JP4466090B2 - Hologram record carrier, recording / reproducing method, and recording / reproducing apparatus - Google Patents

Description

  The present invention relates to a recording medium made of a photosensitive material, a so-called holographic memory, and more particularly to a hologram recording / reproducing method and an optical information recording / reproducing apparatus using the holographic memory.

  A volume holographic recording system is known as a digital information recording system using the principle of hologram. A feature of this system is that recording information is recorded as a change in refractive index on a recording medium made of a photosensitive material such as a photorefractive material.

  One of the conventional hologram recording / reproducing methods is a method of recording / reproducing using Fourier transform.

  As shown in FIG. 1, in a conventional 4f hologram recording / reproducing apparatus, a reference light beam of a laser light beam 12 emitted from a laser light source LED is split into light 12a and 12b by a beam splitter 13. The light 12a is expanded in beam diameter by the beam expander BX, and is applied as parallel light to a spatial light modulator SLM such as a transmissive TFT liquid crystal display (LCD) panel. The spatial light modulator SLM receives the information to be recorded, which has been signal-converted by the encoder, as an electric signal, and forms two-dimensional data, that is, recording information such as a bright and dark two-dimensional dot pattern on a plane. When the light 12a passes through the spatial light modulator SLM, the light 12a is optically modulated to become a signal light beam including a data signal component. The signal light beam 12 a containing the dot pattern signal component passes through the Fourier transform lens 16 separated by the focal length f, the dot pattern signal component is Fourier transformed, and is condensed in the recording medium 10. On the other hand, the reference light beam 12b split by the beam splitter 13 is guided as reference light into the recording medium 10 by mirrors 18 and 19, and crosses and interferes with the optical path of the signal light beam 12a inside the recording medium 10. An optical interference pattern is formed, and the entire optical interference pattern is recorded as a diffraction grating such as a change in refractive index.

  In this way, diffracted light from dot pattern data illuminated with coherent parallel light is imaged with a Fourier transform lens, and the distribution on the focal plane, that is, the Fourier plane, is converted into a coherent reference to the result of the Fourier transform. The interference fringes are recorded on a recording medium near the focal point by interference with light. When the recording of the first page is completed, the rotation mirror 19 is rotated by a predetermined amount, the position is translated by a predetermined amount, and the incident angle of the reference light beam 12b with respect to the recording medium 10 is changed, and the same procedure is performed on the second page. Record with. In this way, angle multiplex recording is performed by performing sequential recording.

  On the other hand, at the time of reproduction, an inverse Fourier transform is performed to reproduce a dot pattern image. In information reproduction, as shown in FIG. 1, for example, the optical path of the signal light beam 12 a is blocked by the spatial light modulator SLM, and only the reference light beam 12 b is irradiated onto the recording medium 10. At the time of reproduction, the mirror position and angle are controlled by changing the combination of rotation and linear movement of the mirror so as to have the same incident angle as the reference light when the page to be reproduced is recorded. On the side opposite to the incident side of the signal light beam 12a of the recording medium 10 irradiated with the reference light beam 12b, a reproduction wave reproducing the recorded signal light appears. When this reproduced wave is guided to the inverse Fourier transform lens 16a and inverse Fourier transformed, the dot pattern signal can be reproduced. Further, the dot pattern signal is received by the image detection sensor 20 at the focal length position, reconverted into an electrical digital data signal, and then sent to the decoder 26, the original data is reproduced.

Conventionally, in order to record information at a high density in a certain volume in a recording medium, multiplex recording is performed in a volume of about several square mm using angle multiplexing or wavelength multiplexing (see Patent Document 1). In a recording medium system in which the reference light and the signal light are incident at a predetermined angle from the same side, it is difficult to separate the reproduction reference light and the reproduction light during information reproduction. Therefore, there is a problem that the read performance of the reproduction signal is deteriorated. Also, stray light prevention means is required, which is disadvantageous for system miniaturization.
Japanese Patent Laid-Open No. 2001-184637.

  Therefore, the problem to be solved by the present invention includes, as an example, providing a hologram recording and reproducing method and a hologram recording and / or reproducing apparatus that can be miniaturized.

  The hologram record carrier according to claim 1 is a hologram record carrier in which information is recorded or reproduced by a diffraction grating by irradiation with a coherent light beam, and a recording medium portion made of a photosensitive material, and the recording medium An incident light processing region part provided on the opposite side of the light beam incident side of the light beam and differentiating the polarization plane of the zero-order light and the polarization plane of the diffracted light of the light beam incident through the recording medium part It is characterized by having.

The hologram recording method according to claim 14 generates a signal light beam by spatially modulating a coherent reference light beam according to recording information, and the signal light beam is generated from a recording medium portion made of a photosensitive material. to pass into the entrance Shako processing area unit, by irradiating the recording medium portion, a region of the diffraction grating by an optical interference pattern portion is zero-order light and diffracted light interferes the signal light beam in the recording medium unit And a recording step of forming a zero-order light of the signal light beam incident on the recording medium portion through the recording medium portion on the opposite side of the recording medium portion from the incident side of the signal light beam. characterized in that a of the incident light processing area portion made different from each other plane of polarization of the polarization plane and the diffracted light.

The hologram reproduction method according to claim 15 generates a signal light beam by spatially modulating a coherent reference light beam according to recording information, and the signal light beam is emitted from a recording medium portion made of a photosensitive material. and irradiating the recording medium part so as to pass into the entrance Shako processing area unit, forming a region of a diffraction grating by an optical interference pattern 0 order light and sites diffracted light interferes in the signal light beam in the recording medium unit A hologram reproducing method for reproducing the recorded information recorded by the recording step,
Wherein the made different polarization plane and the polarization plane of the diffracted light of the 0th order light of the light beam transmitted through the recording medium unit providing the incident light processing area portion, and formed in a region of the diffraction grating was, the reference light beam A reproduction step of generating a reproduction wave corresponding to the signal light beam by irradiating the region of the diffraction grating so as to pass from the recording medium unit to the incident light processing region unit;
Separating the reference light beam and the reproduction wave.

The hologram apparatus according to claim 16 is a hologram apparatus for recording record information as a region of a diffraction grating and / or reproducing record information from the region of the diffraction grating,
A support part for holding a recording medium part made of a photosensitive material in a freely attachable manner;
A light source for generating a coherent reference light beam;
A signal light generation unit including a spatial light modulator that spatially modulates the reference light beam according to recording information to generate a signal light beam;
The signal light beam is irradiated onto the recording medium unit to enter and pass through the recording medium unit, and diffraction is caused by a light interference pattern at a portion of the recording medium unit where the 0th-order light and diffracted light of the signal light beam interfere. A pickup unit that forms a region of the grating, and irradiates the region of the diffraction grating with the reference light beam to generate a reproduction wave corresponding to the signal light beam;
An incident light processing region portion that is disposed on the opposite side of the recording medium portion from the incident side of the signal light beam, and that makes the polarization plane of the zero-order light and the polarization plane of the diffracted light different from each other;
A separation unit for separating the reference light beam and the reproduction wave;
And a detector for detecting recording information imaged by the reproduction wave.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<Hologram record carrier>
FIG. 2 shows a rectangular parallel plate card-type hologram record carrier 11 as an example of the embodiment. The hologram record carrier 11 is configured by integrally coupling a recording medium 10 and an incident light processing region R provided on the opposite side of the light incident side. The hologram record carrier 11 has an incident light processing region R at or near the position of the beam waist of the light beam so that the coherent light beam passes through the recording medium 10 and can be focused and focused on the opposite side to the incident side. It is used so as to be located on the optical axis. The incident light processing region R includes a zero-order light processing region R1 for processing the zero-order light of the incident light beam and a diffracted light processing region R2 for processing the diffracted light (on the optical axis) of the incident light beam. Thus, a process of making the polarization plane of the 0th-order light and the polarization plane of the diffracted light different from each other is performed. Although not shown, the hologram record carrier may be formed in various shapes such as a disk in addition to the card.

  When the coherent incident light beam is light-modulated by a spatial light modulator or the like, zero-order light and diffracted light are generated, and when it is not modulated, zero-order light is generated. The signal light beam used for hologram recording is composed of zero-order light that always has the same wavefront regardless of spatial modulation and diffracted light corresponding to spatial modulation, and the reference light beam used for hologram reproduction is spatial It consists of zero-order light that always has the same wavefront regardless of the modulation.

  In order to make the polarization planes of the 0th-order light and the diffracted light of the incident light beam to the incident light processing region R different from each other, the 0th-order light processing region R1 and the diffracted light processing region R2 that receive the light beams are spatially separated. It is necessary to keep. In addition, any one of the 0th-order light processing region R1 and the diffracted light processing region R2 can reflect or transmit at least the diffracted light of the light beam to the recording medium.

  First, when the incident light processing region R has a region that reflects at least the diffracted light of the light beam to the recording medium, there are the following modes.

  (1) The incident light processing region R reflects the 0th-order light processing region R1 that reflects the 0th-order light of the light beam by rotating its polarization plane, and reflects the diffracted light of the light beam without rotating its polarization surface. The diffracted light processing region R2 is used.

  (2) The incident light processing region R reflects the 0th-order light processing region R1 that reflects the 0th-order light of the light beam without rotating its polarization plane, and the diffracted light of the light beam is reflected by rotating its polarization surface. The diffracted light processing region R2 is used.

  (3) A 0th-order light processing region R1 that transmits, scatters, deflects, or absorbs 0th-order light of a light beam without rotating its polarization plane, and a diffracted light of the light beam with its polarization plane. Is rotated into the diffracted light processing region R2 for reflection.

  (4) The 0th-order light processing region R1 that reflects the incident light processing region R by reflecting the 0th-order light of the light beam by rotating the polarization plane at the first rotation angle; and the polarization of the diffracted light of the light beam The surface is turned into the diffracted light processing region R2 which is reflected by rotating the polarization plane at the second rotation angle.

  Next, when the incident light processing region R has a region that transmits at least the diffracted light of the light beam, there is the following mode.

  (5) The 0th-order light processing region R1 that transmits the 0th-order light of the light beam by rotating the polarization plane thereof, and the diffracted light of the light beam is transmitted without rotating the polarization surface. The diffracted light processing region R2 is used.

  (6) The 0th-order light processing region R1 that transmits the 0th-order light of the light beam without rotating the polarization plane, and the diffracted light of the light beam is transmitted by rotating the polarization surface. The diffracted light processing region R2 is used.

  (7) The incident light processing region R includes a zero-order light processing region R1 that scatters, deflects, reflects, or absorbs the zero-order light of the light beam without rotating its polarization plane; Is rotated to be a diffracted light processing region R2 for transmission.

  (8) The 0th-order light processing region R1 that transmits the 0th-order light of the light beam through the incident light processing region R by rotating the polarization plane at the first rotation angle, and the diffracted light of the light beam is polarized. The surface of the polarizing plate is rotated at the second rotation angle to form a diffracted light processing region R2 for transmission.

  In the recording medium 10, an optical interference pattern such as a photorefractive material, a hole burning material, a photochromic material, or the like is used as a photosensitive material capable of storing an optical interference pattern so that information can be recorded or reproduced by light passing through the recording medium 10. Photosensitive material that can preserve The hologram of the diffraction grating by the light interference pattern is recorded mainly on the light incident side of the recording medium 10.

  As a material for rotating the polarization plane of the incident light beam in the 0th-order light processing region R1 or the diffracted light processing region R2 of the incident light processing region R, the refractive index for polarized light orthogonal to each other is different due to the asymmetry of the molecular structure and crystal structure. An optical rotatory material is used. Examples of optical rotatory substances include quartz, liquid crystal, and Kerr effect materials. An optical rotation film made of an optical rotatory material exhibiting optical activity gives a predetermined phase difference between the two components when incident light consisting of mutually perpendicular electric vectors (polarized components) passes. This phase difference is (2π / λ) (| ne−no |) d {where λ is the wavelength in vacuum, ne and no are the refractive indices of the optical rotating film for two polarization components, and d is the film of the optical rotating film. Show thickness}. The optical rotating film functions as a phase plate. For example, an optical element that cuts a crystal that is a uniaxial crystal parallel to the crystal axis and gives a phase difference (retardation) to incident light, that is, light of a specific wavelength passes. At this time, it is known as a birefringent element that causes a phase difference between S-polarized light and P-polarized light, and functions as a quarter-wave plate and a half-wave plate. For example, an optical rotating film that functions as a quarter-wave plate is arranged so that linearly polarized light is circularly polarized when arranged so that one polarization plane of incident light is at an angle of 45 degrees with respect to the optical axis (crystal axis) of the film. Can be converted to In the half-wave plate, when linearly polarized light oscillating at a predetermined angle θ with respect to the principal axis direction is incident, the emitted light rotates by 180 ° −2θ. When rotating around, it functions as an optical rotator that rotates the deflection surface of the emitted light by 2α. An example of such an optical rotation film has a structure in which the optical axes of crystals of two quartz plates (artificial quartz and the like) polished by setting a thickness corresponding to a specific wavelength are orthogonal to each other and laminated. Further, the optical rotation film can be constituted by an organic material such as polyimide in addition to the inorganic material. Since the amount of birefringence of the constituent material varies depending on the wavelength and its phase difference also varies, it is necessary to select it according to the wavelength used in order to obtain a predetermined phase difference.

  Examples of the material that reflects the incident light beam in the zero-order light processing region R1 or the diffracted light processing region R2 of the incident light processing region R include Al, Au, Ag, and alloys thereof. In addition to metal, the reflective film can be formed as a dielectric multilayer film.

  Therefore, in the case of a region in which incident light is reflected by rotating its polarization plane, the optical rotation film that rotates the polarization plane and a reflection film on the surface opposite to the recording medium 10 are combined. .

  The material that transmits the incident light beam in the zero-order light processing region R1 or the diffracted light processing region R2 of the incident light processing region R is an organic or inorganic material as long as it has a higher transmittance for the wavelength used than the other processing region. It doesn't matter. Further, the exposed surface of the recording medium 10 can be used as a processing region without providing a light transmissive film made of a transmissive material.

  As a material that absorbs the incident light beam in the 0th-order light processing region R1 or the diffracted light processing region R2 of the incident light processing region R, an organic or inorganic material having higher absorbance with respect to the wavelength to be used than the other processing region is used.

  The scattering or deflection of the incident light beam in the 0th-order light processing region R1 or the diffracted light processing region R2 of the incident light processing region R requires an action of reflecting the incident light beam to the inside of the recording medium 10. The reflective film in the processing region R is provided on the surface opposite to the recording medium 10, and a rough surface, a curved surface, or an inclined surface (inclined with respect to the normal line) is provided at the interface with the recording medium 10. Therefore, in the case of a region where incident light is scattered or deflected and reflected, the surface opposite to the recording medium 10 is formed of a rough, curved, or inclined reflective film.

  Furthermore, a linear track is provided in a part of the incident light processing region R, for example, the 0th-order light processing region R1. This track preferably has position information of an incident light processing area on the recording medium. This is because it can be used for tracking servo control of a light beam.

  Thus, in the hologram record carrier of the present embodiment, the reference light of another path is not used at the time of recording. Instead, only the signal light is incident on the recording medium, and the zero-order light and the diffracted light of the signal light are A diffraction grating can be generated and recorded by interference, and signal light can be reproduced from the diffraction grating and separated from the reference light only by irradiation with reference light (0th order light). For this purpose, an incident light processing region is provided on the side opposite to the incident light beam irradiation side of the recording medium to separate the 0th-order light and diffracted light of the incident light and make their polarization planes different from each other.

<First embodiment>
FIG. 3 shows a hologram recording / reproducing apparatus which is an example of a hologram apparatus for recording and / or reproducing information on the hologram record carrier of this embodiment which is the aspect (1).

For the light source LED, for example, a DBR (Distributed Bragg) with a near infrared laser beam wavelength of 850 nm is used.
(Reflector) laser is used. On the optical path of the reference light beam 12, a shutter SHs, a beam expander BX, a spatial light modulator SLM, a half mirror HM, a polarization beam splitter 15, and a condenser lens 160 are arranged. The shutter SHs is controlled by the controller 32 and controls the irradiation time of the light beam on the recording medium.

  The beam expander BX irradiates the reference light beam 12 having passed through the shutter SHs so that the diameter of the reference light beam 12 is enlarged to be a parallel light beam and incident on the spatial light modulator SLM.

  The spatial light modulator SLM receives electrical data (two-dimensional dot pattern data) supplied from the encoder 25 and displays a light and dark dot matrix signal. When the reference light beam passes through the spatial light modulator SLM on which data is displayed, the reference light beam is optically modulated to become a signal light beam 12a including data as a dot matrix component.

  The half mirror HM is provided to guide the reproduction wave to the image detection sensor 20. The half mirror HM is disposed at a position where a reproduction wave can be sent to the image detection sensor 20. The image detection sensor 20 is disposed at a focal length position, and is composed of an array such as a charge coupled device CCD or a complementary metal oxide semiconductor device.

  The polarization beam splitter 15 is a separation unit that separates a reproduction wave to be described later from the optical path of the reference light beam 12 and supplies it to the image detection sensor 20. The polarization beam splitter 15 is provided as a separating unit that separates the reproduction wave and the reference light.

  The condensing lens 160 performs Fourier transform on the dot matrix component of the signal light beam 12a that has passed through the polarization beam splitter 15, and focuses on the rear side (incident light processing region) of the recording medium 10 mounting position of the hologram record carrier 11. Condensate like so. When the shutter SHs is opened by the condenser lens 160, the signal light beam 12a or the reference light beam 12 is irradiated onto the main surface of the recording medium 10 at a predetermined incident angle, for example, zero degree. The spatial light modulator SLM and the image detection sensor 20 are disposed at the focal length of the condenser lens 160.

  Further, a decoder 26 is connected to the image detection sensor 20. The decoder 26 is connected to the controller 32. If the hologram record carrier 11 is previously labeled according to the type of the photorefractive material, when the hologram record carrier 11 is mounted on the movable stage 60 which is a support for moving the hologram record carrier 11, the controller 32 It is also possible to automatically read this mark by an appropriate sensor and perform movement control of the hologram record carrier 11 and recording / reproduction control suitable for the recording medium 10.

<Principle of recording / playback>
The principle of recording / reproducing of the hologram record carrier will be described in the case where a P-polarized light source is used, taking the present embodiment which is the aspect of (1) as an example.

  The hologram record carrier mounted on the movable stage shown in FIG. 4 is configured by integrating and coupling the incident light processing region R provided on the opposite side of the signal light 12a incident side to the recording medium 10. .

The incident light processing region R includes a zero-order light processing region R1 _RR that rotates and reflects the zero-order light of the light beam, and a diffracted light that reflects the diffracted light of the light beam without rotating the polarization surface. comprising a processing region R2 _R. The 0th-order light processing region R1 _RR includes, for example, an optical rotating film 111 that functions as a quarter-wave plate and a reflective film 112 laminated thereon. The diffracted light processing region R2 _R is composed of a light transmission film 110 and a reflection film 112 laminated thereon. The diffraction light processing region R2 _R are omitted light transmitting film 110 can be formed only in the reflective film 112.

At the time of recording, as shown in FIG. 5, the P-polarized signal light 12a (0th-order light zP and diffracted light rP) passes through the polarization beam splitter 15 and is condensed by the condenser lens 160, and is recorded on the recording medium of the hologram record carrier. 10 passes is irradiated with the diffracted light processing area R2 _R in the vicinity thereof and 0-order light processing area R1 _RR.

The zero-order light zP is converted into circularly polarized light when it enters and passes through the optical rotation film 111 in the zero-order light processing region R1 _RR , is further reflected by the reflection film 112, and passes through the optical rotation film 111 again. At this point, the zero-order light becomes S-polarized reflected zero-order light zS having a polarization plane direction different from the incident polarization plane direction by 90 degrees. The S-polarized reflected zero-order light zS passes through the recording medium 10 and is reflected by the polarizing beam splitter 15.

On the other hand, the diffracted light rP of the signal light is reflected by the reflective film 112 in the diffracted light processing region R2 _R , but its polarization plane does not rotate, and passes through the recording medium 10 as P-polarized reflected diffracted light rP, and is polarized beam splitter. 15 is also transmitted.

  Hologram recording is possible when the directions of the polarization planes of the 0th-order light and the diffracted light are the same. Therefore, interference in the recording medium 10 is caused by the incidence of both the P-polarized 0th-order light zP and the diffracted light rP. One set (diffraction grating P1), and one set (diffraction grating P2) of incident P-polarized 0th-order light zP and reflected P-polarized reflected diffracted light rP. Two holograms formed at substantially the same position are multiplexed as holograms recorded by these interferences. In FIG. 5, in order to facilitate understanding of the formation of each optical interference pattern, the propagation direction of diffracted light in hologram recording is indicated by a white arrow, and the propagation direction of zero-order light is indicated by a dark arrow.

At the time of reproduction, as shown in FIG. 6, the P-polarized reference light (0th-order light) 12 passes through the polarization beam splitter 15 along the same optical path, and is condensed by the condenser lens 160, and is recorded on the recording medium 10 of the hologram record carrier. , And the zero-order light processing region R1 _RR is irradiated. Here, the P-polarized reference light is reciprocally transmitted through the optical rotating film 111 via the reflecting film 112 to become S-polarized reflected zero-order light zS, which is transmitted so as to return to the recording medium 10, and is polarized by the polarizing beam splitter 15. Reflected and deviated from the optical path. It should be noted that no reproduction wave is generated by irradiating the diffraction grating with the S-polarized reflected zero-order light zS. This is because the propagation direction differs between the P-polarized zero-order light zP and the S-polarized reflected zero-order light zS.

Reproduced waves are generated from the two holograms by the P-polarized reference light (0th-order light). The generated reproduction wave contains at least the same diffracted light component as the recorded signal light. The reproduction wave RrP from the hologram (diffraction grating P1) due to the P-polarized 0th-order light zP and the diffracted light rP incident together is generated as the P-polarized light in the direction opposite to the light source direction (that is, the incident forward direction). The P-polarized reproduction wave RrP is reflected by the reflection film 112 in the diffracted light processing region R2 _R , but its polarization plane does not rotate, and passes through the recording medium 10 as the P-polarized reflection reproduction wave RrP and is a condensing lens. The light is converted into parallel light by 160 and is also transmitted through the polarization beam splitter 15. Accordingly, the P-polarized reflection reproduction wave RrP is partially reflected by the half mirror HM and received by the image detection sensor.

  On the other hand, the reproduction wave RrP from the hologram (diffraction grating P2) caused by the incident P-polarized 0th-order light zP and the reflected P-polarized reflected diffracted light rP is generated as P-polarized light in the light source direction (that is, the direction opposite to the incident direction). Therefore, the light passes through the polarization beam splitter 15 and is received by the image detection sensor through the half mirror HM.

  Since the P-polarized reproduction wave RrP and the reproduction reference light can be separated in this manner, unnecessary reference light does not enter the image detection sensor that receives the reproduction wave.

  Further, even when the signal light (0th order light and diffracted light) at the time of recording is S-polarized light, the recording / reproducing operation can be performed by changing the arrangement direction of the polarization beam splitter or the like. This can be performed in the same manner as when (light) is P-polarized light. Therefore, in this embodiment, the polarization state of the light beam from the light source is not limited. Regardless of the polarization state and components of the light source during recording, the reference light (0th order light) and the reproduced wave can be separated during reproduction.

<Recording operation of hologram recording / reproducing apparatus>
First, the position of the movable stage 60 holding the recording medium 10 shown in FIG. 3 is controlled by the controller 32, and the target recording medium 10 is moved to a predetermined recording position.

  Next, the recording signal is sent from the encoder 25 to the spatial light modulator SLM, and the spatial light modulator SLM displays a pattern corresponding to the recording information.

  Next, the shutter SHs is opened and the spatial light modulator SLM is irradiated with the reference light beam 12. The reference light beam 12 is spatially modulated by a spatial light modulator SLM on which a pattern corresponding to recording information is displayed, and a signal light beam 12a (0th-order light and diffracted light) is generated. The generated signal light beam 12a passes through the half mirror HM and the polarization beam splitter 15 and is irradiated onto the recording medium 10 to start recording.

  The signal light beam 12a applied to the recording medium 10 generates an optical interference pattern between the 0th-order light and the diffracted light, and the diffraction gratings P1 and P2 corresponding to the light interference pattern have the photorefractive effect as described above to record the recording medium. 10 is recorded.

  After the recording on the recording medium 10 is completed, the shutter SHs is closed by the controller 32.

  When the recording at the predetermined recording position of the recording medium 10 is completed, the recording medium 10 is moved by a predetermined amount (in the y direction in FIG. 3), and the position of the signal light beam 12a with respect to the recording medium 10 is changed to another predetermined recording position. Record in the same procedure as the previous recording procedure. Recording is performed on the recording medium 10 by performing sequential recording in this way.

  FIG. 7 is a diagram showing the spatial light modulator SLM and the incident light processing region R of the recording medium 10 arranged side by side when viewed from the optical axis direction of the signal light beam 12a from the light source side. As shown in FIG. 7, the 0th-order light processing region R1 of the incident light processing region R provided on the opposite side of the recording medium 10 is defined to form a track. The track-shaped zero-order light processing region R1 extends in the y direction in FIG. A plurality of track-shaped 0th-order light processing regions R1 can be intermittently arranged on a line, whereby position information on the recording medium 10 in the 0th-order light processing region R1 is stored in the track-shaped 0th-order light processing region R1. It can be supported. A plurality of track-shaped 0th-order light processing regions R1 can be arranged in parallel at a predetermined pitch and used for tracking servo control.

In the recording medium 10 and the spatial light modulator SLM, the extension direction D _R1 of the track-shaped zero-order light processing region R1 and the extension direction D SLM of the row of the pixel matrix of the spatial light modulator _SLM are at a predetermined angle θ (θ ≠ 0). ) Are relatively arranged so as to cross each other. In addition, the expansion direction of the matrix column may be used for setting the angles of the recording medium 10 and the spatial light modulator SLM. The angle setting configuration of the recording medium 10 and the spatial light modulator SLM is as follows.

  In general, at the time of recording, the reference light beam 12 is incident on a spatial light modulator SLM displaying a two-dimensional dot pattern that is transmitted / non-transmitted for each pixel in accordance with recording information, and is spatially modulated to be a signal light beam 12a. Is generated. The signal light beam 12a is Fourier-transformed by a Fourier transform lens, that is, a condensing lens 160, is incident on the recording medium 10, and enters the Fourier plane FF corresponding to the Fourier transform lens as a zero-order light and diffracted light point images of the signal light beam 12a. Each is imaged.

  As shown in FIG. 8, in the signal light beam 12a (0th-order light and diffracted light) modulated by the spatial light modulator SLM, the diffracted light due to repetition of the spatial light modulator pixels (referred to as pitch a) has the highest frequency. Become an ingredient. The signal light beam 12a is Fourier-transformed by the condenser lens 160, and a spatial frequency spectrum distribution light intensity corresponding to the spatial modulation by the spatial light modulator SLM is generated on the Fourier plane FF shown in FIG.

  Using the spatial frequency (1 / a) depending on the pixel pitch, the wavelength (λ) of the signal light beam 12a, and the focal length (f) of the Fourier transform lens (condensing lens 160), the 0th order light and 1 on the Fourier plane FF The interval (d1) of the next light can be expressed as d1 = (1 / a) · (λ) · (f). For example, when the pixel pitch of the spatial light modulator is 10 μm, the wavelength of the signal light beam 12a is 530 nm, and the focal length of the condensing lens 160 is 14 mm, the distance (d1) between the 0th order light and the 1st order diffracted light on the Fourier plane is According to the above formula, it is about 750 μm. Since the highest spatial frequency component in the spatial light modulation SLM is the pixel pitch, a point image corresponding to the pixel pitch exists at a position farther from the zero-order point image of the signal light beam 12a on the Fourier plane FF. Therefore, the Fourier plane FF has a square-shaped pattern composed of the 0th-order light at the center of the signal light beam 12a, the 1st-order diffracted light and the 0th-order light by the pixel pitch in the row direction and the column direction of the spatial light modulator SLM. A spatial frequency spectrum distribution corresponding to the modulation of the spatial light modulator exists in the space.

In the point image of the diffracted light corresponding to the row direction of the spatial light modulator SLM, the Fourier plane FF is included in the incident light processing region R. When the track shape of the zero-order light extending direction D _SLM angle theta = 0 degree line of the pixel matrix in the extending direction D _R1 and the spatial light modulator SLM process area R1 is on track shape of the zero-order light processing area R1 A point image corresponding to the spatial frequency component in the row direction of the pixel matrix of the spatial modulator SLM is formed.

Accordingly, since the diffracted light corresponding to the row direction of the spatial light modulator SLM is not reflected by the diffracted light processing region R2 _R , the signal light beam 12a corresponding to the row direction of the spatial light modulator SLM is generated in the generation of the optical interference pattern described above. The reflected diffracted light does not exist and optical interference with the 0th-order light of the signal light beam 12a does not occur. That is, when the extension direction D _R1 and the spatial light modulator SLM of the pixel matrix in the extending direction D _SLM angle theta = 0 degree line of track shape of the zero-order light processing region R1, the space in the diffraction grating P2 of the recording medium 10 Information by diffracted light corresponding to the row direction of the optical modulator SLM is not recorded.

In order to effectively use the first-order diffracted light of the diffracted light, that is, the reflected diffracted light of the signal light beam 12a (according to the row direction of the spatial light modulator SLM) and the 0th-order light of the signal light beam 12a are transmitted. In order to cause interference, the recording medium 10 and the spatial light modulator SLM include the extension direction D _R1 of the track-shaped zero-order light processing region R1 and the extension direction D SLM of the row (or column) of the pixel matrix of the spatial light modulator _SLM. Are arranged relatively so as to intersect at a predetermined angle θ (θ ≠ 0).

<Reproducing operation of hologram recording / reproducing apparatus>
Next, a process procedure for reproducing information from the hologram will be described.

  First, the position of the movable stage 60 holding the recording medium 10 shown in FIG. 3 is controlled by the controller 32, and the target recording medium 10 is moved to a predetermined recording position.

  Next, a state in which the reference light beam 12 is not spatially modulated, that is, information on transmission of all pixels is sent from the encoder 25 to the spatial light modulator SLM to display a transmission pattern of all pixels.

  Next, the shutter SHs is opened to irradiate the spatial light modulator SLM with the reference light beam 12, and the recording medium 10 is irradiated with the reference light beam 12 as it is to start reproduction. The reference light beam 12 is not modulated because it passes through the spatial light modulator SLM for full transmission display. Accordingly, diffracted light corresponding to spatial modulation is not generated, and the reference light beam 12 has only the 0th-order light component.

  When the recording medium 10 is irradiated with the reference light beam 12 (0th-order light) at the time of reproduction at the same angle and position as the signal light beam 12a at the time of recording, the diffraction gratings P1 and P2 in the recording medium 10 are irradiated and the reproduced wave is emitted. appear. The reference light beam 12 is reflected by the polarization beam splitter 15 and emitted to the side. Therefore, since the reference light beam 12 is not received by the image detection sensor 20, reproduction of recorded information is facilitated.

  The reproduction wave exits from the incident side of the recording medium 10, passes through the condenser lens 160 and the polarization beam splitter 15, is reflected by the half mirror HM, and forms a dot pattern corresponding to the recording information on the image detection sensor 20. . When this dot pattern signal is received by the light receiver of the image detection sensor 20 and reconverted into an electrical digital data signal, it is sent to the decoder 26 to reproduce the original data.

  Next, after the reproduction of the recording medium 10 at the predetermined recording position is completed, the shutter SHs is closed by the controller 32.

  Next, the recording medium 10 is moved (y direction in FIG. 3), the position of the reference light beam 12 with respect to the recording medium 10 is changed to another predetermined recording position, and reproduction is performed in the same procedure as the previous reproduction procedure. Information reproduction from the recording medium 10 is performed by performing sequential reproduction in this way.

<Second embodiment>
In the hologram record carrier of the first embodiment, the incident light processing region provided integrally on the opposite side of the signal light incident side of the recording medium rotates the polarization plane of the zero-order light in the zero-order light processing region. To reflect. On the other hand, as shown in FIG. 9, the hologram record carrier of the second embodiment (aspect (2) above) reflects incident zero-order light from the zero-order light processing region without rotating its polarization plane. An incident light processing region R is provided as a region R1 _R , and the diffracted light processing region is a region R2 _RR that reflects the diffracted light by rotating its polarization plane. That is, the incident light processing area R is 0 reflects the diffracted light processing area R2 _RR reflecting rotated its polarization plane of the diffracted light of the light beam, the light beam a 0 order light without rotating the polarization plane order It consists of a light processing region R1 _R. The diffracted light processing region R2 _RR includes, for example, an optical rotation film 111 that functions as a quarter-wave plate and a reflective film 112 laminated thereon. The 0th-order light processing region R1 _R is composed of a light transmission film 110 and a reflection film 112 laminated thereon. Further, the zero-order light processing region R1 _R can be configured by only the reflective film 112 without the light transmissive film 110. In addition, although the film | membrane which functions as a quarter wavelength plate is used as the optical rotation film | membrane 111, it is the same also in a 1st Example and the following Examples, However, It is not restricted to this, Other phase plates and wavelength plates A film having a function can be used. The zero-order light processing region R1 _R may be formed as a track structure extending in the y direction.

  As shown in FIG. 10, the hologram recording / reproducing apparatus according to the second embodiment does not use the half mirror HM, but separates the reproduction wave from the optical path of the reference light beam 12 and guides it to the image detection sensor 20. Except for the provision of the splitter 15, it is the same as that of the first embodiment. Therefore, the polarization beam splitter 15 is disposed at a position where the reproduction wave can be sent to the image detection sensor 20.

  A recording / reproducing method of the second embodiment will be described.

In the recording step, as shown in FIG. 11, the signal light 12a, for example, P-polarized light (0th-order light zP and diffracted light rP) passes through the polarization beam splitter 15 and is condensed by the condensing lens 160, and is recorded on the hologram record carrier. The light passes through the recording medium 10 and irradiates the 0th-order light processing region R1 _R and the diffracted light processing region R2 _RR in the vicinity thereof. In the drawing, P-polarized light represents a vibration direction parallel to the paper surface, and S-polarized light represents a vibration direction perpendicular to the paper surface.

  The 0th-order light zP of the signal light is reflected by the reflection film 112, but its polarization plane does not rotate, but passes through the recording medium 10 as the P-polarized reflected 0th-order light zP and also passes through the polarization beam splitter 15.

On the other hand, the diffracted light rP is converted into circularly polarized light when it enters and passes through the optical rotation film 111 in the diffracted light processing region R2 _RR , is further reflected by the reflection film 112, and passes through the optical rotation film 111 again. At this point, the diffracted light becomes S-polarized reflected diffracted light rS having a polarization plane direction different from the incident polarization plane direction by 90 degrees. The S-polarized reflected diffracted light rS passes back through the recording medium 10, is reflected by the polarizing beam splitter 15, and reaches the image detection sensor 20.

  Hologram recording is possible when the directions of the polarization planes of the diffracted light and the 0th-order light are the same. Therefore, interference in the recording medium 10 is caused by the incident P-polarized diffracted light rP and 0th-order light zP. One set (diffraction grating P1), and one set (diffraction grating P2) of incident P-polarized 0th-order light zP and reflected P-polarized reflected diffracted light rP. Two holograms formed at substantially the same position are multiplexed as holograms recorded by these interferences. In FIG. 11, in order to facilitate understanding of the formation of each optical interference pattern, the propagation direction of diffracted light in hologram recording is indicated by a white arrow, and the propagation direction of zero-order light is indicated by a dark arrow.

In the reproduction process, as shown in FIG. 12, the P-polarized reference light (0th-order light) 12 passes through the polarization beam splitter 15 along the same optical path, and is condensed by the condenser lens 160, and recorded on the hologram record carrier. The light passes through the medium 10 and irradiates the zero-order light processing region R1 _R. The zero-order light zP reflected here is reflected by the reflection film 112, but its polarization plane does not rotate, and passes through the recording medium 10 as the P-polarized reflection zero-order light zP and also passes through the polarization beam splitter 15. .

A reproduction wave is generated from each of the two holograms. Hologram (diffraction grating P1) resulting from both incident P-polarized diffracted light rP and 0th-order light zP, and hologram resulting from incident P-polarized diffracted light rP and reflected P-polarized reflected 0th-order light zP (diffraction grating P2) The reproduced waves RrP are generated in the direction opposite to the light source direction (that is, the incident forward direction) as P-polarized light. These P-polarized reproduction waves RrP are reciprocally transmitted through the optical rotation film 111 via the reflection film 112 in the diffracted light processing region R2 _RR , and become S-polarized light when emitted from the hologram record carrier. These S-polarized reproduction waves RrS are converted into parallel light by the condenser lens 160 and reach the polarization beam splitter 15. The polarization beam splitter 15 separates the S-polarized reproduction wave RrS from the optical path of the reference light (0th-order light) 12 and supplies it to the image detection sensor. As described above, the P-polarized reproduction wave RrP becomes the S-polarized reproduction wave RrS through the diffracted light processing region R2 _RR , and can be separated from the reference light. Therefore, an unnecessary zero-order light component may enter the image detection sensor that receives the reproduction wave. Absent.

  Furthermore, even when the signal light (0th-order light and diffracted light) at the time of recording is S-polarized light, the recording / reproducing operation is performed when the signal light at the time of recording is P-polarized light by changing the arrangement direction of the polarization beam splitter or the like. Can be executed as well. Therefore, in this embodiment, the polarization state of the light beam from the light source is not limited. Regardless of the polarization state and components of the light source during recording, the reference light (0th order light) and the reproduced wave can be separated during reproduction.

<Third embodiment>
Furthermore, as shown in FIG. 13, the hologram record carrier of another modification (one of the above aspects (3)) reflects the 0th order light of the signal light beam without rotating its polarization plane. The hologram record carrier of the second embodiment except that it has, instead of the processing region R1 _R , a zero-order light processing region R1 _SC that reflects and scatters the zero-order light to the recording medium without rotating its polarization plane. Is the same. That is, the incident light processing area R, the diffracted light and diffracted light processing area R2 _RR reflecting rotated the plane of polarization of the light beam and reflects scattered 0th order light of the light beam without rotating the polarization plane 0 And a next light processing region R1 _SC . The diffracted light processing region R2 _RR is composed of an optical rotation film 111 and a reflective film 112 laminated thereon, and the 0th-order light processing region R1 _SC is composed of a reflective protrusion 112a to a recording medium formed on the reflective film 112. . The 0th-order light processing region R1 _SC is not limited to a protruding surface, and can be configured as a concave surface, a rough surface, or a curved surface. Further, the optical rotation film 111 in the diffracted light processing region R2 _RR is not essential, and the 0th-order light processing region R1 _SC can be formed integrally with the reflective film. The 0th-order light processing region R1 _SC may be formed as a track extending in the y direction.

The 0th-order light processing region R1 _SC uses the 0th-order light of the signal light beam 12a as scattered light in the recording medium 10, and achieves optical interference caused by the incident diffracted light having the same polarization component as that of the scattered light.

  That is, when a film functioning as a quarter wavelength plate is used as the optical rotation film 111 and recording is performed with, for example, P-polarized light (0th-order light zP and diffracted light rP), hologram recording is performed by polarization of diffracted light and 0th-order light. Since it is possible when the directions of the surfaces are the same, the interference within the recording medium 10 is a combination of the P-polarized diffracted light rP and the 0th-order light zP (diffraction grating P1) and the incident P A set of polarized diffracted light rP and a set (diffraction grating P2) of P-polarized scattered zero-order light zPscattered to be reflected and scattered. Two holograms formed at substantially the same position are multiplexed as holograms recorded by these interferences. The reproduction is executed in the same manner as the method shown in FIG. In FIG. 13, in order to facilitate understanding of the formation of each optical interference pattern, the propagation direction of diffracted light in hologram recording is indicated by a white arrow, and the propagation direction of zero-order light is indicated by a dark arrow.

<Fourth embodiment>
FIG. 14 shows a fourth embodiment. This is not the 0th-order light processing region R1 _SC having the reflection protrusion 112a that reflects and scatters the 0th-order light to the recording medium in the third embodiment, but the inclined reflection that reflects the 0th-order light and deflects it inward. This is the same as the hologram record carrier of the third embodiment except that the 0th-order light processing region R1 _DL having the surface 112b is formed. The inclined reflecting surface 112b can be realized by changing the shape of the reflecting protrusion that reflects and scatters to the recording medium from a curved surface such as a rough surface or a cylindrical surface to a plane that is not parallel to the reflecting film.

The 0th-order light processing region R1 _DL deflects and reflects the 0th-order light of the signal light beam 12a toward one side of the track of the recording medium 10 and returns the incident diffraction of the same polarization component as the polarization component of the deflected reflected light. Achieve optical interference with light.

The deflected zero-order light is emitted from the incident side of the recording medium 10. Since the amount of deflected zero-order light returning to the condenser lens 160 can be controlled by the magnitude of the inclination angle of the zero-order light processing region R1 _DL , it is possible not to return light to the condenser lens 160.

  In recording / reproduction, when a film functioning as a quarter-wave plate is used as the optical rotation film 111 and recording is performed with, for example, P-polarized light (0th-order light zP and diffracted light rP), hologram recording is performed using diffracted light and 0th-order. Since it is possible when the directions of the polarization planes of light are the same, the interference in the recording medium 10 is a pair of P-polarized diffracted light rP and zero-order light zP (diffraction grating P1) incident together. An incident P-polarized diffracted light rP and a set (diffraction grating P2) of P-polarized reflected zero-order light zPdeflected to be reflected and deflected. The reproduction is executed in the same manner as the method shown in FIG.

<Fifth embodiment>
FIG. 15 shows a fifth embodiment. This is because the 0th-order light having the absorbing portion 112c that absorbs the 0th-order light is used instead of the 0th-order light processing region R1 _SC having the reflective protrusion 112a that reflects and scatters the 0th-order light to the recording medium in the third embodiment. Except for the formation of the processing region R1 _AB , it is the same as the hologram record carrier of the third embodiment. The absorber 112c can be realized by filling, for example, a recess in the 0th-order light processing region R1 _AB with an absorbing material that efficiently absorbs the used wavelength.

  In recording / reproduction, when a film functioning as a quarter-wave plate is used as the optical rotation film 111 and recording is performed with, for example, P-polarized light (0th-order light zP and diffracted light rP), hologram recording is performed using diffracted light and 0th-order. Since it is possible when the directions of the polarization planes of light are the same, the interference within the recording medium 10 is only a set of P-polarized diffracted light rP and 0th-order light zP (diffraction grating P1) incident together. is there. The reproduction is executed in the same manner as the method shown in FIG.

<Sixth embodiment>
Further, FIG. 16 shows a sixth embodiment. This is because, instead of the 0th-order light processing region R1 _SC having the reflection protrusion 112a that reflects and scatters the 0th-order light to the recording medium in the third embodiment, the 0th-order light processing region is incident on the 0th-order light. except that the cell region R1 _T i.e. 0 order light transmission without rotation to form a zero-order light processing area R1 _T having a transmission section 112d for transmitting the same as the hologram record carrier of the third embodiment. The transmission part 112d can also be realized by filling, for example, a through-opening part of the 0th-order light processing region R1 _{T with} a through-opening that penetrates the optical rotation film and the reflection film or a transmission material that efficiently transmits the used wavelength.

  In recording / reproduction, when a film functioning as a quarter-wave plate is used as the optical rotation film 111 and recording is performed with, for example, P-polarized light (0th-order light zP and diffracted light rP), hologram recording is performed using diffracted light and 0th-order. Since it is possible when the directions of the polarization planes of light are the same, the interference within the recording medium 10 is only a set of P-polarized diffracted light rP and 0th-order light zP (diffraction grating P1) incident together. is there. The reproduction is executed in the same manner as the method shown in FIG.

<Seventh embodiment>
In the hologram record carrier of the above embodiment, the incident light processing region provided integrally on the opposite side to the signal light incident side of the recording medium is either the zero-order light or the diffracted light processing region. Alternatively, the diffracted light is reflected by rotating its polarization plane. On the other hand, as shown in FIG. 17, the hologram record carrier of the seventh embodiment (embodiment (4) above) converts the 0th-order light and the diffracted light into the polarized light in both the 0th-order light and the diffracted light processing region. The incident light processing region R is configured to reflect the light by rotating the surfaces at different angles. That is, the incident light processing region R includes the 0th-order light processing region R1 _RRa that reflects the 0th-order light of the incident light beam by rotating its polarization plane at the first rotation angle, and the diffracted light of the incident light beam. The diffracted light processing region R2 _RRb reflects the polarization plane by rotating the polarization plane at a second rotation angle. The zero-order light processing region R1 _RRa may be formed as a track structure extending in the y direction.

The zero-order light and the diffracted light processing regions R1 _RRa and R2 _RRb of the incident light processing region R have their optical axes (crystal axes, etc.) oriented in a predetermined direction so as to rotate the polarization plane of the incident light beam by a predetermined angle. The optical rotation films 111a and 111b functioning as half-wave plates and the reflection film 112 laminated thereon are configured.

  At the time of recording, as shown in FIG. 17, the signal light 12a modulated by the spatial light modulator is incident on the recording medium 10, and the zero-order light and the diffracted light interfere to record a hologram. Hologram recording is possible when the directions of the polarization planes of the diffracted light and the 0th-order light are the same. Therefore, the interference in the recording medium 10 is one of the incident P-polarized diffracted light rP and the 0th-order light zP. A set (diffraction grating P1), a set of the P-polarized component of the diffracted light rB reflected and rotated in its polarization plane, and the incident zero-order light zP of the P-polarization (diffraction grating P2), the incident P-polarized diffracted light rP A set of P-polarized components (diffraction grating P3) of the 0th-order light zA reflected and whose polarization plane is rotated (diffractive grating P3), diffracted light rB whose reflection and polarization plane is rotated, and zero-order light zA whose reflection and polarization plane is rotated A set of respective P-polarized components (diffraction grating P4) and a set of S-polarized components (diffraction grating P5). Holograms recorded by these interferences are multiplexed at substantially the same position.

At the time of reproduction, as shown in FIG. 18, reference light (0th-order light) 12 is incident on the recording medium 10, and a P-polarized diffracted light rP and a hologram (diffraction grating P1) resulting from the 0th-order light zP, The reproduction wave RrP from the hologram (diffraction grating P2) due to the P-polarized component of the diffracted light rB whose reflection plane is rotated and the polarization plane is rotated and the incident 0th-order light zP of the P-polarized light is P-polarized and is opposite to the light source direction ( That is, it occurs in the forward direction of incidence. The P-polarized reproduction wave RrP passes through the optical rotation film 111 through the reflective film 112 in a reciprocating manner, and becomes B-polarized light RrB when emitted from the hologram record carrier. The reference light (0th order light) 12 passes through the recording medium 10 and then enters the recording medium 10 as 0th order light zA whose polarization plane is rotated and reflected by the 0th order light processing area R1 _RRa of the incident light processing area R. The Hologram (diffraction grating P3) caused by incident P-polarized diffracted light rP and P-polarized component of 0th-order light zA whose reflection and polarization plane has been rotated, diffracted light rB and reflection and polarization whose reflection and polarization plane have been rotated From the holograms (diffraction gratings P4) caused by the respective P-polarized components of the 0th-order light zA whose surfaces are rotated and the holograms (diffraction gratings P5) caused by the respective S-polarized components, the reproduced wave RrA is converted to the light source direction as A-polarized light. Occurs towards. From the recording medium 10, the reproduction wave RrB, the reproduction wave RrA, and the reference light zA are emitted. These are converted into parallel light by the condenser lens 160 and reach the polarization beam splitter 15. The same polarization component of the reproduction wave RrB, the reproduction wave RrA and the reference light zA in the S polarization direction of the polarization beam splitter 15 is reflected and guided to the image detection sensor 20. In this hologram reproducing apparatus, a rotation mechanism RoM is provided that can control the rotation of the polarization beam splitter 15 around the optical axis of the reference light together with the image detection sensor 20 while maintaining a relative positional relationship with the image detection sensor 20. By the rotation mechanism RoM, the direction of the polarization beam splitter 15 is adjusted so that the S polarization direction of the polarization beam splitter 15 is equal to the B polarization of the B polarization reproduction wave RrB. Therefore, the reproduction wave is reflected by the polarization beam splitter 15 and detected by the image detection sensor 20. In the reference light (0th-order light) reflected by the 0th-order light processing region R1 _RRa , the B-polarized component of the reference light is reflected by the polarization beam splitter 15, but the reference light amount detected by the image detection sensor 20 is reduced. When the zero-order light processing region R1 _RRa and the diffracted light processing region R2 _{RRb cause} the A-polarized light and the B-polarized light to be orthogonal to each other, the reference beam and the reproduction wave can be separated by the polarization beam splitter 15 and reproduced by the image detection sensor 20. Wave detection is easy.

<Eighth embodiment>
In the above-described embodiment, hologram recording / reproduction in which the diffracted light processing region R2 of the incident light processing region R reflects light has been shown. However, even if the diffracted light processing region R2 is used in a mode of transmitting incident light. The same effect can be demonstrated. That is, the embodiment includes the case where the diffracted light processing region R2 is the region R2 _T that transmits the diffracted light of the light beam.

FIG. 19 shows the hologram recording / reproducing apparatus of the eighth embodiment. This reproduces information from the hologram record carrier in which the 0th order light processing region and the diffracted light processing region of the incident light processing region transmit almost all incident light. However, in the recording medium 10 of the hologram record carrier, the 0th-order light processing region R1 _TR that transmits the 0th-order light of the light beam by rotating its polarization plane and the diffracted light of the light beam are transmitted through the incident light processing region R. The polarization plane is divided into a diffracted light processing region R2 _T that transmits without rotating (corresponding to the aspect (5) above). That is, at least one of the 0th-order light processing region R1 and the diffracted light processing region R2 is made light transmissive, and the direction of the polarization plane of the transmitted light is made different to separate the 0th-order light and diffracted light (including reproduced waves). .

  This hologram recording / reproducing apparatus does not use the half mirror HM of the apparatus shown in FIG. 3, and the light beam emitted from the recording medium 10 is connected to the polarization beam splitter 15 and the image detection sensor 20 on the optical system side that generates the reference light and the signal light. The optical system that generates the reference light and the signal light, and a converging lens 16a such as an inverse Fourier transform lens, the polarization beam splitter 15, and the image detection sensor 20 are aligned and used in recording. The apparatus is the same as that shown in FIG. 3 except that the reproduction wave is detected from the incident light processing region R on the exit side of the medium 10.

  The recording / reproducing process of the hologram record carrier of this embodiment will be described for the case where a P-polarized light source is used.

  The hologram record carrier mounted on the movable stage shown in FIG. 19 is configured by integrally coupling the incident light processing region R provided on the opposite side of the signal light 12a incident side to the recording medium 10. .

As shown in FIG. 20, the incident light processing region R in the hologram record carrier of the present embodiment includes a zero-order light processing region R1 _TR that rotates and transmits the zero-order light of the light beam, and a light beam It comprises a diffracted light processing region R2 _T that transmits diffracted light without rotating its polarization plane. The zero-order light processing region R1 _TR is made of, for example, an optical rotation film 111 that functions as a half-wave plate. The optical rotation film 111 is not limited to a half-wave plate, and other phase plates and films having the function of a wave plate can be used. The diffracted light processing region R2 _T is composed of a light transmission film 110 made of a transmission material that efficiently transmits the used wavelength. The diffracted light processing region R2 _T that does not require the light rotation action can be formed by the emission surface itself of the recording medium without providing a light transmission film.

At the time of recording, as shown in FIG. 20, the P-polarized signal light 12a (the 0th-order light zP and the diffracted light rP) is collected by the condenser lens 160, passes through the recording medium 10 of the hologram record carrier, and the 0th-order light. The processing region R1 _TR and the diffracted light processing region R2 _T in the vicinity thereof are irradiated.

The zero-order light zP becomes S-polarized zero-order light zS having a polarization plane direction different from the incident polarization plane direction by 90 degrees when it enters and transmits the optical rotation film 111 in the zero-order light processing region R1 _TR. . The S-polarized zero-order light zS is transmitted through the condenser lens 16a, thereby becoming parallel light, reflected by the polarizing beam splitter 15 shown in FIG. 19, and deviating from the optical path. On the other hand, the diffracted light rP of the signal light passes through the diffracted light processing region R2 _T as P-polarized light as it is, becomes parallel light by the condenser lens 16a, and also passes through the polarizing beam splitter 15 shown in FIG.

  Hologram recording is possible when the directions of the polarization planes of the 0th-order light and the diffracted light are the same. Therefore, interference in the recording medium 10 is caused by the incidence of both the P-polarized 0th-order light zP and the diffracted light rP. Only one set (diffraction grating P1). In FIG. 20, in order to facilitate understanding of the formation of each optical interference pattern, the propagation direction of diffracted light in hologram recording is indicated by a white arrow, and the propagation direction of zero-order light is indicated by a dark arrow.

At the time of reproduction, as shown in FIG. 21, the P-polarized reference light (0th-order light) 12 is collected by the condenser lens 160 along the same optical path as that at the time of recording and transmitted through the recording medium 10 of the hologram record carrier. The next light processing region R1 _TR is irradiated. Here, when the P-polarized reference light (0th-order light) zP is incident on and transmitted through the optical rotation film 111 in the 0th-order light processing region R1 _TR , the direction of the polarization plane is 90 degrees different from the direction of the incident polarization plane. S-polarized 0th-order light zS. The S-polarized zero-order light zS is transmitted through the condenser lens 16a, thereby becoming parallel light, reflected by the polarizing beam splitter 15 shown in FIG. 19, and deviating from the optical path.

The P-polarized reference light (0th-order light) generates a P-polarized 0th-order light zP and a reproduction wave RrP from the hologram (diffraction grating P1) caused by the diffracted light rP. It occurs in the direction opposite to the direction (that is, the forward direction of incidence). The P-polarized reproduction wave RrP passes through the diffracted light processing region R2 _T as it is. The P-polarized reproduction wave RrP is converted into parallel light by the condenser lens 16 a, passes through the polarization beam splitter 15, and reaches the image detection sensor 20. When the image detection sensor 20 at the focal length position reconverts the image of the reproduction wave into an electrical digital data signal and sends it to the decoder 26, the original data is reproduced.

  Since the P-polarized reproduction wave RrP and the reproduction reference light can be separated in this manner, unnecessary reference light does not enter the image detection sensor that receives the reproduction wave.

<Ninth embodiment>
The incident light processing region of the hologram record carrier of the eighth embodiment is configured to transmit the 0th order light by rotating the polarization plane in the 0th order light processing region. On the other hand, as shown in FIG. 22, the hologram record carrier of the ninth embodiment (aspect (6) above) transmits the incident zero-order light through the zero-order light processing region without rotating its polarization plane. An incident light processing region R is provided as a region R1 _T , and the diffracted light processing region is a region R2 _TR that transmits diffracted light by rotating its polarization plane. That is, the incident light processing region R includes a diffracted light processing region R2 _TR that transmits the diffracted light of the light beam by rotating its polarization plane, and a 0th order that transmits the 0th-order light of the light beam without rotating the polarization surface. It consists of a light processing region R1 _T. The diffracted light processing region R2 _TR is made of, for example, an optical rotating film 111 that functions as a half-wave plate. The optical rotation film 111 is not limited to a half-wave plate, and other phase plates and films having the function of a wave plate can be used. The 0th-order light processing region R1 _T is composed of a light transmissive film 110 made of a transmissive material that efficiently transmits the used wavelength. The zero-order light processing region R1 _T that does not require the light rotation action can be realized by a through opening that penetrates the optical rotation film 111 without providing a light transmission film. The 0th-order light processing region R1 _T may be formed as a track structure extending in the y direction.

  A recording / reproducing method according to the ninth embodiment will be described.

In the recording process, as shown in FIG. 22, the signal light 12a, for example, P-polarized light (0th-order light zP and diffracted light rP) is collected by the condenser lens 160, and transmitted through the recording medium 10 of the hologram record carrier. The zero-order light processing region R1 _T and the diffracted light processing region R2 _TR in the vicinity thereof are irradiated.

  The polarization plane of the 0th-order light zP of the signal light does not rotate, passes through the recording medium 10 as the P-polarized 0th-order light zP, and also passes through the polarization beam splitter 15.

On the other hand, the diffracted light rP is incident on the optical rotation film 111 of the diffracted light processing area R2 _TR, the direction of S-polarized diffracted light rS of 90 degrees from the polarization plane to the direction of the polarization plane which is incident upon the transmitted. The S-polarized diffracted light rS passes through the condenser lens 16a and is reflected by the polarizing beam splitter if there is one.

  Hologram recording is possible when the directions of the polarization planes of the diffracted light and the 0th-order light are the same. Therefore, interference in the recording medium 10 is caused by the incident P-polarized diffracted light rP and 0th-order light zP. Only one set (diffraction grating P1). In FIG. 22, in order to facilitate understanding of the formation of each optical interference pattern, the propagation direction of diffracted light in hologram recording is indicated by a white arrow, and the propagation direction of zero-order light is indicated by a dark arrow.

In the reproduction process, as shown in FIG. 23, the P-polarized reference light (0th-order light) 12 is collected by the condenser lens 160, passes through the recording medium 10 of the hologram record carrier, and is subjected to the 0th-order light processing region. Irradiate R1 _T. Here, the zero-order light zP passes through the recording medium 10 as it is, and also passes through the polarizing beam splitter if there is one.

A reproduction wave is generated by P-polarized reference light (0th-order light). The reproduction wave RrP from the hologram (diffraction grating P1) caused by the P-polarized diffracted light rP and the 0th-order light zP incident on both is generated as P-polarized light in the direction opposite to the light source direction (that is, the incident forward direction). Then, the P-polarized reproduction wave RrP passes through the optical rotating film 111 in the diffracted light processing region R2 _TR , and becomes S-polarized light when emitted from the hologram record carrier. These S-polarized reproduction waves RrS are converted into parallel light by the condenser lens 16a, and reflected by a polarizing beam splitter, if any.

  With the polarization beam splitter 15, the S-polarized reproduction wave RrS can be separated from the optical path of the reference light (0th-order light) 12 and supplied to the image detection sensor. Since the P-polarized reproduction wave RrP and the reference light can be separated in this way, unnecessary reference light does not enter the image detection sensor that receives the reproduction wave.

  Therefore, the hologram recording / reproducing apparatus for reproducing information from the medium of the ninth embodiment, as shown in FIG. 24, separates the S-polarized reproduction wave RrS from the optical path of the reference light beam 12 and guides it to the image detection sensor 20. Except for the provision of the polarizing beam splitter 15 and the image detection sensor 20, this is the same as that of the eighth embodiment.

<Tenth embodiment>
FIG. 25 shows a tenth embodiment (one of the above aspects (7)). This is because, instead of the diffracted light processing region R2 _RR that rotates the polarization plane and reflects the diffracted light of the light beam in the third embodiment (FIG. 13), the diffracted light is converted into the polarization plane without providing the reflective film 112. Is the same as the hologram record carrier of the third embodiment, except that the region R2 _TR that is transmitted by rotating is formed. That is, the incident light processing region R reflects and scatters the diffracted light processing region R2 _TR that transmits the diffracted light of the light beam by rotating its polarization plane and the 0th order light of the light beam without rotating the polarizing surface. And a next light processing region R1 _SC . A zero-order light processing region R1 _SC that scatters only the zero-order light of the signal light beam 12a can be provided inside along the track (y direction). Further, the zero-order light processing region R1 _SC extends in the y direction, and a plurality of the zero-order light processing regions R1 _SC can be provided intermittently on the line, thereby supporting position information in the recording medium 10 of the zero-order light processing region R1 _SC. Can be made. The 0th-order light processing region R1 _SC returns the 0th-order light of the signal light beam 12a to the recording medium 10 in a scattered state, and achieves hologram recording using this and optical interference caused by incident 0th-order light and diffracted light as interference fringes. .

  A diffraction grating recording process in the recording medium 10 using the 0th-order light and diffracted light of the signal light beam 12a will be described. The signal light beam 12a applied to the recording medium 10 generates an optical interference pattern between the same P-polarized light of the zeroth-order light and the diffracted light, and a diffraction grating P1 corresponding to the optical interference pattern is formed in the recording medium 10 by the photorefractive effect. To be recorded.

The 0th-order light of the signal light beam 12a is scattered by the 0th-order light processing region R1 _SC of the incident light processing region R, and is again incident on the recording medium 10 as the 0th-order scattered light zPscattered. Diffracted light of the signal light beam 12a passes through the diffractive optical processing area R2 _TR of the incident light processing area R, and is emitted to the opposite side of the incident side of the recording medium 10.

  A light interference pattern between the same P-polarized light of the 0th-order light and the diffracted light scattered by the signal light beam 12a is generated in the recording medium 10, and a diffraction grating P2 corresponding to the light interference pattern is formed by the photorefractive effect in the recording medium. 10 is recorded.

  Therefore, in the modified example shown in FIG. 25, the diffraction gratings P1 and P2 by the photorefractive effect corresponding to at least each of the optical interference patterns are hologram-recorded in the recording medium 10. In FIG. 25, in order to facilitate the understanding of the formation of each optical interference pattern, the propagation direction of diffracted light in hologram recording is indicated by a white arrow, and the propagation direction of zero-order light is indicated by a dark arrow.

  Next, a reproduction process in the recording medium 10 using the reference light beam 12 (0th order light) will be described.

When the recording medium 10 is irradiated with the same P-polarized reference light beam 12 (0th order light) at the time of reproduction at the same angle and position as the signal light beam at the time of recording, the reference light beam 12 (0th order light) is generated in the recording medium 10. Irradiated to the diffraction grating P1, the same P-polarized reproduction wave is generated from the diffraction grating P1 corresponding to the recording information. Next, the reference light beam 12 (0th-order light) is scattered by the 0th-order light processing region R1 _SC of the incident light processing region R and is incident on the recording medium 10 again. The scattered zeroth-order light is applied to the diffraction grating P2 in the recording medium 10, and a P-polarized reproduction wave is generated from the diffraction grating P2 corresponding to the recording information.

These reproduced waves pass through the diffracted light processing region R2 _TR of the incident light processing region R, are emitted to the opposite side of the incident side of the recording medium 10, and pass through the condenser lens 16a. Therefore, at the time of reproduction, at least the reproduction wave is emitted from the side opposite to the incident side of the recording medium 10 and passes through the condenser lens 16a. The subsequent steps are the same as those in the embodiment shown in FIGS.

  Since the scattered zero-order light is emitted from the incident side of the recording medium 10, there is almost no light passing through the condenser lens 16 a, and the image detection sensor 20 hardly receives the light, so that the recorded information can be easily reproduced. .

<Eleventh embodiment>
FIG. 26 shows an eleventh embodiment. Except this, in place of the 0-order light processing area R1 _SC in the tenth embodiment was formed 0-order light processing area R1 _DL having an inclined reflection surface 112b for deflecting biased internally reflects the zero-order light, first This is the same as the hologram record carrier of the tenth embodiment. That is, the incident light processing region R includes the diffracted light processing region R2 _TR that transmits the diffracted light of the light beam by rotating the polarization plane thereof, and the 0th-order light of the signal light beam 12a inside without rotating the polarization plane. It consists of a 0th-order light processing region R1 _DL to be reflected and deflected. The zero-order light processing region R1 _DL can be provided inside in a track shape, and a plurality of zero-order light processing regions R1 _DL can be provided on a line intermittently. As a result, position information in the recording medium 10 of the 0th-order light processing region R1 _DL can be carried. The track-shaped 0th-order light processing region R1 _DL extending in the y direction reflects and returns the 0th-order light of the signal light beam 12a by deflecting it toward one side of the track of the recording medium 10, and incident 0 Hologram recording is achieved by using optical interference by the next light and diffracted light as interference fringes.

  At the time of recording, the signal light beam 12a applied to the recording medium 10 generates an optical interference pattern between the P-polarized light of the 0th-order light and the diffracted light, and the diffraction grating P1 corresponding to the optical interference pattern is formed by the photorefractive effect. 10 is recorded.

Further, 0-order light of the signal light beam 12a is deflected and reflected by the 0-order light processing area R1 _DL of the incident light processing area R, it is incident as a 0-order deflected light zPdeflected again recording medium 10. Diffracted light of the signal light beam 12a passes through the diffractive optical processing area R2 _TR of the incident light processing area R, and is emitted to the opposite side of the incident side of the recording medium 10.

  In the recording medium 10, an optical interference pattern between the P-polarized light of the 0th-order light deflected by the signal light beam 12 a and the diffracted light is generated, and the diffraction grating P 2 corresponding to the optical interference pattern is formed by the photorefractive effect in the recording medium 10. Recorded in.

  Accordingly, the diffraction gratings P1 and P2 by the photorefractive effect corresponding to each of the optical interference patterns are recorded in the recording medium 10 as a hologram.

  Next, a reproduction process in the recording medium 10 using the reference light beam 12 (0th order light) will be described.

When the recording medium 10 is irradiated with the reference light beam 12 (0th order light) at the time of reproduction at the same angle and position as the signal light beam at the time of recording, the reference light beam 12 (0th order light) is the diffraction grating P1 in the recording medium 10. The P-polarized reproduction wave is generated from the diffraction grating P1 corresponding to the recording information. Next, the reference light beam 12 (0th-order light) is deflected and reflected by the 0th-order light processing region R1 _DL of the incident light processing region R, and is incident on the recording medium 10 again. The deflected zero-order light is applied to the diffraction grating P2 in the recording medium 10, and a P-polarized reproduction wave is generated from the diffraction grating P2 corresponding to the recording information.

These P-polarized reproduction wave is transmitted through the diffractive optical processing area R2 _TR of the incident light processing area R, passing through the emitted condenser lens 16a on the opposite side of the incident side of the recording medium 10. Therefore, at the time of reproduction, at least the reproduction wave is emitted from the side opposite to the incident side of the recording medium 10 and passes through the condenser lens 16a. The subsequent steps are the same as those in the embodiment shown in FIGS.

  Since the deflected zero-order light is emitted from the incident side of the recording medium 10, since there is no light passing through the condenser lens 16a, the image detection sensor 20 does not receive the light and recording information can be easily reproduced.

<Twelfth embodiment>
FIG. 27 shows a twelfth embodiment. This is in place of the 0-order light processing area R1 _SC in the tenth embodiment, only except for forming the 0-order light processing area R1 _R having a reflective surface 112 for reflecting hologram recording of the tenth embodiment of the 0-order light Identical to the carrier. That is, the incident light processing region R includes the diffracted light processing region R2 _TR that transmits the diffracted light of the light beam by rotating the polarization plane thereof, and the 0th-order light of the signal light beam 12a inside without rotating the polarization plane. It consists of a 0th-order light processing region R1 _R to be reflected. The zero-order light processing region R1 _R can be provided inside in a track shape, and a plurality of zero-order light processing regions R1 _R can be provided on a line intermittently. As a result, position information on the recording medium 10 in the zero-order light processing region R1 _R can be carried. The track-shaped 0th-order light processing region R1 _R extending in the y direction reflects and returns the 0th-order light of the signal light beam 12a by deflecting it toward one side of the track of the recording medium 10 and incident 0 Hologram recording is achieved by using optical interference by the next light and diffracted light as interference fringes.

  At the time of recording, the signal light beam 12a applied to the recording medium 10 generates an optical interference pattern between the P-polarized light of the 0th-order light and the diffracted light, and the diffraction grating P1 corresponding to the optical interference pattern is formed by the photorefractive effect. 10 is recorded.

Further, the 0th-order light of the signal light beam 12a is reflected and reflected by the 0th-order light processing region R1R of the incident light processing region _R , and again enters the recording medium 10 as the 0th-order reflected light zPreflected. Diffracted light of the signal light beam 12a passes through the diffractive optical processing area R2 _TR of the incident light processing area R, and is emitted to the opposite side of the incident side of the recording medium 10.

  An optical interference pattern between the P-polarized light of the 0th-order light and the diffracted light reflected by the signal light beam 12a is generated in the recording medium 10, and the diffraction grating P2 corresponding to the optical interference pattern is formed by the photorefractive effect in the recording medium 10. Recorded in.

  Accordingly, the diffraction gratings P1 and P2 by the photorefractive effect corresponding to each of the optical interference patterns are recorded in the recording medium 10 as a hologram.

  Next, a reproduction process in the recording medium 10 using the reference light beam 12 (0th order light) will be described.

When the recording medium 10 is irradiated with the reference light beam 12 (0th order light) at the time of reproduction at the same angle and position as the signal light beam at the time of recording, the reference light beam 12 (0th order light) is the diffraction grating P1 in the recording medium 10. The P-polarized reproduction wave is generated from the diffraction grating P1 corresponding to the recording information. Next, the reference light beam 12 (0th-order light) is reflected by the 0th-order light processing region R1 _R of the incident light processing region R and is incident on the recording medium 10 again. The reflected zero-order light is applied to the diffraction grating P2 in the recording medium 10, and a P-polarized reproduction wave is generated from the diffraction grating P2 corresponding to the recording information.

These P-polarized reproduction wave is transmitted through the diffractive optical processing area R2 _TR of the incident light processing area R, passing through the emitted condenser lens 16a on the opposite side of the incident side of the recording medium 10. Therefore, at the time of reproduction, at least the reproduction wave is emitted from the side opposite to the incident side of the recording medium 10 and passes through the condenser lens 16a. The subsequent steps are the same as those in the embodiment shown in FIGS.

  Since the reflected zero-order light is emitted from the incident side of the recording medium 10, there is no light passing through the condenser lens 16 a, so that it is not received by the image detection sensor 20, and the recorded information can be easily reproduced.

<Thirteenth embodiment>
FIG. 28 shows a thirteenth embodiment. This is because the hologram recording carrier of the tenth embodiment is formed except that the zero-order light processing region R1 _AB having the absorbing portion 112c that absorbs the zero-order light is formed instead of the zero-order light processing region R1 _SC in the tenth embodiment. Is the same. Absorbing portion 112c can be realized by filling an absorbent material that absorbs the wavelength used efficiently 0 order light processing area R1 _AB example in coating or recess.

  In recording and reproduction, when a film functioning as a half-wave plate is used as the optical rotation film 111 and recording is performed with, for example, P-polarized light (0th-order light zP and diffracted light rP), hologram recording is performed using diffracted light and 0th-order. Since it is possible when the directions of the polarization planes of light are the same, the interference within the recording medium 10 is only a set of P-polarized diffracted light rP and 0th-order light zP (diffraction grating P1) incident together. is there. Regeneration is performed in the same manner as in the embodiment of FIGS.

<14th embodiment>
FIG. 29 shows a fourteenth embodiment (embodiment (8) above). This constitutes the incident light processing region R so that both the 0th order light and the diffracted light processing region transmit the 0th order light and the diffracted light by rotating their polarization planes at different angles. That is, the incident light processing region R includes the 0th-order light processing region R1 _TRa that transmits the 0th-order light of the incident light beam as A-polarized light by rotating its polarization plane at the first rotation angle, the signal light beam, and the reference light. The diffracted light processing region R2 _TRb transmits the diffracted light of the light beam as B-polarized light by rotating the polarization plane at the second rotation angle. The zero-order light processing region R1 _TRa may be formed as a track structure extending in the y direction.

The zero-order light and the diffracted light processing regions R1 _TRa and R2 _TRb of the incident light processing region R have their optical axes (crystal axes, etc.) oriented in a predetermined direction so as to rotate the polarization plane of the incident light beam by a predetermined angle. The optical rotation films 111a and 111b function as half-wave plates.

At the time of recording, as shown in FIG. 29, the signal light 12a modulated by the spatial light modulator is incident on the recording medium 10, and the zero-order light and the diffracted light interfere to record a hologram. Hologram recording is possible when the directions of the polarization planes of the diffracted light and the 0th-order light are the same. Therefore, interference in the recording medium 10 is caused by the incident P-polarized diffracted light rP and 0th-order light zP. Only one set (diffraction grating P1). The 0th order light is transmitted through the 0th order light processing region R1 _TRa with its polarization plane rotated. Diffracted light is transmitted through the diffracted light processing region R2 _TRb with its polarization plane rotated.

At the time of reproduction, reference light (0th-order light) 12 is incident on the recording medium 10, and a reproduction wave from the hologram (diffraction grating P1) caused by the P-polarized 0th-order light zP and the diffracted light rP incident thereon is converted to P-polarized light. A regenerative wave is generated in the direction opposite to the light source direction (that is, in the incident forward direction). The P-polarized reproduction wave passes through the optical rotating film 111b (diffracted light processing region R2 _TRb ), and becomes B-polarized light when emitted from the hologram record carrier. The B-polarized reproduction wave is converted into parallel light by the condenser lens 16a and reaches the polarization beam splitter.

As shown in FIG. 30, the polarization beam splitter 15 separates the B-polarized reproduction wave from the optical path of the reference light (0th-order light) 12. In the hologram reproducing apparatus of this embodiment, a rotation mechanism RoM is provided that can control the rotation of the polarization beam splitter 15 around the optical axis of the reference light together with the image detection sensor 20 while maintaining a relative positional relationship with the image detection sensor 20. Yes. By the rotation mechanism RoM, the direction of the polarization beam splitter 15 is adjusted so that the S polarization direction of the polarization beam splitter 15 and the B polarization of the B polarization reproduction wave are equal. Therefore, the reproduction wave is reflected by the polarization beam splitter 15 and detected by the image detection sensor 20. The reference light (0th-order light) transmitted through the 0th-order light processing region R1 _TRa reflects the B-polarized component of the reference light by the polarization beam splitter 15, but the reference light amount detected by the image detection sensor 20 decreases. If the relationship between the A-polarized light and the B-polarized light is made orthogonal by the action of the 0th-order light processing region R1 _TRa and the diffracted light processing region R2 _TRb , the reference beam and the reproduction wave can be separated by the polarization beam splitter 15 and reproduced by the image detection sensor 20. Wave detection is easy.

  As described above, the recording medium 10 and the incident light processing region R are described as being integrated in the above embodiment, so that hologram recording / reproducing can be summarized as shown in Table 1 below.

＜第１５−２８実施例＞
記録媒体１０と入射光処理領域Ｒが一体化した形態以外に、記録媒体１０と入射光処理領域Ｒとを離して別体化して、入射光処理領域Ｒを装置側に設けても同等のホログラムの記録及び／又は再生の効果が発揮される。以下に、入射光処理領域Ｒを装置側に設けた実施例を示す。

<Example 15-28>
Besides the form in which the recording medium 10 and the incident light processing region R are integrated, the same hologram can be obtained even if the recording medium 10 and the incident light processing region R are separated and separated, and the incident light processing region R is provided on the apparatus side. The effect of recording and / or reproducing is exhibited. Hereinafter, an embodiment in which the incident light processing region R is provided on the apparatus side will be described.

  FIG. 31 shows a hologram recording / reproducing apparatus according to an embodiment in which an incident light processing region R is provided on the apparatus side. The recording medium 10 is inserted from a slot of a predetermined apparatus and fixed at a predetermined position with respect to the incident light processing region R inside the hologram recording / reproducing apparatus. The incident light processing region R on the apparatus side has a function of separating the 0th-order light and diffracted light of the incident light and returning a part of the light to the inside of the recording medium 10 as described above. The incident light processing region R is held by a movable stage 60a that is translationally controlled in the xy direction inside the apparatus housing. The pickup unit PU is provided facing the incident light processing region R so that the reference light and the signal light are transmitted through the recording medium 10. Inside the pickup unit PU are optical systems such as the light source LED, shutter SHs, beam expander BX, spatial light modulator SLM, half mirror HM, polarization beam splitter 15, condenser lens 160, and image detection sensor 20 described above. Is provided. The pickup unit PU is also provided with a focusing and tracking servo control mechanism (not shown) so that the light beam can be focused on the incident light processing region R via the recording medium 10. The incident light processing region R and the recording medium 10 to be mounted are provided with position markers that fit together, for example, for alignment between them.

The zero-order light processing region R1 of the incident light processing region R performs a process of making the polarization plane different from that of the diffracted light processing region R2. For example, the incident light processing region R includes a 0th-order light processing region R1 _RR that rotates and reflects the 0th-order light of the incident light, and corresponds to the first embodiment, and a diffracted light that has the polarization surface. And a diffracted light processing region R2 _R that reflects without rotating. Therefore, the hologram recording / reproducing apparatus shown in FIG. 31 has the same configuration as that of the apparatus shown in FIG. 3 except that the incident light processing region R is provided separately from the recording medium on the apparatus side.

  Therefore, according to the configuration of the hologram recording / reproducing apparatus shown in FIG. 31, the hologram recording / reproducing apparatus (recording medium 10 and incident light processing region R) of the fifteenth to twenty-first examples shown in Table 2 below for each of the first to seventh examples. Can be separated and the apparatus side can be provided with an incident light processing region R). Further, according to the configuration of the hologram recording / reproducing apparatus according to the embodiment in which the incident light processing region R shown in FIG. 32 is provided on the apparatus side, each of the above-described eighth to fourteenth examples corresponds to the twenty-second to twenty-eighth examples in Table 2 below. A hologram recording / reproducing apparatus (the recording medium 10 and the incident light processing region R are separated and the incident light processing region R is provided on the apparatus side) can be manufactured. In the hologram recording / reproducing apparatus of FIG. 32, the recording medium 10 is inserted from a slot of a predetermined apparatus and fixed at a predetermined position with respect to the incident light processing region R inside the hologram recording / reproducing apparatus. The incident light processing region R on the apparatus side has a function of separating the 0th order light and the diffracted light of the incident light from the recording medium 10 and emitting at least the diffracted light to the opposite side of the incident side as described above. The incident light processing region R is held by a movable stage 60a that is translationally controlled in the xy direction inside the apparatus housing. The pickup unit PU1 is provided to face the incident light processing region R so that the reference light and the signal light are transmitted through the recording medium 10. The pickup unit PU1 includes an optical system such as the light source LED, shutter SHs, beam expander BX, spatial light modulator SLM, and condenser lens 160 described above, and the light receiving unit PU2 includes a polarization beam splitter 15 and a collecting beam. Optical systems such as the optical lens 16a and the image detection sensor 20 are provided.

＜第２９実施例＞
また、記録媒体１０の形態はカードなど種々の形状で構成できるが、図３３に示すように、ディスク状の記録媒体１０をカートリッジＣＲに収納してそのケース内壁面に入射光処理領域Ｒを設けることもできる。ディスク状の記録媒体１０中央のクランプ接合部にクランプに嵌合する媒体側位置マーカや、装置への固定用のカートリッジ側位置マーカを設けることにより、的確なアライメントが可能となる。

<Twenty-ninth embodiment>
The form of the recording medium 10 can be configured in various shapes such as a card. As shown in FIG. 33, the disk-shaped recording medium 10 is accommodated in the cartridge CR and an incident light processing region R is provided on the inner wall surface of the case. You can also. By providing a medium side position marker that fits into the clamp at the center of the disc-shaped recording medium 10 and a cartridge side position marker for fixing to the apparatus, accurate alignment is possible.

<Other examples>
In the above embodiment, the hologram recording / reproducing method and the hologram recording / reproducing apparatus have been described as examples. However, the present invention clearly includes a hologram recording method, a hologram reproducing method, a hologram recording apparatus, and a hologram reproducing apparatus. In the above embodiment, an example of so-called two-dimensional modulation in which spatial modulation is performed according to two-dimensional data has been described. However, the present invention is a one-dimensional modulation hologram recording that is spatially modulated according to one-dimensional data. It can also be applied to playback.

It is a schematic block diagram which shows the conventional hologram recording / reproducing system. It is a schematic perspective view which shows an example of the hologram recording carrier by this invention. It is a schematic block diagram explaining the hologram recording / reproducing apparatus of embodiment by this invention. It is a schematic sectional drawing which shows the hologram recording carrier in the hologram recording / reproducing apparatus of embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of embodiment by this invention. It is a schematic sectional drawing explaining the reproducing process in the hologram recording / reproducing apparatus of embodiment by this invention. It is a schematic plan view explaining the relationship between the hologram record carrier and spatial light modulator of the embodiment according to the present invention. It is a schematic perspective view explaining the relationship between the hologram record carrier and spatial light modulator of embodiment by this invention. It is a schematic sectional drawing which shows the hologram record carrier in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic block diagram explaining the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the reproducing process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the reproducing process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic block diagram explaining the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the reproducing process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the reproducing process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic block diagram explaining the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic sectional drawing explaining the recording process in the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic block diagram explaining the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic perspective view which shows the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic perspective view which shows the hologram recording / reproducing apparatus of other embodiment by this invention. It is a schematic perspective view which shows the recording medium cartridge in the hologram recording / reproducing apparatus of other embodiment by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Recording medium 11 Hologram record carrier 15 Polarization beam splitter 20 Image detection sensor 25 Encoder 26 Decoder 32 Controller 16a, 160 Condensing lens 112 Reflective film 112a Protrusion part 112b Inclination reflection surface 112c Absorption part 112d Transmission part LED light source SHs Shutter BX Beam extract Panda SLM Spatial light modulator HM Half mirror R1 0th order light processing region R2 Diffracted light processing region PU Pickup unit

Claims (28)

  A hologram recording carrier on which information is recorded or reproduced by a diffraction grating by irradiation with a coherent light beam, wherein the recording medium portion is made of a photosensitive material, and the recording medium portion is opposite to the incident side of the light beam. And an incident light processing region that makes the polarization plane of the 0th-order light and the polarization plane of the diffracted light of the light beam incident through the recording medium portion different from each other. Record carrier.   2. The hologram record carrier according to claim 1, wherein the incident light processing region portion has a region that reflects at least diffracted light of the light beam to the recording medium portion.   The incident light processing region portion includes a zero-order light processing region portion that reflects the zero-order light of the light beam by rotating its polarization plane, and a diffracted light processing region portion that reflects the diffracted light of the light beam. The hologram record carrier according to claim 2.   The incident light processing region includes a zero-order light processing region that reflects the zero-order light of the light beam, and a diffracted light processing region that reflects the diffracted light of the light beam by rotating its polarization plane. The hologram record carrier according to claim 2.   The incident light processing region portion transmits, scatters, deflects, or absorbs the zero-order light of the light beam, and diffracted light that reflects the diffracted light of the light beam by rotating its polarization plane. The hologram record carrier according to claim 2, further comprising a processing region portion.   The incident light processing area section reflects the 0th-order light processing area section that reflects the 0th-order light of the light beam by rotating its polarization plane at the first rotation angle, and the diffracted light of the light beam is polarized. 3. The hologram record carrier according to claim 2, further comprising: a diffracted light processing region portion that reflects the surface by rotating the polarization plane at a second rotation angle.   2. The hologram record carrier according to claim 1, wherein the incident light processing region has a region that transmits at least the diffracted light of the light beam.   The incident light processing region portion includes a zero-order light processing region portion that transmits the zero-order light of the light beam by rotating its polarization plane, and a diffracted light processing region portion that transmits the diffracted light of the light beam. 8. The hologram record carrier according to claim 7, wherein:   The incident light processing region has a zero-order light processing region that transmits the zero-order light of the light beam, and a diffracted light processing region that transmits the diffracted light of the light beam by rotating its polarization plane. 8. The hologram record carrier according to claim 7, wherein:   The incident light processing region portion is a zero-order light processing region portion that scatters, deflects, reflects or absorbs the zero-order light of the light beam, and diffracted light that transmits the diffracted light of the light beam by rotating its polarization plane. The hologram record carrier according to claim 7, further comprising a processing region portion.   The incident light processing region unit transmits the zero-order light of the light beam by rotating the polarization plane thereof at a first rotation angle and transmits the diffracted light of the light beam. 8. The hologram record carrier according to claim 7, further comprising: a diffracted light processing region portion that rotates the plane of polarization at a second rotation angle to transmit the surface.   The hologram record carrier according to claim 1, wherein the incident light processing region has a linear track in a part thereof.   13. The hologram record carrier according to claim 12, wherein the track has position information of the incident light processing region portion in the recording medium portion. The coherent reference light beam to generate a spatially modulated to the signal light beam in accordance with recording information, said signal light beam, so as to pass from the recording medium part composed of a light-sensitive material to the entry Shako processing area unit And a recording step of irradiating the recording medium portion to form a diffraction grating region by an optical interference pattern at a portion where the 0th-order light and diffracted light of the signal light beam in the recording medium portion interfere with each other. A recording method, wherein a polarization plane of zero-order light and a polarization plane of diffracted light of the signal light beam incident through the recording medium portion on the opposite side of the recording medium portion from the incident side of the signal light beam hologram recording method, wherein a provided with the incident light processing area portion made different from each other. A coherent reference light beam is spatially modulated according to recording information to generate a signal light beam, and the signal light beam passes from the recording medium portion made of a photosensitive material to the incident light processing region portion. A recording step of irradiating the recording medium portion with the optical interference pattern to form a diffraction grating region in a portion where the 0th-order light and diffracted light of the signal light beam interfere with each other in the recording medium portion. A hologram reproducing method for reproducing recorded information,
Providing the incident light processing region for making the polarization plane of the zero-order light and the polarization plane of the diffracted light of the light beam transmitted through the recording medium portion different; and
A reproduction wave corresponding to the signal light beam is formed by irradiating the region of the diffraction grating so that the reference light beam passes through the formed diffraction grating region from the recording medium unit to the incident light processing region unit. A regeneration process that produces
And a step of separating the reference light beam and the reproduction wave. A hologram apparatus for recording recorded information as a diffraction grating area and / or reproducing recorded information from the diffraction grating area,
A support part for holding a recording medium part made of a photosensitive material in a freely attachable manner;
A light source for generating a coherent reference light beam;
A signal light generation unit including a spatial light modulator that spatially modulates the reference light beam according to recording information to generate a signal light beam;
The signal light beam is irradiated onto the recording medium unit to enter and pass through the recording medium unit, and diffraction is caused by a light interference pattern at a portion of the recording medium unit where the 0th-order light and diffracted light of the signal light beam interfere. A pickup unit that forms a region of the grating, and irradiates the region of the diffraction grating with the reference light beam to generate a reproduction wave corresponding to the signal light beam;
An incident light processing region portion that is disposed on the opposite side of the recording medium portion from the incident side of the signal light beam, and that makes the polarization plane of the zero-order light and the polarization plane of the diffracted light different from each other;
A separation unit for separating the reference light beam and the reproduction wave;
And a detection unit that detects recording information imaged by the reproduction wave. The hologram apparatus according to claim 16, wherein the incident light processing region portion has a region that reflects at least diffracted light of the signal light beam to the recording medium portion. The incident light processing region portion includes a zero-order light processing region portion that reflects the zero-order light of the signal light beam and the reference light beam by rotating their polarization planes, and a diffraction that reflects the diffracted light of the signal light beam. The hologram apparatus according to claim 17, further comprising a light processing region portion. The incident light processing region portion includes a zero-order light processing region portion that reflects zero-order light of the signal light beam and the reference light beam, and diffraction that reflects the diffracted light of the signal light beam by rotating its polarization plane. The hologram apparatus according to claim 17, further comprising a light processing region portion. The incident light processing area unit transmits, scatters, deflects or absorbs the 0th order light of the signal light beam and the reference light beam, and the polarization plane of the diffracted light of the signal light beam. The hologram apparatus according to claim 17, further comprising a diffracted light processing region portion that is rotated and reflected. The incident light processing area unit reflects the 0th order light of the signal light beam and the reference light beam by rotating a polarization plane thereof at a first rotation angle, and reflects the signal light beam. 18. The hologram apparatus according to claim 17, further comprising: a diffracted light processing region portion that reflects the diffracted light of the light by rotating the polarization plane at a second rotation angle. The hologram apparatus according to claim 16, wherein the incident light processing region has a region that transmits at least the diffracted light of the signal light beam. The incident light processing region portion includes a zero-order light processing region portion that transmits the signal light beam and the zero-order light of the reference light beam by rotating their polarization planes, and a diffraction that transmits the diffracted light of the signal light beam. The hologram apparatus according to claim 22, further comprising a light processing region portion. The incident light processing region includes a zero-order light processing region that transmits the zero-order light of the signal light beam and the reference light beam, and diffraction that transmits the diffracted light of the signal light beam by rotating its polarization plane. The hologram apparatus according to claim 22, further comprising a light processing region portion. The incident light processing region portion has a zero-order light processing region portion that scatters, deflects, reflects or absorbs the zero-order light of the signal light beam and the reference light beam, and the polarization plane of the diffracted light of the signal light beam. 23. The hologram apparatus according to claim 22, further comprising a diffracted light processing region portion that is rotated and transmitted. The incident light processing area unit transmits the 0th order light of the signal light beam and the reference light beam by rotating the polarization plane thereof at a first rotation angle, and transmits the signal light beam. 23. The hologram apparatus according to claim 22, further comprising: a diffracted light processing region section that transmits the diffracted light of the first rotation by rotating the polarization plane at a second rotation angle. A spatial light modulator comprising a matrix of rows and columns of pixels for spatially modulating the reference light beam, so that the zero-order light processing region is not irradiated with the diffracted light of the signal light beam; 27. The hologram apparatus according to any one of claims 18 to 21 and 23 to 26, wherein the recording medium section and the recording medium section are relatively disposed. The spatial light modulator and the recording medium section are arranged such that the extension direction of the row or column of the spatial light modulator and the extension direction of the zero-order light processing area section intersect at a predetermined angle θ (θ ≠ 0). 28. The hologram apparatus according to claim 27, wherein the two are arranged relatively.

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