KR100657675B1 - Method and apparatus for coding of reading and playing in holographic worm - Google Patents

Abstract

The present invention is to code and decode to have a relatively small number of on pixels rather than off pixels, while maintaining the same code rate in the case of binary differential code, while excluding patterns that interfere with the frame detection technique. In the holographic warm recording and reproducing method of recording and reproducing external input data to a hologram recording medium by using a reference light and a signal light to be coded, the external input data to be recorded is decoded and the reproduction output from the holographic recording medium is decoded. At the time of setting, the external input data is set in a predetermined number of groups in 2-bit units, and the 2-bit data set in the group is coded into on and off pixels, which are 1x3, to each pixel to be recorded and provided as a signal light processing path. 1 × 3 on pixel and off pick output from the recording medium during the process and playback mode. After separating the reproduced signal coded in, including the step of decoding and outputting the reproduced signal coded with the pixels on the separated off and the 1 × 3 pixel. Therefore, there is an effect that can be said to be an effective coding technique for recording more hologram data in the same area in terms of dynamic range.

Description

Coding method and apparatus for recording and reproducing holographic worms {METHOD AND APPARATUS FOR CODING OF READING AND PLAYING IN HOLOGRAPHIC WORM}

1 is a diagram illustrating a 2: 4 binary differential code in which a conventional on pixel S1 and an off pixel S2 are the same.

2 is a block diagram showing a coding apparatus for recording and reproducing a holographic worm according to the present invention;

FIG. 3 shows an on-pixel (1) (SS1) and off-pixel (3) (SS2) that are 1x3 so as to have a relatively smaller number of on-pixels SS1 than the off-pixel SS2 according to the present invention. One drawing.

<Description of the symbols for the main parts of the drawings>

110: storage and playback block 111: light source

112: optical separator 113, 116: shutter

114, 117: reflector 115: actuator

118: spatial light modulator 119: recording medium

120: CCD 130: data coding block

132: group setting unit 134: coding unit

150: data decoding block 152: group separation unit

154: decoding unit

The present invention relates to a coding method and apparatus for recording and reproducing a holographic write only read many times (H-WORM), and more particularly, to a coding method for improving the recording density of a holographic recording medium. And to the apparatus.

As is well known, in the technical field for recording hologram data, researches are actively conducted everywhere, for example, due to remarkable developments such as semiconductor lasers, charge coupled devices (CCDs), and liquid crystal displays (LCDs). As a result of this research, fingerprint recognition systems for recording and reproducing fingerprints have been put to practical use, and are being expanded to various fields that can apply the advantages of large capacity and ultra-fast data transfer rate.

As described above, the holographic worm system is a hologram recording medium, for example, a crystal, in which an interference fringe generated when the signal light from the target object and the reference light are interfered with each other sensitively to the amplitude of the interference fringe. By recording the intensity and phase of the signal light by a method of changing the angle of the reference light, etc., to display a three-dimensional image of the object, and also to form a page unit of binary data. Hundreds to thousands of holographic data can be recorded in the same place.

On the other hand, in the recording mode in which the hologram data is recorded on the recording medium, the laser light generated by the light source is split into the reference light and the signal light, and the pixels light and shade according to the external input data (that is, the input data to be recorded). An interference fringe obtained by interfering with the modulated signal light and the recording reference light branched off and reflected at a predetermined deflection angle is recorded on the recording medium as hologram data corresponding to the input data.

In this case, the hologram data is superimposed (multiplexed) when recorded on the recording medium. Such multiplexed recording methods include, for example, angular superposition, wavelength superposition, and phase code superposition.

Further, in the reproducing mode of reproducing hologram data, the signal light branched from the laser light generated by the light source is interrupted, the branched reference light is deflected at a preset reproduction angle, and the recording medium is irradiated, and the interference recorded through the irradiation The desired hologram data is reproduced by the pattern diffraction of the reproduction reference light to demodulate one page of binary data composed of the original pixel contrast. At this time, the reproduction reference light used to reproduce the data recorded on the recording medium has substantially the same angle as the reference light applied when the hologram data is recorded on the recording medium.

On the other hand, when the hologram data is recorded on the hologram recording medium and then reproduced, the reproduction signal is entirely in intensity due to various factors such as the intensity of the laser light, the distortion caused by the lens, the scattering and the diffraction in the system. It will have a distribution difference.

That is, the most common method of decoding the reproduction signal is a method using a threshold value, and the method of using the threshold value includes a method using an average or 0.5 value of a pixel and a method using a local threshold value.

In the former case of using the threshold value, a method of reading a value of 1 when the average is larger than the average or 0.5 value of the pixel, and a method of reading the value 0 by less than the average value of the pixel. However, this method has a problem that the code rate is high, but the reproduction error rate (particularly, the reproduction error rate at the corner of one page) is very high for the above-mentioned reasons, so that it is difficult to apply in reality.

In the latter method of using a threshold value (that is, using a local threshold value), the playback signal of one page is divided into several regions, and different threshold values are applied to each divided region, that is, the center of the page. The closer to, the higher threshold is applied, and the farther away from the center of the page (ie, closer to the edge), the lower threshold is applied to determine 1 and 0.

However, this method has the advantage that the code rate is high and the reproduction error rate is low. On the other hand, when the aspect of the noise pattern is different, the compatibility between various systems is inferior. That is, each system has a different pattern of noise according to the characteristics of the system and the surrounding environment. If the threshold values divided by the standardized standards are applied to the systems in which the noise pattern is different from each other, As a result, the reproduction error rate is inevitably increased, thereby increasing the reproduction error rate.

On the other hand, another method for reducing the error rate of the reproduction signal is a binary differential coding scheme, the binary differential coding scheme 1: 2 binary differential code (Binary Differential Code) is input by using a local 1 greater than 0 After coding the data, the data is recorded on the recording medium, and after playback, the decoding is vice versa. For example, 0 is coded as 01 and 1 is coded as 10, and after playback, decoding is performed through the reverse process.

However, Stanford's binary differential coding scheme has the advantage of lowering the reproduction error rate while significantly reducing the code rate (50%). Here, the code rate is 50%, and since the same number of zeros and the same number of ones are used, one and zero can be distinguished by comparing two intensities during decoding.

Also, referring to the 2: 4 binary differential code, as illustrated in FIG. 1, the on pixel S1 and the off pixel S2 are the same, and are mapped to four types of 00, 01, 10, and 11.

That is, even in the case of a 2: 4 binary differential code, the code rate can be brought to 50%, and 2D ISI can be eliminated, which is excellent for recording and reproduction. However, all of the above-described cases use a pattern that may act as an obstacle in the process of performing frame detection, and also have the same number of on pixels S1 and off pixels S2 in terms of dynamics. There is a problem that no more data can be recorded in the same area.

Accordingly, the present invention has been made to solve the above problems, the object of which is to maintain the same code rate in the case of binary differential code, and at the same time to exclude the pattern that interferes with the frame detection technique, rather than off pixels A coding method and apparatus for recording and reproducing a holographic worm which codes and decodes a small number of on pixels are provided.

When recording and reproducing external input data on a hologram recording medium using reference light and signal light generated by a light source according to an aspect of the present invention for achieving the above object, the external input data to be recorded is coded and A holographic worm recording and reproducing method for decoding a reproduction output of the data, wherein in the recording mode, external input data is set to a predetermined number of groups in 2-bit units, and 2-bit data set as a group is recorded on each pixel to be recorded. Coding the on pixel and the off pixel of × 3 to provide a signal light processing path, and separating the 1 × 3 on pixel and the off pixel of the playback signal output from the recording medium in the playback mode, and then separating And decoding and outputting a reproduction signal coded by the 1 × 3 on pixel and the off pixel.

In addition, the laser light generated by the light source according to another aspect of the present invention for achieving the above object is divided into the reference light and the signal light, and generates a signal light through the modulation between the signal light and the external input data, and the divided reference light and the signal light Holographic worm recording and reproducing for storing the interference fringes obtained by interference as hologram data of external input data, and reproducing the data recorded on the recording medium by irradiating the reference light for reproduction generated by branching the laser light at a predetermined angle. In the system, a group setting unit for setting external input data into a predetermined number of groups in 2-bit units, and a 1 × 3 on pixel and an off pixel are coded to each pixel on which the 2-bit data is to be written to the signal light processing path. A coding unit provided, and reproduced in 1 × 3 on pixels and off pixels output from the recording medium in the reproduction mode. And a decoding unit which decodes and outputs a reproduction signal coded by a separated 1 × 3 on-pixel and off-pixel.

Hereinafter, a plurality of embodiments of the present invention may exist, and a preferred embodiment will be described in detail with reference to the accompanying drawings. Those skilled in the art will appreciate the objects, features and advantages of the present invention through this embodiment.

A key technical aspect of the present invention is to keep the same on the 50% code rate for binary differential code, while excluding the pattern that interferes with the frame detection technique, reducing the on pixel by half and increasing the off pixel relatively, i.e. By having a relatively small number of on pixels rather than off pixels, it is possible to code effectively from a dynamic point of view. Through such technical means, the object of the present invention can be easily achieved.

FIG. 2 is a block diagram illustrating a coding apparatus for recording and reproducing a holographic worm according to an exemplary embodiment of the present invention, wherein the recording and reproduction block 110, the data coding block 130, and the data decoding block ( 150).

Referring to FIG. 2, the recording and reproducing block 110 includes a light source 111 for generating a laser light and a recording medium 119 (for example, optical refractive index) for recording hologram data (that is, interference fringes) in three dimensions. Crystal) and CCD 120, and two paths including a plurality of optical systems, that is, a reference light processing path PS1 and a signal light processing path PS2, are formed between the light source 111 and the recording medium 119. do.

First, the optical splitter 112 splits the laser light incident from the light source 111 into reference light and signal light, that is, the reference light of the divided vertical polarization is provided to the reference light processing path PS1, and the split signal light is the signal light processing path. (PS2).

Next, the shutter 113, the reflector 114, and the actuator 115 are provided in the emission direction of the reference light on the reference light processing path PS1, and the hologram data is recorded in the reference light processing path PS1 through the light transmission path. Alternatively, the reference light required for reproduction is reflected at a predetermined deflection angle and provided to the recording medium 119. In this case, although not illustrated in FIG. 2 for convenience of explanation and improvement of understanding, a plurality of optical lenses (for example, a waist configuration lens, a beam expander, etc.) for reference light processing are further added on the reference light processing path PS1. It can be provided.

Accordingly, the vertically polarized reference light branched from the optical separator 112 and incident through the opening of the shutter 113 is adjusted through an optical lens or the like not shown and expanded to an arbitrary size (that is, the signal light processing path (to be described later) PS2) to a size sufficient to cover the size of the signal light extending through the beam expander, and a predetermined angle, for example, a recording angle at the time of recording or reproducing through the reflector 114 After being deflected at the reproduction angle, it is incident (irradiated) onto the recording medium 119.

Here, the reference light used for recording or reproduction changes the deflection angle θ by rotating the reflector 114 using the actuator 115 whenever the binary data of each page unit is recorded on the recording medium 119. The reference light deflection technique may be used to record hundreds to thousands of hologram data on the recording medium 119 or reproduce recorded hologram data.

On the other hand, the shutter 116, the reflector 117 and the spatial light modulator 118 are sequentially provided on the signal light processing path PS2 in the emission direction of the signal light, and the shutter 116 is controlled from the system control means (not shown). Therefore, the open state is maintained in the recording mode, and the cutoff state is maintained in the reproduction mode. In this case, although not illustrated in FIG. 2 for convenience of explanation and improvement of understanding, a plurality of optical lenses (eg, reimaging lenses, beam expanders, field lenses, etc.) for signal light processing are provided on the signal light processing path PS2. ) May be further provided.

Accordingly, the signal light branched from the optical separator 112 and incident through the opening of the shutter 116 is reflected at a predetermined deflection angle through the reflector 117 and then transmitted to the spatial light modulator 118. In the spatial light modulator 118, the signal light transmitted from the reflector 117 is made of light and shade of pixels according to the input data provided from the data coding block 130 (that is, the hologram input data coded according to the present invention). After modulating by one page unit of binary data, i.e., when the input data is image data in one frame unit of an image, the signal light incident to the spatial light modulator 118 is modulated into signal light in one frame unit. The light is incident on the recording medium 119 in synchronization with the reference light incident from the reflector 114 of the reference light processing path PS1.

Thus, in the recording medium 119, in the recording mode, incident from the reflecting mirror 114 has a signal light modulated in units of pages of binary data provided from the spatial light modulator 118 and a deflection angle θ corresponding thereto. The interference fringe obtained through the interference between the reference light for recording is recorded. That is, the light induced phenomenon of the kinetic charge occurs in the recording medium 119 according to the intensity of the interference fringe obtained by the interference between the modulated signal light and the reference light. Through this process, the three-dimensional image on the recording medium 119 is generated. An interference fringe of the hologram data is recorded.

In other words, the recording medium modulates the signal light generated by the spatial light modulator 118 by modulating the signal light incident from the reflector 117 into one block unit of binary data of light and shade, which is composed of pixels. By irradiation with 119, coded hologram data is recorded on the recording medium 119.

Here, the data coding block 130 includes a group setting unit 132 and a coding unit 134. The group setting unit 132 is intended to record the digital input data (ie, the recording medium 119) input from the outside. Input data) into 2 bit units and separated into groups, and each block data divided into groups is transferred to the coding unit 134.

Next, the coding unit 134 has a relatively small number of on-pixels SS1 rather than an off-pixel SS2 formed by mapping each block data 2 bits of each group to match the characteristics of the set group. 1x3 on pixel (e.g., 1 non-contiguous pixel) (SS1) and off pixel (e.g., 3 consecutive pixels) (SS2), and then coded with each block data. The binary data of the page is passed to the spatial light modulator 118.

Meanwhile, in accordance with the present invention, 1 × 3 on pixels SS1 and 3 off pixels SS2 have a smaller number of on pixels SS1 than the off pixels SS2 formed by mapping. In the case of reproducing the hologram data which is coded and recorded on the recording medium 119, the shutter 116 on the signal light processing path PS2 side is cut off and the reference light processing is performed under control from a system control means (not shown). On the path PS1 side, the shutter 113 is in an open state.

Accordingly, the reference light (for example, the reproduction reference light) branched from the optical separator 112 is reflected through the reflector 114 and irradiated to the recording medium 119. As a result, the recording medium 119 is read by the reference light for reading. The recorded interference fringe diffracts the incident reference reading light, and is demodulated into a page of binary data (i.e. checkerboard pattern) composed of original pixel contrast, where the demodulated reproduction signal is irradiated to the CCD 120. do.

Subsequently, the CCD 120 restores the reproduction output irradiated from the recording medium 119 to the original data, that is, the electrical signal, which is then returned to the group separator 152 in the data decoding block 150. Delivered. That is, the data decoding block 150 decodes the coded reproduction signal reproduced from the recording medium 119 and output through the CCD 120 into the original signal before coding. The group separation unit 152 and the decoding unit 154 ).

In other words, the group separator 152 divides and decodes the reproduced signals coded by the 1 × 3 on pixel (SS1) and the off pixels (3) SS2 output from the CCD 120. Output to the unit 154. Then, the decoding unit 154 decodes the reproduction signal coded by the 1 × 3 on pixel (1) SS1 and the off pixel (3) SS2 output from the group separation unit 152 to decode the data. Output

Therefore, the present invention keeps the same 50% of the code rate for binary differential code, while excluding the pattern that interferes with the frame detection technique, reducing the on pixel by half and increasing the off pixel relatively, i.e., rather than the off pixel. By having a relatively small number of on pixels, it is an effective coding technique for writing more hologram data in the same area in terms of dynamic range.

In addition, since the present invention is disclosed as a right within the spirit and claims of the present invention, the present invention may include any modification, use and / or adaptation using general principles, and the present invention as a matter deviating from the description of the present specification. It includes everything that falls within the scope of known or customary practice in the art to which it belongs and falls within the scope of the appended claims.

As described above, the present invention maintains the same as 50% of the code rate in the case of 2: 4 binary differential code, while excluding the pattern that interferes with the frame detection technique, the on pixel is halved and is relatively off pixel. By increasing, i.e., having a relatively small number of on pixels rather than off pixels, there is an effective coding technique for recording more hologram data in the same area in terms of dynamic range.

Claims (6)

The laser beam generated by the light source is divided into reference light and signal light, and a signal light is generated by modulating the signal light and external input data, and an interference fringe obtained by interfering the branched reference light and signal light is used as hologram data of the external input data. A holographic worm recording and reproducing system, wherein a holographic worm recording and reproducing system is stored on a recording medium, and reproduces data recorded on the recording medium by irradiating a reference light for reproduction generated by branching the laser light at a predetermined angle. A group setting unit for setting the external input data into a predetermined number of groups in 2-bit units; A coding unit for coding the on-pixel and off-pixel of 1 × 3 into each pixel to which the 2-bit data is to be written and providing the signal light processing path to the pixel; A group separator for separating a reproduction signal coded with on pixels and off pixels, which are 1 × 3, output from the recording medium in a reproduction mode; A decoding unit for decoding and outputting the reproduced signals coded by the separated 1 × 3 on pixels and off pixels Coding apparatus for recording and reproducing a holographic worm comprising a. The method of claim 1, And the on pixel and the off pixel are composed of one on pixel and three off pixels. The method of claim 2, And said off pixel is a continuous pixel and said on pixel is a discontinuous pixel. In the holographic warm recording and reproducing method of recording and reproducing external input data on a hologram recording medium by using a reference light and a signal light generated by a light source, the external input data to be recorded is decoded and the reproduction output from the hologram recording medium is decoded. , In the recording mode, the external input data is set in a predetermined number of groups in 2-bit units, and the 2-bit data set in the group is coded into 1x3 on pixels and off pixels for each pixel to be recorded, thereby generating the signal light. The process of providing it as a processing path, In the reproducing mode, a 1 × 3 on pixel and an off pixel coded reproduction signal are separated from the recording medium, and then the separated 1 × 3 on pixel and off pixel coded reproduction signals are decoded. Output process A coding method for recording and reproducing a holographic worm comprising a. The method of claim 4, wherein And the on pixel and the off pixel are composed of one on pixel and three off pixels. The method of claim 5, And said off pixel is a continuous pixel and said on pixel is a discontinuous pixel.

Images