KR100600300B1 - Holographic digital data system and method for detecting recording image's unmatching therefor - Google Patents

Abstract

The present invention relates to a holographic digital data system and a method for measuring mismatching of a reproduced image thereof, and in particular, the system of the present invention includes a light separator for separating signal light and a reference light from a light source, and a holographic digital to signal light separated from the light separator. The spatial light modulator for inputting and modulating the data pattern and the alignment mark together, the rotating mirror reflecting the reference light separated by the optical splitter at a predetermined angle, and the reference light of the rotating mirror are incident on the storage medium and are holographic from the storage medium. A CCD array that captures an image of an alignment mark recorded with a digital data pattern, and an alignment mark is detected from a signal output from the CCD array, and the ratio according to the misalignment between the pixel of the alignment mark and the CCD pixel is detected. It includes a signal processing unit for measuring the match. Therefore, the present invention records holographic digital data in which an alignment mark is inserted into a storage medium using a spatial light modulator, and detects an alignment mark in the reproduced image, and then misaligns the pixel between the alignment mark pixel and the CCD pixel. By detecting phosphor, mismatching of the reproduced image and CCD pixels can be measured more accurately.

Holographic digital data system, reproducing image, CCD, misalignment, unmatched

Description

HOLOGRAPHIC DIGITAL DATA SYSTEM AND METHOD FOR DETECTING RECORDING IMAGE'S UNMATCHING THEREFOR}

1 is a block diagram of a typical holographic digital data system,

2 is a diagram showing one page information reproduced from a storage medium in a conventional holographic digital data system;

3 is a block diagram showing a holographic digital data system according to the present invention;

4 is a block diagram showing a reproduction device of a holographic digital data system to which the present invention is applied;

5 is a block diagram showing a mismatch detection apparatus of a reproduced image of a holographic digital data system according to the present invention;

6 is a flowchart illustrating a mismatch detection method of a reproduced image of a holographic digital data system according to the present invention;

7 is a view showing an alignment mark for mismatch detection of a reproduced image according to the present invention;

8A and 8B illustrate alignment marks detected in a CCD array upon matching or mismatching between a reproduced image and a CCD pixel in accordance with the present invention;

FIG. 9 is a view for explaining an example of a mismatch detection method using misaligned marks when mismatching a reproduced image and a CCD pixel according to the present invention; FIG.

<Description of the code | symbol about the principal part of drawing>

102: light source 108: optical separator

118, 122 mirror 110: data pattern

112: alignment mark 124: storage medium

128: CCD 130: Played image

140: signal processing unit 141: input unit

143: alignment mark detection unit 145: detection image buffer

147: Mismatch detection unit 149: CPU

150: decoder

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holographic digital data storage system (HDDS), and more particularly to a method of mismatch detection of a holographic digital data system and a reproduced image thereof.

Recently, technologies for storing holographic digital data have been actively researched in various fields, for example, thanks to remarkable developments such as semiconductor lasers, charge coupled devices (CCDs), and liquid crystal displays (LCDs). As a result, fingerprint recognition systems for storing and reproducing fingerprints have been put to practical use, and are being expanded to various fields that can apply the advantages of large storage capacity and ultra-high data transfer speed. Among them, a holographic digital data system storing a large amount of data is a storage medium, for example, optical refraction, in which an interference fringe generated when the signal light from the target object and the reference light are interfered with each other is sensitive to the amplitude of the interference fringe. By recording to a storage medium such as a photorefractive crystal, it is possible to display a three-dimensional image of an object, and also to display hundreds to thousands of hologram data composed of pages of binary data. Can be stored in place.

1 is a block diagram of a general holographic digital data system. Referring to FIG. 1, a general holographic digital data system is installed at a position corresponding to a light source 12 and a light source 12 for generating a laser light, so that the light of the light source 12 is referred to as a reference beam and a signal beam. a beam splitter 18 separating the beam into a beam, a mirror 32 reflecting the reference light separated from the light splitter 20, and light reflected from the mirror 32 is incident on the storage medium 10. Spatial Light Modulator (SLM) that carries input data, that is, binary data of a plurality of pixels configured in units of pages, on the signal light separated by the rotating mirror 36 and the optical separator 20 for converting the angles to be converted. (26), the interference fringe generated by the interference of the signal light output from the spatial light modulator (SLM) 26 and the reference light reflected by the rotation mirror 36 is recorded and diffracted and outputs the interference fringe recorded by irradiation of the reference light. Storage medium 10, write to storage medium 10 And a CCD 42 for reproducing a one-page binary pixel data image recorded in the form of an interference fringe in the storage medium by scanning only quasi-light, and converting the reproduced data image into electrical data and outputting the same. Unexplained reference numeral 14 denotes an optical magnification lens, 34 denotes a retardation lens, and 30 and 40 denote Fourier lenses.

The holographic digital data system thus constructed operates as follows.

The laser light irradiated from the light source 12 is divided into reference light and signal light in the light separator 18. At this time, the signal light is input to the spatial light modulator 26 and modulated. That is, the signal light is incident on the storage medium 10 after the data input from the spatial light modulator 26 is modulated in units of one page of the binary data of the intensity of real pixels. In addition, the reference light is incident on the storage medium 10 at an angle changed by the rotation mirror 32. That is, the reference light which slightly changes the angle of the rotation mirror 32 corresponding to each page is incident on the storage crystal 10 which is the storage medium 10. The signal light and the reference light cause interference inside the storage medium 10 for recording the hologram, and light-induced generation of mobile charge of the internal kinetic charge of the storage medium 10 according to the intensity of the interference fringe generated at this time. Is generated and an interference fringe is recorded through this process.

In order to read the data recorded in the storage medium 10, only the reference light needs to be irradiated to the storage medium 10. That is, when the reproduction reference light having the same deflection angle as the deflection angle of the recording reference light enters the storage medium 10 on which the interference data is recorded, the reproduction reference light is diffracted to make a single page of binary data (consisting of the original pixel contrast ( That is, the checkerboard pattern) is restored. The binary data (one page unit) reproduced from the storage medium 10 is restored to the original data through the CCD 42, the signal processing unit (not shown), the decoder (not shown), and the like.

In the related art, in order to restore the image data in units of pages reproduced from the storage medium 10, that is, binary pixel data, to the original data through the CCD 42 or the like, a signal matching process of 1: 1 matching has been performed. That is, the pixel of the image reproduced in the storage medium 10 and the pixel of the CCD 42 array are matched 1: 1 to restore original pixel data. However, in a shift multiplexing system employing 1: 1 pixel matching, when the size error between the reproduced image and the CCD pixel is 1/2 of the CCD pixel size, serious degradation occurs in the data detected by the CCD 42 array. As a result, the stored data cannot be obtained correctly.

In order to prevent this, the conventional system oversamples one pixel of the reproduced image of the storage medium 10 to nine pixels (3 × 3) of the CCD 42 array, and restores only one pixel data in the center of the original data to the original data. Technology has emerged.

Meanwhile, referring to FIG. 2, when one page information reproduced from a storage medium in a conventional holographic digital data system has a size of, for example, 1024 × 1024, a data area 100 of 720 × 720 is present in a center portion of a page. A frame area 200 with pixels always ON exists in the outer part of the page, which is the periphery of the data area, and is used as information for separating the data area. That is, when one pixel of a reproduced image of a storage medium is oversampled by nine pixels of a 3x3 CCD array, only pixels of the reproduced image corresponding to the data region except the frame region are oversampled by the 3x3 CCD array. .

However, in the holographic digital data system according to the prior art, in spite of the above oversampling method, mismatching between the pixels of the reproduced image and the pixels of the CCD array occurs due to the interference effect between the pixels. There was a difficult problem.

SUMMARY OF THE INVENTION An object of the present invention is to record holographic digital data in which an alignment mark is inserted into a storage medium by using a spatial light modulator, and to detect an alignment mark in an image reproduced by using a spatial light modulator. The present invention provides a holographic digital data system capable of more accurately measuring a mismatch between a reproduced image and a CCD pixel by providing a device for detecting a misalignment between an alignment mark pixel and a CCD pixel.

Another object of the present invention is to detect an alignment mark in an image reproduced from a storage medium, calculate an average value of x and y pixels in the alignment mark, and then use this average value to determine the alignment mark between the pixel of the alignment mark in the reproduced image and the CCD pixel. A mismatch detection method of a reproduced image of a holographic digital data system capable of more accurately measuring a mismatch or matching between a reproduced image and a CCD pixel by detecting a misalignment is provided.

In order to achieve the above object, the present invention provides a system in which holographic digital data is recorded on a storage medium, comprising: an optical separator for separating signal light and a reference light from a light source, and a rotating mirror for reflecting the reference light separated from the optical separator at a predetermined angle. And a CCD array for capturing an image of reproducing the alignment mark recorded with the holographic digital data pattern on the storage medium by the reference light of the rotating mirror being incident on the storage medium, and detecting the alignment mark from the signals output from the CCD array. And measuring a mismatch between misaligned pixels and CCD pixels according to misalignment.

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In order to achieve the above object, the method of the present invention is a method of reproducing holographic digital data recorded on a storage medium, comprising: alignment marks recorded together with the holographic digital data pattern from the storage medium by injecting reference light into the storage medium. Photographing a reproduced image through a CCD array, detecting an alignment mark in a signal output from the CCD array, and measuring mismatching according to misalignment between the pixel of the alignment mark and the CCD pixel. Steps.

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

3 is a block diagram showing a holographic digital data system according to the present invention. Referring to FIG. 3, a holographic digital data system according to the present invention is installed at a light source 102 for generating a laser light and a position corresponding to the light source 102 to separate light from the light source 102 into reference light and signal light. The optical splitter 108, the mirror 118 reflecting the reference light separated by the optical splitter 108, and the rotating mirror for changing the angle at which the light reflected from the mirror 118 is incident on the storage medium 124. And a align mark 112 together with a holographic digital data pattern, i.e., a binary data pattern 110 composed of a plurality of pixels, on the signal light separated by the optical separator 108. The storage medium 124 in which an interference fringe generated due to interference between the spatial light modulator (SLM) 114 and the signal light output from the spatial light modulator (SLM) 114 and the reference light reflected by the rotation mirror 122 is recorded. Include.

In the system of the present invention, the alignment medium is reproduced together with the data image recorded in the form of an interference fringe when only the reference light is irradiated while the signal medium is blocked. In addition, the system of the present invention, including the CCD 128, photographs the data image and the alignment mark reproduced from the storage medium 124, converts it into an electrical data signal, and outputs the converted data. In the meantime, reference numeral 104 denotes an optical magnification lens, 120 denotes a retardation lens, and 116 and 126 denote Fourier lenses.

The holographic digital data system according to the present invention thus constructed operates as follows during recording.

The laser light irradiated from the light source 102 is divided into the reference light and the signal light in the light separator 108. At this time, the signal light is input to the spatial light modulator (SLM) 114 and modulated. However, the signal light, together with the holographic digital data pattern 110 input from the spatial light modulator (SLM) 114, after the alignment mark 112 is modulated in units of one page of the binary data of the contrast of real pixels Incident to the storage medium 124. In addition, the reference light is incident on the storage medium 124 at an angle changed by the rotation mirror 122. That is, the reference light which slightly changes the angle of the rotation mirror 122 corresponding to each page is incident on the crystal which is the storage medium 124. The reference light and the signal light modulated by the spatial light modulator (SLM) 114 cause interference within the storage medium 124 for recording the hologram, so that an interference fringe is recorded in the storage medium 124.

The holographic digital data system according to the present invention irradiates the storage medium 124 with only the reference light separated by the optical separator 108 while blocking the signal light in order to read the data recorded on the storage medium 124 during reproduction. When the reproduction reference light having the same deflection angle as that of the recording reference light enters the storage medium 124, the reproduction reference light is diffracted in the storage medium 124 to reproduce the binary data of the reproduced image composed of the original pixel contrast. In this case, the reproduced data includes an alignment mark for detecting mismatching or matching between the reproduced image and the CCD pixel.

4 is a block diagram showing a playback device of the holographic digital data system to which the present invention is applied. Referring to FIG. 4, the reproducing apparatus of the holographic digital data system to which the present invention is applied irradiates only the reference light to the storage medium 124 to display a page of binary data recorded in the form of an interference fringe on the storage medium 124. A CCD 128 array for reproducing and converting the reproduced image data 130 into electrical data and outputting the same, and one pixel of the image reproduced from the storage medium 124 by irradiation of reference light is m × m ( m≥2) Detecting the alignment mark 112 in the reproduced image before oversampling to the pixel size and using this to detect mismatches or matches between the reproduced image and the CCD pixels, And a signal processor 140 that performs oversampling between one pixel and m × m (m ≧ 2) CCD pixels. The decoder 150 which is not described decodes the data output from the signal processor 140 into binary data of one page.

In the system of the present invention, the image 130 reproduced from the storage medium 124 includes an alignment mark 112 together with a data pattern 110 modulated by a spatial light modulator (SLM). Here, the alignment mark 112 includes light quantity information in which pixel data at positions intersecting each other in pixels of size n × n (n ≧ 2) is turned on or off.

5 is a block diagram showing an apparatus for detecting mismatch of a reproduced image of the holographic digital data system according to the present invention. Referring to FIG. 5, the signal processor of the holographic digital data system according to the present invention includes an apparatus for detecting mismatching of a reproduced image as follows.

The detection device includes an input unit 141 to which a user command is input, a CCD 128 array for capturing an image reproduced from a storage medium, converting the image into electrical data, and outputting the image; An alignment mark detection unit 143 for detecting an in mark, a detection image buffer 145 for storing data photographed by the CCD 128 array, and an alignment mark detected by the alignment mark detection unit 143 And a mismatch detection unit 147 for measuring mismatches according to misalignment between the pixels of the reproduced image and the CCD pixels, and a CPU 149 for controlling internal components of the signal processing unit.

6 is a flowchart illustrating a mismatch detection method of a reproduced image of the holographic digital data system according to the present invention. 3, 5 and 6, a mismatch detection method of a reproduced image of a holographic digital data system according to the present invention is as follows.

First, the holographic digital data system of the present invention irradiates only the reference light to the storage medium 124 to reproduce one page of binary data recorded in the form of an interference fringe on the storage medium 124. In addition, the CPU 149 in the system controls to photograph an image reproduced from the storage medium 124 through the CCD 128 array, convert the image into electrical data, and output the electrical data. (S10) At this time, the image captured by the CCD 128 array is controlled. The image is stored in the detection image buffer 145.

The CPU 149 detects the alignment mark from the signals output from the CCD 128 array through the alignment mark detection unit 143. (S12)

The CPU 149 uses the mismatch detection unit 147 to determine x, from the amount of light information on which pixel data at positions intersecting with each other in the alignment mark detected by the alignment mark detection unit 143 is turned on or off. Find the y pixel value. The average value of the x and y pixels is calculated, and the x and y misalignment values between the pixel of the alignment mark and the CCD pixel are calculated using the average value of the x and y pixels. (S14 to S18)

The CPU 149 determines whether or not the misalignment value obtained by the mismatch detection unit 147 is in the alignment state included in the set range. (S20) As a result of the S20 determination, the CPU 149 determines whether the misalignment value is in the aligned image. It is measured that the CCD pixels are matched with each other. However, as a result of the determination in S20, in case of misalignment, the CPU 149 measures that the reproduced image and the CCD pixel are mismatched with each other. Such matched or mismatched measurement results can be output via a display in the system.

7 illustrates an alignment mark for mismatch detection of a reproduced image according to the present invention. Align marks 112 with on or off pixel information to intersect with each other are implemented in a spatial light modulator. In the CCD 128 array, the alignment mark 112 as shown in FIG. 7 is captured. For example, a 2x2 align mark is matched with a 4x4 size CCD 128 array pixel by 2x2 oversampling.

8A and 8B illustrate alignment marks detected in a CCD array upon matching or mismatching between a reproduced image and a CCD pixel in accordance with the present invention.

As shown in Fig. 8A, the present invention measures that the reproduced image and the CCD pixel exactly match each other when the alignment mark in the image reproduced on the storage medium is aligned with the CCD array pixel. If the alignment mark is misaligned with the CCD array pixel as shown in FIG. 8B, the reproduction image and the CCD pixel are measured as mismatched with each other. In this case, alignment measurement of the alignment mark and the CCD array pixel is obtained by detecting on and off intensity information of the alignment mark photographed by the CCD. The misalignment measurement is obtained by using the light quantity information of the surrounding pixels of the alignment mark photographed by the CCD. That is, after calculating x and y pixel values from the amount of light information on or off of the alignment mark, calculating the average value of the x and y pixels, and using the average value of the x and y pixels, the pixels of the alignment mark are used. And x and y misalignment values between and CCD pixels are obtained.

)을 구함으로써 얼라인 마크와 CCD 픽셀의 x 방향의 미스 얼라인을 검출한다.FIG. 9 illustrates an example of a mismatch detection method using misaligned aligned marks when mismatching a reproduced image and a CCD pixel according to the present invention. As shown in Figs. 8B and 9, all of the off-pixels around the alignment mark misaligned with the CCD pixel are off pixels, so that the pixels xl (left of the on pixel) and xr (right of the on pixel) of the on pixel are turned off. The sum of the detected amounts of light is the same as the amount of light of the center-on pixel. Therefore, sum the light quantity values of xl and xr (xl + xr) to find the average of x pixels, and determine the ratio of xr or xl (

), The misalignment of the alignment mark and the CCD pixel in the x direction is detected.

)을 구함으로써 얼라인 마크와 CCD 픽셀의 y 방향의 미스 얼라인을 검출한다. 이렇게 구한 x, y방향의 미스 얼라인값은 서브 픽셀 단위 로 계산되므로 종래 프레임을 이용한 재생 이미지와 CCD 픽셀의 매칭 방법에 비해 그 정확도가 높아진다.Similarly, the sum of the amount of light detected in the periphery of the on (on) pixel and the yl (on the bottom of the pixel), respectively (yu + yl), is used to calculate the average of y pixels and the ratio of yl or yu (

), The misalignment of the alignment mark and the CCD pixel in the y direction is detected. Since the misalignment values obtained in the x and y directions are calculated in subpixel units, the accuracy of the misalignment in the x and y directions is higher than that of the matching method of the CCD image and the reproduced image using a conventional frame.

For example, if the alignment mark and CCD pixel are 30% misaligned in the x direction, the average of xl of the on-pixel is 125.3, the average of xr is 53.2, the average of yu of the on-pixel is 178.34, and the average of yl is Is obtained as 5.7. 0.298 is calculated | required by 53.2 / (125.3 + 53.2), and the misalignment value of ax direction is calculated as 0.0310 by 5.7 / (178.34 + 5.7). Therefore, when 0.298, which is the misalignment value in the x direction, is converted to% unit, it becomes about 30%, so that the misalignment in the x direction of the alignment mark and the CCD pixel is accurately detected. In this case, since the misalignment is about 3% in the y direction, this value is excluded when the misalignment is detected when it is limited to an error range such as noise.

As described above, the present invention records holographic digital data in which an alignment mark is inserted into a storage medium using a spatial light modulator, and detects the alignment mark in the reproduced image. By detecting the misalignment between the pixels, the mismatch between the reproduced image and the CCD pixels can be measured more accurately.

Meanwhile, although the present invention has been described with respect to 2x2 oversampling, various modifications may be made by those skilled in the art within the spirit and scope of the present invention described in the following claims rather than being limited to the above-described embodiment.

Claims (7)

delete A system in which holographic digital data is recorded on a storage medium, An optical separator for separating the signal light and the reference light from the light source, A rotating mirror reflecting the reference light separated by the optical splitter at a predetermined angle; A CCD array in which the reference light of the rotating mirror is incident on the storage medium to capture an image of the alignment mark recorded with the holographic digital data pattern on the storage medium; A signal processor for detecting an alignment mark among signals output from the CCD array and measuring mismatching according to misalignment between the pixel of the alignment mark and the CCD pixel Holographic digital data system comprising a. The method of claim 2, The alignment mark is a holographic digital data system, characterized in that the pixel data at the position intersecting with each other in pixels of size n × n (n ≧ 2) includes on or off information. The method of claim 2, The signal processor may include an alignment mark detection unit that detects an alignment mark among the signals output from the CCD array, and a miss between the pixel of the alignment mark and the CCD pixel using an average of x and y pixels of the alignment mark. And a mismatch detector for measuring mismatch between the reproduced image and the CCD pixel by obtaining an alignment value. A method of reproducing holographic digital data recorded on a storage medium, Injecting a reference light into the storage medium and photographing an image reproduced from the alignment mark recorded with the holographic digital data pattern from the storage medium through a CCD array; Detecting an alignment mark among the signals output from the CCD array; Measuring mismatching according to misalignment between the pixel of the alignment mark and the CCD pixel And a mismatch measurement method of a reproduced image of a holographic digital data system comprising a. The method of claim 5, The measuring of mismatching may include obtaining x and y pixel values of the alignment mark, calculating an average value of the x and y pixels, and using the average value of the x and y pixels. Obtaining x, y misalignment values between the pixels and the CCD pixels, and measuring mismatching between the reproduced image and the CCD pixels based on the misalignment values. A method of mismatch measurement of reproduced images of data systems. The method according to claim 5 or 6, The align mark is a reproduction of a holographic digital data system, characterized in that the pixel data at positions intersecting with each other in pixels of size n × n (n ≧ 2) includes on or off information. To measure mismatching of a captured image.

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