodiment, both the object beam 6 and the reference beam 71 are selectively applied to the recording layer 4 of only one area 132 out of the plurality of areas 131 of the medium 130 from above or below the medium. Information is recorded as a hologram by irradiation. This makes it possible to record a plurality of different information on the recording layer 4 in the plurality of areas 131 of the medium 130 and increase the recording capacity per medium 130.
[0028]
At this time, the object light 6 is once condensed or narrowed in the vicinity of or inside the medium 130 and then enlarged outside the medium 130 so as to be imaged on a photodetector for detecting reproduction information. Keep it. As a result, the recording density per region 131 can be increased without depending on the pixel size of either the spatial light intensity modulator or the photodetector that displays the recording information.
FIG. 1B shows an example in which the object light 6 is most condensed or reduced in the vicinity of the medium after passing through the medium 130. This is because the position where the object light 6 is most condensed or narrowed is made to coincide with the position of the opening 101 of the spatial light selector 14 to be described later, thereby improving the selectivity of the reproduction light during the reproduction operation. It is possible to reduce the reproduction signal crosstalk.
[0029]
The wavefront of the reference light 71 in the recording layer 4 is incident on the reference light 72 from one end face of the core layer 1 and propagates in the core layer 73 as shown in FIG. And the recording layer 4 is set to be equal to the wavefront in the recording layer 4 when the propagating light 73 is irradiated with the specific diffracted light 74 of the diffraction grating layer 3.
Further, as shown in FIG. 8, the wavefront of another reference beam 71 in the recording layer 4 is incident on the reference layer 72 from another end face of the core layer 1, and another diffraction grating is applied to the recording layer 4. It is set so as to be equal to the wavefront in the recording layer 4 when the diffracted light 74 different from the unique tip of the layer 3 is irradiated.
Thereby, the hologram reproducing method described in the fourth embodiment to be described later becomes possible.
[0030]
FIG. 1B shows an example in which a transmission hologram is recorded by irradiating the object beam 6 from the same direction as the reference beam 71 when viewed from the recording layer 4 of the medium 130, but FIG. As shown in FIG. 1B, a reflection type hologram can be recorded by irradiating the object beam 6 from the direction facing the reference beam 71 when viewed from the recording layer 4 of the medium 130. .
[0031]
Next, a recording method according to another embodiment will be described with reference to FIGS. 3A (top view) and B (cross-sectional view taken along the line “a-b” in FIG. 3A).
In the present embodiment, one piece of recording information is divided into a plurality of parts in advance, and each part is recorded as a hologram on the recording layer 4 in a different area among the divided areas 131 of the medium 130. For each of the divided portions of the recording information, the object light 6 and the reference light 71 corresponding to each of the divided portions are recorded on the recording layer 4 of only one or more regions 132 of the regions 131 divided into a plurality of portions of the medium 130. On the other hand, partial information divided by irradiation from above or below the medium is selectively recorded as a hologram.
[0032]
As a result, similarly to the case of FIG. 1, a plurality of different information can be recorded on the recording layers 4 of the plurality of regions 131 of the medium 130, and the recording capacity per medium 130 can be increased.
At this time, the setting of the object beam 6 and the reference beam 71 is performed in the same manner as described in FIG. As a result, the same effect as the recording method described above can be obtained.
[0033]
However, in the present embodiment, in order to record the entire recording information, the recording operation is repeated at least once for a piece of recording information, and at most the same number of times as the number of divisions of the recording information. As a result, in the medium 130, as a recording area corresponding to a certain piece of recording information, a set 133 of areas having a number equal to the number of divisions of the recording information in the divided areas 131 is configured. Become.
[0034]
As described above, in this embodiment, one piece of recording information is divided into a plurality of parts, and each part is recorded as a hologram in a different area among the plurality of divided areas 131 in the recording layer 4. Therefore, if the size of the photodetector for detecting the reproduction information and the distance between the medium 130 and the photodetector are constant, the magnification of the object light 6 from the medium position to the photodetector position, that is, the imaging plane Can be reduced, and the optical system of the object light 6 can be easily realized.
[0035]
Also in the present embodiment, the recording of the reflection hologram can be performed by the same method as described with reference to FIG.
Although not particularly shown in the present embodiment, either the object light 6 or the reference light 71 or the object light 6 or the reference light 71 is selectively irradiated to the recording layer 4 only in the region 132 of the medium 130. For both, a spatial light selector provided with a necessary aperture may be used.
[0036]
In the present embodiment, a plurality of sets of the core layer 1 and the diffraction grating layer 3 in the optical waveguide are laminated, the diffraction grating layer 3 is formed on the upper boundary surface between the core layer 1 and the cladding layer 2, and the recording layer 4 is formed. Although an example of a medium configuration arranged on the upper surface of the optical waveguide is shown, even if the core layer 1 and the diffraction grating layer 3 in the optical waveguide are only one layer each, the diffraction grating layer 3 is formed of the core layer 1 and the cladding. Whether the recording layer 4 is formed on either the lower boundary surface of the layer 2 or the inside of the core layer 1, the recording layer 4 is disposed on either the lower surface or both upper and lower surfaces of the optical waveguide, or two optical waveguides Even if the optical waveguide and the recording layer are alternately stacked, the same effect as in the present embodiment can be obtained. That is, it is sufficient that at least one recording layer and at least one optical waveguide are adjacently disposed.
This point is the same in each embodiment (including the reproduction method) having the same configuration as described below.
[0037]
Further, the recording layer 4 has the same effect whether it is disposed on either one of the upper and lower surfaces of the optical waveguide or on both surfaces, and the same effect is obtained even if it is disposed spatially away from the optical waveguide. There is an effect.
The recording layer 4 has the same effect whether it is bonded to the optical waveguide with an adhesive or is fixed without an adhesive, and the recording layer 4 is sandwiched by a protective film on either the upper or lower side. Even if the periphery is covered with a protective film, the same effect is obtained.
These points are also the same in each embodiment (including the reproduction method) having the same configuration as described below.
[0038]
Second Embodiment
4 to 5 show a hologram recording method as a second embodiment of the present invention. In the figure, the difference from the first embodiment is that the excitation light 80 which is the third light is used. In the present embodiment, when the optical recording material forming the recording layer 4 of the medium 130 is recorded by the object light 6 and the reference light 71, excitation by the excitation light 80 having a wavelength different from these two lights is necessary. Is assumed.
[0039]
First, the hologram recording method of this embodiment will be described based on FIGS. 4A (top view) and B (cross-sectional view taken along the line “a-b” in FIG. 4A).
In this embodiment, the object beam 6, the reference beam 71, and the excitation beam 80 are selectively applied to the recording layer 4 of only one region 132 out of the plurality of regions 131 of the medium 130. Information is recorded as a hologram by irradiating from above or below. This makes it possible to record a plurality of different information on the recording layer 4 of the plurality of areas 131 of the medium 130 and increase the recording capacity per medium 130. At this time, the setting of the object light 6 and the reference light 71 is set. Is performed in the same manner as described in the first embodiment. Thereby, also in this embodiment, the same effect as the recording method described in FIG. 1 can be obtained.
[0040]
4B shows an example in which the excitation light 80 is irradiated from above or below the medium 130 independently of the object light 6 and the reference light 71, the excitation light 80 is shown in FIG. As shown in (B), the same effect can be obtained by irradiating the object beam 6 and the reference beam 71 with one or both of them. In addition, excitation light may be incident from the end face of any core layer, and excitation light may be incident on the recording layer using diffracted light from the diffraction grating layer. This is also possible in the following related embodiments. It is.
[0041]
Also in the present embodiment, the recording of the reflection hologram can be performed by the same method as described in the first embodiment.
Also in the present embodiment, similarly to the description in the first embodiment, one piece of recording information is divided into a plurality of parts in advance, and each part is different in each of the divided areas 131 of the medium 130. It is possible to record as a hologram on the recording layer 4 in the region. This also applies to the following related embodiments.
Although not specifically shown in the present embodiment, the object light 6, the reference light 71, and the excitation light 80 are selectively irradiated on the recording layer 4 only in the region 132 of the medium 130, and therefore the object light 6 and the reference light 71. A spatial light selector provided with necessary openings may be used for any or all of the excitation light 80.
[0042]
<Third Embodiment>
6A (top view) and FIG. 6B (a cross-sectional view taken along the line “a-b” in FIG. 6A) show a hologram recording method as a third embodiment of the present invention. The difference from the second embodiment is that a reference beam 72 is used instead of the reference beam 71 in the figure. Reference numerals 73 and 74 denote propagation light in the core layer 1 and its diffraction light by the diffraction grating layer 3.
In the present embodiment, similarly to the second embodiment, since the optical recording material forming the recording layer 4 is recorded by the object beam 6 and the reference beam 72, excitation light having a wavelength different from these two beams is used. The case where the excitation by 80 is required is assumed.
[0043]
In this embodiment, both the object light 6 and the excitation light 80 are selectively applied to the recording layer 4 of only one area 132 out of the plurality of areas 131 of the medium 130 from above or below the medium. At the same time, the reference light 72 is incident from one end face of the core layer 1 to propagate the propagation light 73 in the core layer, and to the recording layer 4 in one or more areas including the area 132 Information is recorded as a hologram by irradiating the propagating light 73 with the specific diffracted light 74 by the diffraction grating layer 3.
This makes it possible to record a plurality of different information on the recording layer 4 in the plurality of areas 131 of the medium 130 and increase the recording capacity per medium 130.
[0044]
At this time, the setting of the object beam 6 is performed by the same method as that described in the first embodiment. As a result, the same effect as the recording method described in the first embodiment can be obtained in this embodiment. It is done.
The wavefront of the diffracted light 74 in the recording layer 4 can be arbitrarily formed by appropriately designing the diffraction grating layer 3. For example, a single diffraction grating layer 3 can generate diffracted light with a uniform wavefront (parallel light, convergent light, or divergent light) over the entire surface, or diffracted light with different wavefronts depending on the position. It is possible to generate the diffracted light or not depending on the position.
[0045]
That is, when a certain diffraction grating layer 3 generates uniform parallel light over the entire surface and the radiation angles of the parallel light generated by the diffraction grating layers 3 of the respective layers are set to be different from each other, Recording / reproduction corresponding to the angular multiple volume hologram method is performed.
In addition, a single diffraction grating layer 3 generates a plurality of convergent lights that converge at one or different positions, and the convergence positions of the convergent lights generated by the diffraction grating layers 3 of the layers are set to be different from each other. In this case, recording and reproduction corresponding to a so-called shift multiple volume hologram in the prior art is performed.
[0046]
Furthermore, when one diffraction grating layer 3 generates light having a wavefront with a certain phase distribution, and the phase distribution of the wavefronts of the light generated by the diffraction grating layers 3 of each layer is set to be orthogonal to each other In the prior art, recording and reproduction corresponding to a so-called phase-multiplexed volume hologram is performed. In any case, the recording / reproducing method of the present invention is effective.
[0047]
6B shows an example in which the excitation light 3 is irradiated from above or below the medium 130 independently of the object light 6 and the reference light 72. However, the excitation light 3 is the same as in FIG. Even if the object light 6 is superimposed and irradiated, the same effect can be obtained.
FIG. 6B shows an example in which a transmissive hologram is recorded by irradiating the object light 6 from the same direction as the diffracted light 74 when viewed from the recording layer 4 of the medium 130. In this embodiment, FIG. Alternatively, it is possible to record a reflection hologram by irradiating the object beam 6 from the direction facing the diffracted beam 74 when viewed from the recording layer 4 of the medium 130.
[0048]
Although not specifically shown in the present embodiment, the object light 6 and the excitation light 80 are selectively irradiated on the recording layer 4 only in the region 132 of the medium 130, so that either the deviation of the object light 6 and the excitation light 80 or For both, a spatial light selector provided with a necessary aperture may be used.
Further, in order to reduce the influence of the reflection of the diffracted light 74 diffracted by the diffraction grating layer 3 on the surface of the medium 130, it is effective to apply an anti-reflective coating on the upper, lower, or both upper and lower surfaces of the medium 130. is there. This also applies to the following embodiments having the same configuration.
[0049]
<Fourth embodiment>
7 to 10 show a hologram reproducing method as a fourth embodiment of the present invention. In each figure, the same parts as those in FIG. Reference numeral 14 denotes a spatial light selector, 101 denotes an opening thereof, and 9 denotes reproduction light.
First, the reproduction method of this embodiment will be described with reference to FIGS. 7A and 7B are top views, and FIG. 7C is a cross-sectional view taken along the line “ab” in FIG. 7B.
[0050]
In order to reproduce the hologram recorded on the hologram medium recorded by the method described in the first to third embodiments, the reference beam 72 is incident from one end face of the core layer 1 as shown in FIG. Then, the propagating light 73 is propagated in the core layer, and the recording layer 4 of one or more areas including the area 132 in which desired information is recorded among the plurality of areas 131 of the medium 130 is recorded. The characteristic diffraction light 74 of the diffraction grating layer 3 of the propagation light 73 is irradiated.
[0051]
Therefore, when recording is performed by the method described in the third embodiment, the recording layer 4 in the region 132 is irradiated with the same diffracted light 74 as in recording, and also in the first or second embodiment. When recording is performed by the method described, the wavefront in the recording layer 4 of the diffracted light 74 applied to the recording layer 4 in the region 132 is equal to the wavefront in the recording layer 4 of the reference light 71 at the time of recording. In either case, the hologram is reproduced and the reproduction light 7 is obtained.
[0052]
Further, as shown in FIG. 8 (a cross-sectional view corresponding to FIG. 7C), if the reference light 72 is incident from another end face of the core layer 1, a distinctive point from the other diffraction grating layer 3 is obtained. Since different diffracted light 74 is irradiated, another hologram is reproduced and another reproduced light 7 is obtained.
Here, the reproduction light emitted from the medium 130 is obtained by superimposing the reproduction light of the hologram recorded on the recording layer 4 in one or more regions irradiated with the diffracted light 74. In order to extract only the desired reproduction light 7 from this, as shown in FIGS. 7 to 8, the spatial light selector 14 having the opening 101 only in the area 132 to be reproduced is arranged close to the medium 130. As a result, only the reproduction light 7 having the information recorded in the area 132 can be selectively reproduced.
As a spatial light selector, a method of changing the size, number, and position of the aperture electrically using a mask with a fixed aperture position, a mask that moves it in two dimensions, or a mask that uses a liquid crystal panel Is mentioned.
[0053]
7 to 8 show an example of reproducing a transmission hologram by disposing the spatial light selector 14 above the medium 130. FIG. 9 (A) is a top view, and FIG. It is also possible to reproduce the reflection hologram by disposing the spatial light selector 14 below the medium 130 as shown in the cross-sectional view along the “a-b” line in FIG. It is.
Further, in order to reproduce a medium on which one piece of recording information is divided and recorded as shown in FIG. 3A, as shown in FIG. 10 corresponding to FIG. The spatial light selector 14 having the opening 101 only in the portion may be disposed close to the medium 130.
[0054]
The wavefront of the diffracted light 74 in the recording layer 4 can be arbitrarily formed by appropriately designing the diffraction grating layer 3, and various multiplexing methods can be achieved by changing the structure of the diffraction grating layer 3. The hologram can be recorded and reproduced as described in the third embodiment.
[0055]
In addition, in order to prevent unnecessary diffracted light 74 other than being irradiated to the desired region 132 from entering the photodetector for detecting reproduction information, the recording layer 4 in the desired region 132 is irradiated as necessary. The region of the diffraction grating layer 3 that generates the diffracted light 74 is set as a region that does not generate the diffracted light 74, and the reference light 72 is incident on the recording layer 4 in another region adjacent to the desired region 132. It is effective to change the core layer 1 so that the diffracted light 74 is generated from the other diffraction grating layer 3.
In order to realize this, a region where the diffracted light 74 is generated in the diffraction grating layer 3 of each layer is, for example, a stripe pattern or a checkered pattern, and the diffraction of the diffraction grating layer 3 of each layer. The regions that generate the light 74 may be arranged alternately.
[0056]
<Fifth Embodiment>
11 to 12 show a hologram reproducing method as a fifth embodiment of the present invention. In these drawings, a difference from the fourth embodiment is that a reference light 71 is used instead of the reference light 72 in FIG. That is, as shown in FIG. 11 (corresponding to FIG. 7), instead of the reference light 72, the reference light 71 is divided into a plurality of areas 131 of the medium 130 where desired information is recorded. The hologram is reproduced by irradiating the recording layer 4 in one or more regions including the recording layer 4 from above or below the medium, and the reproduction light 7 is obtained. The setting of the reference beam 71 is performed in the same manner as described in the first embodiment.
[0057]
Here, the reproduction light emitted from the medium 130 is obtained by superimposing the reproduction light of the hologram recorded on the recording layer 4 in one or more regions irradiated with the reference light 71. In order to extract only the desired reproduction light 7 from this, as shown in FIG. 11, the spatial light selector 14 having the opening 101 only in the region 132 to be reproduced is arranged close to the medium 130. As a result, only the reproduction light 7 having the information recorded in the area 132 can be selectively reproduced.
[0058]
Note that, as shown in FIG. 3A, in order to reproduce a medium in which one piece of recording information is recorded by being divided into a plurality of parts, as shown in FIG. 12 (corresponding to FIG. 11), a set of areas to be reproduced is recorded. The spatial light selector 14 having the opening 101 only at the portion 133 may be disposed close to the medium 130.
[0059]
<Sixth Embodiment>
13 to 14 show a hologram reproducing method as a sixth embodiment of the present invention. The difference from the fifth embodiment is that the spatial light selector 14 is not used and the reference light 71 is set as described in the first embodiment.
That is, in order to reproduce the hologram medium recorded by the method according to any one of the first to third embodiments, FIG. 13A (top view), FIG. 13B (“ab” in FIG. As shown in "Cross-sectional view in line", the reference beam 71 is recorded on the recording layer 4 of only one or more regions 132 in which desired information is recorded among the regions 131 divided into a plurality of media 130. Optionally, the hologram is reproduced by irradiating from above or below the medium, and only the reproduction light 7 having information recorded in one or more areas 132 is obtained.
[0060]
In the present embodiment, it is not particularly necessary to provide a spatial light selector on the output side of the reproduction light 7 of the medium 130, but the spatial light selector 14 and the opening 101 similar to those in the fourth or fifth embodiment may be provided. Good.
Further, in order to reproduce a medium in which one piece of recording information is recorded by being divided into a plurality of parts as shown in FIG. 3A, it is desired to reproduce the reference beam 71 as shown in FIG. 14 corresponding to FIG. The recording layer 4 having only the region set 133 may be selectively irradiated from above or below the medium.
[0061]
Although not specifically shown in the present embodiment, since the reference light 71 is selectively applied to the recording layer 4 of only the region 132 of the medium 130, the spatial light selection in which a necessary opening is provided for the reference light 71. A vessel may be used.
13B and 14B show an example in which a transmission hologram is reproduced by irradiating the reference beam 71 from below as viewed from the recording layer 4 of the medium 130. It is also possible to reproduce a reflection hologram by irradiating the reference beam 71 from above as viewed from the recording layer 4.
[0062]
In each of the above embodiments, the recording layer 4 may be an optical recording material used in general hologram recording. For example, a photopolymerizable material such as a photopolymer that causes photopolymerization due to a change in cyclic structure by light irradiation, a photocrosslinkable material represented by ammonium bichromate-polyvinyl alcohol material, a photochromic material, an azo dye Photoisomerized material represented by a material doped with PMMA (polymethyl methacrylate), or LiNbO₃, BaTiO₃, Ba₁₂SiO₂₀Examples thereof include a photorefractive material typified by an inorganic dielectric crystal such as (BSO) or a polymer photorefractive material.
[0063]
As a specific shape of the hologram medium, a card type, a chip type, a disk type, a tape type, a drum type, and the like can be considered. Any of the methods of the present invention can be applied, and all have the same effect.
The area of the waveguide surface of the optical waveguide and the recording layer are not necessarily the same, and the area of the waveguide surface may be larger or smaller. When the area of the waveguide surface is smaller, the optical waveguide is driven one-dimensionally, two-dimensionally, or three-dimensionally, so that the entire surface of the larger recording layer can be handled.
[0064]
By the way, in order for light to propagate through the core layer 1, the core layer 1 may be sandwiched between media having a refractive index lower than that of the core layer 1. In FIG. 1 and the like, the refractive index of the cladding layer 2 is set lower than the refractive index of the core layer 1.
The clad layer 2 is disposed at a position sandwiching all the core layers 1 as described above in order to maintain and support the shape of the optical waveguide, but the core layer 1 is arranged so that light propagates in the core layer 1. May be sandwiched between lower refractive indexes.
For example, when the refractive index of the free space is lower than the refractive index of the core layer 1 (that is, the lower refractive index portion is air, vacuum, etc.), for example, either the uppermost cladding layer 2 or the lowermost cladding layer 2 Even if one or both of them are absent, light is guided to the core layer 1 sandwiched between air and the like, so that the same effect can be obtained. This is generally the same for each core layer even when there are a plurality of core layers. Further, when the refractive index of the recording layer is lower than the refractive index of the core layer, the recording layer can function as a portion having the lower refractive index.
[0065]
Next, FIGS. 15A to 15D are schematic views showing examples of the diffraction grating layer 3.
The diffraction grating layer 3 includes a sawtooth-shaped groove as shown in FIG. 15A, a sinusoidal groove as shown in FIG. 15B, and FIG. 15C. ) And the like formed by a change in refractive index (the figure shows a configuration in which portions having different refractive indexes are alternately arranged).
[0066]
The diffraction grating layer may or may not be uniform in the waveguide plane, but here the diffraction efficiency of the diffraction grating layer has a predetermined distribution so that the diffracted light from the diffraction grating layer has a desired intensity. An example of this is shown.
As a preferred example, the diffraction grating layer has a distribution in which the diffraction efficiency gradually increases in the propagation direction of the propagation light. In this way, attenuation of the light intensity that occurs as the light is guided can be canceled, and the intensity profile of the diffracted light from each diffraction grating layer can be made uniform or approximately the same in the in-layer direction.
FIG. 16 shows an example in which a diffraction grating layer is formed by a rectangular wave grating and distributed so that the diffraction efficiency gradually increases toward the right depending on the height of the rectangle. In this case, the diffraction efficiency is proportional to the square of the height of the rectangle.
[0067]
In the multilayer optical waveguide, the diffraction efficiency of two or more diffraction grating layers may have a predetermined distribution in the stacking direction. Preferable examples include those having such a distribution that the diffraction efficiency of two or more diffraction grating layers gradually decreases in the direction of emission of diffracted light. In this way, for example, when diffracted light is emitted above the optical waveguide, the phenomenon that the diffracted light from the diffraction grating layer located below the optical waveguide is more easily absorbed by the optical waveguide can be canceled, and which phenomenon can be canceled. The intensity of the diffracted light coming out of the optical waveguide from the diffraction grating layer can be uniform or similar.
[0068]
FIG. 17 shows an example in which a diffraction grating layer (diffraction grating layers 31 to 35 in order from the top) is formed by a rectangular wave grating, and the diffraction efficiency is distributed so as to gradually decrease toward the top by the height of the rectangle. Show. FIG. 17 shows a partial cross section of the optical waveguide along the stacking direction.
In addition, by combining both of the above, it is possible to have a distribution in which the diffraction efficiency of the diffraction grating layer gradually increases in the waveguide direction of light propagating through the core layer and gradually decreases in the emission direction of the diffracted light. . According to this, the intensity | strength of the diffracted light radiate | emitted from which position of which diffraction grating layer can be made uniform or comparable.
[0069]
In the above description, an example has been shown in which the intensity of diffracted light is accurately uniform or equal in the in-layer direction and in the layer thickness direction. In many cases, there is no hindrance if the same level. According to the present invention, by appropriately distributing the diffraction efficiency of the diffraction grating layer in the in-layer direction and the layer thickness direction, the intensity of the diffracted light can be made approximately the same in the in-layer direction and the layer thickness direction. .
[0070]
In the above description, the intensity of the diffracted light has been described with a focus on making it uniform or equal in the in-layer direction and in the layer thickness direction. However, depending on the application field, the distribution of the intensity of the diffracted light may be intentionally made. It may be convenient. According to the present invention, the intensity of the diffracted light can be set to a desired distribution by appropriately distributing the diffraction efficiency of the diffraction grating layer in the in-layer direction and the layer thickness direction.
[0071]
Further, the area of the diffraction grating layer does not need to be the same as the area of the core layer, and the diffraction grating layer may be partially provided or distributed in a plurality. Furthermore, it is not necessary to provide the diffraction grating layer corresponding to all the core layers, and there may be a core layer in which the diffraction grating layer is not provided.
[0072]
Further, at the time of recording / reproducing, the reference light can be made incident from any one of the end faces of the hologram medium below and above the hologram medium, and both have the same effect. Further, at the time of recording, the object light can be incident from either the lower side or the upper side of the hologram medium, and both have the same effect. Further, when excitation light is required at the time of recording, the excitation light can be incident from any one of the end surfaces of the core layer below and above the hologram medium, and both have the same effect.
[0073]
<Seventh embodiment>
18 to 21 show an embodiment example of a hologram recording apparatus for realizing the hologram recording method described in the first embodiment.
In these figures, 130 is a hologram medium having the structure described in the first embodiment, 6 is object light 71 as first light, reference light is second light, and 141 is for object light and reference light. Light source, 151 and 152 are polarization controllers, 161 is an optical splitter, 170 is a light shield, 181 and 182 are reflectors, 20 is a beam expander, 21 is a spatial light intensity modulator, 22 is an imager, and 30 is A spatial light phase modulator 331 is a condenser.
The polarization controllers 151 and 152 are elements that rotate the polarization plane of light, and use, for example, a half-wave plate.
[0074]
The optical splitter 161 is an element that splits a light beam in two directions, and uses, for example, a half mirror or various beam splitters.
The spatial light intensity modulator 21 is an element that displays information to be recorded on the medium 130. For example, a liquid crystal panel or a DMD (Digital Micromirror Device) element is used.
The image forming unit 22 is an optical system for forming an image of the object light 6 on the light detector in the reproducing apparatus, that is, on the image forming surface in the drawing via the medium 130, and uses, for example, a single lens or a combination lens.
[0075]
First, a hologram recording apparatus according to the present invention will be described with reference to FIG.
The light beam emitted from the light source 141 is branched into two by an optical branching device 161, and each branched beam is controlled by two polarization controllers 151 and 152 to a polarization necessary for recording. One of the branched beams is reflected by the reflector 181, expanded to a desired beam width by the beam expander 20, and further given information to be recorded on the medium 130 by the spatial light intensity modulator 21. Thus, the image light 22 becomes object light 6. Further, the other one of the branched beams is reflected by the reflector 182 and becomes the reference light 71.
[0076]
Here, it is assumed that the object light 6 can be irradiated from above or below the medium to the recording layer 4 of only the desired region 132 of the medium 130 by controlling the relative position of the medium 130. Further, the reference light 71 is controlled at the angle and position of the reflector 182 and the relative position of the medium 130, so that the reference light 71 is incident on the recording layer 4 of only the desired region 132 of the medium 130 at a desired incident angle. It is possible to irradiate from above or below the medium.
[0077]
Hereinafter, the principle and effect of the recording operation in this example and each embodiment are exactly the same as those described in the first embodiment.
In FIG. 18, since the reference beam 71 is a parallel beam and the incident angle with respect to the medium 130 can be changed by controlling the angle and position of the reflector 182, it corresponds to the conventional angle multiple volume hologram method. Recording and reproduction can be performed. Therefore, as the diffraction grating layer 3 in the medium 130 used in the present embodiment, for example, parallel light is generated and the radiation angles of the parallel light generated by the diffraction grating layers 3 of the layers are set to be different from each other. Use things.
[0078]
18 shows an example in which a transmission hologram is recorded by irradiating the object beam 6 from the same direction as the reference beam 71 when viewed from the recording layer 4 of the medium 130. However, as shown in FIG. It is also possible to record a reflection hologram by irradiating the object beam 6 from the direction facing the reference beam 71 as viewed from the 130 recording layers 4.
[0079]
Next, another example of the hologram recording apparatus will be described with reference to FIG.
In this embodiment, the wavefront of the reference beam 71 is converted by the condenser 331, and the object beam 6 and the reference beam 71 can be irradiated to the recording layer 4 at a desired position in the desired region 132 of the medium 130. Except for the point to be, the configuration is exactly the same as FIG. The condenser 331 is an element that converts the reference light 71 into convergent light. For example, a single lens or a combination lens is used.
[0080]
In this embodiment, it is possible to perform recording and reproduction corresponding to the conventional shift multiple volume hologram method. Therefore, as the diffraction grating layer 3 in the medium 130 used in the present embodiment, for example, a plurality of convergent lights that converge at one or different positions are generated, and the convergence generated by the diffraction grating layers 3 of each layer is generated. The light convergence positions are set to be different from each other.
[0081]
Next, another example of the recording apparatus will be described with reference to FIG. This embodiment has the same configuration as that shown in FIG. 18 except that the wavefront of the reference light 71 is modulated by the spatial light phase modulator 30. The spatial light phase modulator 30 is an element that modulates the reference light 71 into light having a wavefront with a certain phase distribution. For example, a liquid crystal panel or a phase plate made of a transparent dielectric is used. Also in this example, the principle and effect of the recording operation are exactly the same as described in the first embodiment.
[0082]
The liquid crystal panel can actively modulate the phase distribution of the wavefront of transmitted light or reflected light by applying an electric signal or an optical signal from the outside.
The phase plate is a surface of a transparent dielectric plate such as glass provided with a pattern such as fine irregularities by etching or vapor deposition, and changes the phase distribution of the wavefront of transmitted light according to the pattern. Is. Therefore, in order to change the phase distribution of the wavefront of the transmitted light in various ways, a plurality of phase plates having different patterns may be prepared in advance and these may be exchanged. Alternatively, when a phase plate having a plurality of patterns different from each other is used, it is possible to change the phase distribution of the wavefront of the transmitted light simply by moving this and changing the light transmission position.
[0083]
FIG. 22 shows an example of a spatial light phase modulator using a phase plate. This is an example of a phase plate 301 in which a plurality of different patterns are provided on a single circular transparent dielectric plate. By rotating the phase plate 301, the phase distribution of the wavefront of transmitted light can be changed variously. Can do. This spatial light phase modulator has the advantage that very high speed optical phase modulation can be easily realized by rotating the phase plate at high speed.
FIG. 23 shows a partial configuration example of an apparatus using the phase plate shown in FIG. By adopting a configuration in which the phase plate 301 is rotated around the object light 6 in this way, the apparatus can be reduced in size.
[0084]
In this embodiment, it is possible to perform recording / reproduction corresponding to the phase multiplexing volume hologram system of the prior art. Therefore, as the diffraction grating layer 3 in the medium 130 used in the present embodiment, for example, light having a wavefront with a certain phase distribution is generated and the wavefront phase of the light generated by the diffraction grating layer 3 of each layer is generated. A distribution set to be orthogonal to each other is used.
In FIGS. 20 and 21 as well, the recording of the reflection hologram may be performed by the same method as described in FIGS. The same applies to the following embodiments.
[0085]
Also in this embodiment and the following related embodiments, as described in the first embodiment, one piece of recording information is divided into a plurality of parts in advance, and each part is divided into a plurality of media 130. It is possible to record as a hologram on the recording layer 4 in different areas of the area 131.
Although not specifically shown in the present embodiment, either the object light 6 or the reference light 71 or the object light 6 and the reference light 71 are selectively irradiated to the recording layer 4 of only the region 132 of the medium 130. For both, a spatial light selector provided with a necessary aperture may be used.
These variations are also effective in the following embodiments.
[0086]
<Eighth Embodiment>
FIG. 24 shows a second example of the recording apparatus for realizing the recording method described in the first embodiment.
This embodiment has the same configuration as that in FIG. 18 except that the object light after passing through the medium 130 is imaged on the photodetector in the reproducing apparatus, that is, the imaging plane in the drawing, using the imaging device 23. It has become.
As the imager 23, for example, a single lens or a combination lens is used. The image forming device 23 is unnecessary for a recording-only device because it does not have a photodetector, but is shown here for the purpose of explanation. Also in this example, the principle and effect of the recording operation are the same as those described in the first embodiment.
[0087]
In the present embodiment, the function of irradiating the object light 6 onto the medium 130 so as to be condensed or reduced, and enlarging the object light after passing through the medium 130 to form an image on the image plane in FIG. Since only one imager 22 and 23 need to be realized, there is an advantage that the design of the optical system becomes easier as compared with the case where the same function is realized with only one imager 22.
[0088]
Further, in the present embodiment, as in FIG. 18, a configuration for performing recording / reproduction corresponding to the angle-multiplexed volume hologram system is shown. However, as described in the seventh embodiment, the spatial light phase modulator 30 or the light collecting unit. In addition, a phase multiplex volume hologram method or a shift multivolume hologram method is realized by adding a device 331 and allowing the object beam 6 and the reference beam 71 to be irradiated to a desired position in a desired region of the medium 130. Corresponding recording and reproduction can be performed. The same applies to the following ninth embodiment.
[0089]
<Ninth Embodiment>
25 and 26 show a third example of the hologram recording apparatus for realizing the recording method described in the first embodiment.
This embodiment has the same configuration as that of FIG. 18 except that a spatial light phase modulator 221 is used as the imager 22. The spatial light phase modulator 221 is an element that modulates the object light 6 into light having a wavefront with a certain phase distribution. For example, a liquid crystal panel or a transparent dielectric plate is used.
[0090]
In FIG. 25, since the spatial light intensity modulator 21 and the spatial light phase modulator 221 are arranged in close contact with each other, an arbitrary intensity and phase distribution can be realized in the wavefront of the object light 6. Therefore, in this embodiment, the object light 6 is irradiated so as to be condensed or narrowed down on the medium 130 with a greater degree of freedom than when a normal single lens or a combination lens is used as the imager 22. There is an advantage that it can be set.
[0091]
In addition, when the spatial light intensity modulator 21 and the spatial light phase modulator 221 cannot be disposed in close contact due to restrictions such as element dimensions, they are disposed via a so-called 4f lens 222 as shown in FIG. It is good also as a structure which optically couples these. The 4f lens 222 is a combination of two lenses having the same focal length f with an interval of d = 2f. For example, a single lens or a combination lens is used as each lens. By doing so, the same effect as that obtained when the spatial light intensity modulator 21 and the spatial light phase modulator 221 are arranged in close contact with each other can be obtained.
[0092]
Next, a hologram recording apparatus according to the present invention will be described with reference to FIG. This embodiment has the same configuration as that shown in FIG. 18 except that the imaging device 22 is a combination of the spatial light phase modulator 221 and the imaging lens 223. The imaging lens 223 is an optical system for assisting the imaging function of the spatial light phase modulator 221. For example, a single lens or a combination lens is used.
[0093]
In FIG. 26, the spatial light intensity modulator 21 and the spatial light phase modulator 221 are arranged in close contact as shown in FIG. 25, or are arranged via a so-called 4f lens 222 as shown in FIG. Therefore, in this embodiment, the object light 6 is irradiated so as to be condensed or narrowed down on the medium 130 with a greater degree of freedom than when a normal single lens or a combination lens is used as the imager 22. In addition, since the imaging lens 223 can assist the imaging function of the spatial light phase modulator 221, the optical system can be easily designed.
[0094]
In this case, in the present embodiment, since the irradiation state of the object light 6 on the medium 130 can be set with a greater degree of freedom, the object light is applied to a plurality of areas 132 in the set 133 of areas to be recorded on the medium 130. 6 can be irradiated simultaneously. As a result, the number of repetitions of the recording operation performed on one piece of recording information can be reduced, and as a result, the recording speed can be improved.
[0095]
Further, in the present embodiment, the object light 6 is irradiated on the medium 130 so as to be condensed or narrowed using only one imager 22, and the object light after passing through the medium 130 is enlarged in the drawing. Although a configuration in which an image is formed on the imaging surface is shown, in order to facilitate the design of the optical system, as described in the eighth embodiment, a configuration in which an imager 23 is added may be used. The same applies to the embodiments described later.
[0096]
<Tenth Embodiment>
28 and 29 show a fourth example of a hologram recording apparatus for realizing the hologram recording method described in the second embodiment. That is, the present embodiment is a case where excitation by the excitation light 80 is required at the time of recording the optical recording material forming the recording layer 4.
First, the recording apparatus of the present embodiment will be described with reference to FIG. In this embodiment, after the light beam emitted from the light source 142 passes through the light shield 174, it is reflected by the reflector 184 to become the excitation light 80, and the excitation light 80 includes the angle and position of the reflector 184, In addition, by controlling the relative position of the medium 130, the recording layer 4 of only the desired area 132 of the medium 130 can be irradiated from above or below the medium, and completely the same as FIG. It has the same configuration. Hereinafter, the principle and effect of the recording operation are exactly the same as described in the second embodiment.
[0097]
29 is exactly the same as FIG. 18 except that the light beam emitted from the light source 142 is incident on the optical branching device 161 after passing through the light shield 174 and the polarization controller 154. It becomes the composition of.
The polarization controller 154 is an element that rotates the polarization plane of light, and uses, for example, a half-wave plate. Also in this embodiment, the principle and effect of the recording operation are exactly the same as described in the second embodiment.
If, for example, a polarization beam splitter is used as the light splitter 161, the polarization light 154 controls the polarization plane of the emitted light by the polarization controller 154, so that the excitation light 80 is either the object light 6 or the reference light 71 or It is possible to superimpose both.
[0098]
Further, in the present embodiment, as in FIG. 18, a configuration for performing recording / reproduction corresponding to the angle-multiplexed volume hologram system is shown. However, as described in the seventh embodiment, the spatial light phase modulator 30 or the light collecting unit. A phase multiplex volume hologram method or shift by adding a device 331 and allowing the object beam 6, the reference beam 71, and the excitation beam 80 to be irradiated to a desired position in a desired region of the medium 130; Recording and reproduction corresponding to the multi-volume hologram method can be performed.
[0099]
In the present embodiment, for example, a single lens or a combination lens is used as the imager 22. However, as described in the ninth embodiment, a spatial light phase modulator 221 may be used. The spatial light phase modulator 221 may be used in combination with the 4f lens 222 or the imaging lens 223.
Although not specifically shown in the present embodiment, the object light 6, the reference light 71, and the excitation light 80 are selectively irradiated on the recording layer 4 only in the region 132 of the medium 130, and therefore the object light 6 and the reference light 71. A spatial light selector provided with necessary openings may be used for any or all of the excitation light 80.
[0100]
<Eleventh embodiment>
FIG. 30 shows a fifth example of the hologram recording apparatus for realizing the recording method described in the third embodiment. The configuration of FIG. 30 is a configuration in which a reflecting mirror 183 and a condenser 332 are provided instead of the reflecting mirror 182 of the configuration of FIG. 28 of the tenth embodiment.
The condenser 332 is an element that condenses the reference light 72 so as to enter a specific core layer of the medium 130, and uses, for example, a cylindrical lens.
The other one of the beams branched by the optical splitter 161 is reflected by the reflector 183 and then condensed by the condenser 332 to become the reference light 72.
Further, it is assumed that the reference light 72 can be incident on the desired end face of the core layer 1 of the medium 130 by controlling the position of one or both of the reflector 183 and the condenser 332.
[0101]
Hereinafter, the principle and effect of the recording operation in the present example are exactly the same as those described in the third embodiment.
30 shows an example in which the excitation light 80 is irradiated from above or below the medium 130 independently of the object light 6 and the reference light 72. However, the excitation light 80 is similar to FIG. The same effect can be obtained by irradiating with 6 superimposed.
Also in the present embodiment, the recording of the reflection hologram may be performed by the same method as described in FIGS.
In the present embodiment, a single lens or a combination lens is used as the imager 22, for example. However, as described in the ninth embodiment, a spatial light phase modulator 221 may be used. Alternatively, the spatial light phase modulator 221 and the 4f lens 222 or the imaging lens 223 may be used in combination.
Although not specifically shown in the present embodiment, either the object light 6 or the excitation light 80 or the excitation light 80 is selectively irradiated to the recording layer 4 only in the region 132 of the medium 130, or For both, a spatial light selector provided with a necessary aperture may be used.
[0102]
<Twelfth embodiment>
31 and 32 show a first example of a reproducing apparatus for realizing the reproducing method described in the fourth embodiment.
In the figure, 141 is a light source for reference light, 173 is a shutter, and 24 is a photodetector. The light detector 24 is an element for detecting the reproduction light 7, and is a one-dimensional, two-dimensional or three-dimensional drive of a dot sensor, a line sensor, or an area sensor composed of one or a plurality of photodiodes, CCD, CMOS, or the like. Thus, there is a detection of a reproduced image (reproduced light).
[0103]
Further, a plurality of dot sensors, line sensors, or area sensors as described above may be laid out to form a photodetector. Or the detector of the system which combined these methods may be sufficient. When a plurality of dot sensors, line sensors, or area sensors are used, it is possible to save power by sequentially switching and switching each sensor.
[0104]
First, the reproducing apparatus of the present invention will be described with reference to FIG. The light beam emitted from the light source 141 is reflected by the reflector 183 and then condensed by the condenser 332 to become the reference light 72.
Here, it is assumed that the reference light 72 can be incident on the desired end face of the core layer 1 of the medium 130 by controlling the position of one or both of the reflector 183 and the condenser 332.
[0105]
Hereinafter, the principle and effect of the reproduction operation in this example are exactly the same as those described in the fourth embodiment.
In order to reproduce a medium in which one piece of recorded information is divided into a plurality of parts as shown in FIG. 3A, an opening is provided only in the part 133 of the region set to be reproduced as shown in FIG. The spatial light selector 14 having 101 may be disposed close to the medium 130. The same applies to the following related embodiments.
[0106]
<13th Embodiment>
FIG. 33 shows a second example of the hologram reproducing apparatus for realizing the reproducing method described in the fourth embodiment.
In this example, in order to reproduce the medium recorded by the hologram recording apparatus described in the eighth embodiment, the reproduction light 7 is imaged on the photodetector 24 by using the imager 23. The configuration is exactly the same as in FIG. The image forming unit 23 is an optical system for forming an image of the reproduction light 7 on the photodetector 24. For example, a single lens or a combination lens is used. Also in this example, the principle and effect of the reproduction operation are exactly the same as those described in the fourth embodiment.
[0107]
<Fourteenth embodiment>
FIG. 34 shows a third example of the hologram reproducing apparatus for realizing the hologram reproducing method described in the fifth embodiment. In this configuration, a light shield 172 and a reflector 182 are provided instead of the light shield 173, the reflector 183, and the condenser 332 in the configuration of FIG.
The light beam emitted from the light source 141 is reflected by the reflector 182 and becomes the reference light 71. Here, the reference beam 71 controls the angle and position of the reflector 182 and the relative position of the medium 130, thereby controlling the recording layer 4 in one or more areas including the desired area 132 of the medium 130. Thus, it is possible to irradiate from above or below the medium at a desired incident angle.
[0108]
Hereinafter, the principle and effect of the reproduction operation in this example are exactly the same as those described in the fifth embodiment.
Further, in the present embodiment, a configuration is shown in which the reproduction light 7 emitted from the medium 130 forms an image directly on the photodetector 24 without using an optical system such as a lens, but will be described in the thirteenth embodiment. As described above, the image forming device 23 may be added.
Further, in the present embodiment, as in FIG. 18, a configuration for performing reproduction corresponding to the angle multiplex volume hologram system is shown. However, as described in the seventh embodiment, the spatial light phase modulator 30 or the condenser 331 is added, and the reference beam 71 can be irradiated to a desired position in a desired region of the medium 130, so that recording / reproduction corresponding to the phase multiple volume hologram method or the shift multiple volume hologram method can be performed. It can be carried out. The same applies to the following fifteenth embodiment.
[0109]
<Fifteenth embodiment>
FIG. 35 shows a fourth example of the hologram reproducing apparatus for realizing the reproducing method described in the sixth embodiment.
This embodiment is completely the same as FIG. 34 except that the spatial light selector 14 is omitted and the reference light 71 can be applied to the recording layer 4 in only the desired region 132 of the medium 130. It has the same configuration. Hereinafter, the principle and effect of the reproduction operation in this example are exactly the same as those described in the eighteenth embodiment.
In this embodiment, it is not particularly necessary to provide a spatial light selector on the output side of the reproduction light 7 of the medium 130. However, a spatial light selector 14 similar to that in the twelfth and fourteenth embodiments may be provided. Good.
[0110]
Although not specifically shown in the present embodiment, since the reference light 71 is selectively applied to the recording layer 4 only in the region 132 of the medium 130, the spatial light provided with a necessary opening with respect to the reference light 71. A selector may be used.
FIGS. 13B and 14B show an example in which a transmissive hologram is reproduced by irradiating the reference beam 71 from the opposite side of the photodetector 24 when viewed from the recording layer 4 of the medium 130. However, similarly to FIG. 41, it is also possible to reproduce a reflection hologram by irradiating the reference beam 71 from the side of the photodetector 24 when viewed from the recording layer 4 of the medium 130.
Further, in the present embodiment, a configuration is shown in which the reproduction light 7 emitted from the medium 130 is directly imaged on the photodetector 24 without using an optical system such as a lens, but will be described in the eighth embodiment. In order to reproduce the medium recorded by the recording device, the image forming device 23 may be added as described in the thirteenth embodiment.
[0111]
<Sixteenth Embodiment>
FIG. 36 shows an example of a combined hologram recording / reproducing apparatus for realizing the hologram recording method described in the first embodiment and the hologram reproducing method described in the fourth to sixth embodiments.
In this embodiment, the hologram recording apparatus of FIG. 18 and the hologram reproducing apparatus of FIG. 31 are combined with a polarization controller 153, an optical branching device 162, and a light shield 171 being added.
The polarization controller 153 is an element that rotates the polarization plane of light, and uses, for example, a half-wave plate. The optical splitter 162 is an element that splits the light beam in two directions, and uses, for example, a half mirror or various beam splitters.
[0112]
The light beam emitted from the light source 141 is branched into three by the optical branching devices 161 and 162, and each branched beam is controlled by the three polarization controllers 151, 152, and 153 to the polarization necessary for recording. The One of the branched beams is reflected by the reflector 181, expanded to a desired beam width by the beam expander 20, and further given information to be recorded on the medium 130 by the spatial light intensity modulator 21. Thus, the image light 22 becomes object light 6.
[0113]
Further, the other one of the branched beams is reflected by the reflector 182 and becomes the reference light 71. Further, the remaining one of the branched beams is reflected by the reflector 183 and then condensed by the condenser 32 to become the reference light 72.
Here, it is assumed that the object light 6 can be irradiated from above or below the medium to the recording layer 4 of only the desired region 132 of the medium 130 by controlling the relative position of the medium 130. Further, the reference light 71 is controlled at the angle and position of the reflector 182 and the relative position of the medium 130, so that the reference light 71 is incident on the recording layer 4 in the desired area 132 of the medium 130 at a desired incident angle. It can be irradiated from above or below the medium.
[0114]
Further, it is assumed that the reference light 72 can be incident on the desired end face of the core layer 1 of the medium 130 by controlling the position of one or both of the reflector 183 and the condenser 332.
In this embodiment, first, the recording operation can be performed by opening the light shields 170 and 171 and closing 173. In this case, the principle and effect of the recording operation in this example are exactly the same as those described in the first embodiment.
Further, by closing the light shields 170 and 171 and opening 173, the reproduction operation using the reference light 72 can be performed. In this case, the principle and effect of the reproduction operation in this example are exactly the same as those described in the fourth embodiment.
[0115]
Furthermore, the reproduction operation using the reference light 71 can be performed by opening the light shield 170 and closing the 171 and 173. In this case, the principle and effect of the reproducing operation in this example are exactly the same as those described in the fifth and sixth embodiments.
Here, as in the fifteenth embodiment, the reference beam 71 may be selectively irradiated onto the medium 130.
In the portions corresponding to the hologram recording device of FIG. 18 and the hologram reproducing device of FIG. 31, the functions realized by the respective devices are similarly realized, and the same effects are obtained.
Further, as shown in FIGS. 28 to 30, the recording described in the second and third embodiments is performed by adding a light source 142 for the excitation light 80, a polarization controller 154, a light shield 174, a reflector 184, and the like. It is also possible to implement the method.
[0116]
In each of the above embodiments, the recording layer and the optical waveguide have the same effect regardless of whether they are in contact with each other or are spatially separated. For example, as an operation example of hologram recording / reproduction,
(1) The recording layer and the optical waveguide are integrally formed and loaded into the recording / reproducing apparatus.
(2) The recording layer and the optical waveguide are separated from each other, and after they are stacked, they are loaded into the recording / reproducing apparatus.
(3) The recording layer and the optical waveguide are separated from each other, and the optical waveguide is preliminarily mounted on the recording / reproducing device, and the recording layer portion is loaded during operation, so that they overlap each other.
Either form is possible. Note that the recording / reproducing operation may be spatially separated from each other.
[0117]
<Seventeenth Embodiment>
As an exemplary embodiment for increasing the recording density, a method for multiplex recording of holograms by using a plurality of object beams irradiated so as to be condensed or narrowed as in the first embodiment and shifting them is described.
FIG. 37A shows three object lights 6.₁~ 6₃An example using is shown. Object light 6 with respect to reference light 71₁~ 6₃The hologram is recorded by irradiating while superimposing by shifting little by little in this order.
[0118]
Here, only the recording layer 4 is described, but novel hologram multiplex recording is realized by shifting the object light by using the plane wave as the reference light as compared with the conventional hologram.
This method can also be applied to a combination of the recording layer 4 and the optical waveguide described so far, in which case diffracted light obtained by making reference light incident from the end face of the core layer is incident on the recording layer. Also good.
[0119]
In order to reproduce a multiplex hologram recorded in one area in this way, as shown in FIG. 37B, when the same reference beam 71 as in recording is irradiated, the object beam 6₁~ 6₃Reproducing light 7 corresponding to₁~ 7₃Occur simultaneously.
In order to generate only the specific reproduction light, a spatial light selector 14 (for example, a metal or a liquid crystal mask) is provided on the side from which the reproduction light is emitted, and is passed upward from the opening, and the other reproduction light is provided. Should be cut off. A plurality of openings may be provided as necessary.
[0120]
According to this method, a plurality of pieces of information can be multiplex-recorded at one location on the recording layer, so that the recording density can be increased. Further, since the reference light is parallel (plane wave) and the angle is constant, it is not necessary to control the angle as in the case of the angle multiplexing method. Further, there is an advantage that it is not necessary to collect the reference light (use a spherical wave) as in the shift multiplexing method, and it is not necessary to change the phase of the reference light as in the phase multiplexing method.
[0121]
Note that this method may be appropriately combined with the angle multiplexing, shift multiplexing, and phase multiplexing methods described above to change the angle, wavefront, and phase of the reference light. That is, the reference light does not necessarily have to be parallel and constant in angle, and is combined with angle multiplexing (changing the angle of the reference light), shift multiplexing (reference light is a spherical wave), phase multiplexing (changing the phase of the reference light), It is also possible to further increase the recording density.
In this method, excitation light may be used, and the method of each embodiment relating to the hologram recording / reproducing method described above can be appropriately used as a specific incident method of reference light, object light, and excitation light.
[0122]
【The invention's effect】
As described above, in the hologram recording / reproducing method and recording / reproducing apparatus of the present invention, the hologram medium is divided into a plurality of areas, and the incident angle of the reference light is controlled with high accuracy in each area. Since it is possible to irradiate the object beam, the reference beam, and the excitation beam selectively and intensively in a state where it is not necessary, high-density multiple recording can be realized easily and efficiently.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of recording a transmission hologram, showing a hologram recording method according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an example of recording a reflection hologram in the embodiment.
FIG. 3 is an explanatory diagram showing an example in which information is divided and recorded in the embodiment.
FIG. 4 is an explanatory diagram showing an example of irradiating excitation light independently, showing a hologram recording method according to a second embodiment of the present invention.
FIG. 5 is an explanatory diagram showing an example in which excitation light is irradiated with object light or reference light superimposed in the embodiment.
FIG. 6 is an explanatory diagram showing a hologram recording method according to a third embodiment of the invention.
FIG. 7 is an explanatory diagram showing a hologram reproducing method as a fourth embodiment of the present invention.
FIG. 8 is an explanatory diagram showing an example of reproducing a transmission hologram in the embodiment.
FIG. 9 is an explanatory diagram showing an example of reproducing a reflection hologram in the embodiment.
FIG. 10 is an explanatory diagram showing an example of collectively reproducing divided information in the embodiment.
FIG. 11 is an explanatory diagram showing an example of reproducing undivided information, showing a hologram reproducing method as a fifth embodiment of the present invention.
FIG. 12 is an explanatory diagram showing an example of collectively reproducing divided information in the embodiment.
FIG. 13 is an explanatory diagram illustrating an example of reproducing undivided information, showing a hologram reproducing method according to a sixth embodiment of the present invention.
FIG. 14 is an explanatory diagram showing an example of collectively reproducing divided information in the embodiment.
FIG. 15 is a schematic diagram showing a configuration example of a diffraction grating layer.
FIG. 16 is a cross-sectional view showing one structural example of a diffraction grating layer portion.
FIG. 17 is a cross-sectional view showing an example of the structure of a laminated diffraction grating layer portion.
FIG. 18 is a configuration diagram showing an example of recording a transmission hologram, showing a hologram recording apparatus as a seventh embodiment of the present invention.
FIG. 19 is a configuration diagram showing an example of recording a reflection hologram in the embodiment.
FIG. 20 is a configuration diagram showing an example in which shift multiplex recording is performed in the embodiment.
FIG. 21 is a configuration diagram showing an example in which phase multiplexing recording is performed in the embodiment.
FIG. 22 is an explanatory diagram showing an example of a spatial light phase modulator using a phase plate.
FIG. 23 is an explanatory diagram showing a configuration example of an apparatus using a spatial light phase modulator using a phase plate.
FIG. 24 shows a hologram recording apparatus as an eighth embodiment of the present invention.
FIG. 25 shows a hologram recording apparatus as a ninth embodiment of the present invention, and is a configuration diagram showing an example using a spatial light phase modulator as an imaging optical system.
FIG. 26 is a configuration diagram showing an example in which a spatial light phase modulator and a lens are used in the imaging optical system in the embodiment.
FIG. 27 is a configuration diagram showing an example in which a spatial light phase modulator and a 4f lens are combined in the imaging optical system in the embodiment.
FIG. 28 is a block diagram showing an example of irradiating excitation light independently, showing a hologram recording apparatus as a tenth embodiment of the present invention.
FIG. 29 is a configuration diagram showing an example in which excitation light is superimposed on object light or reference light and irradiated in the embodiment.
FIG. 30 is a block diagram showing a hologram recording apparatus as an eleventh embodiment of the present invention.
FIG. 31 is a block diagram showing an example of reproducing undivided information, showing a hologram reproducing device as a twelfth embodiment of the present invention.
FIG. 32 is a configuration diagram showing an example of collectively reproducing divided information in the embodiment.
FIG. 33 is a block diagram showing a hologram reproducing device as a thirteenth embodiment of the present invention.
FIG. 34 is a block diagram showing a hologram reproducing apparatus as a fourteenth embodiment of the present invention.
FIG. 35 is a block diagram showing a hologram reproducing device as a fifteenth embodiment of the present invention.
FIG. 36 is a block diagram showing an example of a recording / reproducing apparatus as a sixteenth embodiment of the present invention.
FIG. 37 is an explanatory diagram showing a hologram recording / reproducing method as a seventeenth embodiment of the invention.
FIG. 38 is a perspective view showing an example of a conventional hologram recording / reproducing method.
[Explanation of symbols]
1 ... Core layer
2 ... Clad layer
3, 31-35 ... Diffraction grating layer
4. Recording layer
6 ... Object light
71, 72 ... Reference light
73 ... Propagating light
74 ... Diffracted light
7 ... Reproducing light
80 ... Excitation light
14 ... Space light selector
141, 142 ... Light source
151-154 ... Polarization controller
161, 162: Optical splitter
170-174 ... Shading device
181 to 184 ... reflectors
20 ... Flux expander
21 ... Spatial light intensity modulator
22, 23 ... Imager
221, 30 ... Spatial optical phase modulator
222 ... 4f lens
223 ... Imaging lens
24. Photodetector
301 ... Phase plate
331, 332 ... Condensing optical system

Claims (18)

At least one core layer for guiding light sandwiched between lower refractive index portions, and at least one diffraction grating provided in the boundary between the core layer and the lower refractive index portion or in the core layer A hologram is recorded on a hologram medium having an optical waveguide having a layer and at least one recording layer disposed outside the optical waveguide so that reference light can be incident through the optical waveguide. And
As each layer of the optical waveguide of the hologram medium is laminated from below to above, object light is incident from either above or below the hologram medium,
The reference light is incident from either above or below the hologram medium,
A method for holographically recording information on the recording layer with the object beam and the reference beam,
The object light is collected and incident on at least one small area in the recording layer,
A hologram recording method in which the reference light is incident so that the small region is irradiated. The hologram recording method according to claim 1 , wherein excitation light is incident on the recording layer so as to irradiate the small region from above or below the hologram medium. Excitation light is incident on the core layer from the end face of any one of the core layers, and the excitation light is diffracted by the diffraction grating layer corresponding to the incident core layer so that the small region of the recording layer is irradiated. The hologram recording method according to claim 1 , wherein excitation light is incident on the recording layer by irradiated diffracted light. The hologram recording method according to claim 1, wherein another object light whose irradiation position is shifted is irradiated so that the irradiation area of the object light and the irradiation area partially overlap. At least one core layer for guiding light sandwiched between portions having a lower refractive index, and at least one diffraction grating provided in a boundary between the core layer and the lower refractive index portion or in the core layer A hologram recorded on a recording layer of a hologram medium having an optical waveguide having a layer, and at least one recording layer disposed outside the optical waveguide so that reference light can be incident through the optical waveguide Is a method of playing
Information is recorded in at least one small area in the recording layer,
Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, the hologram is reproduced by entering reference light from either above or below the hologram medium,
A hologram reproduction method for partially shielding the reproduction light so that the reproduction light emitted from the recording layer is concentratedly emitted from the small area. At least one core layer for guiding light sandwiched between portions having a lower refractive index, and at least one diffraction grating provided in a boundary between the core layer and the lower refractive index portion or in the core layer A hologram recorded on a recording layer of a hologram medium having an optical waveguide having a layer, and at least one recording layer disposed outside the optical waveguide so that reference light can be incident through the optical waveguide Is a method of playing
Information is recorded in at least one small area in the recording layer,
Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, reference light is incident from either above or below the hologram medium to reproduce the hologram, and the reference light is recorded on the recording medium. A hologram reproduction method for selectively irradiating reproduction light emitted from a layer so as to be emitted intensively from the small region. At least one core layer for guiding light sandwiched between portions having a lower refractive index, and at least one diffraction grating provided in a boundary between the core layer and the lower refractive index portion or in the core layer A hologram recorded on a recording layer of a hologram medium having an optical waveguide having a layer, and at least one recording layer disposed outside the optical waveguide so that reference light can be incident through the optical waveguide Is a method of playing
A plurality of information is recorded in a multiplexed manner in at least one small region in the recording layer of the hologram medium,
Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, the hologram is reproduced by entering reference light from either above or below the hologram medium,
A hologram reproduction method for blocking reproduction light corresponding to other information so that any one of the plurality of information is selectively reproduced. At least one core layer for guiding light sandwiched between portions having a lower refractive index, and at least one diffraction grating provided in a boundary between the core layer and the lower refractive index portion or in the core layer An apparatus for recording a hologram on a hologram medium comprising: an optical waveguide having a layer; and at least one recording layer disposed outside the optical waveguide so that reference light can be incident through the optical waveguide. And
A light source that emits light;
A light branching unit for branching the light emitted from the light source into a first light and a second light;
Assuming that each layer of the optical waveguide of the hologram medium is laminated from the bottom to the top, the object light incident on the object light obtained by spatially modulating the first light from either above or below the hologram medium And
A reference light incident part that enters the second light as reference light from either above or below the hologram medium,
Information is recorded on the recording layer by the object beam and the reference beam,
The object light incident part has a condensing incident part that condenses and enters the object light into at least one small region in the recording layer of the hologram medium,
The reference light incident unit is a hologram recording apparatus that makes the reference light incident so that the small region is irradiated. The hologram recording apparatus according to claim 8 , further comprising an excitation light incident unit that makes excitation light incident on the recording layer so that the small region is irradiated from either above or below the hologram medium. Excitation light is incident on the core layer from the end face of any one of the core layers, and the excitation light is diffracted by the diffraction grating layer corresponding to the incident core layer so that the small region of the recording layer is irradiated. The hologram recording apparatus according to claim 8 , further comprising an excitation light incident portion that causes excitation light to be incident on the recording layer by irradiated diffracted light. The hologram recording apparatus according to claim 8 , wherein the condensing incident unit includes an imaging optical system using a lens. The hologram recording apparatus according to claim 8 , wherein the condensing incident part includes a spatial light phase modulator. The hologram recording apparatus according to claim 12 , wherein the spatial light phase modulator includes a transparent dielectric plate. The hologram recording apparatus according to claim 12 , wherein the spatial light phase modulator includes a liquid crystal panel. At least one core layer for guiding light sandwiched between portions having a lower refractive index, and at least one diffraction grating provided in a boundary between the core layer and the lower refractive index portion or in the core layer A hologram recorded on a recording layer of a hologram medium having an optical waveguide having a layer, and at least one recording layer disposed outside the optical waveguide so that reference light can enter through the optical waveguide A device for reproducing
A light source that emits light;
Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, at least part of the light emitted from the light source is incident as reference light from either above or below the hologram medium A light incident part,
The hologram-recorded information is detected as reproduction light by the reference light,
Information is recorded in at least one small area in the recording layer of the hologram medium,
A hologram reproducing apparatus having a spatial light selector that partially shields the reproducing light emitted from the recording layer so as to be intensively emitted from the small area. At least one core layer for guiding light sandwiched between portions having a lower refractive index, and at least one diffraction grating provided in a boundary between the core layer and the lower refractive index portion or in the core layer A hologram recorded on a recording layer of a hologram medium having an optical waveguide having a layer, and at least one recording layer disposed outside the optical waveguide so that reference light can enter through the optical waveguide A device for reproducing
A light source that emits light;
A light branching portion for branching at least part of the light emitted from the light source into first light and second light;
A first reference light incident part that enters the first light as reference light from an end face of any one of the core layers;
Assuming that each layer of the optical waveguide of the hologram medium is laminated from the bottom to the top, a second reference light incident section that enters the second light as reference light from either the top or the bottom of the hologram medium When,
A light-shielding portion that activates one of the first and second reference light incident portions by blocking any one of the first and second lights,
When the first reference light incident part is validated, the reference light incident from the first reference light incident part is diffracted by the diffraction grating layer corresponding to the incident core layer and irradiated to the recording layer. When the information recorded in the hologram is detected as reproduction light by the diffracted light and the second reference light incident part is validated, the information is obtained by the reference light incident from the second reference light incident part. Is detected as reproduction light,
Information is recorded in at least one small area in the recording layer of the hologram medium,
A hologram reproducing apparatus having a spatial light selector that partially shields the reproducing light emitted from the recording layer so as to be intensively emitted from the small area. At least one core layer for guiding light sandwiched between portions having a lower refractive index, and at least one diffraction grating provided in a boundary between the core layer and the lower refractive index portion or in the core layer A hologram recorded on a recording layer of a hologram medium having an optical waveguide having a layer, and at least one recording layer disposed outside the optical waveguide so that reference light can enter through the optical waveguide A device for reproducing
A light source that emits light;
Assuming that each layer of the optical waveguide of the hologram medium is laminated from below to above, at least part of the light emitted from the light source is incident as reference light from either above or below the hologram medium A light incident part,
The hologram-recorded information is detected as reproduction light by the reference light,
Information is recorded in at least one small area in the recording layer of the hologram medium,
The hologram reproduction apparatus that selectively irradiates the reference light so that the reproduction light emitted from the recording layer is intensively emitted from the small region. At least one core layer for guiding light sandwiched between portions having a lower refractive index, and at least one diffraction grating provided in a boundary between the core layer and the lower refractive index portion or in the core layer A hologram recorded on a recording layer of a hologram medium having an optical waveguide having a layer, and at least one recording layer disposed outside the optical waveguide so that reference light can enter through the optical waveguide A device for reproducing
A light source that emits light;
A light branching portion for branching at least part of the light emitted from the light source into first light and second light;
A first reference light incident part that enters the first light as reference light from an end face of any one of the core layers;
Assuming that each layer of the optical waveguide of the hologram medium is laminated from the bottom to the top, a second reference light incident section that enters the second light as reference light from either the top or the bottom of the hologram medium When,
A light-shielding portion that activates one of the first and second reference light incident portions by blocking any one of the first and second lights,
When the first reference light incident part is validated, the reference light incident from the first reference light incident part is diffracted by the diffraction grating layer corresponding to the incident core layer and irradiated to the recording layer. When the information recorded in the hologram is detected as reproduction light by the diffracted light and the second reference light incident part is validated, the information is obtained by the reference light incident from the second reference light incident part. Is detected as reproduction light,
Information is recorded in at least one small area in the recording layer of the hologram medium,
The second reference light incident section selectively irradiates the reference light so that the reproduction light emitted from the recording layer is intensively emitted from the small area.

Images