US20130128711A1 - Method and Apparatus for Multiplexing Optical Information for Recording and Reproducing Optical Information Over Optical Storage Medium - Google Patents
Method and Apparatus for Multiplexing Optical Information for Recording and Reproducing Optical Information Over Optical Storage Medium Download PDFInfo
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- US20130128711A1 US20130128711A1 US13/670,389 US201213670389A US2013128711A1 US 20130128711 A1 US20130128711 A1 US 20130128711A1 US 201213670389 A US201213670389 A US 201213670389A US 2013128711 A1 US2013128711 A1 US 2013128711A1
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording 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
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/0065—Recording, reproducing or erasing by using optical interference patterns, e.g. holograms
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording 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
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/14—Heads, e.g. forming of the optical beam spot or modulation of the optical beam specially adapted to record on, or to reproduce from, more than one track simultaneously
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording 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
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/085—Disposition 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
- G11B7/08547—Arrangements for positioning the light beam only without moving the head, e.g. using static electro-optical elements
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording 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
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/128—Modulators
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording 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
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1353—Diffractive elements, e.g. holograms or gratings
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/32—Holograms used as optical elements
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
- G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
- G03H1/26—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
- G03H1/2645—Multiplexing processes, e.g. aperture, shift, or wavefront multiplexing
- G03H1/265—Angle multiplexing; Multichannel holograms
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
- G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
- G03H1/04—Processes or apparatus for producing holograms
- G03H1/0465—Particular recording light; Beam shape or geometry
- G03H2001/0473—Particular illumination angle between object or reference beams and hologram
Definitions
- the present invention relates to an optical information multiplexing and processing apparatus, and more particularly, to an optical multiplexer for multiplexing a beam by the use of a diffraction grating and a manufacturing method thereof, optical information recording apparatus and method using the optical multiplexer, and optical information reproducing apparatus and method using the optical multiplexer.
- Examples of an optical data processing apparatuses can include a digital versatile disc (DVD), a high definition DVD (HD-DVD), a blue-ray disc (BD), a near-field optical information processing apparatus, and a holographic optical information processing apparatus.
- DVD digital versatile disc
- HD-DVD high definition DVD
- BD blue-ray disc
- near-field optical information processing apparatus a near-field optical information processing apparatus
- holographic optical information processing apparatus holographic optical information processing apparatus.
- the holographic optical information processing apparatus stores data in a storage medium by irradiating an optically modulated signal beam and a reference beam to the storage medium.
- the reference beam forms an interference fringe in the storage medium through intersection with the signal beam.
- the holographic optical information processing apparatus reproduces data by irradiating the reference beam to the interference fringe of the storage medium and outputting the data stored in the storage medium through diffraction resulting from the interference fringe.
- the holographic optical information processing apparatus can store data in a multiplexing manner by irradiating the reference beam to one beam spot at different angles, thereby enhancing the recording capacity of the storage medium.
- the multiplexed recorded data can be output by irradiating the reference beam at different angles at the time of reproducing the data. That is, the holographic optical information processing apparatus is an ultra-high-capacity data processing apparatus which can input data to and output data from one beam spot with the data superposed in multi layers.
- the optical information processing apparatus such as the holographic optical information processing apparatus employs a device or a method for multiplexing a beam.
- the beam multiplexing method include an angular multiplexing method, a phase-code multiplexing method, and a
- wavelength multiplexing method In the angular multiplexing method, a multiplexing operation is performed by changing an incident angle of a reference beam. In the phase-code multiplexing method, a multiplexing operation is performed by spatially modulating a phase. In the wavelength multiplexing method, a multiplexing operation is performed by wavelengths by the use of a variable wavelength laser.
- a known technique of the beam multiplexing method is disclosed in Korean Unexamined Patent Publication No. 2005-0102748, entitled “Holographic Information Recording/Reproducing Apparatus.” As disclosed in the Korean unexamined patent publication, two or more multiplexing methods can be used in the Korean unexamined patent publication.
- a typical complex multiplexing method combines an in-plane multiplexing method and an out-of-plane multiplexing method.
- the known complex multiplexing method disclosed in the Korean unexamined patent publication generally requires complex configuration and control system such as a plurality of rotating mirrors, thereby increasing the size of the apparatus.
- the improved complex multiplexing method disclosed in the Korean unexamined patent publication two wedge prisms are superposed for use and the complex multiplexing operation is performed by rotating a storage medium.
- the wedge prisms are moved in a rotating direction and an optical axis direction by an additional control system.
- the total size of the optical system can be further reduced, compared with the complex multiplexing operation using two rotating mirrors in an additional space.
- the optical control for multiplexing should be performed twice and two wedge prisms having relatively high price should be used.
- an optical multiplexer comprising: a substrate having a plurality of beam transmitting portions; and diffraction gratings diffracting beams irradiated to the beam transmitting portions at different angles, each diffraction grating being formed in the corresponding beam transmitting portion.
- a method of manufacturing an optical multiplexer comprising: irradiating a second beam at a first angle along with a first beam to a first beam transmitting photo-reactant to form a first diffraction grating in the first beam transmitting photo-reactant; and irradiating the second beam at a second angle different from the first angle along with the first beam to a second beam transmitting photo-reactant to form a second diffraction grating.
- an optical information recording apparatus comprising: a light source; a beam splitter splitting a beam emitted from the light source; a signal beam optical system loading data to a beam split by the beam splitter and producing a signal beam; a reference beam optical system guiding another beam split by the beam splitter as a reference beam to an optical information storage medium; and an optical multiplexer multiplexing the reference beam at an angle in a plane and an angle out of the plane and guiding the multiplexed beams to the optical information storage medium.
- an optical information recording method comprising: splitting a beam irradiated from a light source to two beams, using one split beam as a reference beam, and loading data to the other split beam to generate a signal beam; multiplexing the reference beam at a plurality of angles by the use of a diffraction grating, by irradiating the reference beam to a beam transmitting portion in which the diffraction grating is formed and moving the beam transmitting portion; and recording the data in an optical information storage medium by irradiating the multiplexed reference beam and the signal beam to the optical information storage medium.
- an optical information reproducing apparatus comprising: a light source; an optical system guiding a beam emitted from the light source to an optical information storage medium which stores multiplexed optical information; an optical multiplexer multiplexing the beam at an angle in a predetermined plane and an angle out of the plane and then guiding the multiplexed beam to the optical information storage medium; and an optical information detector detecting the optical information reproduced from the optical information storage medium by the multiplexed beam.
- an optical information reproducing method comprising: generating a beam by irradiating a beam to a beam transmitting portion having a diffraction grating and generating the beam with a different angle from the diffraction grating by revolving the beam transmitting portion; irradiating the generated beams to an optical information storage medium in which optical information is stored and reproducing the optical information stored in the optical information storage medium by incident angles of the beams; and detecting the reproduced optical information.
- FIG. 1 is a perspective view illustrating an optical multiplexer according to an exemplary embodiment of the invention
- FIG. 2 is a partially expanded cross-sectional view illustrating beam transmitting portions of the optical multiplexer according to the exemplary embodiment of the invention
- FIGS. 3A and 3B are diagrams illustrating an out-of-plane multiplexing operation of the optical multiplexer according to the exemplary embodiment of the invention.
- FIG. 4 is a flowchart illustrating a method of manufacturing the optical multiplexer according to the exemplary embodiment of the invention.
- FIG. 5 is a diagram illustrating a configuration and an operating state of an optical multiplexer according to another exemplary embodiment of the invention.
- FIG. 6 is a diagram illustrating a configuration and an operating state of an optical multiplexer according to another exemplary embodiment of the invention.
- FIG. 7 is a diagram illustrating a configuration of an optical information recording apparatus according to an exemplary embodiment of the invention.
- FIG. 8 is a flowchart illustrating an optical information recording method according to an exemplary embodiment of the invention.
- FIG. 9 is a diagram illustrating a configuration of an optical information reproducing apparatus according to an exemplary embodiment of the invention.
- FIG. 10 is a flowchart illustrating an optical information reproducing method according to an exemplary embodiment of the invention.
- Embodiments of an optical multiplexer, an optical information reproducing apparatus using the optical multiplexer, and an optical information recording apparatus using the optical multiplexer are separately described.
- the optical multiplexer according to the invention serves to variously change an incident beam in plane or out of plane.
- FIG. 1 is a perspective view illustrating an optical multiplexer according to an exemplary embodiment of the invention
- FIG. 2 is a partially expanded cross-sectional view illustrating beam transmitting portions of the optical multiplexer, according to the exemplary embodiment of the invention.
- the optical multiplexer 100 according to the exemplary embodiment of the invention includes a substrate 110 having a circular disc shape.
- the shape of the substrate 110 is not limited to the disc shape, but may have a variety of shapes.
- a coupling hole 120 is formed at the center of the substrate 110 .
- the coupling hole 120 is coupled to a servo motor (not shown) supplying a rotary power to the substrate 110 . Accordingly, the substrate 110 is revolved by the servo motor.
- the substrate 110 may be made of a material reflecting and/or absorbing light.
- a plurality of beam transmitting portions 130 such as a first beam transmitting portion 130 a , a second beam transmitting portion 130 b , . . . , and a n-th beam transmitting portion 130 n (where n is the number of beam transmitting portions) arranged with a constant interval is formed around the substrate 110 .
- the beam transmitting portions 130 have a rectangular shape, but may have an arc shape, a circular shape, or an elliptical shape.
- the beam transmitting portions 130 are disposed preferably along the circumference of the substrate 110 .
- Each beam transmitting portion 130 includes a through-hole 131 penetrating the substrate 110 and a beam transmitting photo-reactant filled in the through-hole 131 .
- a plurality of diffraction gratings is formed in the beam transmitting photo-reactant.
- the diffraction gratings are holographic interference fringes formed by means of irradiation of a spherical-wave beam and a plane-wave beam.
- a photo-polymer 132 can be used as the beam transmitting photo-reactant.
- An example of the photo-polymer 132 can include “HRR-660” and “OmniDex-760” (product codes) made by Dupont Co., “ULSH-500” (product code) made by Aprils Co., and polymethylmethacrylate (PMMA). Ferroelectric crystals can be used as the photo-polymer 132 .
- a plurality of beam transmitting portions 130 is provided as described above.
- the number of beam transmitting portions 130 may correspond to the number of angles in plane to be multiplexed.
- the first beam transmitting portion 130 a of the beam transmitting portions 130 is designed to perform a multiplexing operation with an angle “ ⁇ 1 ”
- the second beam transmitting portion 130 b is designed to perform a multiplexing operation with an angle “ ⁇ 2 ”
- the n-th beam transmitting portion 130 n is designed to perform a multiplexing operation with an angle “ ⁇ n.”
- n indicates the final beam transmitting portion 130 as described above.
- the respective beam transmitting portions 130 converts an incident beam into a beam with a predetermined angle.
- the angles of the beams emitted from the beam transmitting portions 130 are different from each other.
- the multiplexing operation is an in-plane multiplexing operation with an angle changed in a two-dimensional plane.
- a complex multiplexing operation including an in-plane multiplexing operation and an out-of-plane multiplexing operation is performed.
- the out-of-plane multiplexing operation can be performed by controlling the positions of the beam transmitting portions 130 without adding another element to the optical multiplexer according to the exemplary embodiment.
- FIGS. 3A and 3B are diagrams illustrating the out-of-plane multiplexing operation of the optical multiplexer according to the exemplary embodiment of the invention.
- the beam irradiated to the beam transmitting portion 130 of the optical multiplexer 100 is a spherical-wave beam having the same wavelength as the beam irradiated thereto at the time of forming the diffraction grating.
- the diffraction grating is formed as an interference fringe resulting from interference of the spherical-wave beam and the plane-wave beam.
- the beam transmitting portion 130 converts the irradiated beam into a beam with a different angle out of the plane in the Y axis direction.
- an out-of-plane multiplexed beam corresponding to the changed position is generated from the beam transmitting portion 130 .
- the position of a spherical-wave light source is not changed for the out-of-plane multiplexing operation. Even when the position of the spherical-wave light source is changed, the technical spirit of the invention can be accomplished. However, it is possible to enhance multiplexing efficiency by revolving the substrate 110 . That is, in the optical multiplexer 100 according to the exemplary embodiment of the invention, the substrate 110 is revolved for the out-of-plane multiplexing operation. Incidentally, as shown in FIG.
- the beam emitted from the diffraction grating has a different angle. Accordingly, a beam having a different out-of-plane angle is generated from the same beam transmitting portion 130 (see FIG. 3B ).
- the spherical-wave beam is irradiated to the beam transmitting portions 130 for the in-plane multiplexing operation, and the spherical-wave beam is irradiated to each beam transmitting portion while slightly changing the position of the corresponding beam transmitting portion for the out-of-plane multiplexing operation.
- FIG. 2 is a partially expanded cross-sectional view illustrating beam transmitting portions of the optical multiplexer according to the exemplary embodiment of the invention
- FIG. 4 is a flowchart illustrating a method of manufacturing the optical multiplexer according to the exemplary embodiment of the invention.
- the first beam transmitting portion 130 a filled with the photo-polymer 132 is located at a beam irradiating position.
- a spherical-wave beam (first beam) is irradiated to the first beam transmitting portion 130 a at a fixed angle.
- a plane-wave beam (second beam) is irradiated thereto at a first angle “ ⁇ 1 .” Then, an interference fringe based on the first angle ⁇ 1 is formed in the first beam transmitting portion 130 a (S 100 ).
- the substrate 110 is revolved and thus the second beam transmitting portion 130 b is located at the beam irradiating position.
- a spherical-wave beam having the same fixed angle as the angle of the spherical-wave beam irradiated to the first beam transmitting portion 130 a is irradiated to the second beam transmitting portion 130 b and a plane-wave beam (second beam) is irradiated thereto at a second angle “ ⁇ 2 .”
- ⁇ 2 a plane-wave beam
- n angles correspond to the number of in-plane angular multiplexing operations which can be performed at the time of reproducing optical information from an optical information storage medium.
- the angle “ ⁇ ” for multiplexing can be selected from the range of angle of 0° ⁇ 180° and can be determined on the basis of the traveling distance of the plane-wave beam and the area or width of the beam transmitting portion 130 .
- the change in angle of the plane-wave beam can be carried out by a rotating mirror such as a galvano mirror.
- the in-plane angular multiplexing operation is performed by irradiating the spherical-wave beam to the n beam transmitting portions 130 without change in angle.
- the out-of-plane angular multiplexing operation is performed by irradiating the spherical-wave beam to each beam transmitting portion 130 after moving the corresponding beam transmitting portion 130 to a predetermined angle.
- the angle of the spherical-wave beam may be changed, not the position of the beam transmitting portions.
- diffraction gratings having been subjected to an angular multiplexing process different from that in the above-mentioned exemplary embodiment may be formed. That is, by modifying the type, the wavelength, the phase, the angle, and the like of the irradiated beam for the angular multiplexing process, it is possible to manufacture optical multiplexers capable of performing a variety of angular multiplexing operations. Such modified embodiments cannot depart from the technical scope and spirit of the invention.
- the substrate may be embodied as follows.
- the material and shape of 25 the beam transmitting portions and the shape and operation of the diffraction gratings formed in the beam transmitting portions are similar to those described in the above-mentioned exemplary embodiment, repeated description thereof will be omitted.
- elements are denoted by reference numerals different from those of the above-mentioned exemplary embodiment.
- FIG. 5 is a diagram illustrating a configuration and an operating state of an optical multiplexer according to another exemplary embodiment of the invention.
- a substrate 210 of an optical multiplexer 200 has a longitudinal bar shape.
- a plurality of beam transmitting portions 220 is formed with intervals in the longitudinal direction of the bar.
- a rack 210 a is formed on the upper portion of the bar-shaped substrate 210 .
- a pinion 230 engages with the rack 210 a .
- the pinion 230 is connected to a forward and backward driving motor 240 . Accordingly, the substrate 210 is moved by rotating the forward and backward driving motor 240 forwardly and backwardly.
- the positions of the beam transmitting portions 220 can be controlled by controlling the forward and backward driving motor 240 in a step manner.
- the linear movement of the substrate 210 can be guided by a guide member (not shown).
- a linear driving assembly (not shown) using electromagnetic force can be used to move the substrate 210 , or various other techniques may be used.
- FIG. 6 is a diagram illustrating a configuration and an operating state of an optical multiplexer according to another exemplary embodiment of the invention.
- a substrate 310 of an optical multiplexer 300 has a belt shape.
- the belt-shaped substrate 310 is wound on two reels 340 and 350 .
- the belt-shaped substrate 310 may be made of a flexible resin material.
- a plurality of beam transmitting portions 320 are formed in the traveling direction of the substrate 310 with intervals.
- a forward and backward driving motor 360 is coupled to one of the two reels 340 and 350 .
- a positioning guide 330 positioning the substrate 310 is disposed at a beam irradiating position. By driving the forward and backward driving motor 360 forwardly and backwardly, the substrate 310 is moved.
- the positions of the beam transmitting portions 320 can be controlled by controlling the forward and backward driving motor 360 in a step manner.
- the optical multiplexers according to the exemplary embodiments of the invention can be used to three-dimensionally record optical information in a holographic data storage and to reproduce the data from the holographic data storage in a multiplexing manner.
- the optical multiplexers can be applied to a holographic spectrometer by partially modifying the configuration thereof.
- the optical multiplexers can be applied to a holographic 3D display by partially modifying the configuration thereof.
- FIG. 7 is a diagram illustrating a configuration of an optical information recording apparatus according to an exemplary embodiment of the invention.
- the optical information recording apparatus shown in FIG. 7 serves to record optical information, but may serve as an optical information reproducing apparatus by blocking a signal beam.
- the optical information recording apparatus according to the exemplary embodiment of the invention includes a light source 400 .
- the light source 400 emits a beam with a predetermined wavelength.
- the beam may be a laser beam having excellent coherence.
- the optical information recording apparatus further includes a beam splitter 410 for splitting the beam emitted from the light source 400 .
- the beam splitter 410 has a beam splitter surface 410 a for splitting a beam to two beams in different directions.
- One beam split by the beam splitter 410 travels straightly. Modulated optical information is loaded to the split beam to form a signal beam. Accordingly, the beam is referred to as a signal beam.
- a shutter (not shown) is disposed in the traveling path of the signal beam so as to control the traveling of the signal beam. Then, by disposing an optical information detector (not shown) in the traveling path of the signal beam, the optical information recording apparatus according to the exemplary embodiment can perform an optical information reproducing function.
- a lens system 420 is disposed in the optical path of the signal beam.
- a polarizing beam splitter 430 for signal beam is disposed next to the lens system 420 .
- the signal beam traveling to the polarizing beam splitter 430 for signal beam is a P polarized beam split by the beam splitter 410 . Accordingly, the signal beam passes through the polarizing beam splitter 430 in the traveling direction.
- a spatial light modulator 440 is disposed in the optical path of the P polarized beam passing through the polarizing beam splitter 430 .
- the spatial light modulator 440 modulates desired binary data in units of pixels. That is, the spatial light modulator 440 spatially modulates the intensity of the exit beam and optically loads information to the P polarized beam, by switching a transmitting state and a blocking state of a beam by pixels.
- Examples of the spatial light modulator 440 can include a thin film transistor liquid crystal display device (TFT LCD) which is a representative active
- STN super twisted nematic
- ferroelectric LCD ferroelectric LCD
- PD polymer dispersed LCD
- PA plasma addressing LCD
- DMD digital micro mirror device
- the signal beam passing through the spatial light modulator 440 becomes a signal beam containing optical information. Then, the spatial light modulator 440 reflects the signal beam in the direction opposite to the incident direction of the signal beam.
- a reflecting polarizing plate 441 is provided to convert the signal beam, which is a P polarized beam, into an S polarized beam.
- the reflected signal beam is incident again on the polarizing beam splitter 430 . Since the signal beam is the S polarized beam, the polarizing beam splitter 430 reflects the signal beam by the use of the polarizing beam splitter plane 430 a .
- An objective lens 450 guiding the signal beam reflected by the polarizing beam splitter 430 is disposed in the traveling path of the signal beam.
- An optical information storage medium 490 is positioned in the traveling path of the signal beam passing through the objective lens 450 in a state in which it is tilted at a predetermined angle.
- the optical information storage medium 490 is made of a transparent material.
- the optical information storage medium 490 may be made of a kind of photo-polymer.
- Examples of the photo-polymer can include “HRR-660” and “OmniDex-760” (product codes) made by Dupont Co., “ULSH-500” (product code) made by Aprils Co., and polymethylmethacrylate (PMMA). Other kinds of photo-polymers may be used.
- the optical information storage medium 490 may be formed in a disc shape.
- the split beam split in the other direction by the beam splitter 410 polarizing a beam from the light source 400 serves as a reference beam later.
- the reference beam travels to the optical information storage medium 490 through a reflecting mirror 460 from the beam splitter 410 .
- the reference beam is a plane-wave beam.
- a wavefront converting lens 470 is provided to convert the reference beam into a spherical-wave beam.
- the reference beam passing through the wavefront converting lens 470 becomes the spherical-wave beam.
- Means other than the wavefront converting lens 470 may be used to generate a spherical-wave beam.
- the optical multiplexer 100 transmitting the reference beam is disposed in front of the optical information storage medium 490 .
- the optical multiplexer 100 according to the exemplary embodiment of the invention is used as the optical multiplexer.
- a servo motor (not shown) is disposed to revolve the optical multiplexer 100 at a predetermined control speed. Accordingly, the reference beam is multiplexed at an in-plane angle and an out-of-plane angle by the optical multiplexer 100 and then travels to the optical information storage medium 490 .
- FIG. 8 is a flowchart illustrating an optical information recording method according to an exemplary embodiment of the invention.
- a beam emitted from the light source 400 is split to two beams.
- One beam is used as the reference beam, and data are loaded to the 5 other beam to generate the signal beam (S 400 ).
- the reference beam is allowed to pass through the wavefront converting lens and is converted into a spherical-wave beam.
- the reference beam converted into the spherical-wave beam is incident on the optical multiplexer 100 .
- the optical multiplexer 100 is revolved to multiplex the reference beam. Since the optical multiplexing operation is described above, detailed description thereof is omitted.
- the optical multiplexer 100 multiplexes the reference beam at in-plane angles and out-of-plane angles to generate a plurality of plane-wave beams (S 410 ).
- the multiplexed reference beams and the signal beam are incident on the optical information storage medium 490 .
- the optical information of the signal beam is multiplexed and recorded in the optical information storage medium 490 by means of interference of the reference beams and the signal beam (S 420 ).
- FIG. 9 is a diagram illustrating a configuration of an optical information reproducing apparatus according to an exemplary embodiment of the invention.
- the optical information reproducing apparatus includes a light source 500 .
- the light source 500 emits a reference beam with a predetermined wavelength.
- a wavefront converting lens 510 is provided to convert the beam emitted from the
- a spherical-wave generator may be provided integrally with a laser oscillator which can be used as a light source.
- An optical multiplexer 100 is disposed next to the wavefront converting lens 510 in the traveling path of the reference beam.
- the optical multiplexers described above may be used as the optical multiplexer 100 .
- the optical multiplexer 100 is connected to a servo motor (not shown) so as to be revolved at a predetermined control speed. Accordingly, the reference beam is multiplexed at an in-plane angle and an out-of-plane angle through the optical multiplexer 100 .
- the beam passing through the optical multiplexer 100 is a spherical-wave beam.
- a lens system 520 guiding the multiplexed beam to an optical information storage medium is disposed next to the optical multiplexer 100 .
- the reference beam passing through the lens system 520 is incident on the optical information storage medium 530 storing optical information. Multiplexed optical information is recorded in the optical information storage medium 530 .
- the optical information storage medium 530 is as described in the optical information recording apparatus.
- the optical information detector 550 may be a charge-coupled device (CCD), a complementary metal-oxide semiconductor (CMOS), or an optical device capable of detecting a beam. Accordingly, the optical information stored in the optical information storage medium 530 is detected by the optical information detector 530 .
- CCD charge-coupled device
- CMOS complementary metal-oxide semiconductor
- FIG. 10 is a flowchart illustrating an optical information reproducing method according to an exemplary embodiment of the invention.
- the beam emitted from the light source travels to the optical information storage medium 530 .
- the beam emitted from the light source is a spherical-wave beam.
- the spherical-wave beam is converted into reference beams multiplexed at in-plane angles and out-of-plane angles through the optical multiplexer 100 (S 500 ).
- the beams passing through the optical multiplexer 100 are incident on the optical information storage medium 530 through the lens system 520 (S 510 ). Since the operation of the optical multiplexer 100 has been described above, description thereof is omitted.
- the optical information stored therein is continuously reproduced in a multiplexing manner depending upon the incident angles.
- the optical information is detected by the detector 550 (S 520 ). The detected optical information is restored to data later.
- the optical multiplexer, the optical information recording apparatus and method, and the optical information reproducing apparatus and method according to the exemplary embodiments of the invention elements having other functions may be added or some elements may be replaced with other elements.
- the modified examples include the essential elements of the invention and perform the recording operation and the reproducing operation using the optical multiplexer according to the exemplary embodiments of the invention separately or together, they are all included in the technical scope of the invention.
- the in-plane and out-of-plane multiplexing and recording operations of optical information are performed using a substrate. Accordingly, since the servo control system for controlling mirrors can be simplified greatly and the configuration of the optical system can be simplified, it is possible to reduce misalignment and manufacturing cost of the optical system and to reduce the total size of the recording apparatus and the reproducing apparatus.
Abstract
There is provided an optical multiplexer including: a substrate having a plurality of beam transmitting portions; and diffraction gratings diffracting beams irradiated to the beam transmitting portions at different angles, each diffraction grating being formed in the corresponding beam transmitting portion.
Accordingly, it is possible to reduce an alignment error and manufacturing cost and to reduce the entire size of a recording apparatus or a reproducing apparatus.
Description
- This U.S. application is a Continuation of pending U.S. application Ser. No. 11/486,451, filed Jul. 13, 2006, which claims priority to Korean Patent Application No. 10-2005-0127443, filed Dec. 22, 2005, which are both incorporated herein by reference in their entirety.
- 1. Technical Field
- The present invention relates to an optical information multiplexing and processing apparatus, and more particularly, to an optical multiplexer for multiplexing a beam by the use of a diffraction grating and a manufacturing method thereof, optical information recording apparatus and method using the optical multiplexer, and optical information reproducing apparatus and method using the optical multiplexer.
- 2. Related Art
- Examples of an optical data processing apparatuses can include a digital versatile disc (DVD), a high definition DVD (HD-DVD), a blue-ray disc (BD), a near-field optical information processing apparatus, and a holographic optical information processing apparatus.
- The holographic optical information processing apparatus stores data in a storage medium by irradiating an optically modulated signal beam and a reference beam to the storage medium. Here, the reference beam forms an interference fringe in the storage medium through intersection with the signal beam. The holographic optical information processing apparatus reproduces data by irradiating the reference beam to the interference fringe of the storage medium and outputting the data stored in the storage medium through diffraction resulting from the interference fringe.
- The holographic optical information processing apparatus can store data in a multiplexing manner by irradiating the reference beam to one beam spot at different angles, thereby enhancing the recording capacity of the storage medium. The multiplexed recorded data can be output by irradiating the reference beam at different angles at the time of reproducing the data. That is, the holographic optical information processing apparatus is an ultra-high-capacity data processing apparatus which can input data to and output data from one beam spot with the data superposed in multi layers.
- The optical information processing apparatus such as the holographic optical information processing apparatus employs a device or a method for multiplexing a beam. Examples of the beam multiplexing method include an angular multiplexing method, a phase-code multiplexing method, and a
- wavelength multiplexing method. In the angular multiplexing method, a multiplexing operation is performed by changing an incident angle of a reference beam. In the phase-code multiplexing method, a multiplexing operation is performed by spatially modulating a phase. In the wavelength multiplexing method, a multiplexing operation is performed by wavelengths by the use of a variable wavelength laser.
- A known technique of the beam multiplexing method is disclosed in Korean Unexamined Patent Publication No. 2005-0102748, entitled “Holographic Information Recording/Reproducing Apparatus.” As disclosed in the Korean unexamined patent publication, two or more multiplexing methods can be used in
- parallel to store holographic optical information. A typical complex multiplexing method combines an in-plane multiplexing method and an out-of-plane multiplexing method. However, the known complex multiplexing method disclosed in the Korean unexamined patent publication generally requires complex configuration and control system such as a plurality of rotating mirrors, thereby increasing the size of the apparatus.
- In the improved complex multiplexing method disclosed in the Korean unexamined patent publication, two wedge prisms are superposed for use and the complex multiplexing operation is performed by rotating a storage medium. For this purpose, the wedge prisms are moved in a rotating direction and an optical axis direction by an additional control system. According to the Korean unexamined paten publication, it is disclosed that the total size of the optical system can be further reduced, compared with the complex multiplexing operation using two rotating mirrors in an additional space. However, since the wedge prisms should be rotating or moved, the optical control for multiplexing should be performed twice and two wedge prisms having relatively high price should be used.
- An object of the invention is to provide an optical multiplexer using a diffraction grating and a method of manufacturing the optical multiplexer. Another object of the invention is to provide optical information recording apparatus and method for multiplexing and recording optical information using an optical multiplexer having a diffraction grating therein, and optical information reproducing apparatus and method using the optical multiplexer.
- According to an aspect of the invention, there is provided an optical multiplexer comprising: a substrate having a plurality of beam transmitting portions; and diffraction gratings diffracting beams irradiated to the beam transmitting portions at different angles, each diffraction grating being formed in the corresponding beam transmitting portion.
- According to another aspect of the invention, there is provided a method of manufacturing an optical multiplexer, the method comprising: irradiating a second beam at a first angle along with a first beam to a first beam transmitting photo-reactant to form a first diffraction grating in the first beam transmitting photo-reactant; and irradiating the second beam at a second angle different from the first angle along with the first beam to a second beam transmitting photo-reactant to form a second diffraction grating.
- According to another aspect of the invention, there is provided an optical information recording apparatus comprising: a light source; a beam splitter splitting a beam emitted from the light source; a signal beam optical system loading data to a beam split by the beam splitter and producing a signal beam; a reference beam optical system guiding another beam split by the beam splitter as a reference beam to an optical information storage medium; and an optical multiplexer multiplexing the reference beam at an angle in a plane and an angle out of the plane and guiding the multiplexed beams to the optical information storage medium.
- According to another aspect of the invention, there is provided an optical information recording method comprising: splitting a beam irradiated from a light source to two beams, using one split beam as a reference beam, and loading data to the other split beam to generate a signal beam; multiplexing the reference beam at a plurality of angles by the use of a diffraction grating, by irradiating the reference beam to a beam transmitting portion in which the diffraction grating is formed and moving the beam transmitting portion; and recording the data in an optical information storage medium by irradiating the multiplexed reference beam and the signal beam to the optical information storage medium.
- According to another aspect of the invention, there is provided an optical information reproducing apparatus comprising: a light source; an optical system guiding a beam emitted from the light source to an optical information storage medium which stores multiplexed optical information; an optical multiplexer multiplexing the beam at an angle in a predetermined plane and an angle out of the plane and then guiding the multiplexed beam to the optical information storage medium; and an optical information detector detecting the optical information reproduced from the optical information storage medium by the multiplexed beam.
- According to another aspect of the invention, there is provided an optical information reproducing method comprising: generating a beam by irradiating a beam to a beam transmitting portion having a diffraction grating and generating the beam with a different angle from the diffraction grating by revolving the beam transmitting portion; irradiating the generated beams to an optical information storage medium in which optical information is stored and reproducing the optical information stored in the optical information storage medium by incident angles of the beams; and detecting the reproduced optical information.
- The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
-
FIG. 1 is a perspective view illustrating an optical multiplexer according to an exemplary embodiment of the invention; -
FIG. 2 is a partially expanded cross-sectional view illustrating beam transmitting portions of the optical multiplexer according to the exemplary embodiment of the invention; -
FIGS. 3A and 3B are diagrams illustrating an out-of-plane multiplexing operation of the optical multiplexer according to the exemplary embodiment of the invention; -
FIG. 4 is a flowchart illustrating a method of manufacturing the optical multiplexer according to the exemplary embodiment of the invention; -
FIG. 5 is a diagram illustrating a configuration and an operating state of an optical multiplexer according to another exemplary embodiment of the invention; -
FIG. 6 is a diagram illustrating a configuration and an operating state of an optical multiplexer according to another exemplary embodiment of the invention; -
FIG. 7 is a diagram illustrating a configuration of an optical information recording apparatus according to an exemplary embodiment of the invention; -
FIG. 8 is a flowchart illustrating an optical information recording method according to an exemplary embodiment of the invention; -
FIG. 9 is a diagram illustrating a configuration of an optical information reproducing apparatus according to an exemplary embodiment of the invention; and -
FIG. 10 is a flowchart illustrating an optical information reproducing method according to an exemplary embodiment of the invention. - Hereinafter, exemplary embodiments of the present invention will be described with reference to the attached drawings.
- Embodiments of an optical multiplexer, an optical information reproducing apparatus using the optical multiplexer, and an optical information recording apparatus using the optical multiplexer are separately described. The optical multiplexer according to the invention serves to variously change an incident beam in plane or out of plane.
-
FIG. 1 is a perspective view illustrating an optical multiplexer according to an exemplary embodiment of the invention andFIG. 2 is a partially expanded cross-sectional view illustrating beam transmitting portions of the optical multiplexer, according to the exemplary embodiment of the invention. As shown inFIGS. 1 and 2 , theoptical multiplexer 100 according to the exemplary embodiment of the invention includes asubstrate 110 having a circular disc shape. The shape of thesubstrate 110 is not limited to the disc shape, but may have a variety of shapes. Acoupling hole 120 is formed at the center of thesubstrate 110. Thecoupling hole 120 is coupled to a servo motor (not shown) supplying a rotary power to thesubstrate 110. Accordingly, thesubstrate 110 is revolved by the servo motor. Thesubstrate 110 may be made of a material reflecting and/or absorbing light. - A plurality of
beam transmitting portions 130 such as a firstbeam transmitting portion 130 a, a secondbeam transmitting portion 130 b, . . . , and a n-thbeam transmitting portion 130 n (where n is the number of beam transmitting portions) arranged with a constant interval is formed around thesubstrate 110. In the exemplary embodiment, thebeam transmitting portions 130 have a rectangular shape, but may have an arc shape, a circular shape, or an elliptical shape. Thebeam transmitting portions 130 are disposed preferably along the circumference of thesubstrate 110. - Each
beam transmitting portion 130 includes a through-hole 131 penetrating thesubstrate 110 and a beam transmitting photo-reactant filled in the through-hole 131. A plurality of diffraction gratings is formed in the beam transmitting photo-reactant. The diffraction gratings are holographic interference fringes formed by means of irradiation of a spherical-wave beam and a plane-wave beam. A photo-polymer 132 can be used as the beam transmitting photo-reactant. An example of the photo-polymer 132 can include “HRR-660” and “OmniDex-760” (product codes) made by Dupont Co., “ULSH-500” (product code) made by Aprils Co., and polymethylmethacrylate (PMMA). Ferroelectric crystals can be used as the photo-polymer 132. - A plurality of
beam transmitting portions 130 is provided as described above. The number ofbeam transmitting portions 130 may correspond to the number of angles in plane to be multiplexed. The firstbeam transmitting portion 130 a of thebeam transmitting portions 130 is designed to perform a multiplexing operation with an angle “Θ1”, the secondbeam transmitting portion 130 b is designed to perform a multiplexing operation with an angle “Θ2”, and the n-thbeam transmitting portion 130 n is designed to perform a multiplexing operation with an angle “Θn.” Here, n indicates the finalbeam transmitting portion 130 as described above. The respectivebeam transmitting portions 130 converts an incident beam into a beam with a predetermined angle. The angles of the beams emitted from thebeam transmitting portions 130 are different from each other. - Accordingly, by moving the
substrate 110 and changing a target beam transmitting portion to which the beam is irradiated, the multiplexing of the beam is performed. Here, the multiplexing operation is an in-plane multiplexing operation with an angle changed in a two-dimensional plane. In the exemplary embodiment, a complex multiplexing operation including an in-plane multiplexing operation and an out-of-plane multiplexing operation is performed. The out-of-plane multiplexing operation can be performed by controlling the positions of thebeam transmitting portions 130 without adding another element to the optical multiplexer according to the exemplary embodiment. -
FIGS. 3A and 3B are diagrams illustrating the out-of-plane multiplexing operation of the optical multiplexer according to the exemplary embodiment of the invention. As shown inFIGS. 3A and 3B , the beam irradiated to thebeam transmitting portion 130 of theoptical multiplexer 100 is a spherical-wave beam having the same wavelength as the beam irradiated thereto at the time of forming the diffraction grating. Accordingly, the diffraction grating is formed as an interference fringe resulting from interference of the spherical-wave beam and the plane-wave beam. When the incident position of the spherical-wave beam irradiated to thebeam transmitting portion 130 is changed, thebeam transmitting portion 130 converts the irradiated beam into a beam with a different angle out of the plane in the Y axis direction. By changing the position of the photo-polymer 132 of thebeam transmitting portion 130 out of the plane, an out-of-plane multiplexed beam corresponding to the changed position is generated from thebeam transmitting portion 130. - In the exemplary embodiment of the invention, the position of a spherical-wave light source is not changed for the out-of-plane multiplexing operation. Even when the position of the spherical-wave light source is changed, the technical spirit of the invention can be accomplished. However, it is possible to enhance multiplexing efficiency by revolving the
substrate 110. That is, in theoptical multiplexer 100 according to the exemplary embodiment of the invention, thesubstrate 110 is revolved for the out-of-plane multiplexing operation. Incidentally, as shown inFIG. 3B , when thesubstrate 110 is moved upward without departing from a predetermined range of position of the optical transmittingportion 130 to which the spherical-wave beam is irradiated, the beam emitted from the diffraction grating has a different angle. Accordingly, a beam having a different out-of-plane angle is generated from the same beam transmitting portion 130 (seeFIG. 3B ). - In the
optical multiplexer 100 according to the exemplary embodiment of the invention, the spherical-wave beam is irradiated to thebeam transmitting portions 130 for the in-plane multiplexing operation, and the spherical-wave beam is irradiated to each beam transmitting portion while slightly changing the position of the corresponding beam transmitting portion for the out-of-plane multiplexing operation. - Now, a method of manufacturing the optical multiplexer according to the exemplary embodiment of the invention having the above-mentioned configuration will be described.
-
FIG. 2 is a partially expanded cross-sectional view illustrating beam transmitting portions of the optical multiplexer according to the exemplary embodiment of the invention andFIG. 4 is a flowchart illustrating a method of manufacturing the optical multiplexer according to the exemplary embodiment of the invention. As shown inFIGS. 2 and 4 , the firstbeam transmitting portion 130 a filled with the photo-polymer 132 is located at a beam irradiating position. Then, a spherical-wave beam (first beam) is irradiated to the firstbeam transmitting portion 130 a at a fixed angle. At the same time, a plane-wave beam (second beam) is irradiated thereto at a first angle “Θ1.” Then, an interference fringe based on the first angle Θ1 is formed in the firstbeam transmitting portion 130 a (S100). - Next, the
substrate 110 is revolved and thus the secondbeam transmitting portion 130 b is located at the beam irradiating position. A spherical-wave beam having the same fixed angle as the angle of the spherical-wave beam irradiated to the firstbeam transmitting portion 130 a is irradiated to the secondbeam transmitting portion 130 b and a plane-wave beam (second beam) is irradiated thereto at a second angle “Θ2.” As a result, an interference fringe based on the second angle Θ2 is formed in the secondbeam transmitting portion 130 b (S200). - The same process is repeated with variation in angle of the plane-wave beam. Finally, a plane-wave beam is irradiated to the n-th
beam transmitting portion 130 n at an n-th angle “Θn.” Then, an interference fringe based on the nth angle Θn is formed in the n-thbeam transmitting portion 130 n. As a result, the holographic diffraction gratings based on n different angles are formed in the nbeam transmitting portions 130. The n angles correspond to the number of in-plane angular multiplexing operations which can be performed at the time of reproducing optical information from an optical information storage medium. The angle “Θ” for multiplexing can be selected from the range of angle of 0°<Θ<180° and can be determined on the basis of the traveling distance of the plane-wave beam and the area or width of thebeam transmitting portion 130. The change in angle of the plane-wave beam can be carried out by a rotating mirror such as a galvano mirror. - As described above, the in-plane angular multiplexing operation is performed by irradiating the spherical-wave beam to the n
beam transmitting portions 130 without change in angle. The out-of-plane angular multiplexing operation is performed by irradiating the spherical-wave beam to eachbeam transmitting portion 130 after moving the correspondingbeam transmitting portion 130 to a predetermined angle. - Unlike the above-mentioned exemplary embodiment, the angle of the spherical-wave beam may be changed, not the position of the beam transmitting portions. In this case, diffraction gratings having been subjected to an angular multiplexing process different from that in the above-mentioned exemplary embodiment may be formed. That is, by modifying the type, the wavelength, the phase, the angle, and the like of the irradiated beam for the angular multiplexing process, it is possible to manufacture optical multiplexers capable of performing a variety of angular multiplexing operations. Such modified embodiments cannot depart from the technical scope and spirit of the invention.
- The invention is not to the above-mentioned exemplary embodiment, but may be modified in various embodiments. That is, the substrate may be embodied as follows. In the following description, since the material and shape of 25 the beam transmitting portions and the shape and operation of the diffraction gratings formed in the beam transmitting portions are similar to those described in the above-mentioned exemplary embodiment, repeated description thereof will be omitted. For the purpose of convenient and clear understanding, elements are denoted by reference numerals different from those of the above-mentioned exemplary embodiment.
-
FIG. 5 is a diagram illustrating a configuration and an operating state of an optical multiplexer according to another exemplary embodiment of the invention. InFIG. 5 , asubstrate 210 of anoptical multiplexer 200 has a longitudinal bar shape. A plurality ofbeam transmitting portions 220 is formed with intervals in the longitudinal direction of the bar. - A
rack 210 a is formed on the upper portion of the bar-shapedsubstrate 210. Apinion 230 engages with therack 210 a. Thepinion 230 is connected to a forward and backward drivingmotor 240. Accordingly, thesubstrate 210 is moved by rotating the forward and backward drivingmotor 240 forwardly and backwardly. The positions of thebeam transmitting portions 220 can be controlled by controlling the forward and backward drivingmotor 240 in a step manner. The linear movement of thesubstrate 210 can be guided by a guide member (not shown). A linear driving assembly (not shown) using electromagnetic force can be used to move thesubstrate 210, or various other techniques may be used. -
FIG. 6 is a diagram illustrating a configuration and an operating state of an optical multiplexer according to another exemplary embodiment of the invention. InFIG. 6 , asubstrate 310 of anoptical multiplexer 300 has a belt shape. The belt-shapedsubstrate 310 is wound on tworeels substrate 310 may be made of a flexible resin material. - A plurality of
beam transmitting portions 320 are formed in the traveling direction of thesubstrate 310 with intervals. A forward and backward drivingmotor 360 is coupled to one of the tworeels positioning guide 330 positioning thesubstrate 310 is disposed at a beam irradiating position. By driving the forward and backward drivingmotor 360 forwardly and backwardly, thesubstrate 310 is moved. The positions of thebeam transmitting portions 320 can be controlled by controlling the forward and backward drivingmotor 360 in a step manner. - The optical multiplexers according to the exemplary embodiments of the invention can be used to three-dimensionally record optical information in a holographic data storage and to reproduce the data from the holographic data storage in a multiplexing manner. The optical multiplexers can be applied to a holographic spectrometer by partially modifying the configuration thereof. In addition, the optical multiplexers can be applied to a holographic 3D display by partially modifying the configuration thereof.
- Now, an optical information recording apparatus and an optical information reproducing apparatus using the optical multiplexer will be described. In the following embodiments, since configuration and operation of an optical multiplexer can be easily understood with reference to those of the above-mentioned optical multiplexers and the manufacturing method thereof, repeated description thereof is omitted.
- An optical information recording apparatus according to another exemplary embodiment of the invention will be now described.
FIG. 7 is a diagram illustrating a configuration of an optical information recording apparatus according to an exemplary embodiment of the invention. The optical information recording apparatus shown inFIG. 7 serves to record optical information, but may serve as an optical information reproducing apparatus by blocking a signal beam. The optical information recording apparatus according to the exemplary embodiment of the invention includes alight source 400. Thelight source 400 emits a beam with a predetermined wavelength. The beam may be a laser beam having excellent coherence. The optical information recording apparatus further includes abeam splitter 410 for splitting the beam emitted from thelight source 400. Thebeam splitter 410 has abeam splitter surface 410 a for splitting a beam to two beams in different directions. - One beam split by the
beam splitter 410 travels straightly. Modulated optical information is loaded to the split beam to form a signal beam. Accordingly, the beam is referred to as a signal beam. A shutter (not shown) is disposed in the traveling path of the signal beam so as to control the traveling of the signal beam. Then, by disposing an optical information detector (not shown) in the traveling path of the signal beam, the optical information recording apparatus according to the exemplary embodiment can perform an optical information reproducing function. - A
lens system 420 is disposed in the optical path of the signal beam. Apolarizing beam splitter 430 for signal beam is disposed next to thelens system 420. The signal beam traveling to thepolarizing beam splitter 430 for signal beam is a P polarized beam split by thebeam splitter 410. Accordingly, the signal beam passes through thepolarizing beam splitter 430 in the traveling direction. - A spatial
light modulator 440 is disposed in the optical path of the P polarized beam passing through thepolarizing beam splitter 430. The spatiallight modulator 440 modulates desired binary data in units of pixels. That is, the spatiallight modulator 440 spatially modulates the intensity of the exit beam and optically loads information to the P polarized beam, by switching a transmitting state and a blocking state of a beam by pixels. - Examples of the spatial
light modulator 440 can include a thin film transistor liquid crystal display device (TFT LCD) which is a representative active - matrix device, a super twisted nematic (STN) LCD which is a passive matrix device, a ferroelectric LCD, a polymer dispersed (PD) LCD, a plasma addressing (PA) LCD, and a digital micro mirror device (DMD).
- The signal beam passing through the spatial
light modulator 440 becomes a signal beam containing optical information. Then, the spatiallight modulator 440 reflects the signal beam in the direction opposite to the incident direction of the signal beam. A reflectingpolarizing plate 441 is provided to convert the signal beam, which is a P polarized beam, into an S polarized beam. - The reflected signal beam is incident again on the
polarizing beam splitter 430. Since the signal beam is the S polarized beam, thepolarizing beam splitter 430 reflects the signal beam by the use of the polarizingbeam splitter plane 430 a. Anobjective lens 450 guiding the signal beam reflected by thepolarizing beam splitter 430 is disposed in the traveling path of the signal beam. An opticalinformation storage medium 490 is positioned in the traveling path of the signal beam passing through theobjective lens 450 in a state in which it is tilted at a predetermined angle. - The optical
information storage medium 490 is made of a transparent material. The opticalinformation storage medium 490 may be made of a kind of photo-polymer. Examples of the photo-polymer can include “HRR-660” and “OmniDex-760” (product codes) made by Dupont Co., “ULSH-500” (product code) made by Aprils Co., and polymethylmethacrylate (PMMA). Other kinds of photo-polymers may be used. The opticalinformation storage medium 490 may be formed in a disc shape. - On the other hand, the split beam split in the other direction by the
beam splitter 410 polarizing a beam from thelight source 400 serves as a reference beam later. The reference beam travels to the opticalinformation storage medium 490 through a reflectingmirror 460 from thebeam splitter 410. The reference beam is a plane-wave beam. Accordingly, awavefront converting lens 470 is provided to convert the reference beam into a spherical-wave beam. The reference beam passing through thewavefront converting lens 470 becomes the spherical-wave beam. Means other than thewavefront converting lens 470 may be used to generate a spherical-wave beam. - The
optical multiplexer 100 transmitting the reference beam is disposed in front of the opticalinformation storage medium 490. Theoptical multiplexer 100 according to the exemplary embodiment of the invention is used as the optical multiplexer. A servo motor (not shown) is disposed to revolve theoptical multiplexer 100 at a predetermined control speed. Accordingly, the reference beam is multiplexed at an in-plane angle and an out-of-plane angle by theoptical multiplexer 100 and then travels to the opticalinformation storage medium 490. - Hereinafter, an optical information recording method according to an exemplary embodiment of the invention will be described.
FIG. 8 is a flowchart illustrating an optical information recording method according to an exemplary embodiment of the invention. - As shown in
FIG. 8 , a beam emitted from thelight source 400 is split to two beams. One beam is used as the reference beam, and data are loaded to the 5 other beam to generate the signal beam (S400). - The reference beam is allowed to pass through the wavefront converting lens and is converted into a spherical-wave beam. The reference beam converted into the spherical-wave beam is incident on the
optical multiplexer 100. At this time, theoptical multiplexer 100 is revolved to multiplex the reference beam. Since the optical multiplexing operation is described above, detailed description thereof is omitted. Theoptical multiplexer 100 multiplexes the reference beam at in-plane angles and out-of-plane angles to generate a plurality of plane-wave beams (S410). The multiplexed reference beams and the signal beam are incident on the opticalinformation storage medium 490. The optical information of the signal beam is multiplexed and recorded in the opticalinformation storage medium 490 by means of interference of the reference beams and the signal beam (S420). -
FIG. 9 is a diagram illustrating a configuration of an optical information reproducing apparatus according to an exemplary embodiment of the invention. As shown inFIG. 9 , the optical information reproducing apparatus according to the exemplary embodiment of the invention includes alight source 500. Thelight source 500 emits a reference beam with a predetermined wavelength. Awavefront converting lens 510 is provided to convert the beam emitted from the -
light source 500 into a spherical-wave beam. Means other than thewavefront converting lens 510 may be used to generate the spherical-wave beam. For example, a spherical-wave generator may be provided integrally with a laser oscillator which can be used as a light source. - An
optical multiplexer 100 is disposed next to thewavefront converting lens 510 in the traveling path of the reference beam. The optical multiplexers described above may be used as theoptical multiplexer 100. Theoptical multiplexer 100 is connected to a servo motor (not shown) so as to be revolved at a predetermined control speed. Accordingly, the reference beam is multiplexed at an in-plane angle and an out-of-plane angle through theoptical multiplexer 100. The beam passing through theoptical multiplexer 100 is a spherical-wave beam. Alens system 520 guiding the multiplexed beam to an optical information storage medium is disposed next to theoptical multiplexer 100. - The reference beam passing through the
lens system 520 is incident on the opticalinformation storage medium 530 storing optical information. Multiplexed optical information is recorded in the opticalinformation storage medium 530. The opticalinformation storage medium 530 is as described in the optical information recording apparatus. - When the reference beam is incident on the optical
information storage medium 530, a reproduced beam is emitted from the opticalinformation storage medium 530. Anobjective lens 540 and anoptical information detector 550 are disposed in the traveling path of the reproduced beam. Theoptical information detector 550 may be a charge-coupled device (CCD), a complementary metal-oxide semiconductor (CMOS), or an optical device capable of detecting a beam. Accordingly, the optical information stored in the opticalinformation storage medium 530 is detected by theoptical information detector 530. - Hereinafter, an optical information reproducing method according to an exemplary embodiment of the invention will be described.
FIG. 10 is a flowchart illustrating an optical information reproducing method according to an exemplary embodiment of the invention. - As shown in
FIG. 10 , the beam emitted from the light source travels to the opticalinformation storage medium 530. The beam emitted from the light source is a spherical-wave beam. The spherical-wave beam is converted into reference beams multiplexed at in-plane angles and out-of-plane angles through the optical multiplexer 100 (S500). - The beams passing through the
optical multiplexer 100 are incident on the opticalinformation storage medium 530 through the lens system 520 (S510). Since the operation of theoptical multiplexer 100 has been described above, description thereof is omitted. When the multiplexed reference beam is incident on the opticalinformation storage medium 530, the optical information stored therein is continuously reproduced in a multiplexing manner depending upon the incident angles. The optical information is detected by the detector 550 (S520). The detected optical information is restored to data later. - In the optical multiplexer, the optical information recording apparatus and method, and the optical information reproducing apparatus and method according to the exemplary embodiments of the invention, elements having other functions may be added or some elements may be replaced with other elements. However, if the modified examples include the essential elements of the invention and perform the recording operation and the reproducing operation using the optical multiplexer according to the exemplary embodiments of the invention separately or together, they are all included in the technical scope of the invention.
- In the optical multiplexer, the optical information recording apparatus and method, and the optical information reproducing apparatus and method according to the invention, the in-plane and out-of-plane multiplexing and recording operations of optical information are performed using a substrate. Accordingly, since the servo control system for controlling mirrors can be simplified greatly and the configuration of the optical system can be simplified, it is possible to reduce misalignment and manufacturing cost of the optical system and to reduce the total size of the recording apparatus and the reproducing apparatus.
Claims (1)
1. An optical multiplexer comprising:
a substrate having a plurality of beam transmitting portions; and
a plurality of beam transmitting portions formed in and extended through holes in the substrate from the first surface to the second surface, each of the plurality of beam transmitting portions having a diffraction grating, said diffraction grating formed by irradiating a spherical wave beam and a plane wave beam respectively to the each of the plurality of beam transmitting portions, wherein each irradiation angle formed by the spherical beam and the plane wave beam onto each of the beam transmitting portions is different, and the diffraction grating diffracts a beam irradiated to the each of the plurality of beam transmitting portions at different angle, and the diffracted beam is multiplexed, wherein the multiplexed beam is incident on an optical information storage medium to record and reproduce data.
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KR1020050127443A KR100709762B1 (en) | 2005-12-22 | 2005-12-22 | Optical multiplexer and method for manufacturing thereof, method and apparatus for recording multiplexed optical information, method and apparatus for reproducing multiplexed optical information |
KR10-2005-0127443 | 2005-12-22 | ||
US11/486,451 US8306376B2 (en) | 2005-12-22 | 2006-07-12 | Method and apparatus for multiplexing optical information for recording and reproducing optical information over optical storage medium |
US13/670,389 US20130128711A1 (en) | 2005-12-22 | 2012-11-06 | Method and Apparatus for Multiplexing Optical Information for Recording and Reproducing Optical Information Over Optical Storage Medium |
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Also Published As
Publication number | Publication date |
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JP5068967B2 (en) | 2012-11-07 |
EP1801623A2 (en) | 2007-06-27 |
US8306376B2 (en) | 2012-11-06 |
JP2007172807A (en) | 2007-07-05 |
ATE525667T1 (en) | 2011-10-15 |
KR100709762B1 (en) | 2007-04-23 |
EP1801623A3 (en) | 2009-12-02 |
TW200725604A (en) | 2007-07-01 |
EP1801623B1 (en) | 2011-09-21 |
US20070147735A1 (en) | 2007-06-28 |
CN1987535A (en) | 2007-06-27 |
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