JP2006350258A - Hologram device and hologram recording/reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a reproduced image having quality capable of extracting recording information by recording and reproducing a hologram recording medium at the same temperature while suppressing variation in refractive index of an optical path. <P>SOLUTION: A system control section 14 heats or cools an area different from a recording area or reproduction area of the hologram recording medium 50 by a heating and cooling device 11 to hold the recording area or reproduction area at the same temperature (specified temperature). Consequently, shrinkage and expansion of the hologram recording medium 50 are suppressed to avoid deterioration of the reproduced image or a failure in reproduction. At this time, the area different from the recording area or reproduction area is heated or cooled, so the temperature of air nearby the recording area or reproduction area is not varied so much and then the variation in refractive index of an optical path of signal light 100 and/or reference light 200 can be suppressed, so that information can be recorded or reproduced normally. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hologram apparatus and a hologram recording / reproducing method for recording / reproducing interference fringes of signal light and reference light on a hologram recording medium, and more particularly to temperature management of the hologram recording medium.

  Conventionally, at the time of recording in a hologram data storage, a hologram recording medium is arranged in an area where two light beams of signal light and reference light interfere, and the interference fringes of the two light beams are recorded on the hologram recording medium. At that time, in order to improve the recording density on the hologram recording medium, multiplex recording of holograms by various multiplexing methods such as an angle multiplexing method, a shift multiplexing method, a speckle multiplexing method, and a phase code multiplexing method is performed. .

  For example, in a hologram recording apparatus using an angle multiplexing method, two light beams of signal light and reference light are irradiated onto a hologram recording medium, but the signal light is spatially modulated (intensity modulated) with a data page displayed on a spatial modulator (SLM). Each time, the incident angle (recording angle) of the reference light to the hologram recording medium is changed, and different recording information is multiplexed and recorded in the same recording area.

  In this angle multiplexing type hologram recording apparatus, the change pitch of the recording angle of the reference beam is changed within a range of a maximum of several degrees, for example, in increments of about 0.01 degrees (for example, slightly changed between 88 degrees and 92 degrees). Thus, when different recording information (data pages) in the same recording area are sequentially multiplexed and recorded, a plurality of different recording information such as 50 multiplexing can be recorded in the same recording area. On the other hand, a hologram reproducing apparatus paired with such a hologram recording apparatus reproduces recorded information multiplexedly recorded in the same recording area by gradually changing the angle of the surface of the hologram recording medium with respect to the reproduction reference light. It is configured.

  Here, as one of the major issues for making the hologram recording device and the reproducing device feasible, the hologram recording device records the interference fringes of the hologram, but there is a difference in temperature during recording and reproduction. If there is, there is a problem that the interval between the interference fringes changes due to thermal expansion and contraction of the hologram recording medium, and a reproduced image cannot be obtained. In addition, the hologram recording medium itself tends to shrink to some extent during recording regardless of the temperature difference between recording and reproduction. Therefore, development is underway to suppress shrinkage as a material development issue, but it is currently difficult to completely suppress shrinkage, and there is a problem that a reproduced image cannot be obtained as with temperature change. To do.

  When there is no temperature difference between recording and reproduction of the hologram recording medium, a reproduced image from which the recorded information can be extracted as shown in FIG. 4 is obtained. However, when there is a temperature difference or the recording medium is greatly contracted, FIG. Therefore, it is difficult to extract recording information from such a reproduced image.

Therefore, in order to avoid the above problems, it is known to provide a means for heating the hologram recording medium, and to perform recording and reproduction by using the heating means so that the temperature of the hologram recording medium is the same during recording and during reproduction. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 7-261642 (page 3, FIG. 1)

  However, if the hologram recording medium is heated to make the temperature of the hologram recording medium the same during recording and reproduction, and the recording medium is heated and recorded and reproduced in the same part, this hologram is simultaneously formed with the heating of the hologram recording medium. Since the temperature of the air in the vicinity of the recording / reproducing portion of the recording medium rises, the refractive index changes of the signal light and the reference light optical path occur, causing a problem that recording and reproduction are not performed well due to the fluctuation of the optical path. In order to avoid this, the temperature of the entire block in the apparatus in which the hologram recording medium and the optical system are stored may be the same during recording and during reproduction, but this requires time until the temperature is kept constant. As a result, there is a problem that the start-up of the apparatus is deteriorated and that the temperature is kept constant so that more power is required and energy is not saved.

  The present invention has been devised in view of the above circumstances, and the object of the present invention is to suppress the change in the refractive index of the optical path and make the temperature of the hologram recording medium the same at the time of recording and at the time of recording. It is an object of the present invention to provide a hologram recording / reproducing method capable of obtaining a reproduced image having extractable quality and a hologram apparatus using this method.

  In order to achieve the above object, the present invention provides a hologram apparatus for recording interference fringes of signal light and reference light as information on a hologram recording medium, which is a part of the hologram recording medium and different from the information recording area And a temperature adjusting means for changing the temperature of the recording area to bring the recording area to a predetermined temperature.

  In general, an optical recording medium uses a moving means to change a recording / reproducing part by being continuous, moving or stopped. In this case, the heating part and the recording part are always moving. Using the temperature detection means, the output to the moving means is taken into account so that the temperature of the recording or reproducing part becomes desired, and the output to the temperature adjusting means is controlled.

  The present invention also provides a hologram apparatus for obtaining reproduction information by irradiating a reproduction area of a hologram recording medium with reference light, and changing a temperature of a part of the hologram recording medium that is different from the reproduction area. A temperature adjusting means for setting the regeneration area to a predetermined temperature is provided.

  The present invention also provides a hologram apparatus for obtaining reproduction information by irradiating a reproduction area of a hologram recording medium with reference light, and changing a temperature of a part of the hologram recording medium that is different from the reproduction area. Temperature adjustment means for setting the reproduction area to a predetermined temperature, and a degree of change from the normal size of the hologram recording medium is detected from the reproduction information, and the hologram recording medium is corrected to a normal size or a size close to the detection result from the detection result. Temperature estimation means for estimating the temperature of the regeneration area for setting, wherein the temperature adjustment means sets the predetermined temperature to the estimated temperature and changes the temperature of the different area. .

  Thus, according to the present invention, when the recording medium is moved or moved to a place where recording or reproduction is performed by heating or cooling an area different from the recording area or reproduction area of the hologram recording medium, the same recording area or reproduction area is used. By setting the temperature (predetermined temperature), it is possible to suppress the shrinkage and expansion of the hologram recording medium, to avoid the deterioration or inability to reproduce the reproduction image due to the shrinkage and expansion, and to produce a reproduction image having a quality capable of extracting recorded information. Obtainable. At that time, since the area different from the recording area or the reproduction area is heated or cooled, it is not necessary to change the temperature of the air in the vicinity of the recording area or the reproduction area. Can be suppressed, and information can be recorded and reproduced normally.

  At the time of reproduction, the degree of shrinkage and expansion of the hologram recording medium is detected from the reproduced image information, and the temperature for correcting the shrinkage and expansion of the hologram recording medium is estimated from the detection result. By heating or cooling an area different from the recording area or the reproduction area of the hologram recording medium so that the estimated temperature is reached, the desired temperature is controlled so that the desired temperature is reached when the desired recording area is moved to the reproduction position. The temperature difference during recording of the hologram recording medium and the shrinkage and expansion of the hologram recording medium due to information recording can be corrected in a lump. In this case, a reproduced image without deterioration can be obtained without being aware of the temperature at the time of recording on the hologram recording medium.

According to the present invention, a region different from the recording region or the reproduction region of the hologram recording medium is heated or cooled, and the recording region or the reproduction region is set to the same temperature (predetermined temperature). Therefore, it is possible to obtain a reproduced image having a quality capable of extracting recorded information. Thereby, there is no reproduction failure due to a difference in temperature during hologram recording and reproduction, and the hologram recording / reproducing apparatus can be put into practical use.
At the time of reproduction, the degree of shrinkage and expansion of the hologram recording medium is detected from the reproduced image information, and the temperature for correcting the shrinkage and expansion of the hologram recording medium is estimated from the detection result. By heating or cooling an area different from the recording area or reproducing area of the hologram recording medium so as to reach the estimated temperature, the temperature difference during recording of the hologram recording medium and the shrinkage and expansion of the hologram recording medium due to information recording are collectively performed. In addition to correction, it is possible to obtain a reproduced image without deterioration without being aware of the temperature at the time of recording on the hologram recording medium.

  The purpose of obtaining a reproduced image with a quality capable of extracting recorded information by suppressing the refractive index change of the optical path and making the temperature of the hologram recording medium the same at the time of recording and reproducing is the recording area or reproducing area of the hologram recording medium. The quality of the recorded information can be extracted by suppressing the shrinkage and expansion of the hologram recording medium by heating or cooling the area different from the recording area and keeping the recording area or reproduction area at the same temperature (predetermined temperature). An image can be obtained.

  FIG. 1 is a block diagram showing a configuration of a hologram apparatus according to an embodiment of the present invention. The hologram apparatus includes a laser light source 1, a polarization beam splitter (PBS) 2 that branches the laser light, a spatial modulator (SLM) 3 that spatially modulates signal light, a mirror 4 that changes the path of the signal light 100, and a signal light optical system. Lens 5, rotating mirror 6 for changing the incident angle of reference light 200 to hologram recording medium 50, mirror rotating mechanism 7 for rotating rotating mirror 6, lens 8 for reference light optical system, lens 9 for reproducing light optical system, An imaging device 10 that photoelectrically converts reproduction light to obtain reproduction data, a heating / cooling device 11 that uses a Peltier element that heats and cools a part of the hologram recording medium 50, and an infrared that measures the temperature of a specific portion of the hologram recording medium 50 The temperature sensor 12, the disk rotation mechanism 13 that rotates the disk-shaped hologram recording medium 50 and changes its position, the spatial modulator 3, the mirror rotation Mechanism 7, the disc rotating mechanism 13, the control and the temperature sensor 12 of the heating and cooling device 11, the data processing of the image pickup apparatus 10 is configured with a system control unit 14 for controlling the whole variety of control and apparatus.

  Next, the operation of this embodiment will be described. The laser light emitted from the laser light source 1 is branched into the signal light 100 and the reference light 200 by the PBS 2. The signal light 100 is spatially modulated by passing through the spatial modulator 3 on which the data page is displayed. The modulated signal light 100 is changed in its path by the fixed mirror 4, and then the lens 5 is used for the hologram recording medium 50. Focused on the recording area. On the other hand, the path of the reference beam 200 is changed by the rotating mirror 6, and the recording area of the hologram recording medium 50 is irradiated by the lens 8. At that time, along with the change of the data page of the spatial modulator 3, the angle of the rotating mirror 6 is changed little by little by the mirror rotating mechanism 7, thereby changing the incident angle of the reference beam 200 to the hologram recording medium 50 and the data in the book. Multiple records are recorded. Thus, when the multiple recording of one book is completed, the hologram recording medium 50 is rotated by the disk rotation mechanism 13 so that the signal light 100 and the reference light 200 are irradiated to a new recording area, and a new book is created. It is formed. At the time of reproduction, the SLM 3 is fully closed to irradiate only the reference light 200 to the reproduction area of the hologram recording medium 50 to generate reproduction light, which is imaged on the image pickup device 10 by the lens 9 to form a reproduction image. Thus, the reproduced image data can be obtained by processing the reproduced image.

By the way, the recording area or the reproducing area of the hologram recording medium 50 of the present embodiment is maintained at a predetermined temperature during the recording and reproducing described above. That is, the temperature sensor 12 detects the temperature of the recording area 141 a of the hologram recording medium 50 shown in FIG. 2 and sends it to the system control unit 14. The system control unit 14 controls the heating / cooling device 11 to heat or cool the heating / cooling area 141b away from the recording area 141a so that the temperature becomes a predetermined temperature. In this case, the heating / cooling region 141b comes to a recording region 141a (which is a reproduction region at the time of reproduction, but both are referred to as recording regions here) 141a as the disc-shaped hologram recording medium 50 rotates. In the meantime, the temperature changes to cause a temperature difference. Taking this into account, control is performed so that the temperature of the recording area 141a becomes a predetermined temperature. That is, the heating / cooling area 141b is a part to be recorded from now on, and when this moves by the rotation of the disk-shaped hologram recording medium 50 and arrives at the recording place, it becomes the recording area 141a.
The reason why the distance from the heating / cooling area 141b closest to the heating / cooling apparatus 11 to the recording area 141a is that the recording area 141a is directly warmed by the heating / cooling apparatus 11 or the entire hologram recording medium 50 is used. Is to warm the air in the vicinity of the recording area 141a, thereby causing a change in refractive index and fluctuation in the optical path of the signal light and the reference light, thereby preventing this. The system control unit 14 does not perform recording or reproduction until the recording area 141a reaches a predetermined temperature, and stops the recording or reproduction operation when the recording area 141a deviates from the predetermined temperature.

  The temperature difference between the recording area 141a and the heating / cooling area 141b depends on the rotational speed, rotational speed, etc. of the hologram recording medium 50. Therefore, the system control unit 14 calculates a time constant using these parameters, and finally determines the temperature of the heating / cooling region 141b. Further, the system control unit 14 does not perform recording / reproduction when the recording area 141a measured by the temperature sensor 12 is outside a predetermined temperature range set in advance.

  According to the present embodiment, the heating / cooling portion 141b of the hologram recording medium 50 by the heating / cooling device 11 is different from the recording area 141a, and there is a distance corresponding to a half circumference of the hologram recording medium 50 between them. The temperature of the region 141a can be set to a predetermined temperature without warming the air in the vicinity so much. Therefore, refractive index changes and fluctuations in the optical paths of the signal light 100 and the reference light 200 (refractive index changes and fluctuations in the optical path of the reference light at the time of reproduction) can be suppressed to the extent that there is no practical problem. Can be recorded and reproduced normally. At the same time, since there is no temperature difference between the hologram recording medium 50 at the time of recording and at the time of reproduction, the degree of shrinkage and expansion of the hologram recording medium 50 can be extremely reduced. No data can be played back normally.

  In addition, since a part of the hologram recording medium 50 is heated and cooled, less power is required for heating and cooling, energy is saved, and it takes time to set the recording area 141a to a predetermined temperature. Therefore, the start-up of the device can be made faster.

  At the time of reproduction, the system control unit 14 contracts and expands the hologram recording medium 50 from the state of the reproduced image (interference fringe interval) obtained from the imaging device 10 (this occurs due to data recording, so the temperature during recording and reproduction). The hologram recording medium is detected by setting the temperature of the recording area 141a at the time of reproduction different from that at the time of recording so as to correct the contraction and expansion. The contraction / expansion due to the recording of 50 data can be corrected to some extent, and a higher quality reproduced image can be obtained. In this case, even if the temperature of the hologram recording medium 50 at the time of recording is not dared to be controlled, a change in the interference fringe interval is detected from the state of the reproduced image, and a temperature for correcting the change is obtained. If the recording area is set to the determined temperature by controlling the heating / cooling device 11, hologram recording is caused by both shrinkage and expansion due to the temperature difference of the hologram recording medium 50 during recording and during reproduction, and further due to both shrinkage and expansion due to data recording. The influence of the interference fringe deformation due to the change in the size of the medium 50 can be eliminated. Therefore, a normal and high-quality reproduced image can be obtained only by managing the temperature of the hologram recording medium 50 only during reproduction without being conscious of the temperature of the hologram recording medium 50 during recording. Further, when recording and reproduction are separate apparatuses, there is an advantage that the recording side apparatus does not need to be equipped with this temperature management function.

  In addition, the present invention is not limited to the above-described embodiment, and can be implemented in various other forms in specific configurations, functions, operations, and effects without departing from the gist thereof. For example, in the above embodiment, the heating / cooling device 11 is heated and cooled close to the heating / cooling region 141b. However, as shown in FIG. 3, the heating / cooling heat exchanger 150 sets the air 153 to a predetermined temperature, and this air May be sprayed to the heating / cooling region 141b through the pipe 151 to change the temperature of this portion. In this case, if there is a space in the pipe 151 for blowing air, a predetermined portion of the hologram recording medium 50 can be heated or cooled, and the space property can be maintained well. Furthermore, in this case, energy can be effectively used by sending heat from components such as the laser light source 1 and the galvano scanner mirror and the circuit board to the heating / cooling heat exchanger 150 using a heat pipe or the like. Further, it is also possible to adopt a configuration in which heat generated from a component or a circuit board is directly sent to a predetermined portion of the hologram recording medium 50 by a heat pipe or the like to heat this portion. Furthermore, the present invention can be applied to various hologram recording / reproducing systems and obtain the same effect regardless of the difference in multiplexing systems.

It is the block diagram which showed the structure of the hologram apparatus which concerns on one Embodiment of this invention. It is the figure which showed the positional relationship of the heating / cooling area | region on a hologram recording medium shown in FIG. 1, and a recording area. It is the figure which showed the other means to heat the heating area | region of the hologram recording medium shown in FIG. It is the figure which showed the example of a reproduced image when there is no temperature difference at the time of recording and reproduction | regeneration of a hologram recording medium. FIG. 4 is a diagram showing an example of a reproduced image when there is a temperature difference between recording and reproduction of the hologram recording medium and the recording medium is greatly contracted.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Laser light source, 2 ... Polarizing beam splitter (PBS), 3 ... Spatial modulator, 4 ... Mirror, 5 ... Signal optical system lens, 6 ... Rotating mirror, 7 ... Mirror rotating mechanism , 8... Reference light optical system lens, 9... Reproducing light optical system lens, 10... Imaging device, 11... Heating and cooling device, 12. ... system control unit, 50 ... hologram recording medium, 150 ... heating / cooling heat exchanger, 151 ... pipe.

Claims (12)

A hologram apparatus that records interference fringes between signal light and reference light as information on a hologram recording medium,
A temperature adjusting means for changing the temperature of a part of the hologram recording medium and a region different from the information recording region to bring the recording region to a predetermined temperature when a recording portion reaches a recording location; To
A hologram apparatus characterized by that.   2. The hologram apparatus according to claim 1, wherein the information is recorded only while the recording area is at the predetermined temperature. A hologram apparatus for obtaining reproduction information by irradiating a reproduction area of a hologram recording medium with reference light,
A temperature adjusting means for changing the temperature of a part of the hologram recording medium and a region different from the reproduction region to bring the reproduction region to a predetermined temperature when a recording portion reaches a recording location;
A hologram apparatus characterized by that.   4. The hologram apparatus according to claim 3, wherein the information is reproduced only while the reproduction area is at the predetermined temperature. The temperature adjusting means is a heating means for heating the areas in proximity to the different areas,
Temperature detecting means for detecting the temperature of the recording area;
Control means for controlling the output of the heating means so that the recording area becomes a predetermined temperature based on the detected temperature, and a desired temperature when the recording medium reaches a recording place. A moving means for moving and a control means for giving a movement command therefor;
The hologram apparatus according to claim 1, further comprising:   6. The hologram apparatus according to claim 5, wherein the heating means forms a heat source for the heating using a heat generating component or a circuit board constituting the apparatus. The temperature adjusting means is a cooling means for cooling the area in proximity to the different areas;
Temperature detecting means for detecting the temperature of the recording area;
Based on the detected temperature, a control means for controlling the output of the cooling means so that the recording area becomes a predetermined temperature, and a desired temperature when the recording medium reaches a place where recording is performed. A moving means for moving and a control means for giving a movement command therefor;
The hologram apparatus according to claim 1, further comprising: The temperature adjusting means is a heating / cooling means for heating or cooling this area in the vicinity of the different area;
Temperature detecting means for detecting the temperature of the recording area;
Based on the detected temperature, a control means for controlling the output of the heating / cooling means so that the recording area becomes a predetermined temperature, and a desired temperature when the recording medium reaches a place for recording. A moving means for moving to the control means, a control means for giving a movement command therefor,
The hologram apparatus according to claim 1, further comprising: A hologram apparatus for obtaining reproduction information by irradiating a reproduction area of a hologram recording medium with reference light,
Temperature adjusting means for changing the temperature of a part of the hologram recording medium and an area different from the reproduction area to bring the reproduction area to a predetermined temperature;
A temperature estimation for detecting the degree of change from the normal size of the hologram recording medium from the reproduction information and estimating the temperature of the reproduction area for correcting the hologram recording medium to a normal size or a size close to the normal size from the detection result Comprising means,
The hologram apparatus according to claim 1, wherein the temperature adjusting unit sets the predetermined temperature to the estimated temperature and changes the temperature of the different region. The temperature adjusting means is a heating / cooling means for heating or cooling the areas in proximity to the different areas,
Temperature detecting means for detecting the temperature of the recording area;
Control means for controlling the output of the heating / cooling means so that the recording area reaches a predetermined temperature based on the detected temperature;
The hologram apparatus according to claim 9, further comprising: A hologram recording method for recording interference fringes of signal light and reference light on a hologram recording medium as information,
A hologram recording method, wherein the information is recorded after the temperature of a region different from the information recording region is changed to a predetermined temperature by changing a temperature of a part of the hologram recording medium. A hologram reproduction method for obtaining reproduction information by irradiating a reproduction area of a hologram recording medium with reference light,
A hologram reproducing method, wherein the information is reproduced after changing the temperature of a part of the hologram recording medium that is different from the reproduction area to bring the reproduction area to a predetermined temperature.

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