JP2005321618A - Cartridge housing type hologram recording medium, and hologram recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain S/N of a reproduced image in a preferable state while preventing the reflected light of reference light on a hologram recording medium from entering a signal light optical system when the reference light for reproducing is made incident on a cartridge housing type hologram recording medium. <P>SOLUTION: In performing reproduction, the reference light 200 for reproducing is made incident on the aperture 3 of a chassis 1 of the cartridge housing type hologram recording medium 10 and the recording region 21 of the hologram recording medium 2 is irradiated with the light 200, wherein a part of the aperture 3 is closed by a shutter 4 to prevent the reflected light 201 by the recording medium 2 of the reference light 200 from leaking to the outside. Since the reflected light 201 is not made incident on the lens 46 of the signal light optical system, reproduced light 300 generated from the recording region 21 is not mixed with the reflected light 201 and the S/N of the reproduced image obtained by an imaging apparatus 49 can be kept in a preferable state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cartridge storage hologram recording medium in which a hologram recording medium for recording interference fringes of signal light and reference light is stored in a housing, and a hologram recording / reproducing apparatus using the cartridge storage hologram recording medium.

  In recent years, a hologram recording / reproducing apparatus that records and reproduces large-capacity data using hologram technology has been proposed (for example, see Non-Patent Document 1). This hologram recording / reproducing apparatus has a schematic configuration as shown in FIG. 4, for example.

  FIG. 4 is a schematic diagram showing a configuration example of a conventional hologram recording / reproducing apparatus. The coherent laser light emitted from the laser light source 41 enters the beam splitter 43 through the shutter 42 and is branched into the signal light 100 and the reference light 200. The signal light 100 is incident on the spatial light modulator 45 via the mirror 44, and the signal light 100 is intensity-modulated by the spatial light modulator 45 displaying the data page. The modulated signal light is condensed on the hologram recording medium 30 by the lens 46. On the other hand, the reference light 200 is incident on the lens 51 through the mirror 50, and the hologram recording medium 30 is irradiated by the lens 51. Thereby, the signal light 100 and the reference light 200 interfere with each other in the hologram recording medium 30, and the interference fringes formed as a result are recorded on the hologram recording medium 30 as a fine dense pattern.

  In order to reproduce the data recorded on the hologram recording medium 30, the hologram recording medium 30 is irradiated with the same reproduction reference light as the reference light 200, thereby corresponding to the interference fringes recorded on the hologram recording medium 30. Data is reproduced as diffracted light (reproduced light), and this reproduced light is imaged on an imaging device 49 such as a CCD or CMOS by a lens (inverse Fourier lens) 48. The imaging device 49 photoelectrically converts the received reproduction light, and the obtained light reception signal is analyzed and reproduced as image data.

  In such a hologram recording / reproducing apparatus, a technique called multiple recording is used to improve the recording density. This is different from conventional recording in that a large number of independent pages are recorded in one place.

As representative multiplex recording methods, angle multiplex recording, shift multiplex recording, phase code multiplex recording, and the like are known. In shift multiplexing, multiple recording is performed by gradually shifting the recording position. Angle multiplexing is for recording and reproducing a large number of independent pages in one place by changing the angle of the reference beam. In phase multiplexing, when one page is recorded, reference light is simultaneously applied from various directions, and at that time, a phase change is given to the reference light from each direction. By combining this phase change in various ways, a large number of independent pages are recorded and reproduced in one place. In addition to the above three types, many multiplexing schemes are possible. For example, there is what is called speckle multiplexing (or correlation multiplexing).
IBM J.RES DEVELOP VOL 44 NO.3 MAY 2000 `` Holographic data storage ''

  However, in any of the above-described multiplexing systems, data is read by the reproduction reference beam 200 during reproduction. At that time, as shown in FIGS. 5A, 5B, and 5C, the reference light 200 is reflected by the surface of the hologram recording medium 30 (a cover glass that sandwiches a recording material such as a photopolymer). The incident reflected light 201 enters the lens 46 of the signal light optical system, and is reflected by the signal light optical system and turned back, and may be directed in the same direction as the reproduction light generated in the hologram recording medium 30. This is one of the major reasons for lowering the S / N. 5A shows a case where data recorded by shift multiplexing on the hologram recording medium 30 is reproduced, and FIG. 5B shows a case where data recorded by angle multiplexing on the hologram recording medium 30 is reproduced. (C) shows a case where data recorded on the hologram recording medium 30 by phase code multiplexing is reproduced. In either case, the reflected light 201 on the hologram recording medium 30 is folded back by the lens 46 of the signal light optical system. Accordingly, the light travels in the same direction as the reproduction light, that is, mixed with the reproduction light and travels toward the image pickup device (not shown), which becomes noise during photoelectric conversion and deteriorates the S / N of the reproduction image.

  By the way, data is recorded on the hologram recording medium 30 as a hologram. Since the hologram recording medium 30 is photosensitive, it must be handled in a dark place. Therefore, in reality, there is a high possibility that the disc-shaped hologram recording medium 30 is provided in a light-shielding cartridge, and a cartridge-contained hologram recording medium is used. The same problem occurs.

  The present invention has been devised in view of the above circumstances, and an object of the present invention is to reflect reflected light from a hologram recording medium when the reference light for reproduction is incident on the cartridge-containing hologram recording medium. It is an object of the present invention to provide a cartridge-contained hologram recording medium and a hologram recording / reproducing apparatus that can satisfactorily maintain the S / N of a reproduced image so that the signal light optical system is not incident on the signal light optical system.

  To achieve the above object, the present invention provides a housing, a hologram recording medium that is rotatably housed in the housing and records interference fringes of signal light and reference light, provided on the housing surface, and the signal light. And an opening for allowing the reference light to enter the housing, and shielding means for slidingly covering a part of the opening.

  The present invention also provides a housing, a hologram recording medium that is rotatably housed in the housing and records interference fringes of signal light and reference light, and is provided on the housing surface, the signal light and the reference light. And a shielding means for moving between the opening and the optical system of the signal light to block the optical path.

  The present invention also provides a housing, a hologram recording medium that is rotatably housed in the housing and records interference fringes of signal light and reference light, and is provided on the housing surface, the signal light and the reference light. And an reflecting portion that moves between the opening and the optical system of the signal light to change the optical path.

  The present invention also relates to a hologram recording / reproducing apparatus that records interference fringes of reference light and signal light on a cartridge-housing hologram recording medium and reproduces recorded data by irradiating the cartridge-housing hologram recording medium with the reproducing reference light. And an incident preventing means for preventing the reflected light from the hologram recording medium of the reproduction reference light incident in the housing of the cartridge-containing hologram recording medium from entering the optical system of the signal light. It is characterized by that.

  As described above, according to the present invention, during reproduction, the reflected light from the hologram recording medium that is incident on the housing from the opening of the housing of the cartridge storage hologram recording medium is prevented from entering the signal light optical system. In addition, a part of the opening is blocked by shielding means such as a shutter so that the reflected light is not emitted to the outside, or a shielding means such as a shutter is provided between the opening and the signal light optical system. The reflected light is changed by changing the optical path of the reflected light by positioning the optical path of the reflected light, or by changing the optical path of the reflected light by positioning a reflecting means such as a mirror between the opening and the signal light optical system. It is possible to prevent the incident light from entering the signal light optical system, being folded back and entering the housing from the opening again, and being mixed with the reproduction light. Can. However, the mirror described in this paper includes not only a mirror that reflects normal light but also a smooth and non-diffuse member.

  According to the present invention, at the time of reproduction, the reflected light from the hologram recording medium, which is incident on the housing from the opening of the housing of the cartridge-containing hologram recording medium, is prevented from entering the signal light optical system. A part of the opening is blocked by shielding means such as a shutter so that the reflected light is not emitted to the outside, or a shielding means such as a shutter is positioned between the opening and the signal light optical system. The reference light for reproduction is changed by blocking the optical path of the reflected light or changing the optical path of the reflected light by positioning a reflecting means such as a mirror between the opening and the signal light optical system. Prevents the reflected light of the reference light from the hologram recording medium from being incident on the signal light optical system when it is incident on the cartridge-containing hologram recording medium, so that the S / N of the reproduced image is maintained well. Door can be.

  When the reference light for reproduction is incident on the cartridge-containing hologram recording medium, the reflected light from the hologram recording medium of the reference light is not incident on the signal light optical system, so that the S / N of the reproduced image is well maintained. The purpose of the shutter is to prevent reflected light from the hologram recording medium, which is incident on the housing from the opening of the housing of the cartridge storage hologram recording medium, from entering the signal light optical system during reproduction. A part of the opening is blocked by shielding means such as to prevent the reflected light from being emitted to the outside, or a shielding means such as a shutter is positioned between the opening and the signal light optical system. This is realized by blocking the optical path of the reflected light or changing the optical path of the reflected light by positioning a reflecting means such as a mirror between the opening and the signal light optical system.

  FIG. 1 is a cross-sectional view showing a configuration of a cartridge storage type hologram recording medium according to the first embodiment of the present invention. The cartridge storage type hologram recording medium 10 is configured such that a disk type hologram recording medium (photopolymer or the like) 2 is rotatably stored in a rectangular housing 1. Furthermore, an opening 3 for allowing the reference light 200 and signal light (not shown) to enter the housing 1 is provided in a part of the front surface of the housing 1, and a part of the opening 3 is shielded. The shutter 4 is disposed so as to be slidable along the front surface.

  Next, the operation of the present embodiment will be described. At the time of reproduction, the cartridge-contained hologram recording medium 10 is set in a hologram recording / reproducing apparatus (not shown). At that time, the shutter 4 is slid (position shown) to a position where a part of the opening 3 is shielded. A reference beam 200 for reproduction is incident on the housing 1 from a reference beam optical system (not shown) through a portion where the opening 3 is open, and irradiates the recording area 21 of the hologram recording medium 2. Thereby, the reproduction light 300 generated from the recording area 21 of the hologram recording medium 2 is imaged on the imaging device 49 by the lens 48 of the reproduction light optical system, and an image is reproduced.

  At that time, a part of the reference light 200 is reflected by the surface of the hologram recording medium 2 and the reflected light 201 travels in the direction of the lens 46 of the signal light optical system, but is blocked by the shutter 4 and is not incident on the lens 46. . Since the shutter 4 is coated with a light absorbing material, the reflected light 201 is absorbed by the shutter 4 so that secondary reflection does not occur.

  At the time of recording, the cartridge storage type hologram recording medium 10 is set in a hologram recording / reproducing apparatus (not shown), and at that time, the shutter 4 is slid so as to fully open the opening 3. Signal light enters the housing 1 through the opening 3 and the reference light 200 enters the housing 1 through the opening 3 from a reference light optical system (not shown) through the opening 46, and interference fringes of both lights are generated in the hologram recording medium 2. Are recorded in the recording area 21.

  According to the present embodiment, it is slidable to shield a part of the opening 3 for allowing the signal light and the reference light 200 provided on the front surface of the cartridge-containing hologram recording medium 10 to enter the housing 1. A shutter 4 is provided, and at the time of reproduction, a part of the opening 3 is shielded by the shutter 4 so that the reflected light 201 of the reference light 200 from the hologram recording medium 2 does not enter the lens 46 of the signal light optical system. Since the light 201 can be prevented from being emitted to the outside of the housing 1, the reflected light 201 can be prevented from being reflected by the signal light optical system and mixed with the reproduction light 300, and the S / N of the reproduction image can be improved. Can be held.

  FIG. 2 is a cross-sectional view showing a configuration of a cartridge storage type hologram recording medium according to the second embodiment of the present invention. However, the same parts as those in the first embodiment shown in FIG.

  The cartridge storage type hologram recording medium 11 is configured such that a disk type hologram recording medium 2 is rotatably stored in a rectangular housing 1. Furthermore, an opening 3 for allowing the reference light 200 and signal light (not shown) to enter the housing 1 is provided in a part of the front surface of the housing 1, and a part of the opening 3 and the signal light are provided. A shutter 5 is movably disposed between the lens 46 of the optical system.

  Here, the end portion 51 of the shutter 5 is attached to the front surface of the housing 1 so as to be slidable (perpendicular to the paper surface). It can be inclined and positioned as shown in the figure. Further, when the shutter 5 is slid and moved to a position away from between a part of the opening 3 and the lens 46 of the signal light optical system, the shutter 5 is brought into close contact with the casing surface with the end 51 as the rotation axis. It is possible to fold it by turning it. Of course, the mechanical installation structure of the shutter 5 is not limited to this.

  Next, the operation of the present embodiment will be described. At the time of reproduction, the cartridge storage type hologram recording medium 11 is set in a hologram recording / reproduction device (not shown), and at that time, the shutter 5 is positioned between a part of the opening 3 and the lens 46 of the signal light optical system (solid line in the figure). doing. A reproduction reference beam 200 is incident on the recording area 21 of the hologram recording medium 2 through a reference beam optical system (not shown) through the opening 3 into the housing 1. Thereby, the reproduction light 300 generated from the recording area 21 of the hologram recording medium 2 is imaged on the imaging device 49 by the lens 48 of the reproduction light optical system, and an image is reproduced.

  At that time, a part of the reference light 200 is reflected by the surface of the hologram recording medium 2, and the reflected light 201 travels in the direction of the lens 46 of the signal light optical system, but between the opening 3 and the signal light optical system. It is blocked by a certain shutter 5 and is not incident on the lens 46. Since the shutter 5 is coated with a light absorbing material, the reflected light 201 is absorbed by the shutter 5 so that secondary reflection does not occur.

  At the time of recording, the cartridge-containing hologram recording medium 11 is set in a hologram recording / reproducing apparatus (not shown). At that time, the shutter 5 is folded away from between the opening 3 and the signal light optical system and is in close contact with the housing surface. Signal light enters the housing 1 through the opening 3 and the reference light 200 enters the housing 1 through the opening 3 from a reference light optical system (not shown) through the opening 46, and interference fringes of both lights are generated in the hologram recording medium 2. Are recorded in the recording area 21.

  According to the present embodiment, at the time of reproduction, the reflected light 201 from the hologram recording medium 2 of the reference light 200 is blocked by the shutter 5 so as not to enter the lens 46 of the signal light optical system. There is an effect similar to the embodiment. In particular, since the shutter 5 is inclined and positioned between the opening 3 and the signal light optical system, even when the angle of incidence of the reference light 200 is changed and the angle is reduced as in angle multiplexing, for example, the shutter 5 5 can irradiate the recording area 21 of the hologram recording medium 2 without being obstructed, and the angle change range of the reference light in the angle multiplexing can be increased accordingly, and if the dynamic range has a margin, the multiplicity Can be raised. In FIG. 2, the hatched portion indicates the position of the shutter 5 when the shutter 5 is a type that closes a part of the opening 3 as in the first embodiment, and the front end of the shutter 5 It can be seen that a part of the reference light 200 is blocked, and a part of the reference light 200 cannot enter the housing.

  FIG. 3 is a cross-sectional view showing a configuration of a cartridge storage type hologram recording medium according to the third embodiment of the present invention. However, the same parts as those in the first embodiment will be described with the same reference numerals.

  The cartridge storage type hologram recording medium 12 is configured such that a disk type hologram recording medium 2 is rotatably stored in a rectangular housing 1. Furthermore, an opening 3 for allowing the reference light 200 and signal light (not shown) to enter the housing 1 is provided in a part of the front surface of the housing 1, and a part of the opening 3 and the signal light are provided. A mirror 6 is movably disposed between the lens 46 of the optical system. However, the mirror 6 includes a member that has a smooth surface and does not diffusely reflect, in addition to a so-called mirror that reflects light.

  Here, the end portion 61 of the mirror 6 is slidably attached to the front surface of the housing 1 (perpendicular to the paper surface), and the mirror 6 is slid so that a part of the opening 3 described above and the lens of the signal light optical system. It can be inclined and positioned as shown in the figure. Further, when the mirror 6 is slid and moved to a position deviated from between a part of the opening 3 and the lens 46 of the signal light optical system, the mirror 6 is brought into close contact with the casing surface with the end 61 as the rotation axis. It is possible to fold it by turning it. Of course, the mechanical installation configuration of the mirror 6 is not limited to this.

  Next, the operation of the present embodiment will be described. At the time of reproduction, the cartridge-containing hologram recording medium 12 is set in a hologram recording / reproducing apparatus (not shown), and at that time, the mirror 6 is positioned between a part of the opening 3 and the lens 46 of the signal light optical system (solid line in the figure). doing. The reproduction reference beam 200 enters the housing 1 through the opening 3 from a reference beam optical system (not shown) and irradiates the recording area 21 of the hologram recording medium 2. Thereby, the reproduction light 300 generated from the recording area 21 of the hologram recording medium 2 is imaged on the imaging device 49 by the lens 48 of the reproduction light optical system, and an image is reproduced.

  At that time, a part of the reference light 200 is reflected by the surface of the hologram recording medium 2, and the reflected light 201 travels in the direction of the lens 46 of the signal light optical system, but between the opening 3 and the signal light optical system. Reflected by the reflecting surface of a certain mirror 6, the optical path is changed and the light does not enter the lens 46. At this time, the installation angle of the mirror 6 is such that the reflected light 201 reflected by the mirror 6 does not enter the housing again from the opening 3.

  At the time of recording, the cartridge-containing hologram recording medium 12 is set in a hologram recording / reproducing apparatus (not shown). At that time, the mirror 6 is folded away from between the opening 3 and the signal light optical system and is in close contact with the housing surface. Signal light enters the housing 1 through the opening 3 and the reference light 200 enters the housing 1 through the opening 3 from a reference light optical system (not shown) through the opening 46, and interference fringes of both lights are generated in the hologram recording medium 2. Are recorded in the recording area 21.

  According to the present embodiment, at the time of reproduction, the reflected light 201 of the reference light 200 from the hologram recording medium 12 is reflected by the mirror 6 and its optical path is changed so that it is not incident on the lens 46 of the signal light optical system. Therefore, the same effects as those of the first and second embodiments can be obtained. Particularly, since the mirror 6 is inclined and positioned between the opening 3 and the lens 46 of the signal light optical system, for example, the angle of incidence of the reference light 200 is changed as in angle multiplexing, and the angle is reduced. Even in this case, it is possible to irradiate the recording area 21 of the hologram recording medium 2 without being disturbed by the mirror 6, and accordingly, the angle change range of the reference light in the angle multiplexing can be increased, and the multiplicity can be increased. it can.

  If the inner wall surface of the housing of the hologram recording / reproducing apparatus for setting the cartridge-containing hologram recording medium 12 is painted black, for example, to absorb the light reflected by the mirror 6, the mirror 6 on the inner wall surface of the housing of the apparatus. It is possible to more completely prevent the reflected light 201 from being absorbed and the reflected light 201 from being incident on the cartridge-containing hologram recording medium 12 again.

  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 sectional drawing which showed the structure of the cartridge storage type hologram recording medium based on the 1st Embodiment of this invention. It is sectional drawing which showed the structure of the cartridge storage type hologram recording medium based on the 2nd Embodiment of this invention. It is sectional drawing which showed the structure of the cartridge storage type hologram recording medium based on the 3rd Embodiment of this invention. It is the schematic which showed the structural example of the conventional hologram recording / reproducing apparatus. It is a figure explaining the behavior of the reflected light from the hologram recording medium of the reference light for reproduction | regeneration.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Hologram recording medium, 3 ... Opening, 4, 5 ... Shutter, 6 ... Mirror, 10, 11, 12 ... Cartridge accommodation type hologram recording medium, 21 ... Recording area , 46, 48... Lens, 49... Imaging device, 51, 61.

Claims (10)

A housing,
A hologram recording medium that is rotatably housed in the housing and records interference fringes of signal light and reference light;
An opening provided on the housing surface for allowing the signal light and the reference light to enter the housing;
Shielding means for slidingly covering a part of the opening;
A cartridge-containing holographic recording medium comprising:   The shielding means is a shutter that is slidably attached to the surface of the casing. During reproduction, reflected light from the hologram recording medium of the reference light that enters the casing from the opening is optical of the signal light. 2. The cartridge-containing holographic recording medium according to claim 1, wherein a part of the opening is shielded so as not to enter the system. A housing,
A hologram recording medium that is rotatably housed in the housing and records interference fringes of signal light and reference light;
An opening provided on the housing surface for allowing the signal light and the reference light to enter the housing;
Shielding means for moving between the opening and the optical system of the signal light to block the optical path;
A cartridge-containing holographic recording medium comprising:   The shielding means is a shutter that is slidably attached at one end in a state inclined to the casing surface, and reflects the reference light incident on the casing from the opening during reproduction from the hologram recording medium. 4. The cartridge-containing holographic recording medium according to claim 3, wherein the optical path is blocked so that light does not enter the optical system of the signal light. A housing,
A hologram recording medium that is rotatably housed in the housing and records interference fringes of signal light and reference light;
An opening provided on the housing surface for allowing the signal light and the reference light to enter the housing;
Reflecting means that moves between the opening and the optical system of the signal light to change the optical path;
A cartridge-containing holographic recording medium comprising:   The reflecting means is a mirror that is slidably attached at one end in a state inclined to the housing surface, and at the time of reproduction, the reference light from the hologram recording medium that enters the housing through the opening is reproduced. 6. The cartridge-contained hologram recording medium according to claim 5, wherein reflected light is reflected so as not to enter the optical system of the signal light. A hologram recording / reproducing apparatus that records interference fringes of reference light and signal light on a cartridge-housing hologram recording medium and irradiates the cartridge-housing hologram recording medium with reproducing light to reproduce recorded data,
An incident preventing means for preventing reflected light from the hologram recording medium, which is incident on the housing of the cartridge-containing hologram recording medium, from entering the optical system of the signal light is provided. Hologram recording / reproducing apparatus.   8. The hologram recording / reproducing apparatus according to claim 7, wherein the incident preventing means is a shutter that slides and covers a part of an opening for allowing the signal light and the reference light to enter the housing.   The said incident prevention means is a shutter which moves between the opening part for making the said signal light and the said reference light enter in a housing | casing, and the said signal light optical system, and interrupts | blocks an optical path. 8. The hologram recording / reproducing apparatus according to 7.   The said incident prevention means is a mirror which moves between the opening part for making the said signal light and the said reference light enter in a housing | casing, and the said signal light optical system, and changes an optical path. 8. The hologram recording / reproducing apparatus according to 7.

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