JP4367201B2 - Hologram recording / reproducing apparatus, hologram recording / reproducing method, and disk cartridge - Google Patents

Description

  The present invention relates to a hologram recording / reproducing apparatus and method, and more particularly, to a disc cartridge that can block unnecessary light incident on an image pickup apparatus in a reproducing mode and the unnecessary light.

  In recent years, holographic technology has been rapidly developed for the practical use of holographic memory, which is attracting attention as a candidate for powerful storage that competes with next-generation and next-generation optical discs. Thus, a hologram recording / reproducing system for recording / reproducing a large amount of data has been proposed (see, for example, Non-Patent Document 1).

  A hologram recording / reproducing apparatus for recording this data on a hologram recording medium in a holographic manner and reproducing the data from the hologram recording medium has a general configuration as shown in FIG. The coherent laser light emitted from the laser light source 1 enters the beam splitter 3 through the shutter 2 and is branched into the signal light 100 and the reference light 200. The signal light 100 is incident on the spatial light modulator 5 via the mirror 4, and the signal light is intensity-modulated by the spatial light modulator 5 displaying the data page. The modulated signal light is condensed on the hologram recording medium 7 by the lens group 6. On the other hand, since the reference light 200 irradiates the hologram recording medium 7 via the mirror 8 and the lens 13, the signal light 100 and the reference light 200 are superimposed in the hologram recording medium 7, and interference fringes formed as a result are formed. Is recorded on the hologram recording medium 7.

  In order to reproduce the data recorded on the hologram recording medium 7, the same reproduced light as the reference light 200 is incident on the hologram recording medium 7, so that the diffracted light corresponding to the interference fringes recorded on the hologram recording medium 7 is obtained. Then, the data is reproduced, and this diffracted light (reproduced light) is imaged on the imaging device 10 such as a CCD or CMOS by the lens group 9. The imaging device 10 photoelectrically converts the received diffracted light, and the obtained light reception signal is analyzed and reproduced as image data.

Here, the detailed configurations of the lens group 6 and the lens group 9 that are arranged to face each other with the hologram recording medium 7 interposed therebetween correspond to the Fourier transform lens group and the inverse Fourier transform lens group as shown in FIG. FIG. 7 shows only one lens 6 and 9 for simplification. Therefore, the data is recorded and reproduced on the hologram recording medium 7 by a Fourier transform hologram. This is because the hologram can be stored in a limited space and the information can be distributed in the inverse space by Fourier transforming the information, and therefore there is an advantage that the recording redundancy can be increased.
IBM J.RES DEVELOP VOL 44 NO.3 MAY 2000 `` Holographic data storage ''

  However, in the two-beam recording / reproducing apparatus as described above, the reference light 200 irradiates the recording area of the hologram recording medium 7 as shown in FIG. 8 during reproduction. At this time, the reference light (illumination reference light) 200 is used. Is partially reflected by a glass or plastic plate (not shown) sandwiching the hologram recording medium 7, and the reflected light 201 enters the Fourier transform lens group 6 of the signal light optical system. The reflected light 201 incident on the Fourier transform lens group 6 is further reflected by the Fourier transform lens group 6 and folded back to the hologram recording medium 7 side, and the reference light 201 passes through the hologram recording medium 7 and is reproduced optical system. Is incident on the Fourier transform lens group 9.

  Accordingly, since the reference light 201 is incident on the imaging device 10 in addition to the reproduction light reproduced from the hologram recording medium 7, the image of the reference light 201 is placed as noise on the reproduced image captured by the imaging device 10. As a result, the S / N of the reproduced image is deteriorated.

  The present invention has been devised in view of the above circumstances, and an object of the present invention is to prevent S / N degradation of image data caused by unnecessary light other than diffracted light entering the reproduction light optical system during reproduction. It is possible to provide a hologram recording / reproducing apparatus, a hologram recording / reproducing method, and a disk cartridge that can improve the quality of reproduced image data.

In order to achieve the above object, the present invention records the interference fringes between the signal light and the reference light on the hologram recording medium in the recording mode, and irradiates the hologram recording medium with the same illumination reference light as the reference light in the reproduction mode. A hologram recording / reproducing apparatus that receives diffracted light generated by the imaging device to obtain reproduction data, a signal light optical system that focuses the signal light on the hologram recording medium, and the diffracted light to the imaging apparatus A reproducing light optical system that forms an image on the optical recording medium, a hologram recording medium disposed between the signal light optical system and the reproducing light optical system, and a light beam disposed between the signal light optical system and the hologram recording medium. a reflecting object, the reflecting object produces the illumination reference beam to the reproduction mode when irradiated to the hologram recording medium, the light reflected by the hologram recording medium of the illumination reference beam , It is prevented from being incident on the front relaxin No. optical system, the reflected light, and wherein the reflecting in a direction as not to be incident to the reproducing optical system.

Further, the present invention is caused by recording the interference fringes between the signal light and the reference light on the hologram recording medium in the recording mode and irradiating the hologram recording medium with the same illumination reference light as the reference light in the reproduction mode. A hologram recording / reproducing apparatus that receives diffracted light with an imaging device to obtain reproduction data, and a signal light optical system that focuses the signal light on the hologram recording medium;
A reproduction light optical system that forms an image of the diffracted light on the imaging device, a hologram recording medium disposed between the signal light optical system and the reproduction light optical system, and signal light in the recording mode in the hologram recording The signal light optical system at a position where the light is focused on the medium is placed at a position where the reflected light from the hologram recording medium of the illumination reference light is not incident on the signal light optical system in the reproduction mode. And moving means for shifting .

Further, the present invention is caused by recording the interference fringes between the signal light and the reference light on the hologram recording medium in the recording mode and irradiating the hologram recording medium with the same illumination reference light as the reference light in the reproduction mode. A hologram recording / reproducing method for obtaining reproduction data by receiving diffracted light with an imaging device, wherein the reflected light from the hologram recording medium generated when the illumination reference light is irradiated onto the hologram recording medium in the reproduction mode , An incident blocking step for blocking signal light from being incident on the signal light optical system for condensing the signal light on the hologram recording medium, wherein the incident blocking step converts the reflected light of the illumination reference light into the diffracted light; The reproducing light optical system that forms an image on the imaging apparatus is provided with a reflecting object that reflects in a direction not to be incident .

  The present invention also provides a hologram recording medium that records interference fringes of signal light and reference light, a housing that houses the hologram recording medium, and the signal light and reference light irradiated from the outside to the hologram recording medium. The illumination reference light in a reproduction mode in which the hologram recording medium is irradiated with a transparent portion disposed in a part of the casing for incidence and the hologram recording medium is irradiated with the same illumination reference light as the reference light. Is provided with a light shielding means for preventing reflected light generated when the hologram recording medium is irradiated through the transparent portion and leaking to the outside.

  As described above, in the present invention, the reflected light from the hologram recording medium (hologram recording medium) generated when the illumination reference light is irradiated onto the hologram recording medium in the reproduction mode is prevented from entering the signal light optical system. In order to prevent the reflected light from entering the signal light optical system, for example, the signal light optical system is used as a hologram recording medium and a reproduction light optical system. By shifting the reflected light, it is possible to prevent the reflected light of the illumination reference light from being reflected by the signal light optical system and folded back to the hologram recording medium side. Therefore, since only the diffracted light generated by irradiating the hologram recording medium with the illumination reference light forms an image on the image pickup device through the reproduction light optical system, the S / N of the image data reproduced from the hologram recording medium can be improved. Can do. Further, the light shielding member is movably disposed in a transparent portion on which the recording light and the reference light incident on the housing of the disk cartridge are incident, and the reflected light of the illumination reference light leaks to the outside in the reproduction mode. By moving to such a position that the reflected light is not incident on the signal light optical system, it is possible to prevent the reflected light from being reflected by the signal light optical system and folded back to the hologram recording medium side. The S / N ratio of the image data reproduced from the hologram recording medium can be improved.

  According to the present invention, the light shielding member for preventing the reflected light from the hologram recording medium, which is generated when the hologram recording medium is irradiated with the illumination reference light in the reproduction mode, from being incident on the signal light optical system is disposed. Alternatively, in order to prevent the reflected light from entering the signal light optical system, one or both of the signal light optical system and the reproduction light optical system are shifted with respect to the optical axis, for example, to refer to the illumination. It is possible to prevent the reflected light of the light from being reflected by the signal light optical system and folded back toward the hologram recording medium, and passing through the hologram recording medium and entering the reproduction light optical system. Therefore, since only the diffracted light generated by irradiating the hologram recording medium with the illumination reference light forms an image on the image pickup device through the reproduction light optical system, the S / N of the image data reproduced from the hologram recording medium can be improved. Can do.

  It is possible to prevent S / N degradation of image data caused by incident unnecessary light other than diffracted light entering the reproduction light optical system during reproduction, thereby improving the quality of the reproduction image data. A light blocking member is disposed in the optical path of the reflected light so that the reflected light from the hologram recording medium generated when the hologram recording medium is irradiated is not incident on the signal light optical system that focuses the signal light on the hologram recording medium. Alternatively, it is realized by changing the relative position of the signal light optical system and the reproduction light optical system.

  FIG. 1 is a side view showing the configuration of the main part of the hologram recording / reproducing apparatus according to the first embodiment of the present invention. In the hologram recording / reproducing apparatus, a hologram recording medium 23 is disposed between the signal light optical system 21 and the reproducing light optical system 22, and a shutter 24 is disposed between the hologram recording medium 23 and the signal light optical system 21. Yes. Further, the signal light optical system 21 and the reproduction light optical system 22 are a Fourier transform lens group and an inverse Fourier transform lens group, and 211 and 221 indicate the outermost lenses.

  FIG. 2 is a cross-sectional view showing the structure of the hologram recording medium 23 shown in FIG. It has a sandwich structure in which a recording material (photopolymer or the like) 232 is sandwiched between transparent glass plates (or transparent plastic plates) 231.

  Next, the operation of the present embodiment will be described. The shutter 24 is openable and closable at the center. In the recording mode in which data is recorded on the hologram recording medium 23, the shutter 24 is opened as shown. For this reason, the signal light 100 whose intensity is modulated in accordance with the data irradiated from the lens 211 of the signal light optical system 21 passes through the opening of the shutter 24 and reaches the recording area of the hologram recording medium 23. The signal light 100 interferes with the separately irradiated reference light 200, and interference fringes are recorded in the recording material 232 of the hologram recording medium 23.

  In the reproduction mode, as shown in FIG. 3, the shutter 24 is closed, and only the reference light (illumination reference light) 200 is applied to the recording area of the hologram recording medium 23. As a result, diffracted light 300 is generated in the recording area of the hologram recording medium 23, and this diffracted light 300 is incident on the reproduction light optical system 22 as reproduction light and forms an image on the imaging device 25. At this time, a part of the reference light 200 is reflected by the hologram recording medium 23 and the reflected light 201 travels in the direction of the signal light optical system 21, but this is blocked by the shutter 24 and almost absorbed, and this reflection The light 201 is prevented from being folded back to the hologram recording medium 23 side.

  According to the present embodiment, part of the reference light 200 reflected by the hologram recording medium 23 is blocked by the shutter 24 disposed between the signal light optical system 21 and the hologram recording medium 23 in the reproduction mode. Therefore, the reflected light 201 of the reference beam 200 is folded back to the hologram recording medium 23 side and further transmitted through the hologram recording medium 23. It can be prevented from being incident on the reproduction light optical system 22. For this reason, only the reproduction light is incident on the imaging device 25, and the S / N of the reproduction image can be improved.

  In the above embodiment, the shutter 24 is disposed between the signal light optical system 21 and the hologram recording medium 23. However, this is not limited to the shutter 24, and any light shielding member may be used. The signal light emitted from the system 21 is excluded from the optical path so as to reach the hologram recording medium 23, and the reflected light 201 of the reference light 200 from the hologram recording medium 23 is not incident on the signal light optical system 21 in the reproduction mode. If it has a function of being inserted into the optical path of the reflected light 201 and blocking it, the same effect can be obtained.

  The light shielding member described above preferably absorbs light, but may be an object that scatters light. In this case, when the reflected light 201 from the hologram recording medium 23 hits, the light is scattered and the hologram recording medium 23 side is scattered. If almost no return is made, the same effect as described above is obtained. Further, the light shielding member may reflect light. In this case, if the arrangement angle of the light shielding member is set so that the reflected light 201 of the reference light 200 from the hologram recording medium 23 does not enter the reproduction light optical system 22, the reflected light 201 is shielded from this light. When it hits the member, it can be reflected so as not to enter the signal light optical system 21, and the same effect can be obtained.

  FIG. 4 is a diagram showing a case where the disc cartridge according to the second embodiment of the present invention is mounted on the hologram recording / reproducing apparatus. However, the same parts as those in the first embodiment will be described with the same reference numerals. In the disk cartridge 26, a hologram recording medium 27 is rotatably accommodated in a flat box-shaped housing. A part of the housing is transparent, and signal light and reference light are incident on the inside from the transparent part 261 so that the recording area of the hologram recording medium 27 can be irradiated. A shutter 28 for preventing the reflected light from being emitted to the outside is slidably attached. In addition, the back surface of the housing facing the transparent portion 261 is also transparent (see FIG. 5), so that the diffracted light 300 can be extracted in the reproduction mode.

  Next, the operation of the present embodiment will be described. The disk cartridge 26 is used by being mounted between the signal light optical system 21 and the reproduction light optical system 22. In the recording mode, the shutter 28 of the disk cartridge 26 slides sideways as shown in FIG. 5A and the transparent portion 261 is fully opened, so that the signal light 100 and the reference light 200 are contained in the housing of the disk cartridge 26. The light enters the body and irradiates the recording area 40 of the hologram recording medium 27. As a result, data is recorded on the hologram recording medium 27.

  In the reproduction mode, the shutter 28 of the disc cartridge 26 is positioned so as to slide sideways and cover a part of the transparent portion 261 as shown in FIG. Thus, even if a part of the transparent portion 261 is covered, the reference light (illumination reference light) 200 can enter the housing of the disk cartridge 26 and is irradiated onto the hologram recording medium 27. At this time, a part of the reference light 200 is reflected by the hologram recording medium 27, but this reflected light is blocked by the shutter 28 and is not emitted outside the disk cartridge 26. For this reason, the reflected light of the reference light 200 enters the signal light optical system 21, which is folded and re-entered on the hologram recording medium 27 side, passes through the hologram recording medium 27, and enters the reproduction light optical system 22. To prevent that.

  According to the present embodiment, even when the hologram recording medium 27 is used while being housed in a housing, the reference light 200 from the hologram recording medium 27 is obtained by attaching the shutter 28 to the cartridge 26 side. The reflected light can be prevented from being emitted to the outside, and there is an effect similar to that of the first embodiment.

  FIGS. 6A and 6B are side views showing the configuration of the main part of a hologram recording / reproducing apparatus according to the third embodiment of the present invention. However, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate. In the hologram recording / reproducing apparatus, a hologram recording medium 23 is disposed between the signal light optical system 21 and the reproducing light optical system 22. The signal light optical system 21 is movable in the direction perpendicular to the optical axis. This moving means uses a servo mechanism for tracking control, but a dedicated moving mechanism may be provided separately.

  Next, the operation of the present embodiment will be described. In the recording mode, the signal light optical system 21 is positioned so that the optical axis of the signal light optical system 21 and the optical axis of the reproduction light optical system 22 coincide with each other as shown in FIG. As a result, the signal light 100 and the reference light 200 are incident on the recording area of the hologram recording medium 23 to record data.

  In the reproduction mode, the signal light optical system 21 moves in the vertical direction as shown by an arrow 80 with respect to the optical axis as shown in FIG. For this reason, the reflected light 201 of the reference light (illumination reference light) 200 from the hologram recording medium 23 does not enter the signal light optical system 21 and escapes to the outside as it is. Therefore, the reflected light 201 does not enter the imaging device 25 from the reproduction light optical system 22 together with the diffracted light 300.

  According to the present embodiment, in the reproduction mode, the signal light optical system 21 is shifted from the hologram recording medium 23 of the reference light 200 to a position where the reflected light 201 of the reference light 200 does not enter the signal light optical system 21. Can be prevented from entering the image pickup device 25 from the reproduction light optical system 22 together with the diffracted light 300, thereby improving the S / N of the reproduction data.

  In the above embodiment, the signal light optical system 21 is shifted, but the reproduction light optical system 22 including the position of the hologram recording medium 23 is moved to a position where the reflected light 201 of the reference light 200 does not enter the signal light optical system 21. Even if it is shifted to the same level, the same effect is obtained. Further, since it is sufficient that the reflected light 201 of the reference light 200 does not enter the signal light optical system 21, the signal light optical system 21 may be moved by any rotational movement, and the same applies when the reproduction light optical system 22 is shifted. It is. Further, the same effect can be obtained even if the signal light optical system 21 and the reproduction light optical system 22 are simultaneously shifted so that the reflected light 201 of the reference light 200 does not enter the signal light optical system 21.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can implement also with another various form in a concrete structure, a function, an effect | action, and an effect.

It is the side view which showed the structure of the principal part of the hologram recording / reproducing apparatus which concerns on the 1st Embodiment of this invention. It is sectional drawing which showed the structure of the hologram recording medium shown in FIG. FIG. 2 is a side view showing a state of the hologram recording / reproducing apparatus shown in FIG. 1 in a reproduction mode. It is the figure which showed the case where the disc cartridge based on the 2nd Embodiment of this invention is mounted | worn with the hologram recording / reproducing apparatus. FIG. 5 is a cross-sectional view showing a state of a shutter of the disk cartridge shown in FIG. 4. It is the side view which showed the structure of the principal part of the hologram recording / reproducing apparatus which concerns on the 3rd Embodiment of this invention. It is the block diagram which showed the structural example of the conventional hologram recording / reproducing apparatus. It is the side view which showed the periphery structure of the hologram recording medium of the hologram recording / reproducing apparatus shown in FIG.

  21... Signal light optical system, 22... Reproducing light optical system, 23 and 27... Hologram recording medium, 24 and 28... Shutter, 25. 231 ... Glass plate, 232 ... Recording material.

Claims (8)

In the recording mode, the interference fringes between the signal light and the reference light are recorded on the hologram recording medium, and in the reproduction mode, the imaging apparatus captures the diffracted light generated by irradiating the hologram recording medium with the same illumination reference light as the reference light. A hologram recording / reproducing apparatus for receiving reproduction data by receiving light,
A signal light optical system for condensing the signal light on the hologram recording medium;
A reproduction light optical system for imaging the diffracted light on the imaging device;
A hologram recording medium disposed between the signal light optical system and the reproduction light optical system;
A reflective object disposed between the signal light optical system and the hologram recording medium;
The reflecting object prevents the reflected light of the illumination reference light from being incident on the signal light optical system, which is generated when the illumination reference light is irradiated onto the hologram recording medium in the reproduction mode. And reflecting the reflected light in a direction not incident on the reproduction light optical system,
And a hologram recording / reproducing apparatus.   2. The hologram recording / reproducing apparatus according to claim 1, wherein the reflecting object includes means for moving or removing the reflecting object from the optical path of the signal light in a recording mode. In the recording mode, the interference fringes between the signal light and the reference light are recorded on the hologram recording medium, and in the reproduction mode, the imaging apparatus captures the diffracted light generated by irradiating the hologram recording medium with the same illumination reference light as the reference light. A hologram recording / reproducing apparatus for receiving reproduction data by receiving light,
A signal light optical system for condensing the signal light on the hologram recording medium;
A reproduction light optical system for imaging the diffracted light on the imaging device;
A hologram recording medium disposed between the signal light optical system and the reproduction light optical system;
In the recording mode, the signal light optical system that is in a position where the signal light is condensed on the hologram recording medium is used. In the reproduction mode, the reflected light of the illumination reference light on the hologram recording medium is not incident on the signal light optical system. Moving means for shifting the signal light optical system to a position,
A hologram recording / reproducing apparatus comprising: In the recording mode, the interference fringes between the signal light and the reference light are recorded on the hologram recording medium, and in the reproduction mode, the imaging apparatus captures the diffracted light generated by irradiating the hologram recording medium with the same illumination reference light as the reference light. A hologram recording / reproducing method for obtaining reproduction data by receiving light,
Reflected light from the hologram recording medium generated when the hologram recording medium is irradiated with the illumination reference light in the reproduction mode is incident on a signal light optical system that focuses the signal light on the hologram recording medium. An incident blocking step for blocking,
The incident blocking step is performed by including a reflecting object that reflects the reflected light of the illumination reference light in a direction not to be incident on a reproduction light optical system that forms an image of the diffracted light on the imaging device.
A hologram recording / reproducing method characterized by the above.   5. The hologram recording / reproducing method according to claim 4, wherein the incident blocking step includes a step of moving or arranging the reflecting object in an optical path of the reflected light when shifting from the recording mode to the reproducing mode. Method. In the recording mode, the interference fringes between the signal light and the reference light are recorded on the hologram recording medium, and in the reproduction mode, the imaging apparatus captures the diffracted light generated by irradiating the hologram recording medium with the same illumination reference light as the reference light. A hologram recording / reproducing method for obtaining reproduction data by receiving light,
Reflected light from the hologram recording medium generated when the hologram recording medium is irradiated with the illumination reference light in the reproduction mode is incident on a signal light optical system that focuses the signal light on the hologram recording medium. An incident blocking step for blocking,
In the incident blocking step, when the recording mode is shifted to the reproduction mode, the signal light optical system that is in a position for condensing the signal light on the hologram recording medium in the recording mode is A step of shifting the signal light optical system to a position where the reflected light from the hologram recording medium is not incident on the signal light optical system;
A hologram recording / reproducing method characterized by the above. A hologram recording medium for recording interference fringes of signal light and reference light;
A housing for housing the hologram recording medium;
In order to make the signal light and reference light irradiated from the outside incident on the hologram recording medium, a transparent portion disposed in a part of the casing;
In the reproduction mode in which the hologram recording medium is irradiated with the same illumination reference light as the reference light to reproduce the recorded data, the reflected light generated when the illumination reference light is irradiated onto the hologram recording medium A light shielding means that transmits and prevents leakage to the outside;
A disk cartridge comprising: The light-shielding means is a light-shielding member that is movably disposed at a part of the transparent portion of the housing or in a close position, and is generated when the illumination reference light is irradiated on the hologram recording medium in the reproduction mode. 8. The disk cartridge according to claim 7, wherein the light shielding member is moved to a position where reflected light passes through the transparent portion and does not leak outside.

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