KR100874400B1 - Holographic optical information storage and reproduction method and device therefor - Google Patents

Abstract

A light source for generating light; A beam splitter for dividing the light generated by the light source into a reference light and a signal light; An optical modulator for optically modulating the signal light corresponding to the input information; A movable first deflection device for deflecting the modulated signal light to a focusing optical system; A focusing optical system for overlapping the signal light and the reference light at the same position; And an optical recording medium provided at an overlapping position where the signal light and the reference light overlap, wherein the holographic optical information storage and reproducing apparatus is provided in which the plurality of signal light is superimposed on the one reference light corresponding to the movement of the deflection apparatus. . The holographic optical information storing and reproducing method and apparatus thereof according to the present invention have the effect of storing high density information in an optical recording medium of the same size.

Description

Holographic recording information storage and reproducing method and apparatus therefor {Holographic recording method and Apparatus}

1 is a perspective view of a diffractive optical modulator module using a piezoelectric body applicable to a preferred embodiment of the present invention.

2 is a plan view of a diffractive light modulator array applicable to a preferred embodiment of the present invention.

3 is a schematic diagram of an image generated on a screen by a diffractive light modulator array applicable to a preferred embodiment of the present invention.

4 is a schematic structural diagram of a holographic optical information storage device according to a preferred embodiment of the present invention;

5 is a flowchart illustrating a holographic optical information storing method according to a preferred embodiment of the present invention.

6 is a schematic structural diagram of a holographic optical information reproducing apparatus according to a preferred embodiment of the present invention;

7 is a flowchart illustrating a holographic optical information reproducing method according to a preferred embodiment of the present invention.

Figure 8 is a comparison of the holographic optical information storage method according to a preferred embodiment of the present invention compared with the storage method according to the prior art.

Figure 9 is a comparison of the holographic optical information reproduction method according to a preferred embodiment of the present invention compared with the reproduction method according to the prior art.

<Explanation of symbols for main parts of the drawings>

405: light source 410: beam expander

415: beam splitter 420: first deflection device

423: shutter 425: cylinder lens

430 optical modulator 435 mirror of the first deflection device

440: focusing optical system 445: second deflection device

450: mirror of the second deflection device 455: deflection mirror

460 optical recording medium 465 optical recording medium moving device

470: reproduction optical system 475: optical detector

The present invention relates to a method and apparatus for storing and reproducing holographic optical information, and more particularly, to a method and apparatus for holographic optical information storing and reproducing using an optical modulator.

In recent years, rewritable optical discs, such as a phase change type or a magneto-optical type, have been widely used as information recording media. Such optical discs require techniques such as reducing the beam spot diameter and shortening the distance between adjacent tracks or adjacent bits in order to further increase the recording density.

As described above, the densification of the optical disc is progressing year by year. On the other hand, since the optical disc records data in plane, its recording density is limited by the diffraction limit of light, thereby approaching the physical limit of high density recording. Therefore, for larger capacity, three-dimensional (volume-type) multiple recording including the depth direction is required.

Therefore, as a next-generation computer file memory, a holographic storage device having both a large capacity derived from three-dimensional multi-recording and a high speed derived from a two-dimensional batch recording / reproducing method has attracted attention. The holographic storage device irradiates signal light and reference light corresponding to recording information to a recording medium formed by sandwiching (interposed) two glass plates with a recording layer made of a photopolymer or the like, for example. The interference fringes generated by the light are recorded as a change in the refractive index of the recording material. When the information is reproduced, only the reference light is irradiated to the recorded interference fringes to extract optical information corresponding to the recorded information.

As a holographic storage device, various types such as a cube type or a card type have been proposed. For example, a holographic storage device that increases the recording capacity by multilayering a recording layer on which a waveguide is formed is known. have.

In the case where the information is multi-recorded on the recording medium of the holographic storage device using the signal light and the reference light, the conventional method uses the reference light and the signal light when the information is recorded and reproduced with respect to the recording layer of the holographic storage medium. Since it is necessary to make incident at an accurate incidence angle, it is necessary to control optical elements, such as a mirror, with high precision.

In addition, an optical modulator for modulating light according to predetermined information is used as a main component in a holographic storage device. However, since it is an expensive product, the application of a low-cost and high-performance optical modulator such as a one-dimensional optical modulator is difficult. need. However, such a one-dimensional light modulator has a problem that it is not easy to manufacture a high density storage capacity because the number of pixels is small.

The present invention provides a holographic optical information storing and reproducing method and apparatus capable of storing high density information in an optical recording medium of the same size.

The present invention also provides a method and apparatus for holographic optical information storing and reproducing which can associate a plurality of signal lights with one reference light and store them in an optical recording medium.

In addition, the present invention provides a method and apparatus for holographic optical information storage and reproducing that can exhibit low cost and high performance by using a one-dimensional optical modulator as an example.

Technical problems other than the present invention will be easily understood through the following description.

According to an aspect of the invention, the light source for generating light; A beam splitter for dividing the light generated by the light source into a reference light and a signal light; An optical modulator for optically modulating the signal light corresponding to the input information; A movable first deflection device for deflecting the modulated signal light to a focusing optical system; A focusing optical system for overlapping the signal light and the reference light at the same position; And an optical recording medium provided at an overlapping position where the signal light overlaps with the reference light, wherein the plurality of signal light overlaps the one reference light in response to the movement of the deflection device. Can be.

Here, the first deflection device may move so that the modulated signal light is irradiated to the overlapping position.

Here, the first deflection device may move in parallel with the focusing optical system.

Here, the signal light and the reference light may overlap at the focus of the focusing optical system.

In addition, the holographic optical information storage and reproducing apparatus according to an embodiment of the present invention further comprises a movable second deflection device positioned between the beam splitter and the focusing optical system, and deflecting the reference light to the focusing optical system. Reference light may be incident on the optical recording medium with different angles of incidence corresponding to the movement of the second deflection apparatus.

In addition, the holographic optical information storage and reproducing apparatus according to an embodiment of the present invention is located between the beam splitter and the focusing optical system, the shutter can block the signal light; And an optical detector configured to detect the signal light irradiated by the reference light to the optical recording medium and reproduced.

The light detector may have a plurality of pixels in a two-dimensional form.

Here, the light modulator may be in a one-dimensional form.

According to another aspect of the present invention, there is provided a method of storing holographic light information using an optical modulator, the method comprising: (a) dividing light generated by a light source into a first reference light and a first signal light by a beam splitter; (b) the optical modulator light modulating the first signal light corresponding to the input information; (c) the modulated first signal light is reflected at a first reflective position of the movable first deflection device and irradiated to a focusing optical system; (d) irradiating an optical recording medium provided at an overlapping position where the first reference light and the first signal light passing through the focusing optical system overlap each other; (e) interfering with the first reference light and the first signal light to generate a first interference fringe in the optical recording medium; (f) dividing the light generated by the light source into a first reference light and a second signal light by a beam splitter; (g) light modulating the second signal light according to the input information by the light modulator; (h) the modulated second signal light is reflected at a second reflective position of the movable first deflection device and irradiated to the focusing optical system; (i) irradiating an optical recording medium provided at the overlapping position where the first reference light passing through the focusing optical system and the second signal light having an incident angle different from the first signal light overlap each other; And (j) the first reference light and the second signal light interfere with each other to generate a second interference fringe in the optical recording medium.

Here, the first reflection position and the second reflection position of the first deflection device may be different positions, and the movement trajectory of the first deflection device may be formed so that the modulated second signal light is irradiated to the overlapping position. .

In addition, the holographic optical information storage and reproduction method according to an embodiment of the present invention comprises the steps of (k) the beam splitter divides the light generated by the light source into a second reference light and a third signal light; (l) light modulating the third signal light according to the input information by the light modulator; (m) the modulated third signal light is reflected at the first reflective position of the movable first deflection device and irradiated to a focusing optical system, and the second reference light is reflected at the first reflective position of the movable second deflection device and focused Irradiating with an optical system; (n) irradiating an optical recording medium provided at an overlapping position where the second reference light and the third signal light passing through the focusing optical system overlap each other; And (o) the second reference light and the third signal light interfere with each other to generate a first interference fringe in the optical recording medium. According to still another aspect of the present invention, there is provided a method of an apparatus for reproducing holographic light information using an optical modulator, the method comprising: (a) dividing light generated by a light source into a first reference light and a signal light; (b) the signal light is blocked by a shutter, and the first reference light is irradiated with a focusing optical system; (c) the first reference light passing through the focusing optical system is incident on an optical recording medium; (d) reproducing a plurality of optical information corresponding to the plurality of first interference fringes recorded in the optical recording medium by the incident first reference light, wherein the first interference fringes correspond to the first reference light; Correspondingly, it may be formed by a plurality of the signal light incident on the optical recording medium at different incidence angles.

Wherein step (d) comprises: (d-1) the plurality of signal lights emitted from the first reference light by irradiating the optical recording medium and reproduced from the optical recording medium with different emission angles; (d-2) The method may further include detecting, by an optical detector, the plurality of signal lights emitted from the different emission angles.

In addition, the holographic optical information storage and reproduction method according to an embodiment of the present invention comprises the steps of: (e) the beam splitter splits the light generated by the light source into a second reference light and a signal light; (f) the signal light is blocked by a shutter, and the second reference light is reflected at a first reflection position of the movable second deflection device and irradiated to a focusing optical system; (g) the second reference light passing through the focusing optical system is incident on the optical recording medium with an angle of incidence different from that of the first reference light; (h) reproducing a plurality of optical information corresponding to the plurality of second interference fringes recorded in the optical recording medium by the incident second reference light, wherein the second interference fringes are connected to the second reference light; Correspondingly, it may be formed by a plurality of the signal light incident on the optical recording medium at different incidence angles.

Hereinafter, a preferred embodiment of the holographic optical information storing and reproducing method and the apparatus according to the present invention will be described in detail with reference to the accompanying drawings, and in the following description with reference to the accompanying drawings, the same configuration regardless of reference numerals Elements are given the same reference numerals and redundant descriptions thereof will be omitted. In the following description of the present invention, if it is determined that the detailed description of the related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, the first and second identification codes are merely tools for explaining that they are different components, signals, and the like, and the case of replacing them with each other or substituting other components may belong to the present invention. Of course. Hereinafter, the optical modulator applied to the present invention will be described first before describing the preferred embodiments of the present invention in detail.

Optical modulators are largely divided into a direct method of directly controlling the on / off of light and an indirect method using reflection and diffraction, and the indirect method may be divided into an electrostatic method and a piezoelectric method. Herein, the optical modulator is applicable to the present invention regardless of the manner in which the optical modulator is driven. For example, the electrostatically driven grating light modulator disclosed in US Pat. No. 5,311,360 includes a plurality of uniformly spaced deformable reflective ribbons having reflective surface portions and suspended above a substrate. An insulating layer is deposited on the silicon substrate. Next, the deposition process of the sacrificial silicon dioxide film and the silicon nitride film is followed.

The nitride film is patterned from the ribbon and a portion of the silicon dioxide layer is etched so that the ribbon is held on the oxide spacer layer by the nitride frame. To modulate light with a single wavelength [lambda] 0, the modulator is designed such that the thickness of the ribbon and the thickness of the oxide spacers are [lambda] 0/4.

The lattice amplitude of this modulator, defined by the vertical distance d between the reflective surface on the ribbon and the reflective surface of the substrate, is the conduction of the ribbon (reflective surface of the ribbon serving as the first electrode) and the substrate (substrate serving as the second electrode). Film). Hereinafter, a case in which a piezoelectric diffraction type optical modulator is applied to an embodiment of the present invention will be described.

1 is a perspective view of a micromirror included in a diffractive light modulator element using a piezoelectric element among indirect light modulators applicable to the present invention. Referring to FIG. 1, an optical modulator 100 including a substrate 110, an insulating layer 120, a sacrificial layer 130, a ribbon structure 140, and a piezoelectric body 150 is shown.

The substrate 110 is a commonly used semiconductor substrate, and the insulating layer 120 is deposited as an etch stop layer, and an etchant for etching a material used as a sacrificial layer, wherein the etchant is an etching gas or an etching solution. Solution). The insulating layer 120 may be coated with a reflective layer 120 (a) to reflect incident light.

The sacrificial layer 130 supports the ribbon structure 140 at both sides so that the ribbon structure 140 can be spaced apart from the insulating layer 120 at regular intervals, and forms a space at the center.

As described above, the ribbon structure 240 causes diffraction and interference of incident light to optically modulate the signal. The shape of the ribbon structure 140 may be configured in the form of a plurality of ribbons according to the electrostatic method, or may be provided with a plurality of open holes in the center of the ribbon according to the piezoelectric method. In addition, the piezoelectric member 150 controls the ribbon structure 140 to move up and down according to the degree of contraction or expansion of up and down or left and right generated by the voltage difference between the upper and lower electrodes.

For example, when the wavelength of light is λ, the insulating layer 120 having the ribbon structure 140 and the lower reflective layer 120 (a) formed with the light modulator unmodified (no voltage applied) is formed. The interval between is equal to λ / 2. Therefore, in the case of zero-order diffracted light (reflected light), the total path difference between the light reflected from the ribbon structure 140 and the light reflected from the insulating layer 120 is equal to λ, so that the interference of constructive interference has a maximum value. Here, in the case of the + 1st and -1st diffracted light, the light intensity has a minimum value due to destructive interference.

In addition, when an appropriate voltage is applied to the piezoelectric body 150, the distance between the ribbon structure 140 and the insulating layer 120 on which the lower reflective layer 120 (a) is formed is equal to λ / 4. Therefore, in the case of the zero-order diffracted light, the total path difference between the light reflected from the ribbon structure 140 and the insulating layer 120 is equal to λ / 2, and thus the interference of the light has a minimum value. Here, in the case of + 1st and -1st diffraction light, the intensity of light has a maximum value due to constructive interference. As a result of this interference, the light modulator can adjust the amount of reflected or diffracted light to carry the signal on the light. In the above, the case in which the distance between the ribbon structure 140 and the insulating layer 120 on which the lower reflective layer 120 (a) is formed is λ / 2 has been described. However, the intensity of interference caused by diffraction and reflection of incident light can be adjusted. Naturally, various embodiments capable of driving at intervals can be applied to the present invention.

Referring to FIG. 2, the optical modulator includes a first pixel (pixel # 1), a second pixel (pixel # 2),. And n micromirrors 100-1, 100-2,..., 100-n that are responsible for the n-th pixel (pixel #n). The optical modulator is responsible for the image information of the one-dimensional image of the vertical scanning line or the horizontal scanning line (assuming that the vertical scanning line or the horizontal scanning line is composed of n pixels), and each micromirror 100-1, 100-2. , ..., 100-n) is in charge of any one of the n pixels constituting the vertical scan line or the horizontal scan line. Thus, the reflected and diffracted light in each micro mirror is then projected on the screen as a two dimensional image by the light scanning device.

Referring to FIG. 3, when n micro mirrors 100-1, 100-2,..., 100-n are arranged vertically, a screen 310 generated by horizontally scanning the screen 300 by an optical scanning device. -1, 310-2, 310-3, 310-4, ..., 310- (n-3), 310- (n-2), 310- (n-1), 310-n are shown. Here, the scanning direction is shown in a left to right direction (arrow direction), but it is obvious that the image can be scanned in the reverse direction.

According to an embodiment of the present invention, the signal light is reflected from a micromirror corresponding to each pixel of the light modulator as described above, light modulated according to predetermined information, and is deflected into a series of focusing optical systems and incident on the optical recording medium. . Here, the deflecting device for injecting the signal light into the focusing optical system is movable and may have different incidence angles when the plurality of signal lights are incident on the optical recording medium through the focusing optical system. Therefore, various optical information can be stored by changing the incident angle of the signal light at the same position of the optical recording medium, and then the various optical information stored by the incident of the same reference light is emitted as signal light having different emission angles, Information storage density can be high. Therefore, the number of signal lights can be determined in correspondence with the reflection position formed in accordance with the movement of the deflecting device movable at the same position of the optical recording medium. For example, m signal lights having different incident angles may correspond to the same reference light and may be stored and reproduced.

In addition, according to another embodiment, when the reference light is deflected into the focusing optical system and incident on the optical recording medium, the deflection device for injecting the reference light into the focusing optical system is also movable, so that a plurality of reference light is incident on the optical recording medium through the focusing optical system. In this case, the plurality of reference lights may have different incidence angles. Therefore, various optical information can be stored by changing the incident angle of the reference light at the same position of the optical recording medium, and since the optical information stored by the incident light of the reference light is emitted as signal light, the optical information storage density can be increased. . For example, n reference lights having different incidence angles with respect to the same position of the optical recording medium can be stored and reproduced correspondingly. Therefore, when the optical information is stored by the signal light and the reference light being irradiated at the same position of the optical recording medium at different incidence angles by the respective deflecting devices, the optical storage density can be increased, for example, m * n (m: signal light , N: number of reference light) pieces of information may be stored in the same position of the optical recording medium. The storage position of the optical recording medium can be moved by rotating or horizontally moving the optical recording medium so that the optical information can be stored in the overall area of the optical recording medium. For example, peristrophic multiplexing is performed when the optical recording medium rotates, and shift multiplexing is performed when moving in a direction perpendicular to the optical axis of the focusing optical system.

In the above description, a perspective view and a plan view of an optical modulator applicable to an exemplary embodiment of the present invention and a summary of the present invention have been schematically described. Hereinafter, the holographic optical information storage and reproduction according to the present invention will be described with reference to the accompanying drawings. The method and the device will be described with reference to specific embodiments. Embodiments according to the present invention are divided into a storage method and a reproduction method, which will be described in turn below.

4 is a schematic structural diagram of a holographic optical information storage device according to a preferred embodiment of the present invention. Referring to FIG. 4, the light source 405, the beam expander 410, the beam splitter 415, the first deflector 420, the shutter 423, the cylinder lens 425, the light modulator 430, and the first The deflection apparatus mirror 435, the focusing optical system 440, the second deflection apparatus 445, the second deflection apparatus mirror 450, the deflection mirror 455, the optical recording medium 460, the optical recording medium moving device 465, reproduction optical system 470, and light detector 475 are shown.

Predetermined light (for example, laser light) collimated from the light source 405 is emitted, and the width of the light is increased by the beam expander 410. The light having a larger width is then divided into a signal light S and a reference light R by the beam splitter 415, and proceed in different directions. Here, the signal light S will be described centering on the structure parallel to the predetermined light collimated from the light source 405 and the reference light R proceeds in a direction perpendicular thereto. However, the present invention is not limited to this direction. Of course. For example, the signal light S may be perpendicular to the predetermined light collimated from the light source 405, the reference light R may travel parallel thereto, and the light may not necessarily be divided vertically.

The signal light S passes through the open shutter 423 and the cylinder lens 425 to be light modulated in accordance with information input from the micromirror corresponding to each pixel of the light modulator 430. Here, a controller (not shown) for driving the micro mirrors provided in the light modulator 430 may be separately provided. Here, the arrangement of the micro mirrors in the optical modulator 430 is not particularly limited, but, for example, may be formed in a one-dimensional array.

Thereafter, the light modulated by the light modulator 430 is directed to the focus optical system 440 by the mirror 435 of the first deflecting device. The mirror 435 of the first deflection device may be moved by the movable first deflection device 420. The position of the mirror 435 of the first deflection device is determined by the first reflection position, the second reflection position,. , N-th reflection position (n is any natural number). Here, the first deflecting device 420 moves in parallel with the focusing optical system 440 so that the signal light S may overlap the reference light R at the same position regardless of the movement, and the plurality of signal lights S may be When incident on the optical recording medium 460, each signal light S has a different angle of incidence. That is, the first deflecting device 420 moves in parallel with the focusing optical system 440, so that the mirror 435 of the first deflecting device receives a plurality of signal lights S parallel to the optical axis of the focusing optical system 440. By reflecting, the angles incident on the optical recording medium 460 are different from each other depending on the distance from the center of the focusing optical system 440 to which the plurality of signal lights S are incident, and therefore, at the same position of the optical recording medium 460. A plurality of signal lights S having different incident angles may be incident. Accordingly, each signal light S overlaps the incident reference light R to generate an interference fringe, and the generated interference fringe is recorded on the optical recording medium 460, thereby storing optical information in the optical recording medium 460. Can be. Here, the signal light S and the reference light R may overlap each other at the focal point of the focusing optical system 440.

The reference light R is reflected by the mirror 450 and the deflection mirror 455 of the second deflection apparatus and irradiated to the focusing optical system 440. In this case, the reference light R may be irradiated to the focus optical system 440 in parallel with the above-described signal light S, and then overlapped at the same position. Here, the mirror 450 of the second deflecting device may be moved by the movable second deflecting device 445, and the plurality of reference lights reflected by the mirrors 450 of the second deflecting device corresponding to different positions of the deflecting devices may be moved. R) has different incidence angles and can be incident on the optical recording medium 460. Here, the optical recording medium 460 is attached to the optical recording medium moving device 465 which can move it. The reproduction optical system 470 and the light detector 475 may then control the light emitted in correspondence with the stored interference fringe, and convert the light into an electrical signal to generate an image.

Therefore, the holographic optical information storage device according to the embodiment of the present invention stores the interference fringes generated by the plurality of signal lights S and the reference light R at the same position of the optical recording medium 460, thereby storing the optical light. Information storage density can be increased.

5 is a flowchart illustrating a holographic optical information storing method according to an exemplary embodiment of the present invention.

In step S510, the collimated light is emitted from the light source 405 so that the width of the light is increased by the beam expander 410. In step S515, the emitted light is divided into the signal light S and the reference light R by the beam splitter 415.

In step S520, the signal light S passes through the open shutter 423 and the cylinder lens 425 to be light modulated in accordance with information input from the micromirror corresponding to each pixel of the light modulator 430.

In step S525, the light modulated by the light modulator 430 is directed to the focusing optical system 440 by the mirror 435 of the first deflection device provided in the movable first deflection device 420.

In step S530, the reference light R is reflected from the mirror 450 and the deflection mirror 455 of the second deflecting device while the signal light S is irradiated to the focusing optical system 440 through a series of processes, and thus the focusing optical system 440. Is investigated.

In step S535, the signal light S and the reference light R overlap to generate an interference fringe, and the generated interference fringe is recorded in the optical recording medium 460, so that one signal light S for one reference light R is generated. Optical information corresponding to the &quot; The signal light S corresponding to the stored light information is referred to as a first signal light for convenience of description.

In step S540, the mirror on which the signal light S is reflected, that is, the mirror 435 of the first deflecting device provided in the movable first deflecting device 420 moves to a position different from the position of the previous step. In step S545, the number of repetitions is checked in order to repeat the above-described steps S510 to S540 by a predetermined number of times. Here, the number of repetitions is equal to the number of signal lights S corresponding to one reference light R. FIG. Therefore, the signal light S corresponding to the stored light information includes the second signal light, the third signal light,... , M-th signal light.

In step S550, the mirror on which the reference light R is reflected, that is, the mirror 450 of the second deflecting device provided in the movable second deflecting device 445 moves to a position different from the position of the previous step. In step S555, the number of repetitions is checked to repeat the above-described steps S510 to S550 by a predetermined number of times. Here, the number of repetitions is equal to the number of reference lights R corresponding to the plurality of signal lights S. FIG. Here, the reference light R corresponding to the stored light information includes the first reference light, the second reference light,... , May be the nth reference light.

Therefore, the plurality of signal lights S may correspond to the plurality of reference lights R. FIG. For example, when the signal light S is repeatedly irradiated m times and the reference light R is repeatedly irradiated n times in accordance with each signal light, m * n interference fringes are located at the same position of the optical recording medium 460. Can be generated.

In step S560, by changing the position of the optical recording medium 460 attached to the movable optical recording medium moving device 465 in which the signal light S and the reference light R overlap, the recording position is changed, and in step S565 This series of processes is repeated corresponding to the storage area of the optical recording medium 460 and the like, thereby storing the optical information in the overall position.

6 is a schematic structural diagram of a holographic optical information reproducing apparatus according to a preferred embodiment of the present invention. Referring to FIG. 6, the light source 605, the beam expander 610, the beam splitter 615, the first deflector 620, the shutter 623, the cylinder lens 625, the light modulator 630, and the first Deflection device mirror 635, focusing optics 640, second deflection device 645, second deflection device mirror 650, deflection mirror 655, optical recording medium 660, optical recording medium moving device 665, playback optics 670 and light detector 675 are shown. The differences from the above-described holographic optical information storage device will be mainly described.

If the above-mentioned reference light R is necessary to reproduce the optical information corresponding to the interference fringe stored in the optical recording medium 660, the signal light S is unnecessary. Thus, by closing the shutter 623 to block this, only the reference light R can be incident on the optical recording medium 660. That is, predetermined light collimated from the light source 605 is emitted and the width of the light is increased by the beam expander 610. Thereafter, the wider light is divided into the signal light S and the reference light R by the beam splitter 615, and proceeds in different directions. Here, the signal light S is blocked by the shutter 623, and only the reference light R for reproduction is incident on the optical recording medium 660. Here, the reference light (R) is the same as the nature of the reference light (R) used in the storage, the progress path, etc., and irradiated to the interference fringe recorded on the optical recording medium 660 to reproduce the corresponding light information, the reproduced light An optical detector that generates images by recognizing light and converting it into an electrical signal via a reproduction optical system 670 (for example, may include a collimation lens, a cylinder lens, etc.), which is a series of optical systems required for reproduction. Incident at 675.

The optical detector 675 may be a complementary metal oxide semiconductor (CMOS) image sensor or a charge coupled device (CCD) image sensor. A complementary metal oxide semiconductor (CMOS) image sensor is composed of a plurality of unit pixels including a photo diode, which is driven by a control circuit and signal processing. A charge coupled device (CCD) image sensor includes a plurality of MOS capacitors, and is operated by moving charges (carriers) to the MOS capacitors. The image sensor 380 has a plurality of pixels capable of sensing light. Here, the light detector 675 may be formed by unit pixels arranged in two dimensions.

7 is a flowchart illustrating a holographic optical information reproducing method according to a preferred embodiment of the present invention.

In step S710, the collimated light is emitted from the light source 605 to increase the width of the light by the beam expander 610. In operation S720, the emitted light is divided into the signal light S and the reference light R by the beam splitter 615.

In step S730, the signal light S is blocked by the closed shutter 623, and in step S740, the reference light R is reflected by the mirror 650 and the deflection mirror 655 of the second deflecting device to focus the optical system 640. Is investigated.

In step S750, the reference light R is incident on the optical recording medium 660 in which the interference fringe is recorded, and in step S760, the optical information is reproduced by the incident reference light R. As shown in FIG. Here, since the same reference light R stores a plurality of interference fringes corresponding to the plurality of signal lights S, the incident reference light R reproduces a plurality of lights having different emission angles. The light corresponding to the reproduced light information is then incident to the light detector 675, which can recognize the light through the reproducing optical system 670, convert the light into an electrical signal, and generate an image.

In step S770, the mirror on which the reference light R is reflected, that is, the mirror 650 of the second deflecting device provided in the movable second deflection device 645 moves to a position different from the position of the previous step. Accordingly, reference light R having different incidence angles may be incident on the optical recording medium 660. In this case, different light information stored corresponding to the reference light R having different incidence angles is reproduced, thereby having different emission angles. A plurality of lights can be reproduced.

8 is a comparison diagram comparing a holographic optical information storage method according to a preferred embodiment of the present invention with a storage method according to the prior art.

Referring to FIG. 8, in (a) of the holographic optical information storage method according to the related art, one reference light R corresponds to one signal light S to provide an interference fringe to the optical recording medium 810. Create However, referring to (b), which is a holographic optical information storage method according to an embodiment of the present invention, one reference light R corresponds to a plurality of signal lights S1, S2, and S3. Generate interference fringes on the.

9 is a comparison diagram comparing the holographic optical information reproducing method according to the preferred embodiment of the present invention with the reproducing method according to the prior art.

Referring to FIG. 9, in (a), which is a holographic optical information storage method according to the related art, one reference light R corresponds to one signal light S stored in an interference fringe in an optical recording medium 810. Play the information. However, referring to (b), which is a holographic optical information storage method according to an embodiment of the present invention, one reference light R corresponds to a plurality of signal lights S1 corresponding to incident angles of the stored signal lights S1, S2, and S3. , S2, S3) can be emitted.

The present invention is not limited to the above embodiments, and many variations are possible by those skilled in the art within the spirit of the present invention.

As described above, the holographic optical information storing and reproducing method and the apparatus according to the present invention have an effect of storing high density information in an optical recording medium of the same size.

In addition, the holographic optical information storing and reproducing method and apparatus thereof according to the present invention have the effect of storing a plurality of signal lights in correspondence with one reference light and storing them in an optical recording medium.

In addition, the holographic optical information storage and reproducing method and the apparatus according to the present invention has an effect that can exhibit low cost and high performance by using a one-dimensional optical modulator.

Although the above has been described with reference to a preferred embodiment of the present invention, those of ordinary skill in the art to the present invention without departing from the spirit and scope of the present invention and equivalents thereof described in the claims below It will be understood that various modifications and changes can be made.

Claims (14)

A light source for generating light; A beam splitter for dividing the light generated by the light source into a reference light and a signal light; An optical modulator for optically modulating the signal light corresponding to the input information; A movable first deflection device for deflecting the modulated signal light to a focusing optical system; A focusing optical system for overlapping the signal light and the reference light at the same position; And An optical recording medium provided at an overlapping position where the signal light and the reference light overlap, In response to the movement of the deflecting device, the plurality of signal lights overlap and overlap the one reference light, And the first deflecting device moves in parallel with the focusing optical system. The method of claim 1, And the first deflecting device moves so that the modulated signal light is irradiated to the overlapping position. delete The method of claim 1, And the signal light and the reference light overlap at the focal point of the focusing optical system. The method of claim 1, A second movable deflection device positioned between the beam splitter and the focusing optical system and configured to deflect the reference light to the focusing optical system, And the reference light is incident on the optical recording medium having a different angle of incidence in response to the movement of the second deflection apparatus. The method of claim 1, A shutter positioned between the beam splitter and the focusing optical system and blocking the signal light; And And an optical detector capable of sensing the signal light irradiated by the reference light to the optical recording medium to reproduce the signal light. The method of claim 6, And the optical detector has a plurality of pixels in a two-dimensional form. The method according to any one of claims 1, 2 or 4 to 7, And the optical modulator has a one-dimensional shape. A method performed by an apparatus for storing holographic optical information using an optical modulator, (a) dividing the light generated by the light source into a first reference light and a first signal light by the beam splitter; (b) the optical modulator light modulating the first signal light according to the input information; (c) the modulated first signal light is reflected at a first reflective position of the movable first deflection device and irradiated to a focusing optical system; (d) irradiating an optical recording medium provided at an overlapping position where the first reference light and the first signal light passing through the focusing optical system overlap each other; (e) interfering with the first reference light and the first signal light to generate a first interference fringe in the optical recording medium; (f) dividing the light generated by the light source into a first reference light and a second signal light by a beam splitter; (g) light modulating the second signal light according to the input information by the light modulator; (h) the modulated second signal light is reflected at a second reflective position of the movable first deflection device and irradiated to the focusing optical system; (i) irradiating an optical recording medium provided at the overlapping position where the first reference light passing through the focusing optical system and the second signal light having an incident angle different from the first signal light overlap each other; And (j) the first reference light and the second signal light interfere with each other to generate a second interference fringe in the optical recording medium. The method of claim 9, The first reflection position and the second reflection position of the first deflection device are different positions, and the movement trajectory of the first deflection device is formed so that the modulated second signal light is irradiated to the overlapping position. How to store holographic optical information. The method of claim 9, (k) dividing the light generated by the light source into a second reference light and a third signal light by the beam splitter; (l) light modulating the third signal light according to the input information by the light modulator; (m) the modulated third signal light is reflected at the first reflective position of the movable first deflection device and irradiated to a focusing optical system, and the second reference light is reflected at the first reflective position of the movable second deflection device and focused Irradiating with an optical system; (n) irradiating an optical recording medium provided at an overlapping position where the second reference light and the third signal light passing through the focusing optical system overlap each other; And and (o) the second reference light and the third signal light interfere with each other to generate a first interference fringe in the optical recording medium. A method performed by an apparatus for reproducing holographic optical information using an optical modulator, (a) dividing the light generated by the light source into a first reference light and a signal light by the beam splitter; (b) the signal light is blocked by a shutter, and the first reference light is irradiated with a focusing optical system; (c) the first reference light passing through the focusing optical system is incident on an optical recording medium; (d) reproducing a plurality of optical information corresponding to the plurality of first interference fringes recorded in the optical recording medium by the incident first reference light, The first interference fringe is formed by the plurality of signal lights incident on the optical recording medium at different incident angles corresponding to the first reference light. Step (d) is, (d-1) emitting the first reference light from the optical recording medium having a plurality of emission angles of the plurality of signal lights irradiated and reproduced by the optical recording medium; and (d-2) detecting a plurality of the signal lights emitted from different emission angles by an optical detector. delete The method of claim 12, (e) dividing the light generated by the light source into a second reference light and a signal light by a beam splitter; (f) the signal light is blocked by a shutter, and the second reference light is reflected at a first reflection position of the movable second deflection device and irradiated to a focusing optical system; (g) the second reference light passing through the focusing optical system is incident on the optical recording medium with an angle of incidence different from that of the first reference light; (h) reproducing a plurality of optical information corresponding to the plurality of second interference fringes recorded in the optical recording medium by the incident second reference light, And the second interference fringe is formed by the plurality of signal lights incident on the optical recording medium at different incident angles corresponding to the second reference light.

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