KR100681612B1 - Pick-up system having function of angle multiplex and rotation multiplex in a hdds - Google Patents

Abstract

The present invention relates to a pickup system for a holographic optical storage device capable of angular multiplexing and rotation multiplexing. That is, in the present invention, in the pickup system of the holographic optical storage device capable of multiplexing and rotating multiplexing, the system can be made compact by implementing all the optical systems only on one side of the disc, and also driving like a conventional pickup. This allows easy random access to arbitrary data. Unlike the conventional method, the beam expander is implemented in a structure that can simultaneously perform beam expansion and data image transmission without separately configuring an optical system for transmitting a data image to the media. Instead of constructing a separate optical system from the outside, the optical system for the reference light is also shared with the Fourier lens, thereby preventing the deadly mechanical limitation caused when the reference light is incident. In addition, by using a phase-conjugated wave as a reference light during regeneration, there is no need to use a separate imaging optical system for forming an image reproduced in the DETECTOR. In addition, the device for each multiplexing and rotation multiplexing proposed in the present invention is implemented in a significantly simpler structure than the conventional one so that the entire 360-degree area can be used by eliminating the limitation of the angular range for rotation multiplexing, which is known in the prior art. .

Description

Pick-up system of holographic optical storage device capable of multiplexing and rotating multiplexing {PICK-UP SYSTEM HAVING FUNCTION OF ANGLE MULTIPLEX AND ROTATION MULTIPLEX IN A HDDS}

1 is a configuration diagram of a conventional rotation multiplexable holographic optical storage device;

2 is another configuration diagram of a conventional rotation multiplexable holographic optical storage device;

3 is a conceptual view illustrating an operation in the holographic optical storage device of FIG. 2;

4 is a configuration diagram of a pickup system of a holographic optical storage device capable of multiplexing and rotating multiplexing according to an embodiment of the present invention;

5 is a conceptual diagram of data recording / reproducing in a holographic optical storage device according to an embodiment of the present invention;

6 is a view illustrating a signal light formation in a holographic optical storage device according to an embodiment of the present invention;

7 is an exemplary view of forming reference light in a holographic optical storage device according to an embodiment of the present invention;

8 is a block diagram of a pickup system of a holographic optical storage device capable of multiplexing and rotating multiplexing according to another embodiment of the present invention;

9 is a block diagram of a holographic optical storage pickup system capable of multiplexing and rotating multiplexing according to another embodiment of the present invention.

The present invention relates to a holographic digital data storage system (HDDS), and more particularly to a pickup system for a holographic optical storage device capable of angular multiplexing and rotation multiplexing.

In general, HDDS system is a page-oriented memory that uses the principle of volume hologram on the principle of data recording / reproducing, and can use the parallel data processing method as the input / output method to make the input / output speed higher than 1Gbps. In addition, it is possible to configure the system without the mechanical driving part, so that the data access time can be implemented very quickly with less than 100 ms.

Hologram data storage methods in the HDDS system as described above are each multiplexed and rotated multiplexed. In general, each multiplexing is a multiplexing method of recording multiple data images while changing the angle of the reference light, and rotation multiplexing is a method of multiplexing by rotating the media around the optical axis or by sending the image reproduced by rotating the reference light out of the DETECTOR. Way. See "Holographic Data Storage", page 22-59, by H.J. Coufal, D. Psaltis, and G.T.Sincerbox, Springer-Verlag. It is disclosed in detail.

On the other hand, in recent years, the holographic optical storage device has been actively studied to use two or more multiplexing methods in order to improve the recording density. Thus, the holographic optical storage device in which each of the multiplexing and rotation multiplexing methods are mixed is used. For each, multiplexing and rotation multiplexing mixed holographic optical storage devices such as "Method for Holographic Storage Using Peristrophic Multiplexing" disclosed in US Pat. No. 5,483,365 and "SYSTEM AND METHOD FOR HOLOGRAPHIC STORAGE" disclosed in US Pat. No. 6,700,686 are disclosed. It is.

1 is a representative view of "Method for Holographic Storage Using Peristrophic Multiplexing" disclosed in U.S. Patent No. 5,483,365. In U.S. Patent No. 5,483,365, the beam splitter 10 divides the laser beam 20 into a reference light and a signal light, respectively, into a recording medium 40. Incident. The SLM 50 serves to load desired data in the signal beam, and the image containing the data is focused by the lens 55 having the focal length F and incident on the recording medium. The above reference light and the signal beam meet to form an interference pattern, and the pattern is recorded by the optical reaction of the recording material. At the time of reproduction, when a beam having the same angle used in recording is incident, the signal beam is reproduced to form an image on the DETECTOR 60 by the lens 80. Each multiplexing is performed by rotating the recording material about the Y axis. The Y axis is perpendicular to the plane defined by the reference light and the signal light. Rotation multiplexing is achieved by rotating the recording medium about the Z axis. At this time, the center of rotation is the position where the hologram is recorded. In other words, when the position of the hologram changes, the center of rotation must be moved. Another way is to return the reference light.

However, in "Method for Holographic Storage Using Peristrophic Multiplexing," the system becomes complicated because the axis of rotation must constantly change during rotation multiplexing. It is conceivable to rotate the reference light, but this structure also has a problem that is not easy because the laser and various optical systems are entangled.

2 is a representative view of "SYSTEM AND METHOD FOR HOLOGRAPHIC STORAGE" disclosed in US Pat. No. 6,700,686. In US Pat. No. 6,700,686, the beam oscillated by the laser 105 is divided into a reference light and a signal light by the beam splitter 115. The double reference light is incident on the 2D Scanning Mirror 130. This mirror can turn the beam up and down or left and right. The beam reflected from this mirror is incident on the elliptical mirror 135. At this time, 130 is placed in one focal position of the elliptical mirror 135 and the recording medium is placed in the other focal plane. This ensures that the beam always converges to a point on the recording media, even if the mouth is incident on the elliptical mirror 135 at an angle from 130. The key point of this invention is to achieve the angle change of the reference light for angular multiplexing and rotation multiplexing using 2D Scanning Mirror 130 and elliptical mirror 135.

3 is a description of the above system, in which the mirror 130 performs angle multiplexing while scanning in the up and down directions, 142 directions, and implements rotation multiplexing while scanning in the left and right directions, or 144 directions. It is not very different from the optical system.

However, the system of FIG. 3 also has a limitation in implementing rotation multiplexing. The optics for recording and playing the first media are on both sides, not on one side of the media. This makes it difficult to make the optical system into a conventional compact pickup form, which increases the overall size of the system and makes it difficult to randomly access data.

The second system is also limited in size reduction. The main factor of the limit is a structure in which a beam expander is separately mounted to increase the signal light beyond the SLM size, and the reference light must be incident from the outside of the lens 170. When the focal length of the lens 170 is shortened, the angle of incidence must be increased with respect to the vertical plane of the disk. In this case, there is a problem that the oval mirror 135 needs to be large.

This is a limitation of the 2D Scanning Mirror 130, which is a device for changing the angle of the third reference light. Typically the range of angles required for angle multiplexing is around 20-40 degrees. This degree of angle is the range that can be covered by the mirror 130. But for rotation multiplexing, the angle must cover the entire 360-degree area. However, there is a problem that can not cover the entire area using the mirror 130.

It is therefore an object of the present invention to provide a pickup system for a holographic optical storage device capable of multiplexing and rotating multiplexing.

The present invention for achieving the above object is a pickup system of a holographic optical storage device capable of multiplexing and rotating multiplexing, which generates a reference light for recording / reproducing hologram data, and in a horizontal direction opposite to the holographic storage media surface. A first light path that rotates the reference light to the hologram storage medium at a predetermined angle, and converts the data recording reference light into a signal light through the reflective SLM, and then enters the hologram storage medium to receive the reference light of the first light path A second light path diffracted and stored in the recording medium, the hologram reproduction light diffracted by the reproduction reference light and outputted from the storage medium to the upper surface of the storage media; and a hologram reproduction light emitted by the reference light from the second light path. It characterized in that it comprises a light detecting unit for detecting.

The first optical path includes a light source unit for oscillating reference light for data recording / reproducing to hologram storage media, a concave lens for diffusing the beam width of the reference light oscillated from the light source unit, and a reference light incident through the concave lens. A beam splitter for reflecting and transmitting at the same time as the second optical path, a first laser line mirror for reflecting the reference light transmitted through the beam splitter by 180 °, and a reference light reflected from the first laser line mirror for 180 degrees A second laser line mirror to be reflected by a beam splitter, and a λ / 4 modified plate positioned between the beam splitter and the laser line mirrors so as to modify the polarization of the reference light so that the reference light reflected from the laser line mirror is reflected from the beam splitter and incident on the storage medium Including;

In the second optical path, a reflective SLM for converting the reference light reflected from the beam splitter into a signal coded data and reflecting the reflected light to the beam splitter, and a signal light reflected from the reflective SLM located between the beam splitter and the reflective SLM A λ / 4 strain plate for modifying the polarization of the signal light so as to penetrate the beam splitter and enter the storage medium, and focus the signal light transmitted through the beam splitter and enter the storage medium to diffract the data recording reference light incident from the first light path A hole which is positioned between the objective lens and the beam splitter and the objective lens, and has a hole formed in a central portion thereof to change the polarization of the reference light incident on the storage medium without changing the polarization of the signal light and the reproduction light passing through the hole portion. A hole that is located between a type λ / 2 strain plate and the λ / 4 strain plate and a reflective SLM and is reproduced from a storage medium And the gram reading radiation characterized in that it includes a third laser line mirror for reflecting the optical detector.

Hereinafter, with reference to the accompanying drawings will be described in detail the operation of the preferred embodiment according to the present invention.

4 illustrates a pickup system for a holographic optical storage device capable of multiplexing and rotating multiplexing according to an embodiment of the present invention.

Referring to FIG. 4, the pickup system of the holographic optical storage device capable of multiplexing and rotating multiplexing of the present invention generates a reference light for recording / reproducing hologram data, and faces the surface of the holographic storage medium 420. A first optical path S1 for injecting the reference light into the hologram storage medium at a predetermined angle while rotating in the horizontal direction; and converting the data recording reference light into signal light through the reflective SLM, and then entering the hologram storage medium to enter the first light path. A second optical path S2 diffracted with the reference light of the optical path and stored in the recording medium, and emitting a holographic reproduction light diffracted by the reproduction reference light and outputted from the storage medium onto an upper surface of the storage medium; and from the second optical path. And a photo detector (PDIC) 430 for detecting the hologram reproduction light emitted by the reference light.

The first optical path includes a light source unit 402 for oscillating reference light for data recording / reproducing to hologram storage media, a concave lens 404 for diffusing the beam width of the reference light oscillated from the light source unit 402, and the concave A beam splitter (PBS) 406 for reflecting and simultaneously transmitting the reference light incident through the lens 404 to the second light path S2 and for reflecting the reference light transmitted through the beam splitter 406 by 90 °. The first laser line mirror 412 and the second laser line mirror 414 reflecting the reference light reflected from the first laser line mirror 412 again by 90 ° to reflect the beam splitter 406. And a focusing lens 410 positioned between the λ / 4 strain plate 408 and the first laser line mirror 412 to focus the reference light transmitted through the beam splitter, and the beam splitter 406 and the laser line mirrors 412. Reference light reflected from the laser line mirror Is reflected from the beam splitter 406 includes a λ / 4 byeonhyeongpan 408 to transform the reference beam such that the polarization incident on the storage medium 420.

In the second optical path, a reflective SLM 428 for converting the reference light reflected from the beam splitter 406 into a signal light coded with data and reflecting the reflected light to the beam splitter 406, and the beam splitter 406 and the reflective type A λ / 4 strain plate 422 which modifies the polarization of the signal light such that the signal light reflected between the SLMs 428 and reflected from the reflective SLM 428 passes through the beam splitter 406 and is incident on the storage medium 420, and An objective lens 418 which focuses the signal light transmitted through the beam splitter 406 and enters the storage medium 420 and diffracts the data recording reference light incident from the first optical path S1, and the beam splitter 406. A hole type λ / positioned between the objective lens 418 and a hole formed in the center portion to change the polarization of the reference light incident on the storage medium 420 without changing the polarization of the signal light and the reproduction light passing through the hole portion. 2 modified plates 416 and the λ / 4 side And a third laser line mirror 426 positioned between the template 422 and the reflective SLM 428 to reflect the hologram reproduction light reproduced from the storage medium 420 to the photodetector 430.

The operating principle of the system is as follows. The laser light source 402 employed in the present invention is a laser that emits two wavelengths of beams, green and red, in one module of the laser system. Of course, the two beam exits are inconsistent and physically slightly apart. These lasers are not the same wavelength but are already used in DVD and CD compatible pickups.

Green laser light is used for data recording and red laser light is used for reproduction. First, referring to the recording process, the green laser light (45 degree polarized light) oscillated by the laser light source 402 is incident on the lens 404. The lens 404 may be composed of a single concave lens or a plurality of lenses, and serves to spread the incident beam. The green laser light diffused from the lens 404 is then incident to the beam splitter (PBS) 406, which has a property of reflecting S-polarized light and transmitting P-polarized light as it is. Therefore, since the incident beam has a 45 degree polarization, some of it is reflected and used as signal light, and some passes through and is used as reference light.

6 shows the beam propagation toward the signal light in detail. The reflected signal light is incident on the lens 424. The lens 424 may be a convex lens or a lens composed of several sheets. The lens 404 and the lens 424 are combined to serve as a beam expander to enlarge the beam. The beam is circularly polarized by a λ / 4 strained plate (QWP) 422 during enlargement. The magnified beam is loaded back by the reflective SLM 428, and again passes through the QWP 422 and becomes P-polarized light. The P-polarized signal light passes through the PBS 406 as it is. It then meets a ring type λ / 2 strain plate (Half Wave Plate) 416, which has a ring-like shape. That is, the center part is a device designed to transmit the beam as it is without changing the polarization and the ring part, which is an edge, is made of a λ / 2 strain plate. The beam passing through the PBS 406 is focused in the vicinity of the RING HWP 416 and passes through the hole in the center portion of the ring without changing the polarization. The beam passing through the RING HWP 416 is focused again by the objective lens 418 and is incident to the storage medium 420.

Meanwhile, a detailed path for the reference light is shown in FIG. 7. The reference light transmitted through the PBS 406 is made of the reference light focused by the lens 410. In this case, the lens 410 may be composed of one convex lens or several lenses. The reference light is first reflected by the first laser line mirror 412 and then incident to the second laser line mirror 414 which is a moving mirror. This moving mirror 414 is a mirror moving up and down. The reference light reflected by the moving mirror 414 is returned to the PBS 406 again. In this process, the reference light passes through the QWP 408 twice, so that the S-polarized light is reflected. The reference light reflected from the PBS 406 is changed to P polarized light by the ring type HWP 416. This reference light is collected at the front focal plane of the objective lens 418 and becomes parallel light by the objective lens 418 to reach the rear focal plane of the objective lens 418 in which the storage medium 420 is located and causes interference with signal light. The data is saved.

In this case, when the angle change for each multiplexing moves the moving mirror 414 up and down as shown in FIG. 7, the reference light may move from the center of the lens 418 to the edge. Regardless of which part of the lens 418 the reference light enters, when the reference light enters side by side, it always gathers at the rear focal plane of the lens 418. It just changes the angle of incidence. At this time, even if the moving mirror 414 moves up and down, the focal plane where the beams are gathered always becomes the front focal plane of the objective lens 418 and becomes parallel light when passing through the objective lens 418. The angle change for rotation multiplexing is then achieved by rotating a module consisting of a laser, a lens 404, a PBS 406, a lens 410, and a mirror 412, 414 about the center of the PBS 406. . Rotating this module has no effect on the beam path towards the signal light.

Next, description will be given on playback. At the time of reproduction, a red laser light is oscillated from the light source unit 402. The oscillated reproduction reference light has P polarization. Thus, the light path after passing through the PBS 406 as it is is the same as the green laser light at the time of recording. However, during regeneration, the rotation module 400 rotates 180 °. On the other hand, the storage medium 420 is coated with a reflective layer 421 reflecting only the red laser light on the substrate under the media. In this case, as shown in FIG. 5, the light is reflected by the reflective layer 421 of the substrate under the media 420 to be incident in the opposite direction to the green laser light used for recording. That is, it becomes a phase conjugate wave. When the phase conjugate wave of the reference light used for recording is irradiated to the storage medium 420 in which the data is recorded, the signal light rises upside down along the original path.

On the other hand, since the polarization of the reproduced image is the same as the reference light, it has P polarization. Therefore, the reproduced image passing through the central portion of the RING HWP 416 passes through the PBS 406 as it is to meet the third laser line mirror 426. Since the mirror 426 reflects the red laser light, the mirror 426 is reflected and enters the photodetector 430. At this time, if the position of the light detector 430 is separated from the laser line mirror 426 by the same distance as the reflective SLM 428, a clean image is formed on the light detector 430.

In the above process, since the beam used for reproduction is actually green laser light, it should not be incident in the opposite direction to the direction of the green laser light used for recording, and a little BRAGG DETUNING should be performed. In general, it should be incident at a slightly larger angle than the green laser light. However, since the red laser light oscillates slightly below the green laser light, it can be seen that the light is incident at a slightly larger angle than the green laser light when the light path is followed. Therefore, by adjusting the oscillation position of the red laser light to have the necessary DETUNING angle value, it is possible to generate a phase conjugated wave without any adjustment. However, if necessary, the angle of incidence can be adjusted by adjusting the moving mirror during reproduction to produce an accurate phase conjugate wave.

8 is a pickup system of a holographic optical storage device according to another embodiment of the present invention, and separates the green laser light source unit 801 and the red laser light source unit 802 as shown in FIG. It is possible.
That is, the green laser light from the green laser light source unit 801 proceeds with the optical path for data recording as described in FIG. 4 described above to record data on the storage medium 420. In addition, the red laser light from the red laser light source unit 802 passes through a laser line mirror 804 through which the red laser light is transmitted, and is reflected by 90 degrees from the moving mirror 414 so that the beam splitter PBS ( After entering 406, it proceeds with the optical path for data reproduction as described in FIG. 4 above to reproduce the data recorded on the storage medium 420.
As shown in FIG. 8, when the green laser light source unit 801 and the red laser light source unit 802 are separately provided, the fixed mirror, as described above, reflects the green laser light and transmits the red laser light. 804 is used.
In this way, the position of the red laser light can be adjusted more easily, so that the position of the red laser light source unit 802 can be adjusted by assembling precisely the value of the DETUNING angle generated when the red laser light is used, or the red laser light can be adjusted during assembly. You can adjust the position by firing and playing.

FIG. 9 is a pickup system of a holographic optical storage device according to still another embodiment of the present invention. As shown in FIG. 9, the photodetector may be disposed opposite the storage medium. The laser is oscillated and uses an HWP that can then be rotated. HWP has a characteristic of changing linearly polarized light into linearly polarized light having a different polarization direction as it rotates. Therefore, the polarization is adjusted to about 45 degrees so that the beam can be directed toward both the reference light and the signal light during recording, and the polarization is made P polarized light so that the beam proceeds only toward the reference light during reproduction. In this case, the storage medium is used without a reflective film as in the prior art. At the time of recording, the beam proceeds along the optical path as in the previous case, and at the time of reproduction, unlike the case where the red laser light is used, playback is performed on the spot where it was recorded without rotating 180 °. In this case, there is an advantage of using only one green laser light.

Meanwhile, in the above description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the invention should be determined by the claims rather than by the described embodiments.

As described above, in the present invention, in the pickup system of the holographic optical storage device capable of multiplexing and rotating multiplexing, the system can be made compact by implementing all the optical systems only on one side of the disk. There is an advantage in that it can be driven like a conventional pickup, making it easy to random access to arbitrary data.

In the present invention, unlike the prior art, the beam expander is implemented as a structure capable of simultaneously performing beam expansion and data image transmission without separately configuring the optical system for transmitting the data image to the media, and separating the reference light from the signal light as before. Instead of constructing an incident optical system from the outside of the Fourier lens and sharing the optical system for the reference light with the Fourier lens, the deadly mechanical limitation caused when the reference light is incident is prevented. In addition, by using a phase-conjugated wave as the reference light during regeneration, it is not necessary to use a separate imaging optical system for forming an image reproduced in the detector. Therefore, by using such a structure, the number of optical parts in the present invention is greatly reduced compared to the conventional method. It has the advantage of reducing the complexity of the system and drastically reducing the holographic optical storage device to make it look like a pickup.

In addition, the device for angular multiplexing and rotation multiplexing proposed by the present invention is implemented in a dramatically simpler structure than the conventional one, so that the entire 360-degree area can be used by eliminating the limitation of the angular range for rotation multiplexing, which is known in the prior art. There is an advantage.

Claims (18)

A pickup system of a holographic optical storage device capable of multiplexing and rotating multiplexing, A light source unit for oscillating reference light for recording / reproducing data on the hologram storage medium; A concave lens for diffusing the beam width of the reference light oscillated from the light source unit; A beam splitter for reflecting or transmitting the reference light incident through the concave lens according to a polarization component; A first laser line mirror which reflects the reference light transmitted through the beam splitter by 90 °; A second laser line mirror which reflects the reference light reflected from the first laser line mirror again by 90 ° and reflects the reflected light to the beam splitter; A first λ / 4 strain plate positioned between the beamsplitter and the laser line mirrors to modify polarization of the reference light reflected from the laser line mirrors; A reflective SLM for converting the reference light reflected from the beam splitter into signal light coded with data and reflecting the reflected light to the beam splitter; A second λ / 4 strain plate positioned between the beam splitter and the reflective SLM to modify polarization of the signal light reflected from the reflective SLM; An objective lens which focuses the signal light transmitted through the beam splitter and enters the storage medium and diffracts the data recording reference light; A hole type λ / 2 positioned between the beam splitter and the objective lens and having a hole formed at a central portion thereof to change the polarization of the reference light incident to the storage medium without changing the polarization of the signal and reproduction light passing through the hole portion; Variant The pickup system of the holographic optical storage device comprising a. The method of claim 1, The system includes a third laser line mirror positioned between the λ / 4 strain plate and the reflective SLM to reflect the hologram reproduction light reproduced from the storage medium to a photodetector. system. The method of claim 1, And the light source unit oscillates green laser light with the concave lens when data is recorded, and oscillates red laser light during reproduction. The method of claim 3, wherein The light source unit, the pickup system of the holographic optical storage device, characterized in that it comprises two exit holes in the spaced apart position from which the green laser light and the red laser light is oscillated. The method of claim 4, wherein And the light source unit polarizes the green laser light oscillated during data recording by 45 ° so that both reflection and transmission occur through the beam splitter. The method of claim 1, The light source unit is rotated by 180 ° during data reproduction to inject the red laser light for data reproduction into the storage medium in a direction opposite to the incident angle in the storage medium of the green laser light used for the recording. Pickup system of the device. The method of claim 6, The red laser light for data reproduction is incident on the storage medium so as to be a phase conjugate wave with the reference light used in the recording, and the hologram reproduction light that is diffracted and output by the red laser light is incident upon the recording from the surface of the storage medium. A pickup system of a holographic optical storage device, characterized in that the output is upside down along the signal light path. The method of claim 1, And the second laser line mirror is moved by the actuator in a vertical direction with respect to the first laser line mirror to perform angular multiplexing of reference light. The method of claim 1, The beamsplitter is a pickup system of a holographic optical storage device, characterized in that S polarized light is reflected, P polarized light is transmitted as it is. The method of claim 1, And the pickup system further comprises a focusing lens positioned between the λ / 4 strain plate and the first laser line mirror to focus the reference light transmitted through the beam splitter. The method of claim 10, The focusing lens is a pickup system of a holographic optical storage device, characterized in that formed by a single convex lens or a plurality of lenses. The method of claim 1, The first λ / 4 strain plate is positioned between the beamsplitter and the laser line mirrors so as to modify the polarization of the reference light so that the reference light reflected from the laser line mirror is reflected from the beamsplitter and incident on the storage medium. Pickup system of holographic optical storage device. The method of claim 1, The second λ / 4 strain plate is positioned between the beamsplitter and the reflective SLM to modify the polarization of the signal light so that the signal light reflected from the reflective SLM is transmitted through the beamsplitter and incident on the storage medium. Pickup system of holographic optical storage. A pickup system of a holographic optical storage device capable of multiplexing and rotating multiplexing, A first light source unit for oscillating a reference light for recording data into the hologram storage medium; A concave lens for diffusing the beam width of the reference light oscillated from the first light source unit; A beam splitter for reflecting or transmitting the reference light incident through the concave lens according to polarization characteristics; A first laser line mirror which reflects the reference light transmitted through the beam splitter by 90 °; A λ / 2 strain plate positioned between the beam splitter and the first laser line mirror to modify polarization of the reference light transmitted through the beam splitter; A second laser line mirror reflecting the angle of λ / 2 polarized reference light reflected from the first laser line mirror to the beam splitter by reflecting the light back to the beam splitter by 90 ° so as to be reflected to the storage media; A second light source unit for oscillating reference light for data reproduction with the storage medium; A reflective SLM for converting the reference light reflected from the beam splitter into signal light coded with data and reflecting the reflected light to the beam splitter; A λ / 4 strained plate positioned between the beam splitter and the reflective SLM to modify polarization of the signal light reflected from the reflective SLM; An objective lens which focuses the signal light transmitted through the beam splitter and enters the storage medium and diffracts the data recording reference light; A hole type λ / 2 positioned between the beam splitter and the objective lens and having a hole formed at a central portion thereof to change the polarization of the reference light incident to the storage medium without changing the polarization of the signal and reproduction light passing through the hole portion; Variant The pickup system of the holographic optical storage device comprising a. The method of claim 14, Wherein said first light source oscillates green laser light for data recording, and said second light source oscillates red laser light for data reproduction. The method of claim 14, And said first laser line mirror reflects green laser light from said first light source portion and transmits red laser light from said second light source portion. The method of claim 14, The system includes a third laser line mirror positioned between the λ / 4 strain plate and the reflective SLM to reflect the hologram reproduction light reproduced from the storage medium to the photodetector. system. The method of claim 14, The second light source unit is located at the rear end of the first laser line mirror, the holographic light storage, characterized in that to generate a red laser light during reproduction to enter through the first laser line mirror to the second laser line mirror. Pickup system of the device.

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