JP2001023169A - Hologram information recording / reading method and apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To perform high-density hologram storage and reconstruction with a simple structure. A hologram memory structure records a hologram from interference between a plane wave and light diffracted from a data pattern to be stored. The localized portion of the hologram can be reconstructed using the readout spherical beam. Scanning the hologram area with a spherical beam searches for different parts of the stored data. Multiple holograms can be recorded in the same volume by recording different patterns using different wavelengths or reference light beams of different angles. This structure is well suited for disk-based storage systems.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram data storage device, and more particularly to a method and a device for recording and reading holograms.

[0002]

2. Description of the Related Art A hologram data storage device is usually
Multiple pages of data are recorded in one or more positions in one hologram storage medium. Data of different pages are multiplexed at one position by changing the characteristics of the reference light beam used for recording, such as the angle or wavelength.

A spatial light modulator (SLM) such as a liquid crystal display panel is used to give information to be recorded on a signal light beam. To read the stored hologram, a desired hologram is searched using a reference light beam having the same characteristics as used for recording, and a reconstructed data page is read using a two-dimensional detector.

[0004] These architectures have various limitations. The recording density of each data page is limited by the SLM and the detector array. To compensate for this, hundreds or thousands of holograms need to be multiplexed at each location to achieve high density.

[0005] Upon readout, the reconstruction of a large two-dimensional page means that the laser power is divided into many pixels, which results in a greater demand for laser power. In addition, conventional structures often require an imaging lens system to focus the reconstructed data page on the detector array, and move the reference light beam to different directions and positions. Complex mechanisms are also required. These are costly in system and equipment complexity.

Also, in the prior art, the number of multiplexed holograms at each point on the medium varies, depending on the method of multiplexing used and on the overlap between the spatial locations of the medium. Depending on the amount of wrap (overlap), the shape of the volume occupied by each hologram changes. Both of these factors result in non-uniform intensity between different holograms in the medium, and also non-uniform intensity between different pixels in one hologram, reducing the probability of making errors when reading data. Therefore, complicated compensation technology is required. If the spatial locations do not overlap in the recording medium, the dynamic range is lost in the unused material between the discrete locations.

Furthermore, there is currently no method for high-speed duplication of hologram memories recorded using such a system. In the conventional method, each hologram must be recorded sequentially for each multiplexed page and at each spatial location in the recording medium. In order to obtain holograms of equal intensity on all pages, complex exposures must be repeated at all positions.

[0008]

SUMMARY OF THE INVENTION In view of the above situation, the present invention has the following objects. (A) Ensure that high-density data pages are recorded and read out, with pixel size limited only to optical resolution. (B) A large data page can be recorded as one hologram without increasing the number of pixels of the detector. (C) To enable recording and reading without requiring an optical element in one of the recording and diffraction signal paths. (D) Use a low power laser for reading without increasing the error rate. (E) Provides a simple and fast means of replicating hologram memory. (F) The hologram can be recorded and reproduced with good uniformity.

In the special case of disk-type recording media, an additional object and advantage of the present invention is to provide compatibility with existing readout mechanisms for optical disks, and the data must be stored in the prior art. Instead of reading at discrete locations on the disk as in the case of the hologram disk structure in the above, it is read continuously.

[0010]

According to a first aspect of the present invention, there is provided a hologram information recording / reading method including the following means. That is,
A method for recording and reading information on a hologram in a recording medium, wherein a signal light beam and a recording reference light beam modulated with data are focused on a spot on a recording medium on which the hologram is recorded, and the hologram is recorded. Creating a read reference light beam having a substantially different wavefront shape from the recording reference light beam, irradiating the hologram with the read reference light beam, and obtaining reproduction image information enlarged to a predetermined magnification,
A hologram information recording / reading method for reproducing a part of the data using the image information is provided.

In the method according to the first aspect, the read reference light beam is applied substantially in the same direction as the signal light beam, thereby reproducing the reproduced image information substantially in the direction of the recording reference light beam. A hologram information recording / reading method characterized by the above feature is also provided. The first
In the method according to the aspect, there is also provided a hologram information recording / reading method, wherein the read reference light beam is applied in a direction substantially opposite to a traveling direction of the signal light beam. Furthermore, in the method of the first aspect, there is also provided a hologram information recording / reading method which determines a magnification of the reproduced image information according to a wavefront shape of the read reference light beam.

Further, in the method of the first aspect, there is also provided a hologram information recording / reading method for reproducing a different part of the data by moving a relative position of the read reference light beam with respect to the recording medium. In the method according to the first aspect, a plurality of holograms are recorded on a recording medium by changing an incident angle of the recording reference light beam on the recording medium with respect to each hologram, thereby applying the read reference light beam. The present invention also provides a hologram information recording / reading method for obtaining a plurality of pieces of corresponding reproduced image information.

In the method of the first aspect, a plurality of holograms are recorded on the recording medium by changing the wavelengths of the signal light beam and the recording reference light beam for each hologram, and A hologram information recording / reading method for reproducing a different hologram by changing a wavelength is also provided. Further, in the method according to the first aspect, there is also provided a hologram information recording / reading method, wherein the recording medium is a substantially disk-type recording medium.

According to a second aspect of the present invention, there is provided a hologram information recording / reading method including the following means. That is, a method of accumulating and reading information in a hologram in a recording medium, wherein a signal light beam modulated with data and a recording reference light beam of a substantially plane wave are focused on a selected spot on the recording medium, and thereby the hologram is Record
A hologram information recording / reading method in which a readout reference light beam of a substantially spherical wave is created, the hologram is irradiated with the readout reference light beam, and a part of the data is reconstructed as an image having a predetermined magnification. In the method according to the second aspect, the read reference light beam is provided in substantially the same direction as the signal light beam.
There is also provided a hologram information recording / reading method for causing a reconstructed image to propagate substantially in the direction of the recording reference light beam.

Further, there is provided a hologram information recording / reading method according to the second aspect, wherein the read reference light beam is provided in a direction facing the signal light beam. Further, in the method according to the second aspect, there is also provided a hologram information recording / reading method in which a magnification of the reconstructed image is determined by a focal position of the read reference light beam. Still further, in the method of the second aspect, there is also provided a hologram information recording / reading method for reconstructing a different part of the data by changing the read reference light beam in relation to the recording medium.

In the method according to the second aspect, a plurality of holograms are recorded on the recording medium by changing an incident angle of the recording reference light beam on the recording medium with respect to each hologram, and the read reference light beam is provided. Accordingly, a hologram information recording / reading method for obtaining a plurality of corresponding reconstructed images in parallel is also provided. In the method according to the second aspect, a plurality of holograms are recorded in the recording medium by changing the wavelengths of the signal light beam and the recording reference light beam for each hologram, and the wavelength of the read reference light beam is changed. The hologram information recording / reading method of reconstructing a different hologram by changing the hologram information is also provided. Furthermore, in the method according to the second aspect,
A method for recording and reading hologram information wherein the recording medium is substantially a disk type is also provided.

According to a third aspect of the present invention, there is provided a data storage method comprising the following means. That is, a method of recording data over substantially the entire surface of a substantially disk-shaped recording medium as a single continuous hologram, and a method of reconstructing a part of the data by applying an appropriate read reference light beam, (A) condensing a recording reference light beam and a signal light beam modulated with data on a selected area in the recording medium to record a hologram; (b)
(C) data for reconstructing a part of the data as an image by irradiating the hologram with the read reference light beam and creating a read reference light beam having a substantially different wavefront shape from the recording reference light beam Provide a storage method.
In the method according to the third aspect, a data storage method is also provided in which the recording reference light beam has a substantially plane wave at each point where the recording reference light beam enters the recording medium, and the read reference light beam has a substantially spherical wave.

In the method of the third aspect, the read reference light beam is applied substantially in the direction of the signal light beam, whereby the reconstructed image propagates substantially in the direction of the recording reference light beam. A method for storing data to be performed is also provided. In the method according to the third aspect,
A data storage method is also provided, wherein a magnification of the reconstructed image is determined by a position of the read reference light beam. Still further, in the method according to the third aspect, there is provided a data storage method for reconstructing a different part of the data by changing a read reference light beam with respect to the recording medium.

In the method according to the third aspect, a plurality of holograms are recorded in the recording medium by changing an incident angle of the recording reference light beam on the recording medium with respect to each hologram, and the readout reference light beam is recorded. And a data storage method for obtaining a corresponding plurality of reconstructed images in parallel. In the method according to the third aspect, a plurality of holograms are recorded on the recording medium by changing the wavelengths of the signal light beam and the recording reference light beam for each hologram, and the wavelength of the read reference light beam is changed. It also provides a data storage method for reconstructing different holograms by changing. Furthermore,
In the method of the third aspect, the information in the data is encoded as a displacement of an edge position in a track extending direction in a substantially circular track pattern on the disk, whereby the disk-type recording medium is encoded. There is also provided a data storage method that allows reading in substantially the same manner as an optical disc. In the method according to the third aspect, the optical disk is a compact disk or a DVD.

According to a fourth aspect of the present invention, there is provided a hologram recording apparatus comprising the following means. That is,
(A) means for producing coherent light, (b) a substantially disk-shaped recording medium suitable for hologram recording, and (c) a light beam that is spatially modulated on the recording medium and is continuous over the entire surface of the medium. A hologram recording apparatus includes: a spatial modulation unit that forms a hologram; and (d) a unit that irradiates the recording medium with light modulated by the spatial light modulation and a reference light beam. Further, in the apparatus according to the fourth aspect, there is also provided a hologram recording apparatus in which the means for irradiating the reference light beam can be adjusted to change an incident angle of the reference light beam on the recording medium. In the apparatus according to the fourth aspect, the present invention also provides a hologram recording device configured such that the means for producing the coherent light can change a wavelength. Still further, in the apparatus according to the fourth aspect, there is also provided a hologram recording apparatus, wherein the means for generating the coherent light includes a plurality of light sources having different wavelengths.

According to a fifth aspect of the present invention, there is provided a hologram reading device comprising the following means. That is,
(A) means for producing coherent light; (b) means for converting the coherent light into a substantially spherical wave beam;
(C) at least one photodetector, (d) a hologram medium on which information is recorded by interference of a substantially plane wave and light modulated by the information, and (e) movement of moving the spherical wave beam with respect to the medium. And a hologram readout device comprising: Further, in the apparatus according to the fifth aspect, there is also provided a hologram readout apparatus in which the means for producing the coherent light can select a wavelength. In the apparatus according to the fifth aspect, the means for producing coherent light also includes a hologram readout apparatus including a plurality of light sources having different wavelengths. Still further, in the apparatus according to the fifth aspect, there is also provided a hologram reading device in which the medium is encoded such that portions of the plurality of holograms are simultaneously reconstructed by the spherical wave beam.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described. FIG. 1 shows one embodiment of the present invention for recording a hologram. As shown in the figure, using a spatial light modulator or a data pattern 25, a beam vertically incident on the same pattern 25 from the left side of the figure is applied to information to be recorded (that is, given to the pattern 25). Information) and the light beam 20 modulated to the right of the pattern 25
Is output.

The light beam diffracted and modulated by the data pattern 25 is incident on the hologram medium 35 as a signal light beam 20. The hologram medium 35 stores data
It is oriented parallel to the pattern 25 and is formed of a thin film such as a photosensitive polymer or a light diffraction crystal. Hologram medium 35
Is applied with a plane wave reference light beam 30 as shown in FIG.
The signal light beam 20 and the reference light beam 30 interfere inside the hologram medium 35 to form interference fringes. In the present embodiment, the reference light beam 30 is incident on the surface of the hologram medium 35 facing the signal light beam 20.
Therefore, the hologram medium 35 should be a material suitable for recording on the reflection outer surface.

FIG. 2 shows a preferred embodiment for reconstructing the hologram recorded by the method of FIG. As shown in the figure, a focusing element 45 such as a lens forms a convergent spherical wave light beam 40, and focuses the light beam 40 near a hologram medium 35 on which information is recorded as a reference light beam. Tie). The direction of irradiation is opposite to the direction of the signal light beam 20 used to record the hologram.

The signal light beam 50 including the reconstructed information output from the hologram medium 35 as a result of irradiating the reference light beam propagates in a direction opposite to the reference light beam used to record the hologram. I do. The position of the focal point 55 of the spherical wave reference light beam 40 determines the position and size of the reconstructed image. That is, if the distance between the focal point 55 and the hologram medium 35 is shorter than the distance between the data pattern 25 being recorded and the hologram medium 35, a real image is formed in the direction of the reconstructed signal light beam 50. Otherwise, a virtual image is created in the direction opposite to the reconstructed signal light beam 50.

The approximate distance zi of the reconstructed image from the hologram medium 35 is given by equation (1). (1 / zi) = (1 / z0) − (1 / z1) ‥‥ (1) where z0 is the distance between the data pattern 25 and the hologram medium 35 during recording, and z1 is This is the distance between the focal point 55 and the hologram medium 35 during reading. The size M of the reconstructed image is given by equation (2). M = z1 / (z1-z0) ‥‥ (2)

The portion of the reconstructed data pattern 25 is an area near the same abscissa as the center of the irradiation spot of the spherical wave beam 40 on the hologram medium 35. Moving the hologram medium 35 or the spherical wave beam 40 laterally relative to each other reconstructs different parts of the data pattern 25.

This method works best if the hologram medium 35 is thin. For thick media, the reconstructed image will cause some blurring and distortion, but can still be used depending on the tolerances of the application. As an experiment, a 2 μm repetitive pattern was recorded on a 20 μm thick photosensitive polymer by this method. It was confirmed that this 2 μm pattern was enlarged to a size of 5 mm or more by focusing a spherical wave read beam on the entire hologram using a lens having a numerical aperture of 0.40. This corresponds to an enlargement factor of 2500.

Next, a second embodiment of the present invention will be described below. The hologram memory according to the first embodiment includes:
It can be used in systems that allow the multiplexing of different holograms in the same hologram medium. In contrast, FIG.
The second embodiment is a system that allows multiplexing during recording. The beam from the coherent laser source 65 is converted to a plane wave by a beam expander and collimator 70.

The expanded plane wave is split by a beam splitter 75 into a signal light component and a reference light component. The signal light component is modulated by the data pattern 25, and the modulated signal light beam 20 illuminates the hologram medium 35. On the other hand, the reference light component of the plane wave split by the beam splitter 75 travels toward the fixed mirror 80, is reflected by the mirror, and is guided to the mirror 85. The mirror 85 is a rotatable mirror located at the front focal plane of the 4-F imaging system 90.

The hologram medium 35 is located at the rear focal plane of the 4-F imaging system 90 described above. With this arrangement, by changing the angle of the rotatable mirror 85, the signal light beam 20 inside the hologram medium 35 is changed.
The angle of the reference light beam 30 that interferes with the angle can be changed. The system shown in FIG. 3 allows multiplexing in two ways. One way is to change the angle of beam 30 for different data patterns 25. Another method is to apply wavelength multiplexing by changing the wavelength of the laser source 65 for different data patterns 25.

FIG. 4 shows a second preferred form for reading a hologram recorded by the system shown in FIG. This read operation is the same as that described for the first embodiment shown in FIG. The difference is that the wavelength of the spherical wave beam 40 is changed to read out different holograms recorded at different wavelengths.

If multiple angles are used during writing, the reconstructed signal light beam 50 propagates in the opposite direction to each angle used for recording, and the corresponding angle recorded at that angle. Conveys data from data pattern 25.
Therefore, to avoid crosstalk, the angle used for recording should be large enough to avoid substantial overlap in image reconstruction during readout. Detector array 95 may be used to read multiple reconstructed spots.

An advantage of the memory structure of the present invention is that any large data page can be recorded as one hologram, but in order to reproduce a small portion of the information in the hologram, read light is applied to a small portion of the hologram. It can also be focused. This allows more data to be stored in each hologram than with the prior art hologram architecture, reduces the total recording time, reduces the complexity of programming the laser output in recording,
It also makes it easier to achieve uniformity within each hologram as well as between different holograms.

This architecture is particularly well suited for disk-based memories. This is because continuous holograms can be recorded over the entire area of the disk, but specific data locations can be accessed by moving a read beam focused on the surface of the disk.

However, with a disk-based structure, one complication that arises from reading data from a rotating disk is that for all rotational positions of the disk and radial position of the read head, There is a desire to maintain a read position relatively fixed to the head.

FIGS. 5, 6A and 6B show a third preferred embodiment which cooperates with the devices of the first and second embodiments in recording information on a hologram disc. FIG. 5 shows a conventional system for splitting light from a laser into a signal light beam and a reference light beam. The beam from the coherent laser source 65 is converted to an expanded plane wave by a beam expander and collimator 70.
This expanded plane wave is output by the beam splitter 75.
It is split into a signal light component 110 and a reference light component 130. The signal light and reference light components are directed to the recording subsystem at an appropriate angle of incidence by an optical system such as a set of mirrors 80. The recording subsystem includes a data pattern to be recorded and a hologram recording medium.

FIG. 6A shows one possible recording subsystem. The signal light component 110 is modulated by a disk-shaped data pattern 25. Accordingly, the modulated signal light beam 20 is directed substantially parallel to the data pattern 25 and impinges on a disk-type hologram medium 35 located sufficiently close to the data pattern to capture most of the modulated light. I do.

For hologram reconstruction during reading, a spherically symmetric reference light beam is used to maintain a fixed position relative to the read reference light beam while the disk is rotating. Must be prepared. Because this can be achieved by using a beam shaping element 131 (such as a lens, optical diffractive element, or hologram) in the path of the reference light component 130, the shaped reference light beam 132 is substantially a plane wave across the surface of the disk. Incident on the disk at the same radial angle.

FIG. 6B shows an alternative recording system. In this case, the reference light component 130 irradiates the hologram medium 35 at a predetermined angle only along the stripe type recording area 134. The modulated signal light beam 20 from the data pattern 25 also illuminates the same area 134. A rotating spindle 138 with drive can be used to rotate the data pattern 25 and the hologram medium 35 together for a full 360 ° rotation during recording, and a single continuous Effective hologram is formed.

FIG. 7 shows a third preferred embodiment for reading data from the disk-type hologram medium 35 recorded by one of the above methods. Read head 1
Reference numeral 42 is mounted above the surface of the hologram medium 35. The hologram medium 35 is set on a rotating spindle 138 equipped with a driving device so that the head 142 can access all the track positions on the disk.

The head 142 is held by a transducing mechanism, such as a sliding track or a rotating arm, to allow the head to move to different radial positions on the disk. The head 142 has a coherent laser source 6
5, including the focusing element 45 and one or more detector arrays 95 in place to achieve the readout described in the preferred first and second embodiments. All positions on the disk can be accessed by the head by rotating the disk, moving the head radially, or a combination of the two.

As described above, the recording and reading apparatus of the present invention records a page of an arbitrary size of high-resolution information as a hologram and easily controls the magnification for restoring the recorded fine pattern. A device for reading out a plurality of portions of the hologram accumulated in the step (a).

Although the above description has been set forth in detail, these are not intended to limit the scope of the invention and should be taken as illustrative of the preferred embodiments. Therefore,
Various other modifications are also possible. For example, FIG.
2 and 3 illustrate the case where the signal light beam 20 and the reference light beam 30 are incident on the opposite sides of the hologram medium 35. However, the method described herein can also be used when the signal light beam 20 and the reference light beam 30 are incident on the same side of the medium.

The spherical wave readout beam 40 need not be exactly spherical and need not be in the opposite direction to the signal light beam 20. Some distortion of the spherical wave beam shape is allowed within the permissible range of the detection method, the spherical wave readout beam 40 can be applied at an offset angle, and causes the tilt of the reconstructed signal light beam 50 in the direction. Becomes

The readout beam 40 for spherical waves during recording
It can be applied in the same direction as the signal light beam 20, and can be a convergent beam or a divergent beam, depending on the form of the recording surface selected. In the case of a reflective surface, a signal light beam 20 and a reference light beam 30 that directly face each other during recording can be used. In this case, the reconstructed signal light beam 50 passes through the focusing element 45 and the distance and magnification of the reconstructed image must be adjusted for the other lens elements.

In the system of FIG. 3, the angle of the reference light beam 30 is changed using any suitable means. Similarly, the change in angle may have a component perpendicular to the plane of FIG. Different wavelengths can be generated by a single wavelength selectable coherent light source or multiple lasers of different wavelengths.

The data pattern 25 may be of a transmissive or reflective type and may take any desired form of information. For example, on a disk-type medium, instead of in the on or off state of the pixels in a normal array, a circular track pattern in which information is encoded at the edge transition of the data pattern may be recorded.

Thus, the data pattern stored on the hologram disk can be read in the same manner as the pits on the optical disk. When a large number of holograms are multiplexed, the data pattern can be adjusted by using appropriate means such as an electrically controllable spatial light modulator or by replacing the data pattern with a different one between multiple recordings. Can be changed.

The hologram medium 35 can be a storage medium of any appropriate shape and dimensions. Spherical wave beam 4
Zero can be generated by any suitable means, such as a laser, diffractive optics, or hologram element. The magnification of the reconstructed image may be selected to image any suitable amount of data. A single bit can be reconstructed for serial readout, and many bits are reconstructed for parallel readout. To scan the entire surface of the hologram medium 35 for reading out different parts of the storage hologram with the spherical wave readout beam 40, an appropriate mechanism may be used.

If the projection of the raw image is sufficient for the application, detectors 60 and 95 are not needed. Therefore, the technical scope of the present invention should not be determined only by the illustrated embodiments, but should be determined by the appended claims and the terms equivalent thereto.

[0052]

The method and apparatus for recording and reading hologram information according to the present invention have the following advantages. -Recording and reading operations can be performed using a simple optical system. No optical mechanism is required in the recording or reading signal path. -High-speed recording of large-capacity memory is possible. This is because a large number of data can be stored in a small number of holograms with a large page size and a high data density per page. -A simpler recording scheme can be used for uniformity of the recording process across a small number of holograms and each data page. -The power required for the laser can be reduced by focusing the power available to read a small amount of data. -A hologram disk compatible with existing optical disk reading mechanisms is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a hologram recording device of the present invention.

FIG. 2 is a schematic view showing an example of the hologram reading device of the present invention.

FIG. 3 is a schematic diagram illustrating an example of an apparatus that multiplexes a hologram during recording.

FIG. 4 is a schematic diagram illustrating an example of an apparatus that reads a multiplexed hologram.

FIG. 5 is a schematic diagram of an optical system that divides a laser beam into a signal light beam and a reference light beam.

FIG. 6A is a schematic diagram showing a recording subsystem for recording a hologram of a disk size, and FIG. 6B is a schematic diagram showing a recording subsystem for recording a continuous hologram.

FIG. 7 is a schematic diagram of a system for reading a hologram part from a disk-type hologram medium.

[Explanation of symbols]

20 ° modulated signal light beam, 25 ° input data pattern, 30 ° reference light beam, 35 ° hologram medium, 40 ° spherical wave readout beam, 45 ° focusing element, 50 ° reconstructed Signal light beam, 5
5 ° spatial beam focus, 60 ° detector, 65 °
Coherent laser source, 70 ° beam expander and collimator, 75 ° beam splitter, 80 ° mirror, 85 ° rotatable mirror, 90 ° 4-F imaging system, 95 ° detector array, 110 ° {Signal component, 130} reference component, 131} beam shaping element, 132} shaped reference light beam, 134 {striped recording area, 138} rotating spindle with drive, 142} read head, 143 ‥‥ radial direction conversion mechanism

Claims (33)

[Claims] 1. A method for recording and reading information on a hologram in a recording medium, comprising: condensing a signal light beam modulated by data and a recording reference light beam onto a spot on a recording medium on which a hologram is recorded. Recording a hologram, creating a read reference light beam having a substantially different wavefront shape from the recording reference light beam, irradiating the hologram with the read reference light beam,
A hologram information recording / reading method for obtaining reproduction image information enlarged to a predetermined magnification and reproducing a part of the data by the image information. 2. The method according to claim 1, wherein the read reference light beam is applied in substantially the same direction as the direction of the signal light beam, whereby the reproduced image information is applied substantially in the direction of the recording reference light beam. A hologram information recording / reading method characterized in that the hologram information is recorded and read out. 3. The hologram information recording / reading method according to claim 1, wherein the read reference light beam is applied in a direction substantially opposite to a traveling direction of the signal light beam. 4. The method according to claim 1, wherein a magnification of the reproduced image information is determined according to a wavefront shape of the read reference light beam. 5. The hologram information recording / reading method according to claim 1, wherein a relative position of the read reference light beam with respect to the recording medium is moved to reproduce different portions of the data. 6. The method according to claim 1, wherein a plurality of holograms are recorded on a recording medium by changing an incident angle of the recording reference light beam on the recording medium with respect to each hologram, whereby the read-out reference is performed. A hologram information recording / reading method for obtaining a plurality of corresponding reproduced image information by applying a light beam. 7. The method according to claim 1, wherein a plurality of holograms are recorded on the recording medium by changing the wavelengths of the signal light beam and the recording reference light beam for each hologram, and the read reference light is recorded. Hologram information recording and reading method for reproducing different holograms by changing the wavelength of the hologram. 8. The method according to claim 1, wherein the recording medium is a substantially disk-type recording medium. 9. A method for storing and reading information in a hologram in a recording medium, comprising: condensing a signal light beam modulated by data and a recording reference light beam of a substantially plane wave on a selected spot on the recording medium;
The hologram is thereby recorded, a readout reference light beam of a substantially spherical wave is created, the hologram is irradiated with the readout reference light beam, and a part of the data is reconstructed as an image having a predetermined magnification. Hologram information recording and reading method. 10. The method of claim 9, wherein the read reference light beam is provided in substantially the same direction as the signal light beam, so that a reconstructed image propagates substantially in the direction of the recording reference light beam. Hologram information recording and reading method. 11. The hologram information recording / reading method according to claim 9, wherein the read reference light beam is provided in a direction facing the signal light beam. 12. The hologram information recording and reading method according to claim 9, wherein a magnification of the reconstructed image is determined by a focal position of the read reference light beam. 13. The hologram information recording and reading method according to claim 9, wherein the read reference light beam is changed in relation to the recording medium to reconstruct a different part of the data. 14. The method according to claim 9, wherein a plurality of holograms are recorded on the recording medium by changing an incident angle of the recording reference light beam on the recording medium with respect to each hologram, and the read reference light beam is formed. A hologram information recording / reading method for obtaining a plurality of corresponding reconstructed images in parallel by giving the hologram information. 15. The method according to claim 9, wherein a plurality of holograms are recorded in the recording medium by changing the wavelengths of the signal light beam and the recording reference light beam for each hologram, and the read-out reference is performed. A hologram information recording and reading method for reconstructing a different hologram by changing the wavelength of a light beam. 16. The method according to claim 9, wherein the recording medium is substantially a disk type. 17. A method for recording data over substantially the entire surface of a substantially disk-shaped recording medium as a single continuous hologram, wherein a part of the data is reconstructed by applying an appropriate read-out reference light beam. In the method,
(A) condensing a recording reference light beam and a signal light beam modulated with data on a selected area in the recording medium to record a hologram; (b) substantially defining the recording reference light beam (C) A data storage method for creating a read reference light beam having a different wavefront shape, and (c) irradiating the hologram with the read reference light beam to reconstruct a part of the data as an image. 18. The method of claim 17, wherein at each point where the recording reference light beam is incident on the recording medium, the shape is a substantially plane wave, and the readout reference light beam is a substantially spherical wave. Method. 19. The method of claim 17, wherein the read reference light beam is applied substantially in the direction of the signal light beam, so that the reconstructed image is substantially in the direction of the recorded reference light beam. A data storage method that propagates. 20. The method according to claim 17, wherein a magnification of the reconstructed image is determined by a position of the read reference light beam. 21. The data storage method according to claim 17, wherein a different portion of the data is reconstructed by changing a read reference light beam with respect to the recording medium. 22. The method according to claim 17, wherein a plurality of holograms are recorded in the recording medium by changing an incident angle of the recording reference light beam on the recording medium with respect to each hologram, and the read reference light is recorded. A data storage method for applying beams to obtain a plurality of corresponding reconstructed images in parallel. 23. The method according to claim 17, wherein a plurality of holograms are recorded on the recording medium by changing the wavelengths of the signal light beam and the recording reference light beam for each hologram, and the read reference light is recorded. A data storage method that reconstructs different holograms by changing the wavelength of the beam. 24. The method according to claim 17, wherein the information in the data is encoded as a displacement of an edge position in a track extending direction in a substantially circular track pattern on the disk, whereby the information is encoded. A data storage method that enables a disk-type recording medium to be read in substantially the same manner as an optical disk. 25. The method according to claim 24, wherein the optical disc is a compact disc or a DV.
D. A data storage method, characterized by being D. 26. (a) means for producing coherent light;
(B) a substantially disk-type recording medium suitable for hologram recording; (c) a spatial modulation means for spatially modulating a light beam on the recording medium to create a continuous hologram over the entire surface of the medium; d) means for irradiating the recording medium with light modulated by the spatial light modulation and a reference light beam. 27. The hologram recording apparatus according to claim 26, wherein the means for irradiating the reference light beam can be adjusted to change an incident angle of the reference light beam on the recording medium. 28. The hologram recording apparatus according to claim 26, wherein the means for producing the coherent light can change a wavelength. 29. The hologram recording apparatus according to claim 26, wherein said means for producing coherent light includes a plurality of light sources having different wavelengths. 30. (a) means for producing coherent light;
(B) means for converting the coherent light into a substantially spherical wave beam; (c) at least one photodetector;
A hologram reading apparatus, comprising: (d) a hologram medium on which information is recorded by interference of a substantially plane wave and light modulated by information; and (e) a moving means for moving the spherical wave beam with respect to the medium. 31. The hologram readout device according to claim 30, wherein the means for producing the coherent light can select a wavelength. 32. An apparatus according to claim 30, wherein said means for producing coherent light includes a plurality of light sources having different wavelengths. 33. The apparatus according to claim 30, wherein the medium is encoded such that portions of the plurality of holograms are reconstructed simultaneously by the spherical wave beam.