WO2014073041A1 - Holographic optical pickup device, holographic device, and high-speed image pickup device - Google Patents

Holographic optical pickup device, holographic device, and high-speed image pickup device Download PDF

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Publication number
WO2014073041A1
WO2014073041A1 PCT/JP2012/078776 JP2012078776W WO2014073041A1 WO 2014073041 A1 WO2014073041 A1 WO 2014073041A1 JP 2012078776 W JP2012078776 W JP 2012078776W WO 2014073041 A1 WO2014073041 A1 WO 2014073041A1
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Prior art keywords
light
pickup device
optical pickup
optical
image sensor
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PCT/JP2012/078776
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French (fr)
Japanese (ja)
Inventor
和良 山崎
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日立コンシューマエレクトロニクス株式会社
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Priority to PCT/JP2012/078776 priority Critical patent/WO2014073041A1/en
Publication of WO2014073041A1 publication Critical patent/WO2014073041A1/en

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    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1365Separate or integrated refractive elements, e.g. wave plates
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/13Optical detectors therefor
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03HHOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00Holographic processes or apparatus using light, infra-red or ultra-violet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/26Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/004Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/0065Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/007Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track
    • G11B7/00772Arrangement of the information on the record carrier, e.g. form of tracks, actual track shape, e.g. wobbled, or cross-section, e.g. v-shaped; Sequential information structures, e.g. sectoring or header formats within a track on record carriers storing information in the form of optical interference patterns, e.g. holograms
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/085Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
    • G11B7/08547Arrangements for positioning the light beam only without moving the head, e.g. using static electro-optical elements
    • G11B7/08564Arrangements for positioning the light beam only without moving the head, e.g. using static electro-optical elements using galvanomirrors

Abstract

The purpose of the present invention is to provide a holographic optical pickup device capable of performing high-speed reproduction, a holographic device, and a high-speed image pickup device. Disclosed is an optical pickup device that reproduces information from a recording medium having an interference pattern of signal light and reference light recorded thereon as a hologram. The optical pickup device is characterized in being provided with: a laser output section that outputs the reference light; a lens through which the reference light outputted from the laser output section is inputted to an optical information recording medium; and a detection optical section that detects diffracted reproducing light from the optical information recording medium on the basis of the reference light. The optical pickup device is also characterized in that the detection optical section includes a plurality of image pickup elements.

Description

Hologram optical pickup device, hologram device, high-speed imaging device

The present invention relates to a hologram optical pickup device, a hologram device, a high-speed imaging device, and the like.

Currently, the Blu-ray Disc standard using a blue-violet semiconductor laser has made it possible to commercialize an optical disc having a recording density of about 50 GB even for consumer use. In the future, it is desired to increase the capacity of optical disks to the same level as the HDD (Hard Disk Drive) capacity of 100 GB to 1 TB.

However, in order to realize such an ultra-high density with an optical disk, a high-density technology by a new method different from the high-density technology by shortening the wavelength and increasing the objective lens NA is necessary.

While research on next-generation storage technology is underway, hologram recording technology that records digital information using holography is drawing attention.

Hologram recording technology is a method in which signal light having page data information two-dimensionally modulated by a spatial light modulator is superimposed on reference light inside the recording medium, and the interference fringe pattern generated at that time is placed in the recording medium. This is a technique for recording information on a recording medium by causing refractive index modulation.

When reproducing the information, when the recording medium is irradiated with the reference light used for recording, the hologram recorded in the recording medium acts like a diffraction grating to generate diffracted light. This diffracted light is reproduced as the same light including the recorded signal light and phase information.

Regenerated signal light is detected two-dimensionally using an image sensor such as a CMOS or CCD. As described above, the hologram recording technique enables two-dimensional information to be recorded on the optical recording medium at once by one hologram and further reproduces this information. Since the page data can be overwritten, large-capacity and high-speed information recording / reproduction can be achieved.

As a hologram recording technique, for example, there is JP-A-2004-272268 (Patent Document 1). Patent Document 1 describes that “the achievable density / capacity of a holographic medium is increased” as a problem, and “a hologram is spatially caused by a partial spatial overlap between adjacent stacks of holograms” as a solution. Multiplexing methods and devices are disclosed, each stack further taking full advantage of another multiplexing technique such as angle, wavelength, phase code, peritropy, or fractal multiplexing. An amount equal to the beam waist of the signal light that writes the hologram separates the individual stacks of holograms, and at the time of reproduction, a hologram and its adjacent holograms are all read out simultaneously. By placing a filter at the waist, the read out adjacent holograms Until the camera surface is not transmitted. Or reproduce these are not desirable, in the optical system having a limited angular passband, they are described as may be filtered. "By the intermediate plane of the angular filter.

As another background art, there is JP-A-2005-233998. This publication describes that "a plurality of diffracted lights are simultaneously generated in different directions by irradiating a single reproducing reference beam, and these are simultaneously received by a plurality of image sensors to reproduce a record." . Another background art is WO2012-053198. This publication describes that "the second reference light is branched into a plurality of parts, each of which has a different phase change and is reproduced by detecting the interfered light with a plurality of CCDs".

JP 2004-272268 A JP 2005-233998 A WO2012-053198 Publication

Patent Document 1 increases the achievable density / capacity of the holographic medium as described above. On the other hand, high speed reproduction is a problem in the hologram system. The reproduction speed depends on the number of pixels of the image sensor and the frame rate, and it is difficult for the hologram system using page data with high pixels to increase the reproduction speed. In Patent Documents 2 and 3, there are only a plurality of light receiving surfaces of the imaging device, and there is a problem in high-speed reproduction of a large number of pages.

Therefore, an object of the present invention is to provide a hologram optical pickup device, a hologram device, and a high-speed imaging device that can realize high-speed reproduction.

The above object can be achieved by the invention described in the claims. As an example, an optical pickup device that reproduces information from a recording medium in which an interference pattern of signal light and reference light is recorded as a hologram, and includes a laser emitting portion that emits reference light, and an output from the laser emitting portion. And a detection optical unit that detects the reproduction light diffracted from the optical information recording medium based on the reference light. The detection optical unit includes a plurality of detection optical units. The above object can be achieved by using an optical pickup device characterized in that the image pickup element is included.

It is possible to provide a hologram optical pickup device, a hologram device, and a high-speed imaging device that can realize high-speed reproduction.

2 is a diagram illustrating an optical system in Embodiment 1. FIG. FIG. 3 is a diagram illustrating a method for detecting an image sensor in the first embodiment. 3 is a timing chart of an image sensor and a galvanometer mirror in the conventional hologram system in Embodiment 1. FIG. 3 is a timing chart of an image sensor and a galvanometer mirror in the hologram system in Embodiment 1. FIG. FIG. 5 is a diagram illustrating another image sensor in Example 1. FIG. 6 is a diagram illustrating an optical system in Example 2. It is a figure explaining the division | segmentation wavelength plate in Example 2. FIG. FIG. 6 is a diagram illustrating an optical system in Example 3. The imaging device in Example 3 is an imaging device and timing chart in one hologram system. FIG. 10 is a diagram illustrating a timing chart of an image pickup element and a high-speed polarization control element in a hologram system in Example 3. 6 is a diagram showing a hologram optical information recording / reproducing apparatus in Example 4. FIG. It is a figure explaining the optical system in another Example.

Hereinafter, each example will be described.

FIG. 1 shows an optical system of a two-beam angle multiplexing hologram pickup apparatus according to a first embodiment of the present invention.

First, the recording method of this embodiment will be described. The light beam emitted from the light source 11 passes through the collimator lens 12 and is converted into a desired beam diameter, and then enters the polarization control element 14 through the shutter 13. The light beam is converted into P-polarized light and S-polarized light by the polarization control element 14. The polarization control element 14 is an element that converts outgoing polarized light into predetermined polarized light according to recording or reproduction. In this embodiment, it is assumed that P-polarized light and S-polarized light are converted during recording, and S-polarized light is converted during reproduction.

The light beam emitted from the polarization control element 14 enters the PBS prism 15, P-polarized light is transmitted, and S-polarized light is reflected. Here, the light beam transmitted through the PBS prism is called signal light, and the reflected light beam is called reference light. The signal light transmitted through the PBS prism 15 is converted into a desired beam diameter by the beam expander 25. The signal light transmitted through the beam expander 25 enters the spatial light modulator 29 through the phase mask 26, the relay lens 27, and the PBS prism 28, and is added with two-dimensional data. The spatial light modulator 29 is an optical element that adds two-dimensional data to signal light.

The signal light to which information is added by the spatial light modulator 29 is reflected by the PBS prism 28, and is condensed in the optical information recording medium 300 through the relay lens 30, the spatial filter 31, and the objective lens 32.

On the other hand, the reference light reflected by the PBS prism 15 reflects the mirrors 36 and 37 and enters the galvano mirror 38. The galvanometer mirror 38 is an element capable of controlling the mirror angle. By using this galvanometer mirror 38, the angle of incidence of the reference light on the optical information recording medium can be changed, so that angle multiplexing can be realized. The reference light reflected from the galvanometer mirror 38 enters the optical information recording medium 300 through the scanner lens 39. At this time, when the signal light and the reference light are incident on the optical information recording medium 300 so as to overlap each other, an interference fringe pattern is formed in the optical information recording medium 300. This interference fringe pattern is recorded as a hologram in the recording medium. In this embodiment, a hologram in which two-dimensional data is recorded is called a page, and a region where pages are multiplexed is called a book.

After the information is recorded on the optical information recording medium 300, the shutter 13 is closed and the information to be recorded next is displayed by the spatial light modulator 29. At the same time, the galvanometer mirror 38 is rotated by a small angle, and the incident angle of the reference light to the optical information recording medium 300 is changed. Thereafter, when the shutter 13 is opened, the next recorded information is recorded at an angle different from the angle previously recorded in the same book of the optical information recording medium 300. By repeating this, angle multiplex recording is performed.

Next, the reproduction method of this embodiment will be described with reference to FIG. The light beam emitted from the light source 11 passes through the collimator lens 12 and is converted into a desired beam diameter, and then passes through the shutter 13 and enters the polarization control element 14. Then, the light beam is converted into S-polarized light by the polarization control element 14 and reflected by the PBS prism 15. Hereinafter, the light beam reflected from the PBS prism 15 is referred to as reference light.

The reference light reflected by the PBS prism 15 is reflected by the mirrors 36 and 37 and enters the galvanometer mirror 38. The reference light reflected by the galvanometer mirror 38 enters the galvanometer mirror 50 through the scanner lens 39, the optical information recording medium 300, and the quarter wavelength plate 51. The galvanometer mirror 50 is controlled so that the incident reference light is substantially perpendicular to the galvanometer mirror 50. For this reason, the incident reference light is reflected in a substantially opposite direction, and reenters the optical information recording medium 300 through the quarter-wave plate 51. When the reference light is incident on the optical information recording medium 300 again, reproduction light (diffracted light of the reference light) having predetermined information is generated in the direction of the objective lens 32 from the recording area.

Then, the reproduction light enters the high-speed polarization control element 100 through the objective lens 32, the relay lens 30, the spatial filter 31, and the PBS prism 28. The high-speed polarization control element 100 of this embodiment is a liquid crystal element such as a ferroelectric liquid crystal, and is an element capable of converting outgoing polarized light into P-polarized light and S-polarized light at high speed.

The reproduction light emitted from the high-speed polarization control element 100 enters the image sensor 102 or the image sensor 103 via the PBS prism 101. Then, reproduction image data is generated based on the reproduction light incident on the image sensor 102 or the image sensor 103. Next, the galvanometer mirrors 38 and 50 rotate by a small amount, the incident angle of the reference light to the optical information recording medium 300 is changed, and the reproduction light of the next page enters the image sensor 103 or the image sensor 102. Then, reproduction image data is generated based on the reproduction light incident on the image sensor 103 or the image sensor 102. As a result, the reproduction image data of the angle-multiplexed page in the optical information recording medium is generated.

FIG. 2 is a diagram illustrating a detection method of the image sensors 102 and 103 according to the present embodiment. Here, FIG. 2A shows a case where odd pages are reproduced, and FIG. 2B shows a case where even pages are reproduced.

When reproducing odd pages, the high-speed polarization control element 100 emits P-polarized light. Therefore, the reproduction light emitted from the high-speed polarization control element 100 passes through the PBS prism 101 and enters the imaging element 101 (FIG. 2A). When reproducing even pages, the high-speed polarization control element 100 emits S-polarized light. Therefore, the reproduction light emitted from the high-speed polarization control element 100 is reflected by the PBS prism 101 and enters the image sensor 102. As described above, the present embodiment is characterized in that a plurality of image sensors are switched.

Here, the effect of the present embodiment will be described. For the sake of simplicity, the image pickup device of the present embodiment will be described by a single buffer system in which one buffer is mounted. However, the same effect can be obtained even in a multi-buffer system in which two or more buffers are mounted.

First, a conventional hologram system using one image sensor will be described. FIG. 3 shows a timing chart of the image sensor and the galvanometer mirrors 38 and 50 in the conventional hologram system using one image sensor. Note that the description will be given with the reproduction of five pages, but the actual number of multiplexing is not limited to this.

In the case of a conventional hologram system using one image sensor, the image sensor is composed of exposure and transfer as shown in FIG. During reproduction, after exposure for a predetermined time Te, the obtained reproduction signal is transferred to a signal processing circuit (not shown) at time Tt. At this time, exposure cannot be performed while the reproduction signal is being transferred. In addition, while the reproduction signal is being transferred, the galvanometer mirrors 38 and 50 rotate over time Tr so that the incident angle of the reference light on the optical information recording medium 300 matches the next page.

For holograms, it is necessary to increase the recording capacity of one page from the viewpoint of recording speed / capacity. The transfer time of the image sensor depends on the number of pixels, and the transfer time becomes longer as the number of pixels increases. For this reason, if the recording capacity of one page is increased (higher pixels), the transfer time becomes longer. In an actual hologram system, the transfer time becomes longer than the exposure time and the galvanometer mirror rotation time.

Next, the hologram system of this embodiment using two image sensors will be described. FIG. 4 shows a timing chart of the image sensor and the galvanometer mirrors 38 and 50 in the hologram system of this embodiment.

The reproduction of the first page is the same as that of the conventional hologram system shown in FIG. However, in the case of the present embodiment, the galvanometer mirrors 38 and 50 are rotated and the output polarization of the high-speed polarization switching element 100 is switched when the exposure of the image sensor 102 is completed. Thereby, the reproduction light of the next page (second page) enters the image sensor 103. Then, the image sensor 103 is exposed. During this time, the reproduction signal is transferred in the image sensor 102. When the exposure of the image sensor 103 is completed, the galvanometer mirrors 38 and 50 are rotated and the outgoing polarization of the high-speed polarization switching element 100 is switched. As a result, the reproduction light of the next page (third page) enters the image sensor 102. By repeating this, continuous reproduction becomes possible.

In the case of the conventional hologram system shown in FIG. 3, exposure could not be performed while the reproduction signal was being transferred. On the other hand, in the case of the hologram system of the present invention, another image sensor can perform exposure while one image sensor transfers a reproduction signal. For this reason, it becomes possible to improve a frame rate compared with the past.

Here, as described above, it can be seen that this embodiment has a great effect when the transfer time is long. For example, when the effective transfer time is shortened as in the multi-buffer method, the effect of this embodiment is reduced. However, the effect of the present embodiment can be improved by doing the following.

The transfer time of the image sensor depends on the number of pixels, and the transfer time becomes longer as the number of pixels increases. For this reason, if the recording capacity of one page is increased (higher pixels), the transfer time becomes longer. The playback speed is the product of the recording capacity per page and the frame rate.

In the case of a conventional hologram system, if the recording capacity per page is increased, the frame rate of the image sensor is lowered, and the product reproduction speed cannot be changed greatly. On the other hand, in the case of this embodiment, even if the recording capacity per page is increased, the decrease in the frame rate of the single image sensor is compensated by using a plurality of image sensors. That is, it is possible to improve the reproduction speed with respect to the conventional hologram system.

As described above, in this embodiment, high-speed reproduction can be realized by using a plurality of imaging elements and a branch element using polarization (polarization control element and polarization branch element (PBS prism)). In addition, the present embodiment is characterized in that the polarization is selectively switched in accordance with the information to be reproduced, and the image sensor on which the reproduction light is incident is switched in accordance with the switching.

In this embodiment, two image sensors are used, but a plurality of image sensors may be used. For example, when four image sensors are used, the configuration shown in FIG. In this way, it is possible to further increase the speed. In the present embodiment, the angle multiplexing method has been described. However, for example, the same effect can be obtained even with the shift multiplexing method. In addition, the same effect can be obtained with other systems as long as the two-dimensional data is detected by the image sensor. Furthermore, since high pixels and high-speed transfer can be realized by using this embodiment, the present invention may be applied to an imaging camera or the like.

In this embodiment, the galvanometer mirror is used to change the incident angle to the optical recording medium, but the present invention is not limited to this. For example, an optical axis angle variable element such as an acousto-optic element may be used. In this embodiment, the image sensor is switched by reproducing odd pages and even pages, but the switching method is not limited. Furthermore, the high-speed polarization control element 100 to the imaging elements 102 and 103 may be configured as one component or may be divided.

In this embodiment, the hologram optical pickup device for recording / reproduction is described. However, a hologram optical pickup device for reproduction may be used.

FIG. 6 shows an optical system of a hologram pickup device of a two-beam angle multiplexing system according to the second embodiment of the present invention. The difference from the first embodiment is the detection optical system (from the area division wavelength plate 180 to the image pickup devices 112 and 113), and other than that is the same as the first embodiment. For this reason, the recording method of the present embodiment is the same as that of the first embodiment. Further, since the same operation is performed except for the detection optical system at the time of reproduction, the following will be described with respect to the reproduction light transmitted through the PBS prism 28.

The reproduction light transmitted through the PBS prism 28 enters the division wavelength plate 180. FIG. 7 shows the divided wave plate 180. The divided wave plate 180 is a wave plate having a region A and a region B. The light beam transmitted through the region A is P-polarized light, and the light beam transmitted through the region B is S-polarized light. For example, in the case of the present embodiment, since the polarized light incident on the divided wave plate 180 is P-polarized light, the region A can be realized by a wave plate having a phase difference of 1 / 2λ, an azimuth axis of 45 degrees, and the region B having a phase difference of 0λ. The divided wave plate is, for example, a lamination of different wave plates, a photonic crystal, a liquid crystal wave plate, or the like. In addition, the division | segmentation wavelength plate of a present Example is arrange | positioned in the position corresponded to the image surface which arrange | positions an image pick-up element in the conventional hologram system, It is characterized by the above-mentioned.

The reproduction light transmitted through the divided wavelength plate 180 enters the PBS 101 through the relay lens 127. Here, since a part of the reproduction light transmitted through the region A of the divided wavelength plate 180 is P-polarized light, it passes through the PBS 101 and enters the image sensor 112. Further, since a part of the reproduction light transmitted through the region B is S-polarized light, it reflects the PBS 101 and enters the image sensor 113. Then, reproduction image data is generated based on the reproduction light incident on the image sensors 112 and 113. Next, the galvanometer mirrors 38 and 50 rotate by a small amount, the incident angle of the reference light to the optical information recording medium 300 is changed, and the reproduction light of the next page enters the image sensors 112 and 113. Then, reproduction image data is generated based on the reproduction light incident on the image sensors 112 and 113. As a result, the reproduction image data of the angle-multiplexed page in the optical information recording medium is generated.

Hereinafter, the effect of this embodiment will be described. The present embodiment is the same as the first embodiment in terms of branching to a plurality of image sensors using polarized light. However, instead of switching the two image sensors for each page to be reproduced as in the first embodiment, A page is detected by two image sensors. Here, in this embodiment, since the divided wavelength plate is placed on the image plane, it is possible to divide the reproduced signal without deterioration.

In this embodiment, since one page is divided into two, the number of pixels of the image sensor may be small, so that the transfer time of the single image sensor can be shortened. Further, since the high-speed polarization control element is not driven with respect to the first embodiment, it is not necessary to perform complicated control, and the control can be simplified. As a timing chart in the present embodiment, the transfer time Tt in FIG. 3 is halved.

As described above, in this embodiment, high-speed reproduction can be realized by using a plurality of imaging elements and a branch element using polarized light (a divided wavelength plate and a polarization branch element (PBS prism)). In addition, the present embodiment is characterized in that the reproduction light transmitted through different regions of the divided wavelength plate has two types of polarization components that are substantially orthogonal, and the two types of polarization components are incident on different image pickup devices.

Although two image sensors are used in this embodiment, the same effect can be obtained if the incident light of the reproduction light is divided into a plurality of image sensors. Further, the division method is not limited.

In this embodiment, the angle multiplexing method has been described, but the same effect can be obtained even with the shift multiplexing method, for example. In addition, the same effect can be obtained with other systems as long as the two-dimensional data is detected by the image sensor. Furthermore, since this embodiment can realize high pixel and high-speed transfer, it may be applied to an imaging camera.

In this embodiment, the galvanometer mirror is used to change the incident angle to the optical recording medium, but the present invention is not limited to this. For example, an optical axis angle variable element such as an acousto-optic element may be used. Further, the divided wavelength plate 180 to the imaging elements 112 and 113 may be configured as one component or may be divided.

In this embodiment, the hologram optical pickup apparatus for recording / reproduction is described. However, a hologram optical pickup apparatus for reproduction may be used.

Further, as shown in FIG. 12, the divided wavelength plates of the first embodiment and the present embodiment may be combined. In this case, first, the optical path of the reproduction light is selected by switching the high-speed polarization switching element 200 with respect to the reproduction light. Then, the light is incident on the divided wave plate 701 or 702 having the same characteristics as in FIG. At this time, the reproduction light transmitted through different regions of the divided wavelength plate has two types of polarization components that are substantially orthogonal, and the two types of polarization components are different image sensors (image sensors 900 and 901 or image sensors 902 and 903). Is incident on. By adopting such a configuration, there is an advantage that the number of control components is reduced as compared with FIG. 5 of the first embodiment. Moreover, it becomes advantageous also from a viewpoint of cost. As a timing chart in the present embodiment, the transfer time Tt in FIG. 4 is halved.

FIG. 8 shows an optical system of a two-beam angle multiplexing type hologram pickup apparatus according to a third embodiment of the present invention. The difference from the first embodiment is that there are two galvano mirrors used for angle multiplexing, and it corresponds to recording / reproduction from two different directions.

First, the recording method of this embodiment will be described. The light beam emitted from the light source 11 passes through the collimator lens 12 and is converted into a desired beam diameter, and then passes through the shutter 13 and enters the polarization control element 14. The light beam is converted into P-polarized light and S-polarized light by the polarization control element 14. The polarization control element 14 is an element that converts the light into predetermined polarized light according to recording or reproduction. In this embodiment, it is assumed that P-polarized light and S-polarized light are converted during recording, and S-polarized light is converted during reproduction.

The light beam emitted from the polarization control element 14 enters the PBS prism 15, P-polarized light is transmitted, and S-polarized light is reflected. Here, the light beam transmitted through the PBS prism is called signal light, and the reflected light beam is called reference light. The signal light transmitted through the PBS prism 15 is converted into a desired beam diameter by the beam expander 25. The signal light transmitted through the beam expander 25 enters the spatial light modulator 29 through the phase mask 26, the relay lens 27, and the PBS prism 28, and is added with two-dimensional data.

The signal light to which information is added by the spatial light modulator 29 is reflected by the PBS prism 28, and is condensed in the optical information recording medium 300 through the relay lens 30, the spatial filter 31, and the objective lens 32.

On the other hand, the reference light reflected from the PBS prism 15 enters the high-speed polarization control element 133. When recording a predetermined page, the high-speed polarization control element 100 converts the reference light into P-polarized light. The P-polarized reference light emitted from the high-speed polarization control element 100 passes through the PBS prism 134 and enters the half-wave plate 35. The reference light emitted from the half-wave plate 35 is converted into S-polarized light. Then, the reference light emitted from the half-wave plate 35 enters the optical information recording medium 300 through the mirrors 36 and 37, the galvanometer mirror 38, and the scanner lens 39. At this time, when the signal light and the reference light are incident on the optical information recording medium 300 so as to overlap each other, an interference fringe pattern is formed in the optical information recording medium 300. The interference fringe pattern is recorded as a hologram in the recording medium (Recording 1).

After the information is recorded on the optical information recording medium 300 by the recording 1, the shutter 13 is closed and the information to be recorded next is displayed by the spatial light modulator 29. Then, the high-speed polarization control element 133 is switched, and the reference light is converted into S-polarized light. Thereafter, the shutter 13 is opened, and the S-polarized reference light emitted from the high-speed polarization control element 133 is incident on the optical information recording medium 300 through the PBS prism 134, the mirrors 135, 136, 137, the galvanometer mirror 138, and the scanner lens 139. At this time, when the signal light and the reference light are incident on the optical information recording medium 300 so as to overlap each other, an interference fringe pattern is formed in the optical information recording medium 300. This interference fringe pattern is recorded as a hologram in the recording medium (Recording 2). Further, during the recording 2, the galvano mirror 38 is rotated by a minute angle, and the incident angle of the reference light to the optical information recording medium 300 is changed. By repeating such recording 1 and recording 2, angle multiplex recording is continuously performed.

Next, the reproduction method of this embodiment will be described with reference to FIG. The light beam emitted from the light source 11 passes through the collimator lens 12 and is converted into a desired beam diameter, and then passes through the shutter 13 and enters the polarization control element 14. The light beam is converted into S-polarized light by the polarization control element 14. Then, the light beam transmitted through the polarization control element 14 reflects the PBS prism 15. Hereinafter, the light beam reflected from the PBS prism 15 is referred to as reference light.

When reproducing a predetermined page, the high-speed polarization control element 133 converts the reference light into P-polarized light. The P-polarized reference light emitted from the high-speed polarization control element 133 passes through the PBS prism 134 and enters the half-wave plate 35. The reference light emitted from the half-wave plate 35 is converted into S-polarized light. The reference light emitted from the half-wave plate 35 enters the galvanometer mirror 50 through the mirrors 36 and 37, the galvanometer mirror 38, the scanner lens 39, the optical information recording medium 300, and the quarter-wave plate 51. The galvanometer mirror 50 is controlled so that the incident reference light is substantially perpendicular to the galvanometer mirror 50. For this reason, the incident reference light is reflected in a substantially opposite direction, and reenters the optical information recording medium 300 through the quarter-wave plate 51. When the reference light is incident on the optical information recording medium 300 again, reproduction light (diffracted light of the reference light) having predetermined information is generated in the direction of the objective lens 32 from the recording area.

Then, the reproduction light enters the high-speed polarization control element 100 through the objective lens 32, the relay lens 30, the spatial filter 31, and the PBS prism 28. Here, when reproducing a predetermined page, the high-speed polarization control element 100 emits P-polarized reproduction light.

The reproduction light emitted from the high-speed polarization control element 100 passes through the PBS prism 101 and enters the image sensor 102. Then, reproduction image data is generated based on the reproduction light incident on the image sensor 102 (reproduction 1).

Next, the high-speed polarization control elements 100 and 133 are switched so that the outgoing polarized light becomes S-polarized light. The S-polarized reference light emitted from the high-speed polarization control element 133 passes through the PBS prism 134, mirrors 135, 136, and 137, the galvano mirror 138, the scanner lens 139, the optical information recording medium 300, and the quarter wavelength plate 151, and then the galvano. Incident on the mirror 150. The galvanometer mirror 150 is controlled so that the incident reference light is substantially perpendicular to the galvanometer mirror 150. For this reason, the incident reference light is reflected substantially in the opposite direction, and reenters the optical information recording medium 300 via the quarter-wave plate 151. When the reference light is incident on the optical information recording medium 300 again, reproduction light (diffracted light of the reference light) having predetermined information is generated in the direction of the objective lens 32 from the recording area.

Then, the reproduction light enters the high-speed polarization control element 100 through the objective lens 32, the relay lens 30, the spatial filter 31, and the PBS prism 28. Here, the high-speed polarization control element 100 converts the reproduction light into S-polarized light. Therefore, the reproduction light is reflected by the PBS prism 101 and enters the image sensor 103. Then, reproduction image data is generated based on the reproduction light incident on the image sensor 103 (reproduction 2).

Here, the effect of the present embodiment will be described. For the sake of simplicity, the image pickup device of the present embodiment will be described using a single buffer system in which one buffer is mounted, but the same effect can be obtained even in a multi-buffer system in which two or more buffers are mounted.

FIG. 9 shows an image sensor and a timing chart in a hologram system with one image sensor. Note that the description will be given with the reproduction of five pages, but the actual number of multiplexing is not limited to this.

When there is one image sensor, the next exposure cannot be performed until the transfer is completed as in the first embodiment. As a result, the galvanometer mirror has the same transfer speed as that of one hologram system (Example 1).

Next, the hologram system of this embodiment using two image sensors will be described. FIG. 10 shows a timing chart of the image sensor and the high-speed polarization control elements 100 and 133 in the hologram system of this embodiment. Note that the galvanometer mirror does not contribute to the frame rate because the galvanometer mirrors 138 and 150 for the reproduction 2 are rotated during the reproduction 1, for example.

In the case where the image pickup device shown in FIG. 9 is a single hologram system, exposure could not be performed while the reproduction signal was being transferred. On the other hand, in the case of the hologram system of the present invention, another image sensor can perform exposure while one image sensor transfers a reproduction signal. For this reason, it is possible to improve the frame rate as compared with the case where detection is performed by one image sensor.

As described above, in this embodiment, high-speed reproduction can be realized by using a plurality of imaging elements and a branch element using polarization (polarization control element and polarization branch element (PBS prism)). In addition, the present embodiment is characterized in that the polarization is selectively switched in accordance with the information to be reproduced, and one image sensor on which the reproduction light is incident is switched in accordance with the switching.

In this embodiment, two image sensors are used, but a plurality of image sensors may be used. For example, when four image sensors are used, the configuration shown in FIG. By doing so, it is possible to further increase the speed.

In this embodiment, the angle multiplexing method has been described, but the same effect can be obtained even with the shift multiplexing method, for example. In addition, the same effect can be obtained with other systems as long as the two-dimensional data is detected by the image sensor. Furthermore, since high pixels and high-speed transfer can be realized by using this embodiment, the present invention may be applied to an imaging camera or the like.

In this embodiment, the galvanometer mirror is used to change the incident angle to the optical recording medium, but the present invention is not limited to this. For example, an optical axis angle variable element such as an acousto-optic element may be used. Furthermore, the high-speed polarization control element 100 to the imaging elements 112 and 113 may be configured as one component or may be divided.

In this embodiment, the hologram optical pickup apparatus for recording / reproduction is described. However, a hologram optical pickup apparatus for reproduction may be used.

In this embodiment, the description has been made on the two-beam angle multiplexing in which the reference light beam is branched into two, but the same principle can be used to realize the three-beam, four-beam and multi-beam recording.

FIG. 11 shows the overall configuration of an optical information recording / reproducing apparatus that reproduces or records / reproduces digital information using a hologram. The optical information recording / reproducing apparatus includes, for example, a hologram optical pickup apparatus 60 configured as shown in FIG. 1, a phase conjugate optical system 512, an optical information recording medium Cure optical system 513, an optical information recording medium position detection optical system 514, and an optical information recording. A medium driving element 70 is provided, and the optical information recording medium 300 is configured such that the recording position relative to the optical pickup device can be changed.

The optical pickup device 60 plays a role of emitting reference light and signal light to the optical information recording medium 300 and recording digital information using a hologram. At this time, the information signal to be recorded is sent by the controller 89 to the spatial light modulator in the optical pickup device 60 via the signal generation circuit 86, and the signal light is modulated by the spatial light modulator. When reproducing information recorded on the optical information recording medium 300, the phase conjugate light of the reference light emitted from the optical pickup device 60 is generated by the phase conjugate optical system 512. Here, the phase conjugate optical system 512 indicates, for example, the galvanometer mirror 50 in the case of FIG. The phase conjugate light is a light wave that travels in the opposite direction while maintaining the same wavefront as the input light. The reproduction light reproduced by the phase conjugate light is detected by a plurality of image sensors in the optical pickup device 60, and the signal is reproduced by the signal processing circuit 85. The irradiation time of the reference light and the signal light applied to the optical information recording medium 300 can be adjusted by controlling a shutter opening / closing time described later in the optical pickup device 60 through the shutter control circuit 87 by the controller 89. The optical information recording medium Cure optical system 513 plays a role of generating a light beam used for pre-cure and post-cure of the optical information recording medium 300. Here, the pre-cure is a pre-process in which, when information is recorded at a desired position in the optical information recording medium 300, a predetermined light beam is irradiated in advance before the reference light and signal light are irradiated to the desired position. . Post-cure is a post-process for irradiating a predetermined light beam after recording information at a desired position in the optical information recording medium 300 so that additional recording cannot be performed at the desired position. The optical information recording medium position detection optical system 514 is used to detect the position of the optical information recording medium 300. When adjusting the optical information recording medium 300 to a predetermined position, a signal corresponding to the position is detected by the optical information recording medium position detection optical system 514, and the controller 89 uses the detected signal to pass the position control circuit 88. Thus, the position of the optical information recording medium 300 can be controlled.

A predetermined light source driving current is supplied from the light source driving circuit 82 to the light sources in the optical pickup device 60, the optical information recording medium Cure optical system 513, and the optical information recording medium position detecting optical system 514. Can emit a light beam.

Since the recording technology using holography is a technology capable of recording ultra-high density information, for example, an allowable error with respect to the tilt of the optical information recording medium 300 tends to be extremely small. Therefore, a signal for detecting the angle error signal is output in the optical pickup device 60 of the present embodiment. Using this signal, the servo signal generation circuit 83 generates an angle error signal for servo control, and an angle control element such as a galvanometer mirror is provided to correct the deviation amount via the servo control circuit 84. Further, the hologram optical pickup device 60, the phase conjugate optical system 512, the optical information recording medium Cure optical system 513, and the optical information recording medium position detection optical system 514 combine several optical system configurations or all optical system configurations into one. It may be simplified. In FIGS. 1 and 6 of the first, second, and third embodiments, the hologram optical pickup device 60 and the phase conjugate optical system 512 are shown together.

Here, in the present embodiment, the recording / reproducing hologram apparatus has been described. However, for example, the signal generating circuit 86, the shutter 87, the optical information recording medium Cure optical system 513, and the like may be deleted to form a reproducing hologram apparatus.

In addition, the hologram apparatus according to the present embodiment performs not only high-speed reproduction using information captured by a plurality of image sensors in the optical pickup device 60 according to the first and third embodiments, but also controls the following image sensors. May be.

For example, when the reproduction performance of information captured by a predetermined image sensor is poor, the same information may be reproduced by different image sensors. By doing so, for example, it is possible to improve the deterioration of the reproduction signal due to a defect of a predetermined image sensor, a positional shift in the optical path to the image sensor, an aberration, or the like. Also, if the reproduction performance of a given image sensor is significantly degraded, the high-speed polarization variable element is controlled so that the reproduction light does not enter the image sensor, and reproduction is performed using only the image sensor that can obtain the reproduction performance. good. Thereby, more stable reproduction can be performed with respect to the hologram system with one image sensor.

Also, this embodiment can be expressed as follows. That is, an optical pickup device that reproduces first page data and second page data from an optical information recording medium in which an interference pattern of signal light and reference light is recorded as a hologram, and a laser that emits reference light A detection optical system comprising: an emission unit; a lens that makes the reference light emitted from the laser emission unit enter the optical information recording medium; and a detection optical unit that detects reproduction light diffracted from the optical information recording medium based on the reference light. The unit includes a first image sensor and a second image sensor. After obtaining the first page data by the first image sensor, the second image data is obtained by the second image sensor. To do. Further, after obtaining the second page data by the second image sensor, the third image data is obtained by the first image sensor. Thereafter, the fourth image data is acquired by the second image sensor, and high-speed data processing can be performed by properly using the first image sensor and the second image sensor.

In addition, this invention is not limited to the above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

11: light source, 12: collimating lens, 13: shutter, 14: polarization control element, 15: PBS prism, 25: beam expander, 26: phase mask, 27: relay lens, 28: PBS prism, 29: spatial light modulation 30: Relay lens, 31: Spatial filter, 32: Objective lens, 35: 1/2 wavelength plate, 36: Mirror, 37: Mirror, 38: Galvano mirror, 39: Scanner lens, 50: Galvano mirror, 51: 1/2 wavelength plate, 60: optical pickup device, 70: optical information recording medium drive element, 82: light source drive circuit, 83: servo signal generation circuit, 84: servo control circuit, 85: signal processing circuit, 86: signal generation Circuit 87: shutter control circuit 88: position control circuit 89: controller 100: high-speed polarization control element 101: PBS pre 102: Image sensor, 103: Image sensor, 112: Image sensor, 113: Image sensor, 133: High-speed polarization control element, 134: PBS prism, 135 to 137: Mirror, 138: Galvanometer mirror, 139: Scanner lens, 150: Galvano mirror, 151: 1/2 wavelength plate, 180: Divided wave plate, 200 to 202: High-speed polarization control element, 400 to 403: Image sensor, 500 to 502: PBS prism, 512: Phase conjugate optical system, 513 : Optical information recording medium Cure optical system, 514: Optical information recording medium position detection optical system

Claims (10)

  1. An optical pickup device that reproduces first page data and second page data from an optical information recording medium in which an interference pattern of signal light and reference light is recorded as a hologram,
    A laser emitting section for emitting reference light;
    A lens that enters the optical information recording medium with the reference light emitted from a laser emitting unit;
    A detection optical unit that detects reproduction light diffracted from the optical information recording medium based on the reference light,
    The detection optical unit includes a first image sensor and a second image sensor. After the first page data is acquired by the first image sensor, the second image sensor An optical pickup device for acquiring the second page data.
  2. The optical pickup device according to claim 1,
    The detection optical unit has a branching unit using the first image sensor, the second image sensor, and polarized light,
    An optical pickup device, wherein the reproduction light branched by the branching unit is imaged by the first imaging element and the second imaging element.
  3. The optical pickup device according to claim 2, wherein
    The optical pickup device, wherein the branching unit includes at least a polarization control element and a polarization branching element.
  4. The optical pickup device according to claim 3, wherein
    The reproduction light incident on the detection optical unit is selectively switched in polarization according to the page data to be reproduced by the polarization control element,
    2. An optical pickup device according to claim 1, wherein an image pickup element on which the reproduction light is incident is switched according to switching of polarization of the polarization variable element.
  5. The optical pickup device according to claim 2, wherein
    The optical pickup device, wherein the branching unit includes at least a divided wavelength plate and a polarization branching element.
  6. The optical pickup device according to claim 5, wherein
    The divided wavelength plate has a plurality of regions,
    The reproduction light incident on the detection optical unit passes through a plurality of regions of the divided wavelength plate,
    The reproduction light transmitted through the divided wave plate is two kinds of polarization components that are substantially orthogonal to each other according to the area of the divided wave plate.
    An optical pickup device, wherein components having different polarizations are incident on different image sensors.
  7. An optical pickup device according to claim 1;
    A light source driving circuit for driving the light source in the optical pickup device;
    A position control circuit for controlling the relative position of the optical information recording medium and the optical pickup device;
    A signal processing circuit for reproducing page data of the optical information recording medium detected by the first image sensor and the second image sensor in the optical pickup device;
    Hologram device equipped with
  8. An optical pickup device according to claim 1;
    A light source driving circuit for driving the light source in the optical pickup device;
    A position control circuit for controlling the relative position of the optical information recording medium and the optical pickup device;
    A signal processing circuit for reproducing an information signal of the optical information recording medium detected by the first image sensor and the second image sensor in the optical pickup device;
    A hologram device equipped with
    A hologram apparatus, wherein when the page data imaged by a predetermined image sensor in the optical pickup device cannot be reproduced, the same page data is imaged by the other image sensor.
  9. A high-speed imaging device having a plurality of imaging elements,
    The high-speed imaging device has a branching unit using polarized light,
    A high-speed imaging apparatus, wherein the reproduction light branched by the branching unit is detected by a plurality of imaging elements.
  10. An information recording apparatus for recording an interference pattern of signal light and reference light as a hologram,
    A laser light source for emitting laser light;
    A first beam splitter for branching laser light emitted from the laser light source into signal light and reference light;
    A second beam splitter for branching the reference light into a plurality of parts;
    A plurality of mirrors for controlling the angles of a plurality of reference beams branched by the second beam splitter;
    Have
    The signal light and the plurality of reference lights from a plurality of directions are guided into a recording medium to perform multi-beam angle multiplex recording.
    Information recording device.
PCT/JP2012/078776 2012-11-07 2012-11-07 Holographic optical pickup device, holographic device, and high-speed image pickup device WO2014073041A1 (en)

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PCT/JP2012/078776 WO2014073041A1 (en) 2012-11-07 2012-11-07 Holographic optical pickup device, holographic device, and high-speed image pickup device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2012/078776 WO2014073041A1 (en) 2012-11-07 2012-11-07 Holographic optical pickup device, holographic device, and high-speed image pickup device

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Citations (5)

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Publication number Priority date Publication date Assignee Title
JPH0946477A (en) * 1995-07-26 1997-02-14 Konica Corp Image reader
JPH09212910A (en) * 1995-11-29 1997-08-15 Sharp Corp Optical pickup
JP2004212205A (en) * 2002-12-27 2004-07-29 Olympus Corp Angle detecting apparatus, light signal switching system, and information recording and reproducing system
JP2010061750A (en) * 2008-09-04 2010-03-18 Toshiba Corp Optical information recording and reproducing device and method
JP2010061718A (en) * 2008-09-02 2010-03-18 Nippon Hoso Kyokai <Nhk> Hologram reproducing device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0946477A (en) * 1995-07-26 1997-02-14 Konica Corp Image reader
JPH09212910A (en) * 1995-11-29 1997-08-15 Sharp Corp Optical pickup
JP2004212205A (en) * 2002-12-27 2004-07-29 Olympus Corp Angle detecting apparatus, light signal switching system, and information recording and reproducing system
JP2010061718A (en) * 2008-09-02 2010-03-18 Nippon Hoso Kyokai <Nhk> Hologram reproducing device
JP2010061750A (en) * 2008-09-04 2010-03-18 Toshiba Corp Optical information recording and reproducing device and method

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