JP2007149254A - Optical information recording/reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording/reproducing device capable of eliminating aligning between a spatial light modulation element and a light receiving element and an expensive relay lens system, and obtaining a reproducing signal with good S/N simultaneously with reductions in cost and size of an optical system. <P>SOLUTION: When information is recorded or reproduced to/from a hologram disk by using a holographic memory technology, a spatial light modulation element SLM and a light receiving element (CMOS sensor or the like) are formed on the same substrate, and a shifting means 124 for performing parallel shift of parallel luminous fluxes made incident on the spatial light modulation element and the light receiving element is provided. The shifting means 124 switches the state of not shifting the parallel luminous fluxes and the state of shifting the parallel luminous fluxes between the recording time and the reproducing time of information to/from the hologram disk 118. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical information recording / reproducing apparatus, and more particularly to optical information recording for recording information on a recording medium for recording information using holography technology or reproducing information from a recording medium on which information is recorded. The present invention relates to a playback device.

  Conventionally, as a well-known literature of holographic memory, for example, “Measurement and nano-control technology supporting holographic memory / HVD (TM)” (Proceeding of 35th Meeting on Lightwave Sensing Technology (LST35-12) June, 2005) Kochi, Hideyoshi Horime) (Non-Patent Document 1). Hereinafter, the holographic memory technology according to the same document will be described.

  FIG. 11 is a diagram for explaining an optical system of a coaxial type holographic memory (collinear method). First, a case where recording is performed on the hologram disk 216, which is a recording medium, using the optical system will be described. The light beam emitted from the green laser 201 as the light source is converted into a parallel light beam by the collimator 202 and reflected by the mirror 203 to illuminate the spatial light modulator SLM 204.

  In FIG. 11, a DMD (Deformable Mirror Device) is used as the SLM 204. The light reflected by the pixel representing the information “1” on the SLM 204 is reflected in the direction of the hologram disk 216, and the light reflected by the pixel representing the information “0” is not reflected in the direction of the hologram disk 216. On the collinear SLM 204, there are provided a portion for modulating the information light 206 and a portion for modulating the reference light 205 surrounding the ring.

  The reference light 205 and the information light 206 reflected by the pixel representing the information “1” by the SLM 204 are transmitted through the polarization beam splitter PBS 207 as P-polarized light, and relay lens 1 (208), mirror 209, relay lens 2 (210 ) And is directed to the hologram disk 216 via the dichroic BS 211. At this time, the reference light 205 and the information light 206 that have been transmitted through the quarter-wave plate QWP 212 and converted into circularly polarized light (for example, clockwise circularly polarized light) are reflected by the mirror 213 and are the objective lens 214 having the focal length F. Is incident on.

  By the two relay lenses 1 (208) and 2 (210), the pattern displayed on the SLM 204 forms an intermediate image in front of the objective lens 214 by F. Thus, a so-called 4F optical system is configured in which a pattern image (not shown) on the SLM 204, the objective lens 214, and the hologram disk 216 are all separated by a distance of F.

  The hologram disk 216 is rotatably held on the spindle motor 215. The reference light 205 and the information light 206 are collected on the hologram disk 216 by the objective lens 214 and interfere to form interference fringes. On the polymer material in the hologram disk 216, the interference fringe pattern at the time of recording is recorded as a refractive index distribution, and a digital volume hologram is formed. A reflection film is provided in the hologram disk.

  In addition to the green laser 201 for recording and reproducing the hologram, a non-photosensitive red laser 220 is provided on the hologram disk 216, and the displacement of the hologram disk 216 is detected with high accuracy using the reflective film as a reference plane. It is possible. As a result, even if surface blurring or eccentricity occurs in the hologram disk 216, it is possible to dynamically follow the recording spot using the optical servo technology and record the interference fringe pattern with high accuracy. I can do it. Briefly described below.

  The linearly polarized light beam emitted from the red laser 220 is transmitted through the beam splitter BS 221, converted into a parallel light beam by the lens 222, reflected by the mirror 223 and the dichroic BS 211, and directed to the hologram disk 216. At that time, the light beam transmitted through the quarter-wave plate QWP 212 and converted into circularly polarized light (for example, clockwise circularly polarized light) is reflected by the mirror 213 and enters the objective lens 214, and is reflected on the hologram disk 216. It is collected as a small light spot on the surface.

  The reflected light beam becomes reverse circularly polarized light (for example, counterclockwise circularly polarized light), re-enters the objective lens 214 to become a parallel light beam, is further reflected by the mirror 213, and passes through the quarter-wave plate QWP212. However, it is converted into a linearly polarized light beam perpendicular to the forward path.

  The light beam reflected by the dichroic BS 211 passes through the mirror 223 and the lens 222 as in the forward path, is reflected by the beam splitter BS 221, and is guided to the photodetector 224. The photodetector 224 has a plurality of light receiving surfaces (not shown), detects position information of the reflecting surface by a known method, and can perform focusing and tracking control of the objective lens 214 based thereon.

  Next, a case where recorded information is reproduced from the hologram disk 216 as a recording medium using the optical system will be described. The light beam emitted from the green laser 201 as the light source illuminates the spatial light modulation element SLM 204 in the same manner as in recording. At the time of reproduction, only the portion that modulates the reference beam 205 on the SLM 204 displays “1” information, and all the portions that modulate the information beam 206 display “0” information. Therefore, only the light reflected by the pixels of the reference light portion is reflected in the direction of the hologram disk 216, and the information light is not reflected in the direction of the hologram disk 216.

  As in the recording, the reference beam 205 is circularly polarized (for example, clockwise circularly polarized light) and collected on the hologram 216, and information light is reproduced from the recorded interference fringes. The information light reflected by the reflection film of the hologram disk 216 becomes reverse circularly polarized light (for example, counterclockwise circularly polarized light), re-enters the objective lens 214 to become a parallel light beam, is reflected by the mirror 213, and is 1 / 4 wavelength plate QWP212 is transmitted and converted into a linearly polarized light beam (S-polarized light) perpendicular to the forward path. At this time, an intermediate image of the display pattern of the SLM reproduced at a distance F from the objective lens 214 is formed.

  The light beam transmitted through the dichroic BS 211 is directed to the polarization beam splitter PBS 207 via the relay lens 2 (210), the mirror 209, and the relay lens 1 (208). The light beam reflected by the PBS 207 is re-imaged as an intermediate image of the SLM display pattern at a position conjugate with the spatial light modulation element SLM 204 by the relay lenses 2 (210) and 1 (208).

  An opening 217 is previously placed at this position, and unnecessary reference light around the information light is shielded. The intermediate image re-formed by the lens 218 forms an SLM display pattern of only the information light portion on the CMOS sensor 219. Thereby, since unnecessary reference light does not enter the CMOS sensor 219, a reproduction signal having a good S / N can be obtained.

Other documents related to the holographic memory technology include Nikkei Electronics, 2005, 1.17, 105-114P (holographic media close to take-off, realizing 200 GB in 2006, Horime et al.) (Non-patent document) 2).
Measurement and nano-control technology that supports holographic memory / HVD (TM) (Proceeding of 35th Meeting on Lightwave Sensing Technology (LST35-12) June, 2005 Authors: Satoshi Kochi, Hideyoshi Horime) Nikkei Electronics, 2005, 1.17, 105-114P (holographic media close to take-off, realized 200GB in 2006, Horime et al.)

  In the above conventional technique, it is necessary to align the shift, tilt and rotation of the two-dimensional spatial light modulation element SLM204 and the CMOS sensor 219 with high accuracy, and it is difficult to reduce the cost. Further, the relay lens system used in the optical system needs to be an expensive lens with reduced distortion and curvature of field in order to accurately project the pattern of the spatial light modulator SLM204 onto the CMOS sensor 219. It was.

  It is an object of the present invention to eliminate the alignment of the spatial light modulation element and the light receiving element and the expensive relay lens system, and to obtain a reproduction signal with good S / N while reducing the cost and size of the optical system. It is an object of the present invention to provide an optical information recording / reproducing apparatus capable of performing the above.

  In order to solve the above problems, the present invention irradiates a spatial light modulation element with a light beam from a laser light source, generates reference light and information light by the spatial light modulation element, and converts the reference light and information light into laser optics. The information is guided to the objective lens through the system, and information is recorded on the recording medium using the holography by the objective lens, or only the reference light from the spatial light modulation element is irradiated to the recording medium, and the reflection by the recording medium In an optical information recording / reproducing apparatus that reproduces recorded information by receiving light with a light receiving element, the spatial light modulating element and the light receiving element are formed on the same substrate, and the spatial light modulating element and the light receiving element Shifting means for parallelly shifting the incident parallel light beam is provided.

  In the present invention, a spatial light modulation element and a light receiving element are formed on the same substrate, and a shift means for parallelly shifting parallel light beams incident on the spatial light modulation element and the light receiving element is provided. The shift means switches between a state in which the parallel light flux is not shifted and a state in which it is shifted during recording and during reproduction, and causes a pattern image generated on the SLM during recording to enter a CMOS element shifted by a pitch (p) during reproduction. Thus, it is possible to obtain a reproduction signal with a good S / N.

  According to the present invention, since the spatial light modulation element and the light receiving element are integrally formed on the same substrate, optical components can be reduced, and the optical system can be made compact and the cost can be reduced. In addition, since the light beams incident on the spatial light modulation element and the light receiving element on the substrate are shifted during recording and reproduction, it is possible to obtain a reproduction signal with a good S / N.

  Next, the best mode for carrying out the invention will be described in detail with reference to the drawings.

(First embodiment)
1 to 3 are views for explaining an optical system of a collinear holographic memory according to a first embodiment of the present invention. FIG. 1 is a diagram showing an optical system from a light source during recording to a spatial light modulation element, and FIG. 2 is a diagram similarly showing an optical system from the spatial light modulation element during recording to a hologram disk. FIG. 3 is a diagram showing an optical system during reproduction.

  First, the case where recording is performed on the hologram disk 118 as a recording medium will be described with reference to FIGS. 1 and 2. In FIG. 1, a light beam emitted from a green laser 101 as a light source is converted into a parallel light beam by a collimator 102 and is incident on a mask element 103. The mask element 103 has a function of masking a portion corresponding to the information light at the center of the light beam.

  In this embodiment, a liquid crystal element is used as the mask element 103. However, a mask that shields the central portion may be inserted in the optical path. At the time of recording, the mask element 103 does not function and transmits all the light beams.

  In the present embodiment, for example, a liquid crystal element is used as the mask element 103, and on / off of a drive voltage from a drive circuit (not shown) to the liquid crystal element is switched between recording and reproduction based on the control of the controller 152. By doing so, the entire light beam is transmitted during recording, and the portion corresponding to the information light at the center of the light beam is masked during reproduction.

  The P-polarized light beam that has passed through the polarization beam splitter PBS 104 passes through the quarter-wave plate QWP 105 provided as necessary, and passes through the relay lens A 106 and the relay lens B 107. Further, a spatial light modulation element / light receiving element (indicated as SLM / CMOS 108 in the drawing) in which the spatial light modulation element SLM and the CMOS sensor are mounted on one chip via a parallel plate 124 arranged to be tiltable with respect to the light beam. Lighting 108).

  Although details of the parallel plate 124 will be described later, the parallel plate 124 is configured to be tiltable with respect to the optical axis by driving of the drive mechanism 150. At the time of recording, as shown in FIG. 1, the parallel plate 124 is not inclined but is perpendicular to the optical axis. On the other hand, at the time of reproduction, as will be described later, the parallel plate 124 is tilted with respect to the light beam by the control of the controller 152.

  As the drive mechanism 150 for the parallel plate 124, for example, a drive mechanism using a plunger is used so that the parallel plate 124 can be switched between a vertical state and an inclined state with respect to the optical axis. The controller 152 controls the drive circuit 151 to switch on / off the drive voltage from the drive circuit 151 to the drive mechanism 150 during recording and during reproduction. By doing so, the parallel plate 124 is made perpendicular to the light beam during recording, and the parallel plate 124 is inclined with respect to the light beam during reproduction.

  Further, the parallel plate 124 may be driven using a stepping motor. In that case, the parallel plate 124 can be rotated about its center as shown in FIG. 4 by the rotation of the stepping motor, and the parallel plate 124 can be switched between the vertical state and the inclined state with respect to the optical axis. Like that. Then, by controlling the controller 152 to turn on / off the drive voltage from the drive circuit 151 to the stepping motor during recording and during reproduction, the parallel flat plate 124 is made perpendicular to the luminous flux during recording, and is converted into the luminous flux during reproduction. On the other hand, the parallel plate 124 is inclined.

  Here, in the case of an interferometric modulator having a configuration that does not change the polarization state as the SLM, a quarter-wave plate QWP 105 may be provided in advance. In addition, in the case of a reflective liquid crystal (LCOS) element configured to change the polarization state by 90 ° as the SLM, the quarter-wave plate QWP 105 is not necessary.

  When the modulation / light receiving element 108 is an interferometric modulation element / CMOS element, the light beam transmitted through the quarter-wave plate QWP 105 is converted into circularly polarized light (for example, clockwise circularly polarized light), and the relay lens A106 and the relay lens The modulation / light receiving element 108 is illuminated via B107.

  The light reflected by the pixel representing the information “1 (white)” on the SLM is reflected toward the hologram disk 118 with a high reflectance, and is reflected by the pixel representing the information “0 (black)”. Is slightly reflected in the direction of the hologram disk 118 due to interference. Similar to the conventional example, on the collinear SLM, a portion for modulating the information light 110 and a portion for modulating the reference light 109 surrounding the information light 110 in an annular shape are provided.

  In FIG. 2, the light beam reflected by the modulation / light receiving element 108 is reversely circularly polarized light (for example, counterclockwise circularly polarized light). Further, the light flux that has passed through the parallel plate 124, the relay lens B 107, and the relay lens A 106 passes through the quarter-wave plate QWP 105, is converted to S-polarized light, is reflected by the PBS 104, and is directed toward the hologram disk 118.

  When the modulation / light receiving element 108 is an LCOS element / CMOS element, the light beam illuminates the modulation / light receiving element 108 via the relay lens A 106 and the relay lens B 107. On the SLM, the light reflected by the pixel representing “1 (white)” information is converted to S-polarized light, and the light reflected by the pixel representing “0 (black)” information maintains the P-polarized state. . Similar to the conventional example, on the collinear SLM, a portion for modulating the information light 110 and a portion for modulating the reference light 109 surrounding the information light 110 in an annular shape are provided.

  In FIG. 2, among the light beams reflected by the modulation / light receiving element 108, S-polarized light is reflected by the PBS 104 and directed toward the hologram disk 118, and P-polarized light is transmitted through the PBS 104 and directed toward the hologram disk 118. Absent.

  In either case, the reference beam 109 and the information beam 110 reflected by the pixel representing the information “1 (white)” by the SLM of the modulation / light receiving element 108 are reflected by the polarization beam splitter PBS 104. Further, it is directed to the hologram disk 118 via the relay lens 1 (111), the mirror 112, the relay lens 2 (113), and the dichroic BS 114, is reflected by the mirror 115, and enters the objective lens 116 having a focal length F.

  By the two relay lenses 1 (111) and 2 (113), the pattern displayed on the SLM forms an intermediate image in front of the objective lens 116 by F. Thus, a so-called 4F optical system is configured in which a pattern image (not shown) on the SLM, the objective lens 116, and the hologram disk 118 are all arranged at a distance of F.

  The hologram disk 118 is rotatably held on the spindle motor 117. The reference light 109 and the information light 110 are collected on the hologram disk 118 by the objective lens 116 and interfere to form interference fringes. On the polymer material in the hologram disk 118, the interference fringe pattern at the time of recording is recorded as a refractive index distribution, and a digital volume hologram is formed. In addition, a reflection film is provided in the hologram disk 118.

  Similar to the conventional example, in addition to the green laser 101 for recording and reproducing the hologram, the hologram disk 118 is provided with a non-photosensitive red laser 119, and the hologram disk 118 is highly displaced with the reflective film as a reference plane. It is possible to detect with accuracy. As a result, even if surface blurring or eccentricity occurs in the hologram disk 118, it is possible to dynamically follow the recording spot using the optical servo technology and record the interference fringe pattern with high accuracy. I can do it.

  Briefly described below. The light beam emitted from the red laser 119 passes through the beam splitter BS120, is converted into a parallel light beam by the lens 121, is reflected by the mirror 122 and the dichroic BS 114, and is directed to the hologram disk 118. Thereafter, the light is reflected by the mirror 115 and enters the objective lens 116, and is collected as a minute light spot on the reflection surface on the hologram disk 118.

  The reflected light beam re-enters the objective lens 116 to become a parallel light beam, and the light beam sequentially reflected by the mirror 115 and the dichroic BS 114 passes through the mirror 122 and the lens 121 in the same way as the forward path, and is integrated by the beam splitter BS120. The light flux of the part is reflected and guided to the photodetector 123. The photodetector 123 has a plurality of light receiving surfaces (not shown), detects position information of the reflecting surface by a known method, and can perform focusing and tracking control of the objective lens 116 based on the detected position information. In the present embodiment, these focus control and tracking control circuits are omitted.

  Next, a case where the recorded information is reproduced from the hologram disk 118 as a recording medium will be described with reference to FIG. The light beam emitted from the green laser 101 as the light source illuminates the spatial light modulation element SLM108 in the same manner as at the time of recording. At the time of reproduction, as described above, the mask element 103 has a function of masking a portion corresponding to the information light at the center of the light beam.

  In the present embodiment, a liquid crystal element is used, and the polarization direction is rotated by 90 ° only in the central part of the light beam to form S-polarized light, which is reflected by the subsequent PBS 104 so as not to reach the spatial light modulator SLM108. Further, a mask for shielding the central portion may be inserted into the optical path.

  The two relay lenses A (106) and B (107) also serve to form an image of the mask element 103 on the spatial light modulation element SLM108, and only the element of the reference light portion is illuminated and information light This portion is properly shielded from light by a mask element image (not shown).

  Only the portion that modulates the reference light 109 on the SLM 108 displays “1 (white)” information, and all the portions that modulate the information light 110 display “0 (black)” information. Accordingly, only the light reflected by the pixels of the reference light portion is reflected in the direction of the hologram disk 118. Since the luminous flux of the pixels in the information light portion is not reflected in the direction of the hologram disk 118, it is not even illuminated, so that it is possible to reproduce information light with a much better S / N compared to the conventional example.

  At the time of reproduction, the parallel plate 124 is inclined by θ with respect to the light beam by driving of the driving mechanism 150 based on the control of the controller 152. Thereby, the light beam emitted from the green laser 101 and passed through the relay lenses A106 and B107 is shifted by s with respect to the light beam at the time of recording, and illuminates the spatial light modulation element SLM108. The light reflected by the pixels of the reference light portion again passes through the parallel plate 124 and travels on the same optical axis as the forward path toward the relay lens B107.

  FIG. 4 shows a detailed view of the parallel plate 124. When the shift amount is s, the thickness of the parallel plate is t, and the tilt (tilt angle) is θ, the relationship between s and θ is as shown in FIG. In this case, the refractive index of the parallel plate 124 is 1.51, and t is 1 mm and 2 mm. In order to obtain a desired shift amount s described later, t and θ can be arbitrarily set.

  As in the recording, the reference beam 109 is reflected by the PBS 104, collected on the hologram disk 118, and information light is reproduced from the recorded interference fringes. The information light reflected by the reflective film in the hologram disk 118 is incident again on the objective lens 116 to be converted into a parallel light beam and reflected by the mirror 115. At this time, an intermediate image of the display pattern of the SLM reproduced at a distance F from the objective lens 116 is formed.

  The light beam transmitted through the dichroic BS 114 is directed to the polarization beam splitter PBS 104 via the relay lens 2 (113), the mirror 112, and the relay lens 1 (111), and the relay lenses 2 (113) and 1 (111), the mask. Reimaged as an intermediate image of the SLM display pattern at a position conjugate with the element 103 (not shown). Then, the re-imaged intermediate image is reflected by the PBS 104, passes through the two relay lenses A106 and B107, and further shifts the light beam by s by the parallel plate 124, so that the spatial light modulation element / light receiving element 108 is obtained. Imaged on top.

  The light receiving element (CMOS sensor in this embodiment) portion of the spatial light modulator / light receiving element 108 is disposed only between the pixels of the portion where the information light is illuminated. Due to the action of the mask element 103, unnecessary reference light does not enter between the pixels of the information light portion where the light receiving element is formed in advance, so that a reproduction signal with good S / N can be obtained.

  In this embodiment, since the spatial light modulation element SLM and the light receiving element CMOS sensor are arranged on the same chip, the complicated alignment mechanism and expensive relay lens system of both of them can be eliminated, and the cost of the optical system can be reduced. Compactness can be achieved.

  FIG. 6 shows an element when a reflective liquid crystal type (LCOS type) spatial light modulation element SLM (64 is an SLM element region) and a light receiving element CMOS sensor (65 is a CMOS sensor area) according to the present invention are arranged horizontally. It is sectional drawing (schematic diagram).

  In the figure, 51 is a Si substrate, 52 is a photodiode, 53 is a transfer transistor of a CMOS sensor, 54 is a CMOS sensor wiring, 55 is an SLM element wiring, 56 is a light shielding film, 57 is an optical interference mirror A, and 58 is an optical interference mirror B. It is. Reference numeral 59 denotes an outermost protective film, 60 denotes an interlayer film, 61 denotes a support, 62 denotes a gap, and 63 denotes an SLM data transfer switch. Inter-element insulation (LCOS / STl, etc.), other Tr wiring of the CMOS sensor, and SLM writing Tr wiring are omitted.

  In FIG. 6, the reflectance and transmittance are changed by causing interference between the optical interference mirror A57 and the optical interference mirror B58 and changing the space (for example, air) therebetween.

  Reference numeral 61 denotes a support insulating film on the reflective electrode, for example, a silicon nitride film. Reference numeral 59 denotes a semi-permeable protective film, for example, a silicon oxide film.

  Next, the operation of the interference unit will be described. First, for example, a ground potential of 0 V is applied to the Ti optical interference mirror B58. By the above-described active matrix operation, a voltage is applied to the Ti optical interference mirror A57, and the air gap is adjusted by the Coulomb force of the optical interference mirrors A and B.

FIG. 7 shows the reflectance characteristics when the SLM of the optical interference spatial light modulator is “1” and “0” during recording. FIG.
Uppermost surface protective film 59... SiO ₂ : 10 nm
Optical interference mirror B58... Ti: 5 nm / Si ₃ N ₄ : 20 nm / SiO ₂ : 10 nm / Si ₃ N ₄ : 20 nm
Gap 62: 180 nm for wide gap, 10 nm for narrow gap
Optical interference mirror A (57) ... AlSi: 100 nm (SiO ₂ : 10 nm on the surface)
It is a reflectance of a wide gap and a narrow gap in the layer structure.

  In the light with a wavelength of 550 nm, the reflectance when the air gap is 180 nm and when the air gap is 10 nm is 93.0% and 0.6%. It can be seen that when the air gap is changed from 10 nm to 180 nm by the voltage applied to the optical interference mirror A57, the reflectivity greatly changes accordingly. This interference action can be designed according to the wavelength, the semi-transmissive film material, and the air gap thickness, and it is important to take a necessary configuration in view of characteristics such as physical strength and contrast ratio.

  FIG. 8 is a sectional view (schematic diagram) of the element when the reflective liquid crystal type (LCOS type) spatial light modulation element SLM and the light receiving element CMOS sensor according to the present invention are disposed horizontally. In FIG. 8, the same parts as those in FIG.

  In the figure, 66 is a pixel electrode, 67 is an alignment film, 68 is a liquid crystal, 69 is ITO, and 70 is glass. For example, assuming that the orientation film is an obliquely deposited SiO 2 film, the liquid crystal is a vertical liquid crystal, the pixel electrode is a reflective film, and 69 is a common electrode, in the “1” display, a voltage is applied to the pixel electrode and an electric field is applied to the liquid crystal. Fall down. In the “0” display, the electric field is not applied and the liquid crystal stands almost vertically.

  If light is reflected by PBS (polarization beam splitter) as S-polarized light and incident as linearly polarized light before the light is incident, in the “0” display, it is reflected by the pixel electrode without changing the polarization direction. Although it enters PBS again, the polarization is not changed, so it is reflected again and does not reach the hologram. On the other hand, when “1” is displayed, linearly polarized light is rotated by 90 ° (the liquid crystal and thickness are designed so that a phase shift of λ / 2 occurs when the liquid crystal reciprocates). It is transmitted and written to the hologram.

  Here, the light beam incident on the hologram disk 118 is adjusted and controlled so as to be incident on the disk exactly perpendicularly. In this case, the information light pattern generated on the SLM of the spatial light modulation element / light receiving element 108 is transmitted to the spatial light modulation element / light receiving element 108 via the same path as the reflected light from the hologram disk 118 is incident. It will be incident.

  An example of the arrangement relationship between the spatial light modulation element SLM on the spatial light modulation element / light receiving element 108 and the CMOS sensor is shown in FIG. In FIG. 9, both SLM and CMOS are laid in the same area and shape. Both SLM and CMOS form a column of pixels with a pitch (p) arranged at equal intervals.

  The direction of arrow A in FIG. 9 is the direction of light flux shift. The pixel column is long in the direction orthogonal to the arrow A direction. The pitch (p) is set to be the same as the light beam shift amount (s). With this configuration, the pattern image generated on the SLM during recording enters the CMOS sensor shifted by the pitch (p) during reproduction. Therefore, a signal having a good S / N can be reproduced.

  In the present embodiment, the shift amount s is the same as the pitch p of the pixel row, but it may be an odd multiple and can be arbitrarily set according to the pixel layout. Although the parallel plate 124 in the light beam is driven to be inclined, it is also possible to insert / remove the parallel plate originally inclined with respect to the light beam into the light beam, or to use a method having the same effect.

(Second Embodiment)
FIG. 10 is a diagram showing a second embodiment of the present invention. In FIG. 10, the same parts as those in FIGS. In this embodiment, the parallel plate 124 is omitted from the optical system, and instead, the modulation element / light receiving element 108 is moved in the direction of arrow B by driving the piezoelectric element 125. As in the first embodiment, the pattern image generated on the SLM during recording is incident on the CMOS sensor shifted by the pitch (p) during reproduction.

  Next, the case where the recorded information is reproduced from the hologram disk 118 as a recording medium will be described. In the following description, portions that are features of the present embodiment will be described. The modulation element / light receiving element 108 is mounted on the piezoelectric element 125 and can move in the direction of arrow B in the figure perpendicular to the light beam incident on the modulation element / light receiving element 108.

  At the time of reproduction, the piezoelectric element 125 is energized from the drive circuit 153 under the control of the controller 152 so that the modulation element / light receiving element 108 of the pixel array of the modulation element / light receiving element 108 in the direction of arrow B in FIG. It is moved by the width (p) (see FIG. 9). By doing so, it is possible to obtain a reproduction signal having a large contrast and a good S / N, as in the first embodiment. During recording, the piezoelectric element 125 is not energized, and the modulation element / light receiving element 108 is not moved.

  In the present embodiment, the example in which the piezoelectric element 125 is used as the driving unit for the modulation element / light receiving element 108 has been described. However, the present invention is not limited to this and can be driven by any other driving unit. Is possible.

It is the schematic which shows the optical system at the time of the recording (from a light source to SLM) by the 1st Embodiment of this invention. It is the schematic which shows the optical system at the time of recording (from SLM to a hologram memory medium) by the 1st Embodiment of this invention. It is the schematic which shows the optical system at the time of reproduction | regeneration by the 1st Embodiment of this invention. It is detail drawing which shows the parallel plate at the time of reproduction | regeneration by the 1st Embodiment of this invention. It is a graph which shows the relationship between the tilt ((theta)) of the parallel plate by the 1st Embodiment of this invention, and the shift amount (s) of a light beam. It is sectional drawing which shows the optical interference type spatial light modulation element and light receiving element integrated element (horizontal arrangement) concerning the present invention. It is a figure which shows the characteristic of the reflectance at the time of "1" of the SLM of the optical interference system at the time of recording by 1st Embodiment, and "0". It is sectional drawing which shows the reflection type liquid crystal type spatial light modulation element and light receiving element integrated element (horizontal arrangement) concerning the present invention. It is a figure which shows the in-plane arrangement | positioning of the spatial light modulation element-light receiving element integrated type element (horizontal arrangement | positioning) based on this invention. It is the schematic which shows the optical system at the time of reproduction | regeneration by the 2nd Embodiment of this invention. It is the schematic of the optical system for demonstrating a prior art.

Explanation of symbols

51 Si substrate 52 Photo diode 53 CMOS transistor transfer transistor 54 CMOS sensor wiring 55 SLM element wiring 56 Light shielding film 57 Optical interference mirror A
58 Optical interference mirror B
59 Uppermost surface protective film 60 Interlayer film 61 Post 62 Gap 63 SLM data transfer switch 64 SLM element area 65 CMOS sensor area 66 Pixel electrode 67 Alignment film 68 Liquid crystal 69 ITO
70 Glass 101 Green Laser 102 Collimator 103 Mask Element 104 Polarizing Beam Splitter (PBS)
105 1/4 wave plate (QWP)
106 Relay lens A
107 Relay lens B
108 Spatial light modulator / light detector (SLM / CMOS)
109 Reference beam 110 Information beam 111 Relay lens 1
112 mirror 113 relay lens 2
114 dichroic BS
115 Mirror 116 Objective Lens 117 Spindle Motor 118 Hologram Disc 119 Red Laser 120 Beam Splitter (BS)
121 Lens 122 Mirror 123 Photodetector 124 Parallel Plate 125 Piezoelectric Element 150 Drive Mechanism 151, 153 Drive Circuit 152 Controller 201 Green Laser 202 Collimator 203 Mirror 204 Spatial Light Modulator (SLM)
205 Reference light 206 Information light 207 Polarization beam splitter (PBS)
208 Relay lens 1
209 Mirror 210 Relay lens 2
211 Diclo BS
212 1/4 wave plate (QWP)
213 Mirror 214 Objective lens 215 Spindle motor 216 Hologram disk 217 Aperture 218 Lens 219 CMOS sensor 220 Red laser 221 Beam splitter (BS)
222 Lens 223 Mirror 224 Photodetector

Claims (7)

A spatial light modulation element is irradiated with a light beam from a laser light source, reference light and information light are generated by the spatial light modulation element, the reference light and information light are guided to an objective lens through a laser optical system, and the objective lens By using holography, information is recorded on a recording medium, or only the reference light from the spatial light modulation element is irradiated onto the recording medium, and reflected light from the recording medium is received by a light receiving element. In an optical information recording / reproducing apparatus for reproducing,
The spatial light modulation element and the light receiving element are formed on the same substrate, and are provided with shift means for parallel-shifting parallel light beams incident on the spatial light modulation element and the light receiving element. Playback device. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the shift unit switches between a state in which the parallel luminous flux is not shifted and a state in which the parallel light flux is shifted between when information is recorded on and reproduced from the recording medium. . The said shift means is comprised from the parallel plate inserted in the said parallel light beam, and the drive means which drives so that the said parallel plate may be perpendicular | vertical or inclined with respect to a light beam, The Claim 1 or 2 characterized by the above-mentioned. Optical information recording / reproducing apparatus. The said shift means shifts the said parallel light beam by driving the same board | substrate with which the said spatial light modulation element and the said light receiving element were formed to the orthogonal | vertical direction with respect to a light beam. Optical information recording / reproducing apparatus. 5. The optical information recording according to claim 1, wherein the spatial light modulation element and the light receiving element are integrated with each pixel being arranged without overlapping in a plane. Playback device. 6. The pixel of the spatial light modulation element and the pixel of the light receiving element are continuously arranged in a direction orthogonal to a direction in which a light beam is shifted by the shift unit. 2. An optical information recording / reproducing apparatus according to item 1. The amount of shift of the light beam by the shift means is set corresponding to the width in the parallel direction of the pixel rows arranged continuously in a direction orthogonal to the direction in which the light beam shifts. The optical information recording / reproducing apparatus of any one of 1-6.

Images