KR100426728B1 - Color hologram data writing and reading method - Google Patents

Abstract

The present invention relates to a color hologram data recording / reproducing method, wherein the tunable laser continuously outputs a laser beam having a wavelength of 4880 Å, 5145 Å, 6471 Å at a tunable laser, and outputs the reference light by a beam splitter. Separating the object light, modulating the object light by means of a spatial light modulator, and using a beam of 4880Å, 5145Å, 6471Å on the hologram recording medium of lithium niobate crystal doped with Cu, Fe, Mn. Recording the color image by rearrangement of Cu, Fe, and Mn by performing the step of recording three times and three times, and outputting by continuously changing the three-wavelength laser beam with a tunable laser when reproducing; and a hologram recording medium. Reproducing by inputting a reference wavelength of three wavelengths into the step; and synthesizing the R, G, B three-color pages captured by the photoelectric conversion element. It characterized.

This invention has the advantage that it is possible to implement a color hologram data storage system, and this principle can be very advantageously applied to holographic video. In general, a magnetic video disk has about 40 Gigabit of 120 minutes of film, but the present invention enables recording and playback of 183 movies on a 1 cm ³ hologram recording medium, and has an advantage in that access time is much faster than magnetic tape.

Description

How to record / play color hologram data {COLOR HOLOGRAM DATA WRITING AND READING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color hologram data recording / reproducing method, and more particularly, to a hologram data storage system that enables recording and reproduction of three-color wavelengths by using a tunable laser.

Holographic Recording is on the rise as the need for systems that record a lot of information and require fast data transfer with the advent of the multimedia era. Such holographic recording records not only the intensity but also the phase of the object light reflected from the object, and the intensity and phase of the light of the object is constituted by the interference of the object light and the reference light. The object light and the reference light form an interference fringe, and the interference fringes thus formed are recorded in a material that responds to the intensity of the interference fringe, and the hologram, which is a three-dimensional image of the object, is reproduced by irradiating the reference light on the recorded interference fringe.

The hologram is stored in the cube and only the reference light used in the recording process can read the hologram recorded in the cube, and the reference light having a different wavelength and phase from the reference light used in the recording passes through the hologram recorded in the cube without any effect. .

Using the natural nature of volume holograms, it is possible to store vast amounts of data inside small cubes by recording many holograms in the same place of the storage material with different reference lights. One method of making another reference light is the Angle Multiplexing method in which the angle of the reference light is changed at each recording time. This method allows you to store hundreds to thousands of holograms organized in pages of binary data in the same place. That is, by recording and reproducing a lot of data in the unit of a page in the same place, recording and reproducing with a high storage density and a fast data transfer rate are possible, thereby enabling a digital data storage system using holography.

In the conventional 90 ° geometry holographic digital data storage system, a laser beam generated by a laser oscillator is incident on a beam split, divided into a reference light and an object light, and an object light is applied to the input data. Therefore, the SLM (Spatial Light Modulator) is modulated on a page-by-page basis of the binary data of the dark and dark colors formed by the pixels. In this case, a reference light having a slightly different angle of the rotating mirror is created on each page.

Afterwards, the object light and the reference light cause interference in the storage medium for recording the hologram, and the light induced phenomenon of the movement charge in the storage medium occurs according to the intensity of the interference fringes generated at this time, and the interference pattern is recorded. In order to read the data recorded on the storage medium, only the reference light is irradiated to the storage medium, and the interference pattern is diffracted by the reference light to restore the checkered pattern composed of the original pixel contrast, and the read image is then transferred to the CCD (Charge Coupled Device). ) To restore the original data.

Such a conventional 90 ° batch holographic data storage system is used only for recording / reproducing monochromatic light, cannot implement color holograms, and cannot be used for color imaging devices.

The present invention has been made to solve the above-mentioned defects and problems, and to provide a hologram data storage system that enables recording and reproducing of tricolor wavelengths using a tunable laser.

In order to achieve the above object, the present invention continuously outputs a laser beam of 4880 Å, 5145 Å, 6471 Å wavelength by a tunable laser when recording to a hologram recording medium, and separates the reference light and the object light by a beam splitter. And modulating the object light by a spatial light modulator, and the primary, secondary and tertiary beams of 4880 Å, 5145 Å, and 6471 빔 beams on a hologram recording medium of lithium niobate crystal doped with Cu, Fe, and Mn. Recording the color image by rearranging Cu, Fe, and Mn, and reproducing the laser beam of 4880 Å, 5145 Å, 6471 Å three-wavelength laser beam continuously by tunable laser, Inputting the three-wavelength reference light into a recording medium and synthesizing the R, G, and B pages of three colors captured by the photoelectric conversion element; It provides color holographic data recording / reproducing bangbeopreul characterized in that the raw.

1 to 3 are views of the present invention,

1 is a block diagram of a hologram data storage system.

2 is a light density diagram for each wavelength of a crystal.

3A and 3B are flowcharts of a recording / reproducing process.

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

10: tunable laser 11: laser beam

12: reference light 13: object light

20 beam splitter 50 spatial light modulator

60: hologram recording medium 70: photoelectric conversion element

100 microprocessor

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail as follows.

1 is a block diagram of a color holographic data storage system according to an embodiment of the present invention. As shown in FIG. 1, a laser beam may be formed on an optical path of a laser beam 11 generated by a tunable lazer 10. An optical element, for example, a beam splitter 20, is arranged to separate 11 from the reference light 12 and the object light 13. In addition, the mirror 30 is disposed on the optical path of the reference light 12, and the mirrors 40 are disposed on the optical path of the object light 13, respectively, and have a spatial light modulator (SLM) 50 such as an LCD. ) Is arranged, and a hologram recording medium 60 for recording hologram data on the optical paths of the reference light 12 and the object light 13 is disposed, for example, adjacent to the hologram recording medium 60. A photoelectric conversion element 70 such as a charge coupled device (CCD) is disposed.

The laser 10 is capable of oscillating the laser beam 11 having three color wavelengths of 4880 mW (blue), 5145 mW (green) and 6471 mW (red), for example, a gas laser in which Ar-Kr is mixed. In addition, the hologram recording medium 60 includes, for example, an optical birefringence doped with a transition element Cu, Mn, or the like, such as a Fe-doped lithium niobate (LibO ₃ ) crystal. Photorefractive crystals are used.

The tunable laser 10, the spatial light modulator 50, and the photoelectric conversion element 70 are controlled by the microprocessor 100.

Figure 2 shows the wavelength density diagram of the LINBO ₃ crystal doped with the transition elements Cu, Fe, Mn, the following table shows the optical density by wavelength of Cu, Fe, Mn.

Optical density by wavelength

Circle sofa cabinet Cu Fe Mn 4880Å (blue) 0.7 0.7 0.7 5145 녹색 (green) 0.4 0.7 0.6 6471 Å (red) 0.3 0.3 0.6

As described above, the light density varies depending on the material. As can be seen from the following equation, the larger the light density, the higher the absorption amount and the higher the refractive index change.

D _A = -log10 T _A

Where D _A is water absorption and T _A is transmittance

3A and 3B show a flow chart of the recording and reproducing process by the system of the present invention. As shown in the drawing, the recording / reproducing method according to the present invention uses a tunable laser 10 when recording on the hologram recording medium 60. ) And continuously outputting the laser beam 11 having wavelengths of 4880 kHz, 5145 kHz, and 6471 kHz at 200), and separating the reference light 12 and the object light 13 by the beam splitter 20 (210). ), Modulating the object light 13 by the spatial light modulator 50, and a beam of 4880 에 on the hologram recording medium 60 of the lithium niobate crystal doped with Cu, Fe, and Mn. Difference recording 230, secondary recording 240 with a beam of 5145 GHz, and tertiary recording 250 with a beam of 6471 GHz, to record color images by rearranging Cu, Fe, and Mn. It is supposed to.

Then, when reproducing, the tunable laser 10 continuously outputs the laser beam 11 of 3880 Å, 5145 Å, and 6471 Å three wavelengths, and outputs the beam 300 to the hologram recording medium 60. (12) is inputted, a step (320) of synthesizing (320) pages of R, G, and B three-color pages captured by the photoelectric conversion element (70), and output (330) to a monitor or the like are performed. It is supposed to play.

In the holographic data storage system to which the present invention is applied as described above, the laser beam 11 generated by the laser 10 is incident on the beam splitter 20 to be divided into the reference light 12 and the object light 13, and the object light ( 13 is reflected by the mirror 40 disposed on the optical path, and then modulated by the spatial light modulator 50 in units of one page of light and dark binary data formed by the pixels according to the input data. And the reference light 12 is reflected on the mirror 30, which is disposed on the optical path and whose angle is variable, and then reaches the hologram recording medium 60.

Afterwards, the object light 13 and the reference light 12 cause interference in the hologram recording medium 60 for recording the hologram, and the light induction of the movement charges inside the hologram recording medium 60 depends on the intensity of the interference pattern. A phenomenon occurs, and through this process, an interference fringe is recorded.

When recording in this manner, the absorption by Cu, Fe, and Mn occurs at 4880 kV in the first time, and the absorption by Fe, Mn occurs when recording at 5145 kV in the second time. Absorption occurs.

In addition, rearrangement by Cu, Fe, and Mn occurs when recording at 4880 ms, and rearrangement by Fe and Mn occurs when recording at 5145 ms is erased. The arrangement state of Fe and Mn (5145Å) is recorded, and the rearrangement state by Mn is recorded by recording to the extent that the recording at 5145 지 is erased when recording at 6471Å, resulting in the Cu (4880 () arrangement and the Fe (5145 () arrangement. State, the rearrangement state of Mn (6471 ms) is recorded.

On the other hand, in order to read the data recorded on the hologram recording medium 60, if only the reference light 12 is irradiated to the hologram recording medium 60, the interference pattern is diffracted by the reference light 12 to check the checkered pattern consisting of the contrast of the original pixel. After that, the read image is restored onto the photoelectric conversion element 70 to restore the original data.

When the laser beam 11 of 4880 GHz, 5145 GHz, and 6471 GHz three wavelengths are outputted continuously by the tunable laser 10 during the reproduction in this manner, the 4880 Å wavelength represents the distribution by the refractive index of the Cu array. The 5145 kHz and 6471 Å wavelengths represent the distributions due to the refractive indexes of the Fe and Mn arrays, respectively.

In this way, three wavelengths are continuously changed by the tunable laser 10 during reproduction, and the three pages captured by the photoelectric conversion element 70 are merged with the microprocessor 100 and displayed on a monitor using a personal computer or the like. The reproduction of the hologram is completed.

As described above, the present invention has an advantage that the color hologram data storage system can be implemented, and this principle can be very advantageously applied to holographic video. In general, a magnetic video disk is about 40 gigabits of 120 minutes movie, but using the present invention can record and play 183 movies on a 1 cm ³ hologram recording medium, and access time is much faster than magnetic tape.

While the embodiments of the present invention have been described so far, the present invention is not limited thereto, and various embodiments that can be modified and changed within the true spirit and scope of the principles described and claimed are within the protection scope of the present invention. You will have to understand.

Claims (1)

When recording to a hologram recording medium, the tunable laser continuously outputs laser beams of 4880 GHz, 5145 GHz, and 6471 GHz wavelengths, separates reference light and object light by a beam splitter, and an object by a spatial light modulator. Modulating the light, firstly recording on a hologram recording medium of a lithium niobate crystal doped with Cu, Fe, or Mn with a beam of 4880 Å, secondary recording with a beam of 5145 Å, and a beam of 6471 Å Performing a third recording step to record color images by rearranging Cu, Fe, and Mn, and continuously outputting the laser beams of the 4880 GHz, 5145 GHz, and 6471 GHz three-wavelength laser beams with a tunable laser when reproducing; Inputting three wavelengths of reference light into the recording medium, synthesizing R, G, B three-color pages captured by the photoelectric conversion element, monitor, etc. A color hologram data recording / reproducing method, characterized in that for performing reproduction by performing a step of outputting.