CN1688943A - Hologram recording/reproducing method and device thereof - Google Patents

Abstract

A method for holographic recording and reproducing includes a recording process and a reproducing process. In the recording process, a coherent reference beam is spatially modulated in accordance with information to be recorded to generate a signal beam, and the signal beam is converged. The converged signal beam enters and passes through a recording medium made of a photosensitive material. A diffraction grating area according to a light interference pattern is created in a portion where a 0th-order beam and a diffraction beam of the signal beam interfere with each other inside the recording medium. In the reproducing process, a reproduced wave corresponding to the signal beam is generated by illuminating the diffraction grating area with the reference beam.

Description

Method and device for holographic recording and reproduction

technical field

The present invention relates to a recording medium made of a photosensitive material, a so-called holographic memory, and in particular, the present invention relates to a method for holographic recording and reproduction, and an optical information recording and reproducing apparatus using such a holographic memory.

Background technique

A volume holographic recording system is known as a digital data recording system utilizing the principle of holography. Such a system is characterized by recording information on a recording medium made of a photosensitive material such as a photorefractive material in which the refractive index of the medium changes.

A conventional holographic recording and reproducing method utilizes Fourier transform for recording and reproducing.

Referring to FIG. 1, in a conventional 4f series holographic recording and reproducing apparatus, a beam splitter 13 splits a laser beam 12 generated by a laser source 11 into beams 12a and 12b. The beam expander BX expands the diameter of the beam 12a. Then, the parallel light beam 12a acts on a spatial light modulator SLM, such as a panel of a transmissive TFT liquid crystal display (LCD). The spatial light modulator SLM receives the information to be recorded, such as an electronic signal encoded by an encoder, to form two-dimensional data, that is, to form bright and dark light point patterns corresponding to the information on a plane. When the light beam 12a passes through the spatial light modulator SLM, the spatial light modulator SLM optically modulates the light beam 12a into a signal light beam including a data signal component. Since the signal light beam 12a including the light spot pattern signal component passes through the Fourier transform lens 16 arranged at a focal distance f from the spatial light modulator SLM, the light spot pattern signal component is transformed into a Fourier component and converged to on the recording medium 10. The light beam 12 b split by the beam splitter 13 is guided into the recording medium 10 through mirrors 18 and 19 . The beam 12 b intersects the optical path of the signal beam 12 a inside the recording medium 10 as a reference beam. The beam 12b and the signal beam 12a interfere to form an optical interference pattern. The entire optical interferogram is recorded as a diffraction grating, such as a change in the refractive index (refractive index grating), etc.

As described above, the spot pattern data diffracts coherent parallel light beams and forms an optical image using a Fourier transform lens. In the focal plane of the Fourier transform lens, i.e. the image distribution on the Fourier plane interferes with the coherent reference beam. Then, near the focal point, interference fringes are recorded on the recording medium. After the recording of the first page is completed, the rotatable mirror is rotated by a predetermined degree and moved in parallel so as to change the incident angle of the reference beam 12b incident on the recording medium 10 . Then, follow the same process as above to record the second page. Multi-angle recording can be performed in this way.

On the other hand, inverse Fourier transform is used in reproducing the dot pattern image. In reproducing the recorded information, as shown in FIG. 1 , for example, a spatial light modulator SLM, intercepts the optical path of the signal beam 12 a so that only the reference beam 12 b is incident on the recording medium 10 . The position and angle of the mirror can be controlled by changing the combination of its rotation and movement so that the incident angle of the reference beam 12b can be the same as that during recording of the page to be reproduced. The reproduced light beam reproducing the recorded signal light beam appears on the opposite side of the recorded signal light beam 12 a incident on the recording medium 10 . The reproduced light beam is guided to an inverse Fourier transform lens 16a and inverse Fourier transform is performed, whereby a spot pattern signal is reproduced. The dot pattern signal is received by a photodetector 20 such as a charge-coupled device (CCD) placed at the focal position of the lens 16a, and converted into an electrical digital data signal. The digital data signal is then sent to a decoder to decode the original data.

Referring to FIG. 1, a plurality of images are generally recorded in a volume of several millimeters of a recording medium using multi-angles and multi-wavelengths in order to record information in a certain volume of the recording medium at high density. Therefore, wide field-of-view and long-distance coherence of the signal and reference beams are necessary to ensure angular and wavelength selectivity. Thereby, the light beam intensity per light quantity used for recording is lowered. Multiple recording is necessary for high-density recording, and thus a recording medium having a large erasing time constant and easily performing multiple recording is required.

A conventional holographic recording and reproducing device requires two lenses of high spec, that is, a Fourier transform lens and an inverse Fourier transform lens. The device also needs to be equipped with a high-precision page control mechanism for controlling the reference beam during recording and reproducing information. Therefore, there is a disadvantage that the size of the device becomes large.

Contents of the invention

An object of the present invention is to provide a method for hologram recording and reproduction and an apparatus therefor, which can reduce the size and record a hologram on a hologram recording medium.

According to the present invention, there is provided a method for holographic recording and reproduction comprising a recording process and a reproduction process,

The recording process consists of the following steps:

generating a signal beam by spatially modulating a coherent reference beam according to the information to be recorded;

irradiating a recording medium made of a photosensitive material with a signal beam to allow the signal beam to pass through said recording medium; and

In a portion where the zero-order beam of the signal beam and the diffracted beam interfere with each other inside the recording medium, a diffraction grating area recorded by an optical interference pattern is generated; and

The reproduction process consists of the following steps:

The diffraction grating region is irradiated with the reference beam to generate reproduced waves corresponding to the signal beam.

a signal beam is a beam resulting from such an operation of spatially modulating a coherent reference beam in accordance with the information to be recorded, the signal beam including a zero-order beam whose wavefront has the same shape regardless of whether it is spatially modulated; and undergoes spatial modulation diffracted beam. Therefore, the present invention utilizes the zero-order beam of the signal beam as reference light for holographic recording.

In recording, the recording medium is irradiated with a signal beam to generate an optical interference fringe pattern formed by the zero-order beam and the diffracted beam in the optical path of the signal beam, thereby recording a refractive index grating corresponding to the interference fringe pattern in the recording medium .

In reproduction, the recording medium, in particular the index grating therein, is illuminated with a signal beam that has not been spatially modulated, ie an unmodulated reference beam using the same positional and angular conditions as the signal beam used in recording. Since the non-modulated reference beam includes the zero-order beam as a main component, the refractive index grating of the recording medium irradiated by the non-modulated reference beam generates a reproduced wave identical to the wavefront of the signal beam used in recording.

In the detection of the reproduced wave, the reproduced wave emitted from the refractive index grating in the recording medium is superimposed on the non-modulated reference beam for reproduction. Removal or reduction of the unmodulated reference beam for reproduction facilitates easy detection of reproduction waves, and electrical reproduction of recorded information.

According to the present invention, there is also provided a recording medium, which is made of a photosensitive material that can be recorded by irradiation with coherent light beams, the recording medium includes an incident beam processing area, which is arranged in the recording medium on the incident surface of the recording medium where the light beam is incident On the opposite side of the incident beam processing region, the zero-order beam and the diffracted beam of the beam are separated from each other, thereby returning a part of the incident beam to the interior of the recording medium.

In order to remove or reduce the non-modulated reference beam used for reproduction, as shown in FIG. 2, the recording medium 10 has an incident beam processing region R, which includes the zero-order beam for processing the signal beam and the non-modulated reference beam. The zero-order beam processing area R1, and the diffracted beam processing area R2 for processing the diffracted beam of the signal beam, the incident beam processing area is configured in the following manner, that is, the incident beam processing area is placed at the beam waist of the non-modulated reference beam, wherein the non-modulated reference beam The modulated reference beam is converged by a condenser lens and focused on the opposite side of the incident surface from which the beam is incident on the recording medium.

It is considered to use a phase conjugate wave as one of methods for a holographic recording and reproducing system among recording and reproducing methods. Similar to other methods, reproduction methods using phase conjugate beams generally require the use of the same reference beam in recording and reproduction. For example, a method for recording and reproducing information, wherein a refractive index grating is generated and recorded by interference in a recording medium in such a manner that a signal beam is irradiated onto the recording medium and reflected by a mirror to A phase conjugate wave is generated back to the recording medium, so that the phase conjugate wave and the signal beam interfere with each other. In this recording and reproducing method, there are many disadvantages such as the need to insert and remove mirrors, the degradation of the light source due to the return of the signal beam, especially the zero-order beam, and the large-scale device including the optical system to prevent the return light. On the contrary, according to the present invention, the incident light beam processing section solves the above-mentioned problems because the zero-order beam and the diffracted beam in the incident light are processed separately by different processing to return a part of the incident light beam to the inside of the recording medium. .

Furthermore, unlike conventional holographic recording and reproducing methods, the present invention does not need to provide respective two optical systems for the reference beam and the signal beam. Furthermore, the method of the present invention does not require a high-performance condenser lens used as an objective lens or the like. Employing this recording and reproducing method efficiently simplifies and miniaturizes the recording and reproducing apparatus because zero-order beams and diffracted beams (spatially modulated according to information to be recorded) included in signal beams are used.

According to the present invention, there is further provided a method for holographic recording, comprising the following steps:

generating a signal beam by spatially modulating a coherent reference beam according to the information to be recorded;

irradiating a recording medium made of a photosensitive material with a signal beam to allow the signal beam to pass through the recording medium; and

Inside the recording medium, a diffraction grating region recorded by an optical interference pattern is generated in a portion where a zero-order beam of a signal beam and a diffracted beam interfere with each other.

According to the present invention, there is further provided a method for holographic reproduction, comprising the following steps:

A recording medium made of a photosensitive material is provided having a diffraction grating area formed by a recording process comprising the steps of: generating a signal beam by spatially modulating a coherent reference beam according to information to be recorded; illuminating the recording medium with the signal beam , to allow the signal beam to pass through the recording medium, so that a diffraction grating region recorded by an optical interference pattern is formed in a portion where the zero-order beam and the diffracted beam of the signal beam inside the recording medium interfere with each other; and

A coherent reference beam is irradiated onto the diffraction grating region to generate reproduced waves corresponding to the signal beam.

According to the present invention, there is furthermore provided a holographic recording and reproducing apparatus for recording information as a diffraction grating area in a recording medium and for reproducing said recorded information from said diffraction grating area, said holographic recording and reproducing apparatus, include:

a holding portion for detachably holding a recording medium made of a photosensitive material;

a light source for generating a coherent reference beam;

a signal beam generating unit comprising a spatial light modulator for spatially modulating the reference beam according to the information to be recorded to generate a signal beam;

an interference unit comprising an illuminating optical system for illuminating a recording medium with a signal beam to allow the signal beam to enter and pass through said recording medium, said illuminating optical system being inside said recording medium at a zero-order beam of the signal beam In a portion where the diffracted beam interferes with each other, a diffraction grating area is formed according to an optical interference pattern, and the irradiation optical system irradiates the diffraction grating area with the reference beam to generate a reproduced wave corresponding to the signal beam; and

A detecting unit for detecting the record information formed in an image by the reproduced wave.

According to the present invention, there is also provided a holographic recording device for recording information as a diffraction grating area in a recording medium, the recording device comprising:

a holding portion for detachably holding a recording medium made of a photosensitive material;

a light source for generating a coherent reference beam;

a signal beam generating unit comprising a spatial light modulator that spatially modulates the reference beam in accordance with the information to be recorded to generate a signal beam; and

an interference unit including an irradiation optical system for irradiating a recording medium with a signal beam to allow the signal beam to enter and pass through the recording medium, the irradiation optical system diffracting the zero-order beam of the signal beam inside the recording medium A diffraction grating area is formed in a portion where the light beams interfere with each other according to the light interference pattern.

According to the present invention, there is also provided a holographic reproduction device for reproducing information recorded as a diffraction grating area in a recording medium, the holographic reproduction device comprising:

a holding portion for detachably holding a recording medium made of a photosensitive material;

a light source for generating a coherent reference beam;

an irradiating unit comprising an irradiating optical system for irradiating the recording medium with a reference beam to allow the reference beam to enter and pass through a diffraction grating area in the recording medium to generate a reproduced wave corresponding to the signal beam; and

A detecting unit for detecting the record information formed in an image by the reproduced wave.

According to the present invention, there is also provided another holographic recording and reproducing apparatus for recording information as a diffraction grating area in a recording medium and for reproducing said recorded information from said diffraction grating area, said holographic recording and reproducing apparatus include:

a holding portion for detachably holding a recording medium made of a photosensitive material;

a light source for generating a coherent reference beam;

a signal beam generating unit comprising a spatial light modulator for spatially modulating the reference beam according to the information to be recorded to generate a signal beam;

an interference unit including an irradiation optical system for irradiating a recording medium with a signal beam to allow the signal beam to enter and pass through the recording medium, the irradiation optical system being a zero-order beam of the signal beam inside the recording medium and a diffraction grating area is formed according to an optical interference pattern in a portion where the diffracted beams interfere with each other, and the irradiation optical system irradiates the diffraction grating area with the reference beam to generate a reproduced wave corresponding to the signal beam;

an incident beam processing area provided in the recording medium on the opposite side of the incident surface of the signal beam incident on the recording medium, the incident beam processing area separates the zero-order beam and the diffracted beam from each other so that a part of the incident beam returns to the inside the recording medium; and

A detecting unit for detecting the record information formed in an image by the reproduced wave.

According to the present invention, there is also provided another holographic recording device for recording information as a diffraction grating area in a recording medium, comprising:

a holding portion for detachably holding a recording medium made of a photosensitive material;

a light source for generating a coherent reference beam;

a signal beam generating unit comprising a spatial light modulator for spatially modulating the reference beam according to the information to be recorded to generate a signal beam;

an interference unit including an irradiation optical system for irradiating a recording medium with a signal beam to allow the signal beam to enter and pass through the recording medium, the irradiation optical system being a zero-order beam of the signal beam inside the recording medium and forming a diffraction grating region according to a light interference pattern in a portion where the diffracted beams interfere with each other; and

an incident beam processing area provided in the recording medium on the opposite side of the incident surface of the signal beam incident on the recording medium, the incident beam processing area separates the zero-order beam and the diffracted beam from each other so that a part of the incident beam returns to the inside the recording medium.

According to the present invention, another holographic reproducing device is further provided for reproducing information recorded as a diffraction grating area in a recording medium, the holographic reproducing device comprising:

a holding portion for detachably holding a recording medium made of a photosensitive material;

a light source for generating a coherent reference beam;

an irradiating unit comprising an irradiating optical system for irradiating the recording medium with a reference beam to allow the reference beam to enter and pass through the diffraction grating area in the recording medium to generate a reproduced wave corresponding to the signal beam;

an incident beam processing area provided in the recording medium on the opposite side of the incident surface of the signal beam incident on the recording medium, the incident beam processing area separates the zero-order beam and the diffracted beam from each other so that a part of the incident beam returns to the inside the recording medium; and

A detecting unit for detecting the record information formed in an image by the reproduced wave.

Brief description of the drawings

FIG. 1 is a schematic diagram showing the structure of a conventional holographic recording and reproducing system;

2 is a schematic cross-sectional view of a holographic recording medium according to an embodiment of the present invention;

3 is a schematic diagram showing the structure of a holographic recording and reproducing apparatus according to an embodiment of the present invention;

4 is a schematic sectional view for explaining a recording process performed by the hologram recording and reproducing apparatus of this embodiment of the present invention;

Fig. 5 is a schematic sectional view of a holographic recording medium for use in the embodiment of the present invention;

Fig. 6 is a schematic plan view for explaining the relationship between the holographic recording medium and the spatial light modulator of this embodiment of the present invention;

7 is a schematic perspective view for explaining a recording process performed by the hologram recording and reproducing apparatus of the present invention;

8 is a schematic cross-sectional view for explaining a reproduction process performed by the hologram recording and reproduction apparatus of the embodiment of the present invention;

9 and 10 are schematic sectional views for explaining a recording process performed by a hologram recording and reproducing apparatus of a modified example of the embodiment of the present invention;

11 is a schematic diagram showing the structure of a holographic recording and reproducing apparatus according to another embodiment of the present invention;

12 is a schematic sectional view for explaining a recording process performed by the hologram recording and reproducing apparatus of this embodiment of the present invention;

Fig. 13 is a schematic sectional view of a holographic recording medium for use in this embodiment of the present invention;

14 is a schematic cross-sectional view for explaining the reproduction process performed by the hologram recording and reproduction apparatus of the embodiment of the present invention;

15 to 17 are schematic sectional views for explaining a recording process performed by a hologram recording and reproducing apparatus of a modified example of the embodiment of the present invention;

18 is a schematic diagram showing the structure of a holographic recording and reproducing apparatus according to another embodiment of the present invention;

Fig. 19 is a schematic plan view for explaining the relationship between the holographic recording medium and the spatial light modulator of this embodiment of the present invention;

20 is a schematic perspective view for explaining a recording process performed by the hologram recording and reproducing apparatus of the present invention;

21 and 22 are schematic sectional views for explaining a recording process performed by a holographic recording and reproducing apparatus of a modified example of another embodiment of the present invention;

23 is a schematic diagram showing the structure of a holographic recording and reproducing apparatus according to another embodiment of the present invention;

24 to 26 are schematic sectional views for explaining a recording process performed by a hologram recording and reproducing apparatus of a modified example of other embodiments of the present invention;

27 is a schematic perspective view showing devices used in an incident beam processing region of a hologram recording and reproducing apparatus according to still another embodiment of the present invention;

FIG. 28 is a schematic perspective view showing a recording medium disk cartridge of a hologram recording and reproducing apparatus according to still another embodiment of the present invention.

Detailed description of the invention

Various embodiments of the present invention are described below with reference to the accompanying drawings.

During recording, the present invention does not use a reference beam provided by another optical path. Instead, only the signal beam is incident on the recording medium, and the refractive index grating formed by the interference between the zero-order beam of the signal beam and the diffracted beam is recorded. Afterwards, a reproduced wave is reproduced from the refractive index grating by irradiating the refractive index grating with only the reference beam. The incident light beam processing area is entirely disposed on the opposite side of the incident surface on which the light beam is incident in the recording medium. The incident beam processing region separates the zero-order beam of the beam and the diffracted beam of the beam from each other, thereby returning a part of the incident beam to the inside of the recording medium.

<First Embodiment>

Fig. 3 shows a holographic recording and reproducing device according to one embodiment. In this device, a near-infrared laser such as a DBR (Distributed Bragg Reflector) laser having a wavelength of 850 nm is used as the light source 11 . The shutter SH, the beam expander BX, the spatial light modulator SLM, the beam splitter 15 and the condenser lens 160 are placed in the optical path of the reference beam 12 . The shutter SH is controlled by the controller 32 to control the irradiation time of the light beam irradiating the recording medium.

The beam expander BX increases the diameter of the beam 12 passing through the shutter SH. The parallel light beam 12 is incident on the spatial light modulator SLM. The spatial light modulator SLM, according to the electronic data received from the encoder 25, displays bright and dark dot matrix signals. Electronic data is represented as a series of page units corresponding to two-dimensional pages. During the passage of the reference beam through the spatial light modulator SLM displaying the data, the reference beam is optically modulated into a signal beam 12a comprising data as dot matrix components. The condensing lens 160 performs Fourier transform on the lattice component of the signal beam 12 a passing through the beam splitter 15 and converges it so that the signal beam 12 a reaches a focal point behind the mounted recording medium 10 . When the shutter SH is opened, the signal beam 12a or the reference beam 12 is incident on the principal surface of the recording medium 10 by the condenser lens 160 at a predetermined incident angle, for example, zero degrees. The beam splitter 15 is a splitting unit that splits a reproduced wave (described later) from the optical path of the reference beam, thereby supplying the reproduced wave to a photodetector 20 of a photoelectric conversion device such as a CCD. Both the spatial light modulator SLM and the CCD 20 are placed at the focus of the condenser lens 160.

In addition, the beam splitter 15 is placed at a position capable of sending reproduced waves to the CCD 20. The CCD 20 is connected to a decoder 26 . The decoder 26 is connected to the controller 32 . Considering the case where information corresponding to the type of photorefractive crystal is preliminarily added to the recording medium 10, when the recording medium 10 is mounted on the movable stage 60 as a holding part for moving the recording medium 10, the controller 32 automatically uses a suitable sensor This information is read out, thereby controlling movement of the recording medium 10 and performing recording and reproduction suitable for the recording medium 10 .

Referring to FIG. 3 , the recording medium 10 is entirely disposed on the opposite side of the incident surface having an incident beam processing region R including a zero-order beam processing region R1 through which the zero-order beam among the signal beams 12a passes, and Diffraction beam processing region R2 for reflecting the diffracted beam in the signal beam 12a. The incident beam processing region R is provided for processing the signal beam. For example, the incident beam processing region R includes an opening through which the zero-order beam passes, and the diffracted beam processing region R2 defines the opening. As long as the zero-order beam processing region R1 has a role different from that of the diffracted beam processing region R2, the incident beam processing region R is not limited to the configuration described above. A zero-order beam absorbing material may be provided for the zero-order beam processing region instead of the opening. In other words, the zero-order beam processing region R1 in the incident beam processing region R passes the zero-order beam, or absorbs the zero-order beam.

Operations during recording are described below.

The controller 32 shown in FIG. 3 controls the position of the movable stage 60 holding the recording medium 10 so that the objective recording medium 10 is moved to a predetermined recording position.

Then, the recording signal is sent from the encoder 25 to the spatial light modulator SLM, which displays a specific pattern corresponding to the data to be recorded.

Then, the shutter SH is opened and the spatial light modulator SLM is illuminated with the reference beam 12 . A signal beam 12a is generated in a reference beam 12 that is spatially modulated by a spatial light modulator SLM, which displays a pattern thereon in accordance with the information to be recorded. The recording medium 10 is irradiated with the generated signal beam 12a, thereby starting the recording process.

The process of recording the refractive index grating in the recording medium by using the signal beam 12a (ie, the zero-order beam and the diffracted beam therein) is described in detail below.

As shown in FIG. 4, the signal beam 12a includes a zero-order beam and a diffracted beam subjected to spatial modulation. The zeroth order beam of the signal beam 12a has a wavefront of constant shape that is not affected by any spatial modulation and is therefore referred to as the "hologram reference beam". The diffracted beam of the signal beam 12a subjected to spatial modulation is called "hologram signal beam". Thus, at least in recording, the signal beam 12a includes a hologram reference beam and a hologram signal beam.

Since the recording medium 10 is irradiated with the signal beam 12a, the hologram reference beam and the hologram signal beam optically interfere with each other to form an optical interference fringe pattern P1, thereby recording the refractive index grating P1 in the recording medium 10 due to the photorefractive effect.

The zero-order beam of the signal beam 12a (ie, the hologram reference beam) passes through the zero-order beam processing region R1 of the incident beam processing region R, and emerges from the opposite side of the recording medium 10 from which the signal beam 12a is incident. The diffracted beam of the signal beam 12a (ie, the hologram signal beam) is reflected back to the recording medium 10 by the diffracted beam processing region R2 of the incident beam processing region R. Therefore, the diffracted beam of the signal beam 12a reflected by the diffracted beam processing region R2 is referred to as "reflected hologram signal beam".

The reflected hologram signal beam and hologram reference beam optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P2, so that the refractive index grating P2 corresponding to the optical interference fringe pattern P2 is recorded on the recording medium 10 due to the photorefractive effect. Medium 10.

In this way, in recording, the zero-order beam and the diffracted beam (i.e., the signal beam 12a) from the spatial light modulator SLM, together with the reflected diffracted beam from the diffracted beam processing region R2, form a three-dimensional A collection of interferograms. As shown in FIG. 5, the refractive index gratings P1, P2 corresponding to the optical interference patterns P1, P2 are recorded in the recording medium 10 in the form of holograms due to the photorefractive effect.

After the recording on the recording medium 10 , the shutter SH is closed by the control of the controller 32 .

Upon completion of recording at a predetermined recording position of the recording medium 10, the recording medium 10 is forced to move (in the "y" direction of FIG. 3) in order to reach another predetermined position of the signal beam 12a relative to the recording medium 10. Then, the next recording follows the previous procedure. Recording can be performed sequentially like this.

Fig. 6 shows the recording medium 10 and the spatial light modulator SLM placed side by side as viewed from the direction from the light source along the optical axis of the signal beam 12a. The zero-order beam processing region R1 of the incident beam processing region R provided on the opposite side of the incident surface in the recording medium 10 defines a track TR which acts as an opening, mainly enabling the zero-order beam of the signal beam 12a to pass through the track, As shown in Figure 6. The track TR continues in the "y" direction of FIG. 6 . A plurality of tracks TR may be intermittently provided in a linear form. In this case, the plurality of tracks TR may store position information of the zero-order beam processing region R1 in the recording medium 10 .

The recording medium 10 and the spatial light modulator SLM are disposed relative to the optical axis in such a manner that the extension direction D _TR of the track TR is at a predetermined angle to the extension direction D _SLM of a row in the pixel matrix of the spatial light modulator SLM. (θ≠0) angle. In addition, the direction of extension of a column of the pixel array of the spatial light modulator SLM can also be used for the angular setting between the recording medium 10 and the spatial light modulator SLM. The reason for this configuration of the angular setting between the recording medium 10 and the spatial light modulator SLM is as follows.

In general, the spatial light modulator SLM, according to the information to be recorded in the recording process, shows whether to allow light to pass through the two-dimensional light spot pattern of each pixel. The spatial light modulator SLM spatially modulates the reference beam 12 passed by it, producing a signal beam 12a. Then, the Fourier transform lens or condensing lens 160 Fourier transforms the signal beam 12a to irradiate the recording medium 10, and forms a point image generated by the zero-order beam and the diffracted beam on the Fourier plane FF.

As shown in Fig. 7, the highest frequency component in the signal beam 12a modulated by the spatial light modulator SLM corresponds to diffraction according to its pixel matrix (with pitch "a"). According to the spatial modulation due to the spatial light modulator SLM, the signal beam 12a is Fourier transformed by the condenser lens 160, and then the light intensity distribution spectrum with respect to the spatial frequency appears on the Fourier plane FF, as shown in FIG. 7 .

If the spatial frequency (1/a) based on the pixel pitch of the spatial light modulator SLM is utilized, the wavelength (λ) of the signal beam 12a and the focal length (f) of the Fourier transform lens (condensing lens 160), then in Fourier The distance (d1) between the zero-order beam and the first-order diffracted beam on the leaf plane FF can be expressed as follows: d1=(1/a)·(λ)·(f). According to the above equation, take the following situation as an example, for example, the pixel pitch of the spatial light modulator is 10 μm, the wavelength of the signal beam 12a is 530nm, the focal length is 14mm, the distance between the zero-order beam and the first-order diffracted beam (d1) is about 750 μm. Because the highest frequency component in the signal beam 12a modulated by the spatial light modulator SLM corresponds to the pixel matrix spacing, the point image corresponding to this pixel matrix spacing appears on the Fourier plane FF with the zero-order beam of the signal beam 12a The generated point image is at the farthest position. Thus, on the Fourier plane FF, the largest part of the spectral distribution of the spatial frequencies produced by the spatial light modulator lies in the region centered on the zeroth order beam of the signal beam 12a and drawn by the first order diffracted beam , the first-order diffracted beam corresponds to the pixel pitch along the row and column directions in the spatial light modulator SLM.

The point image produced by the diffracted beam corresponding to the direction of extension D _SLM of a row of the pixel matrix of the spatial light modulator SLM is comprised in the incident beam processing region R in the Fourier plane FF. When the extension direction D _TR of the track TR and the extension direction D _SLM of a row in the pixel matrix of the spatial light modulator SLM form an angle θ=0 with respect to the optical axis of the signal beam intersecting them, the row of the spatial light modulator SLM Point images corresponding to spatial frequency components in the direction of extension D _SLM fall on the track TR.

Thus the diffracted beam corresponding to the row extension direction D _SLM of the spatial light modulator SLM is not reflected by the diffracted beam processing region R2. Therefore, there is no hologram signal beam originating from the reflection of the signal beam 12a (corresponding to the row extension direction D _SLM of the spatial light modulator) in the formed above-mentioned optical interference fringe pattern P2, and thus does not overlap with the signal beam 12a. Optical interference occurs with the hologram reference beam. In other words, when the extension direction D _TR of the track TR and the extension direction D _SLM of a row in the pixel matrix of the spatial light modulator SLM form an angle θ=0 with respect to the optical axis of the signal beam intersecting them, there will be no recording In the refractive index grating P2 of the medium 10 is recorded any information based on the diffracted light beam corresponding to the row extension direction of the spatial light modulator SLM.

The low-frequency components of the information to be recorded are concentrated near the zero-order beam, but the zero-order beam is passed on purpose. This embodiment utilizes the remaining diffracted beams occurring at various points around the zero order beam.

In order to effectively utilize the diffracted beam, that is, to make the reflected hologram signal beam of the signal beam 12a (corresponding to the row extension direction of the spatial light modulator SLM) and the zero-order beam of the signal beam 12a (ie, the hologram reference beam) occur Optical interference, the recording medium 10 and the spatial light modulator SLM are relatively arranged with respect to the optical axis in such a way that the extension direction D TR of the track TR and the extension direction _D of a row (or a column) in the pixel matrix of the spatial light modulator SLM _{The SLM} is at a predetermined angle θ (θ≠0).

Operations during recording are described below.

The controller 32 controls the position of the movable stage 60 holding the recording medium 10, as shown in FIG. 3, thereby moving the target recording medium 10 to a predetermined recording position.

Then, in order not to modulate the reference beam 12 spatially modulated by the spatial light modulator SLM, information to make all pixels transparent is sent from the encoder 25 to the spatial light modulator SLM, and the spatial light modulator SLM displays a transparent pattern.

Then, the shutter SH is opened, and the spatial light modulator SLM is irradiated with the reference beam 12 to generate the signal beam 12a. The recording medium 10 is then irradiated with the signal beam 12a. In this way, the reproduction process is started. It is to be noted that during reproduction, the signal beam 12a is not spatially modulated because the spatial light modulator SLM exhibits a transparent pattern. Therefore, there is no diffracted beam due to spatial modulation, so that the signal beam 12a only includes the zero-order beam (ie, the hologram reference beam).

The process of reproducing the refractive index grating in the recording medium using the signal beam 12a (ie, the hologram reference beam) is described in detail below.

As shown in FIG. 8, a signal beam 12a (without spatial modulation, ie, a hologram reference beam) is made to irradiate the recording medium 10 under the same positional and angular conditions as the signal beam used in recording. At this time, the refractive index gratings P1 and P2 in the recording medium 10 are irradiated with the signal beam 12a, so first reproduction waves are emitted from the refractive index grating P1 and second reproduction waves are emitted from the refractive index grating P2, respectively, corresponding to the recording information. The signal beam 12a passing through the zero-order beam processing region R1 exits from the opposite side of the incident surface of the recording medium 10 on which the beam enters. Therefore, the signal beam 12 a does not return to the condensing lens 160 and does not reach the photodetector 20 . This phenomenon contributes to simplified reproduction of recorded information.

The first reproduced wave is reflected back to the recording medium 10 through the diffracted beam processing region R2 of the incident beam processing region R, exits from the incident surface of the recording medium 10 , and passes through the condenser lens 160 . The second reproduced wave originates from the diffraction grating recorded by the light reflected by the diffraction beam processing region R2 during recording, exits from the incident surface of the recording medium 10 , and passes through the condensing lens 160 . In this manner, at least the first and second reproduced waves are emitted from the incident surface of the recording medium 10 and pass through the condensing lens 160 .

After the first and second reproduced waves pass through the condensing lens 160 , they are reflected by the beam splitter 15 and form an image spot pattern corresponding to the recording information on the photodetector 20 . The photoreceptor of CCD 20 then receives this image dot pattern, so that its dot pattern signal is restored to an electronic digital data signal. Then, the digital data signal is sent to a decoder 26 to reproduce the original data.

Next, the shutter SH is closed by the control of the controller 32 after the reproduction of the recording information at the predetermined recording position.

Next, the recording medium 10 is forced to move (in the "y" direction of FIG. 3 ) in order to reach another predetermined recording position of the signal beam 12a relative to the recording medium 10 . Then, follow the previous procedure for the next reproduction. Reproduction can be performed sequentially in this way.

<Second Embodiment>

Fig. 9 shows another modified example of this embodiment. The incident beam processing region R includes a diffractive beam processing region R2 disposed on the opposite side of the incident surface in the recording medium 10, and a zero-order beam scattering region SC disposed inside the recording medium 10 along the track. The zero-order beam scattering region SC functions to separate the zero-order beam of incident light from its diffracted beam and return a part of the beam to another zero-order beam processing region R1 inside the recording medium 10 . The zero-order beam scattering region SC scatters the zero-order beam of the signal beam 12a. The track-shaped zero-order beam scattering region SC extending in the “y” direction sends the zero-order beam of the signal beam 12 a back into the recording medium 10 . Holographic recording is performed by means of interference fringes formed by scattered zero-order beams, incident zero-order beams, incident diffracted beams and reflected diffracted beams.

In other words, the incident beam processing region R of the recording medium 10 includes a zero-order beam scattering region SC that scatters the zero-order beam (i.e., the hologram reference beam) of the signal beam 12a, and scatters the diffracted beam (i.e., the hologram signal beam) The reflected diffracted beam processes region R2. The zero-order beam scattering region SC continues to extend toward the "y" direction in FIG. 9 like a track. A plurality of zero-order beam scattering regions SC may be intermittently provided in a linear form. In this case, the zero-order beam scattering area SC can store position information of the zero-order beam processing area R1 in the recording medium 10 .

A process of recording a refractive index grating in a recording medium using the signal beam 12a (ie, the hologram reference beam and the hologram signal beam) is described below.

Since the recording medium 10 is irradiated with the signal beam 12a, the hologram reference beam and the hologram signal beam optically interfere with each other to generate an optical interference fringe pattern P1, thereby recording the refractive index grating P1 in the recording medium 10 due to the photorefractive effect.

The zero-order beam (ie, the hologram reference beam) of the signal beam 12a is scattered back to the recording medium 10 by the zero-order beam scattering region SC of the incident beam processing region R. This scattered zero-order beam of the signal beam 12a is therefore referred to as "scattered hologram reference beam". The diffracted beam of the signal beam 12a (ie, the hologram signal beam) is reflected back by the diffracted beam processing region R2 of the incident beam processing region R to be incident on the recording medium 10 as the reflected hologram signal beam.

The hologram signal beam and the hologram reference beam reflected by the signal beam 12a optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P2, thereby recording corresponding optical interference fringes in the recording medium 10 due to the photorefractive effect. Refractive index grating P2 of pattern P2.

The scattered hologram reference beam and hologram signal beam of the signal beam 12a optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P3, thereby recording a refractive index grating P3 in the recording medium 10 due to the photorefractive effect.

The scattered hologram reference beam and the reflected hologram signal beam of the signal beam 12a optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P4, thereby recording a refractive index grating P4 in the recording medium 10 due to the photorefractive effect. .

Therefore, in the embodiment shown in FIG. 9, the refractive index gratings P1, P2 corresponding to the optical interference fringe patterns P1, P2, P3 and P4 are recorded holographically at least in the recording medium 10 due to the photorefractive effect, P3 and P4.

The process of reproducing the refractive index grating in the recording medium using the signal beam 12a (ie, the hologram reference beam) is described below.

During reproduction, the signal beam 12a is not spatially modulated because the spatial light modulator SLM exhibits a transparent pattern. Therefore, there is no diffracted beam due to spatial modulation, so that the signal beam 12a includes only the zero-order beam.

The recording medium 10 is irradiated with a signal beam 12a (without spatial modulation, ie, a hologram reference beam) under the same positional and angular conditions as the signal beam used in recording. At this time, the refractive index gratings P1 and P2 in the recording medium 10 are irradiated with the signal beam 12a, so first reproduction waves are emitted from the refractive index grating P1 and second reproduction waves are emitted from the refractive index grating P2, respectively, corresponding to the recording information. Next, the signal beam 12a (ie, the hologram reference beam) is scattered back to the recording medium 10 by the zero-order beam scattering region SC of the incident beam processing region R, and becomes a scattered hologram reference beam. Since the refractive index grating P3 and the refractive index grating P4 in the recording medium 10 are irradiated with the scattered hologram reference beam, the third reproduction wave is emitted from the refractive index grating P3 corresponding to the recording information, and the fourth reproduction wave is emitted from the refractive index grating P4. Wave.

The scattered hologram reference beam is emitted from the incident surface of the recording medium 10 , and a part of the beam passes through the condenser lens 160 . However, the scattered hologram reference beam is hardly received by the photodetector 20 due to scattering. This phenomenon contributes to simplified reproduction of recorded information.

The first and third reproduced waves originating from the diffracted beam components are reflected back to the recording medium 10 by the diffracted beam processing region R2 of the incident beam processing region R, emerge from the incident surface of the recording medium 10, and pass through the condensing lens 160. The second and fourth reproduced waves originate from the diffracted beam components reflected by the diffracted beam processing region R2 during recording, exit the incident surface of the recording medium 10, and pass through the condensing lens 160. In this manner, at least the first, second, third and fourth reproduced waves are emitted from the incident surface of the recording medium 10 and pass through the condensing lens 160 . The subsequent processes are performed in the same manner as in the embodiment in FIG. 3 .

<Third Embodiment>

Fig. 10 shows a further modified example of this embodiment. The incident beam processing region includes a diffractive beam processing region R2 disposed on the opposite side of the incident surface in the recording medium 10, and a zero-order beam deflecting region RL disposed inside the recording medium 10 along the track. The zero-order beam deflecting region RL has an inclined reflective surface for deflecting the zero-order beam of the signal beam 12a inward with respect to the optical axis of the signal beam 12a. The zero-order beam deflection region RL acts as another zero-order beam processing region R1 , that is, to separate the zero-order beam of the incident light from the diffracted beam, and return a part of the beam to the inside of the recording medium 10 . The track-shaped zero-order beam deflection region RL extending in the “y” direction returns the zero-order beam of the signal beam 12 a to the recording medium 10 with deflection toward the track side. Holographic recording is performed by means of interference fringes formed by deflected zero-order beams, incident zero-order beams, incident diffracted beams, and reflected diffracted beams. According to the two modified embodiments described above, since both the signal beam and the diffracted beam are returned to the inside of the recording medium 10, the amount of irradiation light can be effectively used.

In other words, the incident beam processing region R of the recording medium 10 includes a zero-order beam deflecting region RL that deflects the zero-order beam (i.e., the hologram reference beam) of the signal beam 12a, and deflects the diffracted beam (i.e., the hologram signal beam) The reflected diffracted beam processes region R2. The zero-order beam deflection region RL continues like a track in the "y" direction of FIG. 10 . A plurality of zero-order beam deflection regions RL may be intermittently provided in a linear form. In this case, the zero-order beam deflecting area RL can save positional information of the zero-order beam processing area R1 in the recording medium 10 .

A process of recording a refractive index grating in a recording medium using the signal beam 12a (ie, the hologram reference beam and the hologram signal beam) is described below.

Since the recording medium 10 is irradiated with the signal beam 12a, the hologram reference beam and the hologram signal beam optically interfere with each other to generate an optical interference fringe pattern P1, thereby recording the refractive index grating P1 in the recording medium 10 due to the photorefractive effect.

The zero-order beam (ie, the hologram reference beam) of the signal beam 12a is deflected by the zero-order beam deflection region RL of the incident beam processing region R and reflected back to the recording medium 10 . This deflected and reflected zero-order beam of the signal beam 12a is therefore referred to as a "deflected hologram reference beam". The diffracted beam of the signal beam 12 a (ie, the hologram signal beam) is reflected back by the diffracted beam processing region R2 of the incident beam processing region R, and enters the recording medium 10 .

The hologram signal beam and the hologram reference beam reflected by the signal beam 12a optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P2, thereby recording the corresponding optical interference fringe pattern P2 in the recording medium 10 due to the photorefractive effect. P2 Refractive index grating P2.

The deflected hologram reference beam and hologram signal beam of the signal beam 12a optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P3, thereby recording a refractive index grating P3 in the recording medium 10 due to the photorefractive effect.

The deflected hologram reference beam and the reflected hologram signal beam of the signal beam 12a optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P4, thereby recording a refractive index grating P4 in the recording medium 10 due to the photorefractive effect. .

Therefore, in the embodiment shown in FIG. 10, due to the photorefractive effect, the refractive index gratings P1, P2 corresponding to the optical interference fringe patterns P1, P2, P3 and P4 are recorded holographically at least in the recording medium 10. , P3 and P4.

The process of reproducing the refractive index grating in the recording medium using the signal beam 12a (ie, the hologram reference beam) is described below.

During reproduction, the signal beam 12a is not spatially modulated because the spatial light modulator SLM exhibits a transparent pattern. Therefore, there is no diffracted beam due to spatial modulation, so that the signal beam 12a includes only the zero-order beam.

The recording medium 10 is irradiated with a signal beam 12a (without spatial modulation, ie, a hologram reference beam) under the same positional and angular conditions as the signal beam used in recording. At this time, the refractive index gratings P1 and P2 in the recording medium 10 are irradiated with the signal beam, so that first reproduction waves are emitted from the refractive index grating P1 and second reproduction waves are emitted from the refractive index grating P2, respectively. Next, the signal beam 12a (that is, the hologram reference beam) is deflected and reflected back to the recording medium 10 through the zero-order beam deflection zone RL of the incident beam processing zone R to become a deflected hologram reference beam. Since the refractive index grating P3 and the refractive index grating P4 in the recording medium 10 are irradiated with the deflected hologram reference beam, the third reproduction wave is emitted from the refractive index grating P3 corresponding to the recording information, and the fourth reproduction wave is emitted from the refractive index grating P4. Wave.

The deflected hologram reference beam is emitted from the incident surface of the recording medium 10 , and a part of the beam passes through the condenser lens 160 . Alternatively, a structure that prevents the light beam from returning to the condensing lens 160 may be provided by changing the shape of the inclination angle of the zero-order beam deflecting region RL. Even if a part of the light beam returns to the condensing lens 160, it is difficult to be received by the photodetector 20 because of deflection. This phenomenon contributes to simplified reproduction of recorded information.

The first and third reproduced waves originating from the diffracted beam components are reflected back to the recording medium 10 by the diffracted beam processing region R2 of the incident beam processing region R, emerge from the incident surface of the recording medium 10, and pass through the condensing lens 160. The second and fourth reproduced waves originate from the diffracted beam components reflected by the diffracted beam processing region R2 during recording, which exit from the incident surface of the recording medium 10 and pass through the condensing lens 160 . In this manner, at least the first, second, third and fourth reproduced waves are emitted from the incident surface of the recording medium 10 and pass through the condensing lens 160 . The subsequent processes are performed in the same manner as in the embodiment in FIG. 3 .

According to the above-mentioned two adjacent improved embodiments, since the zero-order beam of the signal beam 12a returns to the inside of the recording medium 10 through the incident beam processing area R, the amount of irradiated light can be effectively utilized. In addition, these structures contribute to Simplifies reproduction of recorded information.

<Fourth Embodiment>

In the above embodiments, holographic recording and reproduction in a reflective form is described in which the diffractive beam processing region R2 of the incident beam processing region R reflects the beam, but the transparent diffractive beam processing region R2 having the same effect can also be utilized in the present invention.

Figure 11 shows a holographic recording and reproducing device according to another embodiment, which utilizes a recording medium having a zero-order beam processing region R1 and a diffracted beam processing region R2 through which the beam can pass, i.e. the entire incident beam processing region R is transparent. The holographic recording and reproducing apparatus of this embodiment is the same as that shown in FIG. 1 except that the optical system consisting of beam splitter 13, mirrors 18 and 19 for generating a reference beam is removed. The zero-order beam processing region R1 can be adapted for a track extending continuously in the "y" direction of FIG. 11 for a tracking servo system. The zero-order beam processing region R1 can be provided by the following processing structure, that is, by making the transmittance (or reflectance or absorption coefficient) of the zero-order beam processing region R1 and the diffracted beam processing region R2 different, so that the zero-order beam and Diffracted beams are separated.

In recording, as shown in FIGS. 11 and 12, the zero-order beam and the diffracted beam of the signal beam 12a from the spatial light modulator SLM interfere with each other in the recording medium 10, generating a three-dimensional interference pattern.

Since the recording medium 10 is irradiated with the signal beam 12a, the hologram reference beam and the hologram signal beam optically interfere with each other to generate an optical interference fringe pattern P1, thereby recording a refractive index grating P1 in the recording medium 10 due to the photorefractive effect, as Figure 13 shows.

The zero-order beam of the signal beam 12a (i.e., the hologram reference beam) passes through the zero-order beam processing region R1 of the incident beam processing region R, and the diffracted beam of the signal beam 12a (i.e., the hologram signal beam) passes through the incident beam processing region R. The diffracted beam of zone R processes zone R2.

In the reproduction process, as shown in FIG. 14, under the condition that the spatial light modulator SLM displays a transparent pattern, the signal beam 12a is not spatially modulated, so the signal beam 12a only includes the zero-order beam (ie, the hologram reference beam). The recording medium 10 is irradiated with the hologram reference beam under the same positional and angular conditions as the signal beam used in recording. At this time, the refractive index grating P1 in the recording medium 10 is irradiated with the signal beam, so the first reproduction wave is emitted from the refractive index grating P1 corresponding to the recording information. Since the signal beam 12a is only a zero-order beam, the signal beam 12a exits from the opposite side of the incident surface of the recording medium 10 where the beam enters, and passes through the condensing lens 16a. The first reproduced wave also exits from the side opposite to the incident surface of the recording medium 10, and passes through the condensing lens 16a. Therefore, the first reproduced wave exits from the side opposite to the incident surface of the recording medium 10 at least during reproduction, and passes through the condensing lens 16a. The first reproduced wave contributes to forming image information corresponding to recording information on the photodetector 20 . The photoreceptor of the CCD 20 then receives the image information and restores it to an electronic digital data signal. Then, the digital data signal is sent to a decoder 26 to reproduce the original data.

In the embodiment shown in FIG. 11, it is preferable that the recording medium 10 is made of a photosensitive material having a property that the optical interference fringe pattern P1 emits a large amount of light of the first reproduced wave, so as to improve the reproduction efficiency. Accuracy of recorded information. This is because the photoreceptor also receives the signal beam 12a at the same time.

<Fifth Embodiment>

Fig. 15 shows yet another modified example of this embodiment. This embodiment includes a zero-order beam scattering region SC disposed along the track ("y" direction) on the opposite side of the incident surface in the recording medium 10 for scattering only the zero-order beam of the signal beam 12a. The zero-order beam scattering region SC functions as the zero-order beam processing region R1 , ie, separates the zero-order beam of incident light from its diffracted beam and returns a part of the beam to the inside of the recording medium 10 . The track-shaped zero-order beam scattering region SC extending in the “y” direction scatters the zero-order beam of the signal beam 12 a back into the recording medium 10 . The holographic recording is carried out by using the incident zero-order beam, the interference fringes formed by the incident diffracted beam and the scattered zero-order beam.

In other words, the incident beam processing region R of the recording medium 10 includes a zero-order beam scattering region SC that scatters the zero-order beam (i.e., the hologram reference beam) of the signal beam 12a, and allows the diffracted beam (i.e., the hologram signal beam) Diffraction beam passing through processing region R2. The zero-order beam scattering region SC continues to extend in the "y" direction of FIG. 15 like a track. A plurality of zero-order beam scattering regions SC may be intermittently provided in a linear form. In this case, the zero-order beam scattering area SC can store position information of the zero-order beam processing area R1 in the recording medium 10 .

A process of recording a refractive index grating in a recording medium using the signal beam 12a (ie, the hologram reference beam and the hologram signal beam) is described below.

Since the recording medium 10 is irradiated with the signal beam 12a, the hologram reference beam and the hologram signal beam optically interfere with each other to generate an optical interference fringe pattern P1, thereby recording a refractive index grating P1 in the recording medium 10 due to a photorefractive effect.

The zero-order beam (ie, the hologram reference beam) of the signal beam 12a is scattered back to the recording medium 10 by the zero-order beam scattering region SC of the incident beam processing region R, and becomes a scattered hologram reference beam. The diffracted beam of the signal beam 12a (ie, the hologram signal beam) passes through the diffracted beam processing region R2 of the incident beam processing region R, and emerges from the recording medium 10 on the opposite side of the incident surface on which the beam enters.

The hologram signal beam and the hologram reference beam scattered by the signal beam 12a optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P2, thereby recording the corresponding optical interference fringe pattern P2 in the recording medium 10 due to the photorefractive effect. P2 Refractive index grating P2.

Therefore, in the embodiment shown in FIG. 15, at least the refractive index gratings P1 and P2 corresponding to the optical interference fringe patterns P1 and P2 are holographically recorded in the recording medium 10 due to the photorefractive effect.

The process of reproducing the refractive index grating in the recording medium using the signal beam 12a (ie, the hologram reference beam) is described below.

During reproduction, the signal beam 12a is not spatially modulated because the spatial light modulator SLM exhibits a transparent pattern. The signal beam 12a thus comprises only the zero order beam.

The recording medium 10 is irradiated with the signal beam 12a (hologram reference beam) under the same positional and angular conditions as the signal beam used in recording. At this time, the refractive index grating P1 in the recording medium 10 is irradiated with the signal beam, so the first reproduction wave is emitted from the refractive index grating P1 corresponding to the recording information.

The zero-order beam (ie, the hologram reference beam) of the signal beam 12a is scattered back to the recording medium 10 by the zero-order beam scattering region SC of the incident beam processing region R, and becomes a scattered hologram reference beam. The refractive index grating P2 of the recording medium 10 is irradiated with the scattered hologram reference beam, and thus a second reproduced wave is emitted from the refractive index grating P2 corresponding to the recording information.

The first and second reproduced waves pass through the diffractive beam processing region R2 of the incident beam processing region R, exit from the recording medium 10 on the opposite side of the incident surface on which the beam is incident, and pass through the condensing lens 16a. The subsequent processes are performed in the same manner as in the embodiment in FIG. 14 .

Since the scattered hologram reference beam is emitted from the incident surface of the recording medium 10, the scattered hologram reference beam is hardly received by the photodetector 20 due to scattering. This phenomenon contributes to simplified reproduction of recorded information.

<Sixth Embodiment>

Fig. 16 shows another modified example of this embodiment. A zero-order beam reflection region RR that reflects only the zero-order beam of the signal beam 12 a back inside the recording medium 10 is provided along the track on the opposite side of the incident surface in the recording medium 10 . The zero-order beam reflection region RR functions as a zero-order beam processing region R1 , ie, separates the zero-order beam of incident light from its diffracted beam and returns a part of the beam to the inside of the recording medium 10 . The track-shaped zero-order beam reflection region RR extending in the "y" direction makes the zero-order beam of the signal beam 12a return to the track of the recording medium 10 by reflection. Holographic recording is carried out by using zero-order beams, interference fringes formed by diffracted beams and reflected zero-order beams.

In other words, the incident beam processing region R of the recording medium 10 includes a zero-order beam reflection region RR for reflecting the zero-order beam (ie, the hologram reference beam) of the signal beam 12a, and allowing the diffracted beam (ie, the hologram signal beam) to be diffracted. beam) through the diffractive beam processing region R2. The zero-order beam reflection region RR continues to extend toward the “y” direction in FIG. 16 like a track. A plurality of zero-order beam reflection regions RR may be intermittently provided in a linear form. In this case, the zero-order beam reflection region RR can store the position information of the zero-order beam processing region R1 in the recording medium 10 .

A process of recording a refractive index grating in a recording medium using the signal beam 12a (ie, the hologram reference beam and the hologram signal beam) is described below.

Since the recording medium 10 is irradiated with the signal beam 12a, the hologram reference beam and the hologram signal beam optically interfere with each other to generate an optical interference fringe pattern P1, thereby recording a refractive index grating P1 in the recording medium 10 due to a photorefractive effect.

The zero-order beam (ie, the hologram reference beam) of the signal beam 12a is reflected back to the recording medium 10 by the zero-order beam reflection region RR of the incident beam processing region R. This zero-order beam of the signal beam 12a reflected by the zero-order beam reflecting region RR is therefore referred to as a "reflected hologram reference beam". The diffracted beam of the signal beam 12a (ie, the hologram signal beam) passes through the diffracted beam processing region R2 of the incident beam processing region R, and emerges from the recording medium 10 on the opposite side of the incident surface on which the beam enters.

The hologram reference beam and the hologram signal beam reflected by the signal beam 12a optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P2, thereby recording the corresponding optical interference fringe pattern P2 in the recording medium 10 due to the photorefractive effect. P2 Refractive index grating P2.

Therefore, in the embodiment shown in FIG. 16, at least the refractive index gratings P1 and P2 corresponding to the optical interference fringe patterns P1 and P2 are recorded in the recording medium 10 in the form of a hologram due to the photorefractive effect.

The process of reproducing the refractive index grating in the recording medium 10 using the signal beam 12a (ie, the hologram reference beam) is described below.

During reproduction, the signal beam 12a is not spatially modulated. Therefore, there is no diffracted beam due to spatial modulation, so that the signal beam 12a includes only the zero-order beam.

The recording medium 10 is irradiated with the signal beam 12a (hologram reference beam) under the same positional and angular conditions as the signal beam used in recording. At this time, the refractive index grating P1 in the recording medium 10 is irradiated with the signal beam, so the first reproduction wave is emitted from the refractive index grating P1 corresponding to the recording information.

Next, the signal beam 12a (ie, the hologram reference beam) is reflected back to the recording medium 10 through the zero-order beam reflection region RR of the incident beam processing region R, and becomes a reflected hologram reference beam. The refractive index grating P2 of the recording medium 10 is irradiated with the reflected hologram reference beam, and thus a second reproduced wave is emitted from the refractive index grating P2 corresponding to the recording information.

The first and second reproduced waves pass through the diffractive beam processing region R2 of the incident beam processing region R, exit from the recording medium 10 on the opposite side of the incident surface on which the beam is incident, and pass through the condensing lens 16a. The subsequent processes are performed in the same manner as in the embodiment in FIG. 14 .

The reflected hologram reference beam is emitted from the incident surface of the recording medium 10 and cannot reach the condensing lens 16a. This phenomenon contributes to simplified reproduction of recorded information.

<Seventh Embodiment>

Fig. 17 shows yet another modified example of this embodiment. A zero-order beam deflecting region RL for deflecting the zero-order beam of the signal beam 12 a toward the inside of the recording medium 10 is provided along the track on the opposite side of the incident surface of the recording medium 10 . The zero-order beam deflection region RL extending in the "y" direction reflects the zero-order beam of the signal beam 12a back to the recording medium 10 while deflecting the zero-order beam to the track side. Holographic recording is performed using the interference fringes formed by the zero-order beam, the diffracted beam and the deflected zero-order beam. According to these modified examples of the embodiment of the recording and reproducing apparatus, only the zero-order beam of the signal beam returns to the inside of the recording medium 10, so that the amount of irradiated light can be effectively used.

In other words, the incident beam processing region R of the recording medium 10 includes a zero-order beam deflecting region RL that deflects the zero-order beam (i.e., the hologram reference beam) of the signal beam 12a, and allows the diffracted beam (i.e., the hologram signal beam) to be diffracted. ) through the diffracted beam processing region R2. The zero-order beam deflection region RL continues like a track in the "y" direction of FIG. 17 . A plurality of zero-order beam deflection regions RL may be intermittently provided in a linear form. In this case, the zero-order beam deflecting area RL can save positional information of the zero-order beam processing area R1 in the recording medium 10 .

A process of recording a refractive index grating in a recording medium using the signal beam 12a (ie, the hologram reference beam and the hologram signal beam) is described below.

Since the recording medium 10 is irradiated with the signal beam 12a, the hologram reference beam and the hologram signal beam optically interfere with each other to generate an optical interference fringe pattern P1, thereby recording a refractive index grating P1 in the recording medium 10 due to a photorefractive effect.

The zero-order beam (ie, the hologram reference beam) of the signal beam 12a is deflected by the zero-order beam deflection region RL of the incident beam processing region R and reflected back to the recording medium 10, and becomes the deflected hologram reference beam. The diffracted beam of the signal beam 12a (ie, the hologram signal beam) passes through the diffracted beam processing region R2 of the incident beam processing region R, and emerges from the recording medium 10 on the opposite side of the incident surface on which the beam enters.

The deflected hologram reference beam of the signal beam 12a and the hologram reference beam optically interfere with each other in the recording medium 10 to form an optical interference fringe pattern P2, thereby recording the corresponding optical interference fringe pattern P2 in the recording medium 10 due to the photorefractive effect. P2 Refractive index grating P2.

Therefore, in the embodiment shown in FIG. 17, at least the refractive index gratings P1 and P2 corresponding to the optical interference fringe patterns P1 and P2 are recorded in the recording medium 10 in the form of a hologram due to the photorefractive effect.

The process of reproducing the refractive index grating in the recording medium 10 using the signal beam 12a (ie, the hologram reference beam) is described below.

During reproduction, the signal beam 12a is not spatially modulated. Therefore, there is no diffracted beam due to spatial modulation, so that the signal beam 12a includes only the zero-order beam.

The recording medium 10 is irradiated with the signal beam 12a (hologram reference beam) under the same positional and angular conditions as the signal beam used in recording. At this time, the refractive index grating P1 in the recording medium 10 is irradiated with the signal beam, so the first reproduction wave is emitted from the refractive index grating P1 corresponding to the recording information.

Next, the zero-order beam (ie, the hologram reference beam) of the signal beam 12a is deflected back to the recording medium 10 by the zero-order beam deflection zone RL of the incident beam processing zone R, and becomes a deflected hologram reference beam. The refractive index grating P2 of the recording medium 10 is irradiated with the deflected hologram reference beam, and thus a second reproduced wave is emitted from the refractive index grating P2 corresponding to the recording information.

The first and second reproduced waves pass through the diffractive beam processing region R2 of the incident beam processing region R, exit from the recording medium 10 on the opposite side of the incident surface on which the beam is incident, and pass through the condensing lens 16a. The subsequent processes are performed in the same manner as in the embodiment in FIG. 14 .

The deflected hologram reference beam is emitted from the incident surface of the recording medium 10 and cannot reach the condenser lens 16a. This phenomenon contributes to simplified reproduction of recorded information.

According to these improved embodiments described above, since only the zero-order beam of the signal beam 12a returns to the inside of the recording medium 10 through the incident beam processing area R, the amount of irradiated light can be effectively utilized. In addition, these structures contribute to simplifying recording. information reproduction.

<Eighth Embodiment>

In the above embodiments, holographic recording and reproduction in which the incident beam processing region R is integrally provided in the recording medium 10 is described, but the incident beam processing region R may also be provided to a device having the same advantageous effects as the present invention.

FIG. 18 shows a hologram recording and reproducing apparatus using another recording medium according to another embodiment. The holographic recording and reproducing device includes an incident beam processing region R placed on or adjacent to the recording medium 10 and on the opposite side of the incident surface where the signal beam is incident. The incident beam processing region R separates the zero-order beam and the diffracted beam from each other to return a part of the incident beam to the inside of the recording medium. The incident beam processing region R includes a zero-order beam processing region R1 passing the zero-order beam among the signal beams 12a, and a diffraction beam processing region R2 reflecting the diffracted beam among the signal beams 12a. As long as the processing function of the zero-order beam processing region R1 is different from that of the diffracted beam processing region R2, the zero-order beam processing region R1 may have the function of absorbing the zero-order beam. The zero-order beam processing region R1 may have light transmission or light absorption. The hologram recording and reproducing device shown in FIG. 18 is the same as the device shown in FIG. 3 except that the incident beam processing region R is placed in the device adjacent to the recording medium 10 .

As shown in FIG. 19, in this device, the incident beam processing region R is placed on the opposite side of the incident surface of the recording medium 10, and has a zero beam as a window for passing the zero-order beam in the signal beam 12a. Class beam processing area R1. The recording medium 10 is configured to be movable so as to be movable in the "y" direction in the figure relative to the window of the zero-order beam processing region R1. The recording medium 10 is movably arranged so as to move along a direction D _TR which forms a predetermined angle θ (θ≠0) with an extending direction D _SLM of a row or a column of the pixel matrix of the spatial light modulator SLM.

As shown in FIG. 20, the diffracted beam becomes the highest frequency component of the signal beam 12a modulated by the spatial light modulator SLM based on its pixel matrix (pitch "a"). The signal beam 12a undergoes Fourier transform through the condenser lens 160, and then according to the spatial modulation by the spatial light modulator SLM, a spectral distribution of the light intensity with respect to the spatial frequency appears in the Fourier plane FF, as shown in FIG. 20 .

In this embodiment, except that the incident beam processing region R and the recording medium 10 can move relative to each other, the recording and reproducing process of the hologram is the same as that of the device shown in FIG. 3 .

<Ninth Embodiment>

Furthermore, Fig. 21 shows yet another modified embodiment. Instead of the transparent portion of the zero-order beam processing region, a zero-order beam scattering region SC is provided in the incident beam processing region R on the side opposite to the incident surface of the recording medium 10 . Holographic recording is carried out by means of zero-order beams, diffracted beams, interference fringes formed by scattered zero-order beams and reflected diffracted beams.

<Tenth Embodiment>

Fig. 22 shows a further modified example of this embodiment. A zero-order beam deflecting region RL is provided in the incident beam processing region R on the opposite side of the incident face or adjacent to the opposite side. The zero-order beam deflection region RL has an inclined reflective surface that deflects the zero-order beam of the signal beam 12a inwardly with respect to the optical axis of the signal beam 12a. The zero-order beam deflection region RL functions as another zero-order beam processing region R1 , ie, separates the zero-order beam of incident light from the diffracted beam and returns a part of the beam to the inside of the recording medium 10 . Holographic recording is performed by means of interference fringes formed by zero-order beams, diffracted beams, deflected zero-order beams and reflected diffracted beams.

<Eleventh Implementation Plan>

FIG. 23 shows another holographic recording and reproducing apparatus using a transparent diffracted beam processing region R2 through which a beam can pass in the incident beam processing region R according to still another embodiment. The holographic recording and reproducing apparatus is the same as that shown in FIG. 1 except that the incident beam processing region R is added and the optical system for generating the reference beam consisting of beam splitter 13, mirrors 18 and 19 is removed. Furthermore, the incident beam processing region R includes a zero-order beam scattering region SC for scattering the zero-order beam, and a transparent portion T (diffraction beam processing region R2 ) that allows the diffracted beam to pass therethrough.

As shown in FIG. 24, on the opposite side of the incident surface of the recording medium 10 in this device, a zero-order beam scattering area SC is provided inside the incident beam processing area R, so that the incident beam processing area R can dissipate the zero-order beam of the incident light. The diffracted beam is separated from it, and a part of the beam is returned to the inside of the recording medium 10 . The zero-order beam scattering region SC scatters only the zero-order beam of the signal beam 12a. The track-shaped zero-order beam scattering region SC extending in the “y” direction scatters the zero-order beam of the signal beam 12 a back into the recording medium 10 . Holographic recording is performed by means of interference fringes formed by zero-order beams that generate optical interference fringe patterns, diffracted beams, scattered zero-order beams, and reflected diffracted beams, thereby recording refraction in the recording medium 10 due to the photorefractive effect rate raster. In reproduction, in the same manner as in recording, the recording medium 10 is fixed in the apparatus, and the recording medium 10 is irradiated with a converged reference beam 12 . When the reference beam 12 passes through the recording medium 10 , then reproduced waves are output from the refractive index grating of the recording medium 10 . When the reference beam 12 is incident, then a reproduction beam for reproducing the recorded optical interference pattern appears on the opposite side of the recording medium 10 . The reproduced wave is guided to the inverse Fourier transform lens 16a and inverse Fourier transform is performed, thereby reproducing the light spot pattern signal. The light spot pattern signal is received by a photodetector 20 such as a charge-coupled device (CCD) placed at the focal position, and converted into an electrical digital data signal. This digital data signal is then sent to a decoder to reproduce the original data.

<Twelfth Embodiment>

Figure 25 shows a part of yet another modified embodiment. This holographic recording and reproducing device is the same as the device shown in FIG. 23 except that a zero-order beam reflection region RR that internally reflects only the zero-order beam of the signal beam 12a and a transparent portion that allows the diffracted beam to pass are provided in the device. T (diffraction beam processing region R2).

In other words, the incident beam processing region R adjacent to the recording medium 10 includes the zero-order beam reflection region RR for reflecting the zero-order beam (ie, the hologram reference beam) of the signal beam 12a and allowing the diffracted beam (ie, the hologram reference beam) to be diffracted. Figure signal beam) through the diffracted beam processing region R2.

<Thirteenth Embodiment>

Figure 26 shows a part of another modified embodiment. This holographic recording and reproducing device is the same as the device shown in FIG. 23 except that a zero-order beam deflection region RL that internally reflects only the zero-order beam of the signal beam 12a and a transparent portion that allows the diffracted beam to pass are provided in the device. T (diffraction beam processing region R2). The zero-order beam deflection area RL of the incident beam processing area extending along the "y" direction in the figure deflects the zero-order beam toward one side of the track inside the recording medium 10, thereby by virtue of the zero-order beam, the diffracted beam and the deflected The interference fringes formed by the zero-order beam are used for holographic recording. The zero-order beam deflection region RL has a reflective surface inclined relative to the optical axis of the signal beam 12a for deflecting the zero-order beam of the signal beam 12a inwardly. The zero-order beam deflection region RL functions as another zero-order beam processing region R1 , ie, separates the zero-order beam of incident light from the diffracted beam and returns a part of the beam to the inside of the recording medium 10 . The track-shaped zero-order beam deflection region RL extending in the "y" direction returns the zero-order beam of the signal beam 12a to the recording medium 10, and deflects it toward the track side. Holographic recording is performed by means of interference fringes formed by zero-order beams, diffracted beams, deflected zero-order beams and reflected diffracted beams.

These modified embodiments have a structure in which only the zero-order beam of the signal beam is returned to the inside of the recording medium 10, so that the amount of irradiated light can be effectively used. The incident beam processing area has the function of separating the incident beam to return a part of it to the inside of the recording medium, thereby separately processing the zero-order beam and the diffracted beam in the incident light by different processes. Thus the incident beam processing region may have: a zero order beam processing region which allows the zero order beam to pass through or absorbs the zero order beam; and a diffracted beam reflecting region which reflects or deflects or scatters the diffracted beam. Alternatively, the incident beam processing region may have a zero-order beam processing region that reflects or scatters or deflects or absorbs the zero-order beam; and a diffracted beam reflection region that reflects or deflects the diffracted beam.

<Fourteenth Embodiment>

FIG. 27 shows a part of still another modified embodiment in which an incident beam processing region R is separately provided at a position adjacent to the recording medium 10 compared with the apparatus shown in FIG. 18 . As shown in FIG. 27, the incident beam processing region R and the condensing lens 160 may be integrally fixed on the support frame _RSU to face each other so that the recording medium 10 can be inserted therebetween.

<Fifteenth Embodiment>

Also, according to still another embodiment of the present invention, a disc-shaped or card-shaped recording medium 10 may be provided. For example, a magnetic disk cartridge CR shown in FIG. 28 houses a magnetic disk of a rotatable recording medium 10 . The disk case CR has an incident beam processing region R on its inner side wall, and has an opening for accessing the recording medium disk with the beam.

<Sixteenth Embodiment>

In addition to the above-described embodiments of the hologram recording and reproducing method and apparatus thereof, the present invention obviously includes a hologram recording method, reproducing method, recording apparatus and reproducing apparatus. In the above-described embodiments, the laser beam is spatially modulated according to two-dimensional data, in other words, two-dimensional modulation is utilized. However, the present invention is also applicable to a holographic recording and reproducing method and apparatus for spatially modulating a laser beam according to one-dimensional data. In the above embodiments, the photorefractive material is used for the photosensitive material of the recording medium, but a photosensitive material such as a hole-burning material, a photochromic material, etc. may also be used for the photosensitive material of the recording medium.

Claims (86)

1. method that is used for holographic recording and reproduction, this method comprises recording process and reproduction process,

This recording process comprises step:

According to information to be recorded,, produce signal beams by spatial modulation coherent reference light beam;

Recording medium with this signal beams irradiation is made by photochromics passes described recording medium to allow this signal beams; And

Part in that the zero order beam that is arranged in this signal beams and diffracted beam interfere each other in described recording medium inside produces the diffraction grating zone by the light interference pattern record; And

The reproduction process may further comprise the steps:

Shine described diffraction grating zone with described reference beam, to produce reproduction ripple corresponding to this signal beams.

2. according to the method that is used for holographic recording and reproduction of claim 1, further comprise an incident beam treatment region, it is arranged in the described recording medium, be positioned on the opposite side of the plane of incidence that described signal beams incides described recording medium, this incident beam treatment region is separated from each other this zero order beam and this diffracted beam, so that this incident beam of a part is turned back to described recording medium inside.

3. according to the method that is used for holographic recording and reproduction of claim 2, further be included in the linear track that forms in the part of described incident beam treatment region.

4. according to the method that is used for holographic recording and reproduction of claim 3, wherein said track has the locating information of described incident beam treatment region with respect to described recording medium.

5. according to the method that is used for holographic recording and reproduction of claim 2, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

6. according to the method that is used for holographic recording and reproduction of claim 2, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits the zero order beam treatment region and allows this diffracted beam to pass.

7. according to the method that is used for holographic recording and reproduction of claim 2, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

8. according to the method that is used for holographic recording and reproduction of each claim in the claim 5 to 7, further comprise spatial light modulator, this spatial light modulator comprises the row and column matrix of pixel, with the described reference beam of spatial modulation, wherein, described spatial light modulator and described recording medium are set relatively according to making the diffracted beam of described signal beams can not shine the mode of described zero order beam treatment region.

9. the method that is used for holographic recording and reproduction according to Claim 8, described spatial light modulator and described recording medium relatively are provided with respect to the optical axis of described signal beams, that is, make θ (θ ≠ 0) angle that bearing of trend and a bearing of trend of described zero order beam treatment region of the delegation of described spatial light modulator or row become to be scheduled to.

10. according to the method that is used for holographic recording and reproduction of claim 6, wherein in described reproduction process, the opposite side that incides the plane of incidence of described recording medium from signal beams is exported described reproduction ripple.

11. a method that is used for holographic recording comprises step:

According to information to be recorded,, produce signal beams by spatial modulation coherent reference light beam;

The recording medium that utilizes this signal beams irradiation to be made by photochromics passes described recording medium to allow signal beams; And

Part in that the zero order beam that is arranged in this signal beams and diffracted beam interfere each other in described recording medium inside produces the diffraction grating zone by the light interference pattern record.

12. the method that is used for recorded hologram according to claim 11, further comprise an incident beam treatment region, it is arranged in the described recording medium, be positioned on the opposite side of the plane of incidence that described signal beams incides described recording medium, this incident beam treatment region is separated from each other this zero order beam and this diffracted beam, so that this incident beam of a part is turned back to described recording medium inside.

13., further be included in the linear track that forms in the part of described incident beam treatment region according to the method that is used for recorded hologram of claim 12.

14. according to the method that is used for recorded hologram of claim 13, wherein said track has the locating information of described incident beam treatment region with respect to described recording medium.

15. the method that is used for recorded hologram according to claim 12, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

16. the method that is used for recorded hologram according to claim 12, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and allows this diffracted beam to pass.

17. the method that is used for recorded hologram according to claim 12, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing this zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

18. the method that is used for recorded hologram according to each claim in the claim 15 to 17, further comprise spatial light modulator, this spatial light modulator comprises the row and column matrix of pixel, with the described reference beam of spatial modulation, wherein, described spatial light modulator and described recording medium are set relatively according to making the diffracted beam of described signal beams can not shine the mode of described zero order beam treatment region.

19. the method that is used for recorded hologram according to claim 18, described spatial light modulator and described recording medium relatively are provided with respect to the optical axis of described signal beams, that is, make θ (θ ≠ 0) angle that bearing of trend and a bearing of trend of described zero order beam treatment region of the delegation of described spatial light modulator or row become to be scheduled to.

20. a method that is used for the reconstruction of hologram may further comprise the steps:

The recording medium of being made by photochromics is provided, and it has the diffraction grating zone that forms by recording process, and this recording process comprises step: according to information to be recorded, produce signal beams by spatial modulation coherent reference light beam; Utilize this signal beams to shine this recording medium, to allow this signal beams to pass described recording medium, so that the part in that the zero order beam that is arranged in this signal beams and diffracted beam interfere each other in described recording medium inside forms this diffraction grating zone by the light interference pattern record; And

The coherent reference light beam is shone this diffraction grating zone, to produce reproduction ripple corresponding to this signal beams.

21. the method that is used for reconstructing hologram according to claim 20, further comprise an incident beam treatment region, it is arranged in the described recording medium, be positioned on the opposite side of the plane of incidence that described signal beams incides described recording medium, this incident beam treatment region is separated from each other this zero order beam and this diffracted beam, a part of incident beam is turned back to described recording medium inside.

22., further be included in the linear track that forms in the part of described incident beam treatment region according to the method that is used for reconstructing hologram of claim 21.

23. according to the method that is used for reconstructing hologram of claim 22, wherein said track has the locating information of described incident beam treatment region with respect to described recording medium.

24. the method that is used for reconstructing hologram according to claim 21, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

25. the method that is used for reconstructing hologram according to claim 21, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and allows this diffracted beam to pass.

26. the method that is used for reconstructing hologram according to claim 21, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing this zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

27. the method that is used for reconstructing hologram according to each claim in the claim 24 to 26, wherein comprise that by utilization the spatial light modulator of the row and column matrix of pixel writes down the diffraction grating zone of this recording medium in the following manner, promptly, make described spatial light modulator and described recording medium relatively be provided with, thereby the diffracted beam of described signal beams can not shine described zero order beam treatment region.

28. the method that is used for reconstructing hologram according to claim 27, described spatial light modulator and described recording medium relatively are provided with respect to the optical axis of described signal beams, that is, make θ (θ ≠ 0) angle that bearing of trend and a bearing of trend of described zero order beam treatment region of the delegation of described spatial light modulator or row become to be scheduled to.

29. according to the method that is used for reconstructing hologram of claim 25, wherein in the reproduction process, the opposite side that incides the plane of incidence of described recording medium from described signal beams is exported described reproduction ripple.

30. holographic recording and transcriber are used for information is recorded as the diffraction grating zone of recording medium, and are used for reproducing described recorded information from described diffraction grating zone, described holographic recording and transcriber comprise:

Retaining part is used for removably keeping the recording medium of being made by photochromics;

Light source is used to produce the coherent reference light beam;

The signal beams generation unit comprises spatial light modulator, and described spatial light modulator is modulated described reference beam according to described information space to be recorded, to produce signal beams;

Interference unit, comprise illuminating optical system, be used to utilize this signal beams to shine described recording medium, to allow this signal beams to enter and pass described recording medium, described illuminating optical system, the part that interferes each other in described recording medium inside at the zero order beam that is arranged in this signal beams and diffracted beam, form the diffraction grating zone according to light interference pattern, described illuminating optical system utilizes described reference beam to shine described diffraction grating zone, to produce the reproduction ripple corresponding to this signal beams; And

Detecting unit is used for detecting the described recorded information that is formed in an image by this reproduction waveform.

31. holographic recording and transcriber according to claim 30, further comprise an incident beam treatment region, be arranged in the described recording medium, be positioned on the opposite side of the plane of incidence that described signal beams incides described recording medium, this incident beam treatment region is separated from each other this zero order beam and this diffracted beam, a part of incident beam is turned back to described recording medium inside.

32., further be included in the linear track that forms in the part of described incident beam treatment region according to the holographic recording and the transcriber of claim 31.

33. according to the holographic recording and the transcriber of claim 32, wherein said track has the locating information of described incident beam treatment region with respect to described recording medium.

34. holographic recording and transcriber according to claim 31, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

35. holographic recording and transcriber according to claim 31, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and allows this diffracted beam to pass.

36. holographic recording and transcriber according to claim 31, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing this zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

37. holographic recording and transcriber according to each claim in the claim 34 to 36, further comprise spatial light modulator, this spatial light modulator comprises the row and column matrix of pixel, with the described reference beam of spatial modulation, wherein, described spatial light modulator and described recording medium are set relatively according to making the diffracted beam of described signal beams can not shine the mode of described zero order beam treatment region.

38. holographic recording and transcriber according to claim 37, described spatial light modulator and described recording medium relatively are provided with respect to the optical axis of described signal beams, that is, make θ (θ ≠ 0) angle that bearing of trend and a bearing of trend of described zero order beam treatment region of the delegation of described spatial light modulator or row become to be scheduled to.

39. according to the holographic recording and the transcriber of claim 35, the opposite side that incides the plane of incidence of described recording medium from described signal beams is exported described reproduction ripple.

40. holographic recording and transcriber according to claim 34 or 36 further comprise separative element, and the described reproduction ripple and the light path of described reference beam are separated.

41. a hologram recording apparatus is used for information is recorded as the diffraction grating zone of recording medium, comprising:

Retaining part is used for removably keeping the recording medium of being made by photochromics;

Light source is used to produce the coherent reference light beam;

The signal beams generation unit comprises spatial light modulator, and described spatial light modulator is according to described information to be recorded, and the described reference beam of spatial modulation is to produce signal beams; And

Interference unit, comprise illuminating optical system, be used to utilize this signal beams to shine described recording medium, to allow this signal beams to enter and pass described recording medium, described illuminating optical system, part in that the zero order beam that is arranged in signal beams and diffracted beam interfere each other in described recording medium inside forms the diffraction grating zone according to light interference pattern.

42. hologram recording apparatus according to claim 41, wherein said recording medium comprises an incident beam treatment region, it is arranged in the described recording medium, be positioned on the opposite side of the plane of incidence that described signal beams incides described recording medium, this incident beam treatment region is separated from each other this zero order beam and this diffracted beam, a part of incident beam is turned back to described recording medium inside.

43., further be included in the linear track that forms in the part of described incident beam treatment region according to the hologram recording apparatus of claim 42.

44. according to the hologram recording apparatus of claim 43, wherein said track has the locating information of described incident beam treatment region with respect to described recording medium.

45. hologram recording apparatus according to claim 42, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

46. hologram recording apparatus according to claim 42, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and allows this diffracted beam to pass.

47. hologram recording apparatus according to claim 42, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing this zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

48. hologram recording apparatus according to each claim in the claim 45 to 47, further comprise spatial light modulator, this spatial light modulator comprises the row and column matrix of pixel, with the spatial modulation reference beam, wherein, described spatial light modulator and described recording medium are set relatively according to making the diffracted beam of described signal beams can not shine the mode of described zero order beam treatment region.

49. hologram recording apparatus according to claim 48, described spatial light modulator and described recording medium relatively are provided with respect to the optical axis of described signal beams, that is, make θ (θ ≠ 0) angle that bearing of trend and a bearing of trend of described zero order beam treatment region of the delegation of described spatial light modulator or row become to be scheduled to.

50. a hologram reproduction apparatus is used for reproducing the information that writes down as recording medium diffraction grating zone, this hologram reproduction apparatus comprises:

Retaining part is used for removably keeping the recording medium of being made by photochromics;

Light source is used to produce the coherent reference light beam;

Illumination unit comprises illuminating optical system, is used to utilize this reference beam to shine this recording medium, enters and pass diffraction grating zone in this recording medium to allow this reference beam, to produce the reproduction ripple corresponding to this signal beams; And

Detecting unit is used for detecting the described recorded information that is formed in an image by this reproduction waveform.

51. hologram reproduction apparatus according to claim 50, wherein this recording medium comprises an incident beam treatment region, it is arranged in the described recording medium, be positioned on the opposite side of the plane of incidence that described signal beams incides described recording medium, this incident beam treatment region is separated from each other this zero order beam and this diffracted beam, a part of incident beam is turned back to described recording medium inside.

52., further be included in the linear track that forms in the part of described incident beam treatment region according to the hologram reproduction apparatus of claim 51.

53. according to the hologram reproduction apparatus of claim 52, wherein said track has the locating information of described incident beam treatment region with respect to described recording medium.

54. hologram reproduction apparatus according to claim 51, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

55. hologram reproduction apparatus according to claim 51, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and allows this diffracted beam to pass.

56. hologram reproduction apparatus according to claim 51, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing this zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

57. hologram reproduction apparatus according to each claim in the claim 54 to 56, the spatial light modulator that wherein comprises the row and column matrix of pixel in the following manner by utilization, write down the diffraction grating zone of this recording medium, promptly, be oppositely arranged described spatial light modulator and described recording medium, thereby make the diffracted beam of described signal beams can not shine described zero order beam treatment region.

58. hologram reproduction apparatus according to claim 57, described spatial light modulator and described recording medium relatively are provided with respect to the optical axis of described signal beams, that is, make θ (θ ≠ 0) angle that bearing of trend and a bearing of trend of described zero order beam treatment region of the delegation of described spatial light modulator or row become to be scheduled to.

59. according to the hologram reproduction apparatus of claim 55, wherein the opposite side that incides the plane of incidence of described recording medium from described signal beams is exported described reproduction ripple.

60. according to the hologram reproduction apparatus of claim 54 or 56, further comprise separative element, be used for the described reproduction ripple and the light path of described reference beam are separated.

61. recording medium, make by can realize the photochromics that writes down by the coherent light beam irradiation, comprise an incident beam treatment region, it is arranged on and is positioned in the described recording medium on the opposite side of the plane of incidence that light beam incides this recording medium, this incident beam treatment region is separated from each other the zero order beam and the diffracted beam of light beam, thereby a part of incident beam is turned back to described recording medium inside.

62., further be included in the linear track that forms in the part of described incident beam treatment region according to the recording medium of claim 61.

63. according to the recording medium of claim 62, wherein said track has the locating information of described incident beam treatment region with respect to described recording medium.

64. recording medium according to claim 61, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or the absorption zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

65. recording medium according to claim 61, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and allows this diffracted beam to pass.

66. recording medium according to claim 61, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing this zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

67. holographic recording and transcriber are used for information is recorded as the diffraction grating zone of recording medium, and are used for reproducing described recorded information from described diffraction grating zone, described holographic recording and transcriber comprise:

Retaining part is used for removably keeping the recording medium of being made by photochromics;

Light source is used to produce the coherent reference light beam;

The signal beams generation unit comprises spatial light modulator, and described spatial light modulator is modulated described reference beam according to described information space to be recorded, to produce signal beams;

Interference unit, comprise illuminating optical system, be used to utilize signal beams to shine described recording medium, to allow this signal beams to enter and pass described recording medium, described illuminating optical system, the part that interferes each other in described recording medium inside at the zero order beam that is arranged in described signal beams and diffracted beam, form the diffraction grating zone according to light interference pattern, described illuminating optical system utilizes described reference beam to shine described diffraction grating zone, to produce the reproduction ripple corresponding to described signal beams;

The incident beam treatment region, contiguous described signal beams incides this incident beam treatment region of couple positioned opposite of the plane of incidence of described recording medium, this incident beam treatment region is separated from each other this zero order beam and this diffracted beam, so that a part of incident beam turns back to described recording medium inside; And

Detecting unit is used for detecting the described recorded information that is formed in an image by this reproduction waveform.

68. holographic recording and transcriber according to claim 67, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

69. holographic recording and transcriber according to claim 67, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and allows this diffracted beam to pass.

70. holographic recording and transcriber according to claim 67, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing this zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

71. holographic recording and transcriber according to claim 67, wherein said spatial light modulator comprises the row and column matrix of pixel, and described spatial light modulator and described recording medium relatively are provided with respect to the optical axis of described signal beams, that is, make θ (θ ≠ 0) angle that bearing of trend and a bearing of trend of described zero order beam treatment region of the delegation of described spatial light modulator or row become to be scheduled to.

72. according to the holographic recording and the transcriber of claim 69, wherein the opposite side that incides the plane of incidence of described recording medium from described signal beams is exported described reproduction ripple.

73. holographic recording and transcriber according to claim 68 or 70 further comprise separative element, and the described reproduction ripple and the light path of described reference beam are separated.

74. a hologram recording apparatus is used for information is recorded as the information in the diffraction grating zone of recording medium, comprising:

Retaining part is used for removably keeping the recording medium of being made by photochromics;

Light source is used to produce the coherent reference light beam;

The signal beams generation unit comprises spatial light modulator, and described spatial light modulator is modulated described reference beam according to described information space to be recorded, to produce signal beams;

Interference unit, comprise illuminating optical system, be used to utilize this signal beams to shine this recording medium, to allow this signal beams to enter and pass described recording medium, described illuminating optical system, part in that the zero order beam that is arranged in this signal beams and diffracted beam interfere each other in described recording medium inside forms the diffraction grating zone according to light interference pattern; And

The incident beam treatment region, contiguous this signal beams incides this incident beam treatment region of couple positioned opposite of the plane of incidence of this recording medium, this incident beam treatment region is separated from each other zero order beam and diffracted beam, so that a part of incident beam turns back to described recording medium inside.

75. hologram recording apparatus according to claim 74, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

76. hologram recording apparatus according to claim 74, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and allows this diffracted beam to pass.

77. hologram recording apparatus according to claim 74, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing this zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

78. hologram recording apparatus according to claim 74, wherein said spatial light modulator comprises the row and column matrix of pixel, and described spatial light modulator and described recording medium relatively are provided with respect to the optical axis of described signal beams, that is, make θ (θ ≠ 0) angle that bearing of trend and a bearing of trend of described zero order beam treatment region of the delegation of described spatial light modulator or row become to be scheduled to.

79. a hologram reproduction apparatus is used for reproducing the information as the diffraction grating regional record of recording medium, this hologram reproduction apparatus comprises:

Retaining part is used for removably keeping the recording medium of being made by photochromics;

Light source is used to produce the coherent reference light beam;

Illumination unit comprises illuminating optical system, is used to utilize this reference beam to shine this recording medium, enters and pass diffraction grating zone in this recording medium to allow this reference beam, to produce the reproduction ripple corresponding to this signal beams;

The incident beam treatment region, contiguous this signal beams incides this incident beam treatment region of couple positioned opposite of the plane of incidence of this recording medium, this incident beam treatment region is separated from each other zero order beam and diffracted beam, so that a part of incident beam turns back to described recording medium inside; And

Detecting unit is used for detecting the described recorded information that is formed in an image by this reproduction waveform.

80. hologram reproduction apparatus according to claim 79, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region allows this zero order beam to pass, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and reflects this diffracted beam.

81. hologram reproduction apparatus according to claim 79, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or absorbing this zero order beam, this diffracted beam echo area limits this zero order beam treatment region and allows this diffracted beam to pass.

82. hologram reproduction apparatus according to claim 79, wherein said incident beam treatment region comprises zero order beam treatment region and diffracted beam echo area, this zero order beam treatment region reflects this zero order beam, or this zero order beam of scattering, or this zero order beam of deflection, or allowing this zero order beam to pass, this diffracted beam echo area limits this zero order beam treatment region and absorbs this diffracted beam.

83. the hologram reproduction apparatus of each claim in 0 to 82 according to Claim 8, the spatial light modulator that wherein comprises the row and column matrix of pixel in the following manner by utilization, write down the diffraction grating zone of this recording medium, promptly, be oppositely arranged described spatial light modulator and described recording medium, thereby make the diffracted beam of described signal beams can not shine described zero order beam treatment region.

84. 3 hologram reproduction apparatus according to Claim 8, described spatial light modulator and described recording medium relatively are provided with respect to the optical axis of described signal beams, that is, make θ (θ ≠ 0) angle that bearing of trend and a bearing of trend of described zero order beam treatment region of the delegation of described spatial light modulator or row become to be scheduled to.

85. 1 hologram reproduction apparatus according to Claim 8, wherein in the reproduction process, the opposite side that incides the plane of incidence of described recording medium from described signal beams is exported described reproduction ripple.

86. 0 or 82 hologram reproduction apparatus further comprises separative element according to Claim 8, and the described reproduction ripple and the light path of described reference beam are separated.

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