JP2005331758A - Hologram duplication method, hologram, and optical pickup device and optical disk apparatus using the hologram - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hologram duplication method for duplicating a plurality of hologram regions having different diffraction effects adjacent to one another even when a gap is present between the holograms in the duplication of holograms using a hologram original plate. <P>SOLUTION: A hologram 18 having at least two hologram regions having different diffraction effects from each other and generating the diffracted beams intersecting with each other for a light beam at any wavelengths is duplicated by allowing the diffracted light 4, 7 and the transmitted light 1 by a hologram original plate 17 to interfere with each other in a photosensitive material 11, wherein the hologram original plate 17 has a plurality of hologram regions 3, 6 respectively corresponding to the plurality of hologram regions in the hologram 18. A plurality of hologram regions having different diffraction effects are duplicated adjacent to each other by forming a gap 16 between the plurality of hologram regions 3, 6 in the hologram original plate 17 and by placing the photosensitive material 11 in the position where the diffracted light beams 4, 7 by the respective regions are in the proximity to each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hologram duplication method, a hologram produced by using the duplication method, and an optical pickup device and an optical disc device. More specifically, the present invention relates to a hologram duplication method using a hologram master and a hologram duplicated by the duplication method. And an optical pickup device that includes the hologram, irradiates light onto a recording surface of an information recording medium, and receives reflected light from the recording surface, and an optical disk device including the optical pickup device.

  2. Description of the Related Art Conventionally, various optical pickup devices in an optical disk device have been proposed that include an optical system that branches reflected light from an optical disk, which is an information recording medium, by a hologram and receives light by a photodetector. 1 using a polarization hologram as shown in FIG. FIG. 18 is a schematic configuration diagram of an optical system of the optical pickup device, and FIG. 19 is a schematic cross-sectional view of a main part of a polarization hologram used in the optical pickup device.

As shown in FIG. 18, the optical pickup device includes a semiconductor laser 41 as a light source, a polarization hologram 42, a coupling lens 43, a quarter wavelength plate 44, an objective lens 45, and a photodetector 47. Reference numeral 46 denotes an optical disk as an information recording medium.
Here, the operation of the optical system will be described. The linearly polarized divergent light emitted from the semiconductor laser 41 is transmitted through the polarization hologram 42, converted into substantially parallel light by the coupling lens 43, passes through the quarter wavelength plate 44, and becomes circularly polarized light, and enters the objective lens 45. Then, it is condensed as a minute spot on the recording surface of the optical disk 46. Information is recorded, reproduced, or erased by this spot. The light reflected from the optical disk 46 becomes circularly polarized light opposite to that of the illumination system, is made substantially parallel light again by the objective lens 45, passes through the quarter wavelength plate 44, and becomes linearly polarized light orthogonal to the illumination system, The light is converged by the coupling lens 43, divided and diffracted into a plurality of optical paths by the polarization hologram 42, and reaches the photodetector 47. An information signal and a servo signal are detected from the photodetector 47.

  In the polarization hologram 42, as shown in FIG. 19, an optically anisotropic material 50 having a rectangular concavo-convex shape is disposed on a transparent substrate 51, and an isotropic material 49 is filled in the concave portion. It has a covered configuration. By setting the refractive index of the isotropic material 49 to a refractive index equal to the ordinary light refractive index or the extraordinary light refractive index of the optical anisotropic material 50, a hologram exhibiting polarization can be obtained. That is, it is possible to provide characteristics such that the polarized light in a certain direction is almost totally transmitted and the polarized light orthogonal to the polarized light in a certain direction is almost completely diffracted.

  Accordingly, in the optical pickup device having the configuration shown in FIG. 19, by setting the polarization direction of the light beam emitted from the semiconductor laser 41 to be the polarization direction almost totally transmitted in the polarization hologram, both the illumination system and the detection system are high. An efficient optical pickup device can be realized. At this time, the efficiency of the polarization hologram is approximately 100% transmittance in the illumination system, and in the detection system, an optical pickup device in which only the + 1st order light out of the diffracted light by the polarization hologram 42 is received by the photodetector 47. In the case of this configuration, the diffraction efficiency is about 40%.

Conventionally, diffraction efficiency of about 40% has been sufficient, but when realizing high-speed access (particularly during reproduction) to an information recording medium in an optical disk device, or in the blue wavelength band that has been developed recently. When realizing an optical disc apparatus for accessing a large-capacity optical disc such as a blue-ray disc (for example, DVD + Blue) or an HD-DVD using a semiconductor laser as a light source, the S / N of the light detection signal is secured. For this purpose, a diffraction efficiency exceeding 40% is required.
Further, in order to realize the hologram unit 52 in which the light source 41, the photodetector 47, and the polarization hologram 42 in FIG. 18 are integrated as shown in FIG. 20 for an optical system using a semiconductor laser of the blue wavelength band as a light source. In the grating pitch of the polarization hologram, a narrow pitch on the order of 1 μm is required.

  As described above, a polarization hologram with a narrow pitch and high diffraction efficiency is difficult to realize with the rectangular grating shown in FIG. 19 due to the limit of diffraction efficiency and the difficulty in processing. In addition, a blazed grating, which has been conventionally known as a method for improving the + 1st order diffraction efficiency on one side, can achieve a high diffraction efficiency of 80 to 90%, but a narrow pitch is difficult in processing. High and difficult to implement.

Japanese Patent No. 2594548 JP-A-6-230377

  As a polarization hologram that solves the above-mentioned problems, the present applicant firstly emitted divergent light emitted from a position equivalent to the light emitting point of the light source in the optical pickup device and emitted from a position equivalent to the light receiving point corresponding to each photodetector. Two-beam interference exposure that exposes the interference fringes due to the diverging light to the photosensitive material, or converging light that converges to a position equivalent to the light emitting point of the light source, and condensing to a position equivalent to the light receiving point corresponding to each photodetector Japanese Patent Application No. 2003-120141 proposes a polarization hologram formed by two-beam interference exposure in which a photosensitive material is exposed to interference fringes caused by convergent light. Since this polarization hologram is a hologram optimized for the two light fluxes corresponding to the reflected light beam from the optical disk and the diffracted light to the photodetector, it was replaced with the polarization hologram 42 in the optical pickup device shown in FIG. In this case, a diffraction efficiency of about 100% can be expected in theory, which greatly exceeds 40%. Further, there is no problem in narrowing the pitch because physical processing for forming the uneven portion is unnecessary.

  In the above prior application, in addition to the hologram production method as described above, a hologram replication method for exposing a photosensitive material to interference fringes due to diffracted light and transmitted light by a hologram master has been proposed as a hologram replication method. Patent Document 2 also describes a hologram replication method using a hologram master in a micro-hologram array for a liquid crystal display device, although not for an optical pickup device. According to the hologram duplicating method using such a hologram master, holograms can be mass-produced and the cost of the hologram can be reduced.

However, the hologram master, the photosensitive material, and the resulting duplicate hologram are preferably sandwiched between transparent substrates in consideration of environmental resistance and the like, and it is very difficult to expose the hologram master and the photosensitive material completely in contact with each other. . The hologram replication using the hologram master in this case will be described with reference to FIG.
In FIG. 21, a hologram area 62 and a photosensitive material 63 are sandwiched between transparent substrates 64, 65 and 66, 67, respectively, to constitute a hologram master 69 and a duplicate hologram 70. These transparent substrates are not always necessary, and the problems described below occur when at least the transparent substrate 65 or the transparent substrate 66 is present.

  The hologram master 69 receives light corresponding to the two photodetectors in the optical pickup device when the converging light 53 collected by the condenser lens 61 is incident on the position 54 equivalent to the light emitting point of the light source in the optical pickup device. Two hologram regions 55 and 58 having different diffractive actions are generated so that convergent lights 56 and 59 that are condensed at positions equivalent to the points 57 and 60, respectively, are generated as diffracted light. The convergent lights 56 and 59 cross each other due to the positional relationship between the two photodetectors in the optical pickup device. Reference numeral 61 denotes a condensing lens for coupling to the convergent light 53.

  When the hologram is duplicated by causing the convergent light 56 and convergent light 59 as diffracted light by the hologram master 69 as described above to interfere with the convergent light 53 as transmitted light in the photosensitive material 63, as shown in FIG. A region 68 where diffracted light overlaps occurs in the photosensitive material 63. As a result, when the converging light 53 focused on the position 54 equivalent to the light emission point of the light source in the optical pickup device is incident on the duplicate hologram 70, the light receiving points 57, corresponding to the two photodetectors in the optical pickup device. In addition to the two hologram regions having different diffraction effects, the convergent beams 56 and 59 that are condensed to positions equivalent to 60 are generated as diffracted light, and the multiple exposure is performed so that a desired diffraction effect cannot be obtained between these regions. A region is created. When such a hologram is used in an optical pickup device as described above, there is a concern that the light utilization efficiency of the detection system is reduced or flare light is generated.

The present invention has been made in view of the above circumstances, and a first object of the invention is to reproduce a plurality of holograms each having a different diffraction action even when a gap exists between both holograms in hologram replication using a hologram master. It is an object of the present invention to provide a hologram duplicating method capable of duplicating so that regions are substantially in contact with each other.
In addition, a second object of the present invention is to provide an inexpensive hologram with high diffraction efficiency, which is produced by the above-described hologram duplication method and has a plurality of hologram regions each having a different diffractive action and substantially in contact with each other. is there.
A third object of the present invention is to provide an optical pickup device with high light utilization efficiency that does not cause a decrease in light utilization efficiency near the boundary of a plurality of hologram regions possessed by a hologram and does not cause the occurrence of flare light.
A fourth object of the present invention is to provide an optical disc apparatus that can stably access at a high speed by using an optical pickup device with high light utilization efficiency.

In order to solve the above-described problems, the present invention adopts the following means.
According to a first means of the present invention, a hologram having at least two hologram regions each having a different diffractive action and intersecting diffracted light with respect to a light beam having an arbitrary wavelength is divided into a plurality of hologram regions respectively corresponding to the plurality of hologram regions. A hologram duplicating method in which diffracted light and transmitted light from a hologram master having a hologram region interfere with each other in a photosensitive material for duplication, wherein a gap is provided between a plurality of hologram regions in the hologram master, and the diffracted light by each region is mutually The light-sensitive material is disposed at a position where it is substantially in contact (claim 1).
According to this, in the hologram replication using the hologram master, even when there is a gap between both holograms, the hologram can be replicated so that a plurality of hologram regions each having a different diffraction action are substantially in contact with each other.

According to a second means of the present invention, in the hologram duplicating method of the first means, the hologram master transmits the intensity of transmitted light by the hologram master that causes interference in the photosensitive material between a plurality of hologram regions in the hologram master. Means for making the region including the gap not provided with the hologram and the region provided with the hologram substantially equal to each other (claim 2).
In this case, the intensity of the transmitted light that interferes with the diffracted light by the hologram master in the photosensitive material can be made uniform over the entire surface, so that there is no unevenness in the replicated hologram.

According to a third means of the present invention, in the hologram duplicating method according to the first or second means, the hologram master comprises a computer generated hologram (claim 3).
In this case, it is easy to freely set a plurality of hologram areas in the hologram master.

According to a fourth means of the present invention, in the hologram duplicating method of the first or second means, the hologram master is a volume phase type hologram produced by causing interference between the diffracted light and the light beam corresponding to the transmitted light. It is characterized by.
In this case, the intensity ratio between the diffracted light and the transmitted light generated from the hologram master can be adjusted by the exposure conditions, material, thickness, etc. at the time of preparing the hologram master, and the exposure conditions at the time of hologram replication can be set.

According to a fifth means of the present invention, in the hologram duplication method of the first or second means, the hologram original plate is produced by causing a computer generated hologram or a diffracted light and a light beam corresponding to the transmitted light to interfere with each other. It is characterized by comprising a hologram duplicated by a hologram master comprising a type hologram.
In this case, it is easy to freely set a plurality of hologram areas in the hologram master, and the intensity ratio between the diffracted light and transmitted light generated from the hologram master is adjusted by the exposure conditions, material, thickness, etc. at the time of hologram master preparation. In addition, it is possible to set exposure conditions at the time of hologram duplication.

A sixth means of the present invention is a hologram having at least two hologram regions each having a different diffracting action with respect to a light beam having an arbitrary wavelength and intersecting with the diffracted light. It is produced by the hologram duplicating method of one means (claim 6).
According to this, it is possible to realize an inexpensive hologram with high diffraction efficiency having a plurality of hologram regions that are different in diffraction action and are substantially in contact with each other.

According to a seventh means of the present invention, in the hologram according to the sixth means, the hologram is a polarization hologram.
That is, by using, for example, a holographic polymer dispersed liquid crystal (HPDLC) containing a liquid crystal material or a photopolymerized liquid crystal (PPLC) as a photosensitive material for a replication hologram, polarization can be achieved. It can be a hologram showing the property.

According to an eighth aspect of the present invention, there is provided an optical pickup device for irradiating a recording surface of an information recording medium with light and receiving reflected light from the recording surface, and recording information on a light source and a light beam emitted from the light source. An objective lens for condensing on the recording surface of the medium; and a plurality of photodetectors for receiving the reflected light beam from the recording surface, and means for guiding the reflected light beam to the photodetector as a sixth or seventh The hologram of the means is used (claim 8).
According to this, it is possible to realize an optical pickup device with high light utilization efficiency that does not cause a decrease in light utilization efficiency in the vicinity of boundaries between a plurality of hologram regions of the hologram and that there is no fear of flare light generation.

According to a ninth means of the present invention, in the optical pickup device according to the eighth means, the hologram includes a diffracted light and a transmitted light, which are incident upon duplication, from the diffracted light generated from the hologram and the recording surface, respectively. It is set so that it may substantially correspond to the reflected light beam.
In such a case, considering the influence of refraction of the light beam by the transparent substrate in the hologram master at the time of hologram duplication, the duplication hologram is arranged in the optical pickup device, so that the same almost no aberration wavefront from the duplication hologram as at the time of hologram duplication is obtained. Since it is reproduced, there is no concern about offset due to aberration in signal detection in the photodetector.

According to a tenth aspect of the present invention, there is provided an optical disc apparatus that performs at least one of information recording, reproduction, and erasing with respect to an optical disc that is an information recording medium, the optical pickup of the eighth or ninth means. And a processing device that performs at least one of recording, reproducing, and erasing of information using an output signal from the optical pickup device (claim 10).
According to this, it is possible to provide an optical disc apparatus that can stably access at a high speed by using an optical pickup device with high light utilization efficiency.

  According to the hologram duplicating method of the present invention, in the hologram duplication using the hologram master, even when there is a gap between both holograms, the duplication can be made so that a plurality of hologram regions each having a different diffractive action are substantially in contact with each other. There is.

  According to the hologram of the present invention, there is an effect that it is possible to realize a high-diffraction efficiency and inexpensive hologram having a plurality of hologram regions that are different in diffraction action and are substantially in contact with each other.

  According to the optical pickup device of the present invention, it is possible to realize an optical pickup device with high light utilization efficiency that does not cause a decrease in light utilization efficiency near the boundary of a plurality of hologram regions possessed by a hologram and does not cause the occurrence of flare light. effective.

  According to the optical disk apparatus of the present invention, there is an effect that high-speed access can be stably performed using an optical pickup apparatus with high light utilization efficiency.

  Hereinafter, the best mode for carrying out the present invention will be described in detail based on the embodiments shown in the drawings.

  FIG. 1 is an explanatory diagram of a hologram duplication method showing a first embodiment of the present invention. When the converging light 1 condensing at the point 2 is incident, the duplicate hologram 18 to be finally obtained is divided and diffracted by a plane perpendicular to the paper surface including the optical axis when the converging light 1 enters the point 5, It is assumed that there are two hologram regions with different diffraction effects that are focused on the point 8. That is, since the duplicate hologram 18 divides and diffracts the convergent light 1 on a plane perpendicular to the paper surface including the optical axis, the two hologram areas need to be provided so as to contact each other without overlapping each other. . The hologram region 10 and the photosensitive material 11 are sandwiched between the transparent substrates 12 and 13 and the transparent substrates 14 and 15, respectively, to form a hologram master 17 and a duplicate hologram 18.

  As a method for replicating such a duplicate hologram 18, as shown in FIG. 1, when convergent light 1 focused on point 2 is incident, convergent lights 4 and 7 converged on point 5 and point 8, respectively, are diffracted. A hologram original plate 17 having two hologram regions 3 and 6 having different diffracting actions, which are generated as light, via a gap 16 is arranged at a predetermined position in the convergent light path 1, and the diffracted light 4 , 7 in a plane perpendicular to the paper surface including the optical axis, the diffracted beams 4 and 7 are respectively combined with the convergent beam 1 in a state where the duplicate hologram 18 is arranged so that the photosensitive material 11 is arranged substantially in contact with the gap. The duplicate hologram 18 may be duplicated by causing interference. Reference numeral 9 in the figure denotes a condenser lens for coupling to the convergent light 1. The predetermined position in the converging optical path 1 where the hologram original plate 17 is disposed is a position where the converging light 1 is diffracted into points 5 and 8 with a minimum aberration. Further, it is desirable that the transparent substrate 13 and the transparent substrate 14 are in contact with each other because there is no interface reflection with air, and an index matching liquid may be used.

  According to the hologram duplicating method as described above, the diffracted lights 4 and 7 by the hologram master 17 are substantially in contact with each other without overlapping in the photosensitive material 11, so that there are two hologram regions having substantially different diffracting action that are in close contact with each other without any gap. 18 can be duplicated.

  As shown in FIG. 2, the region 19 and the gap 16 described above are regions where the intensity of transmitted light that contributes to interference in the photosensitive material 11 is high because diffracted light is not generated when the convergent light 1 passes. Therefore, it is preferable to provide means for making the intensity ratio of the diffracted light and the transmitted light that interfere in the photosensitive material 11 uniform over the entire surface. Specifically, in the hologram area 10 where the hologram is not formed, a reflection film or an absorption film that makes the intensity of transmitted light equal to the area where the hologram is formed, or a hologram required for the photosensitive material 11 A hologram that diffracts outside the region may be provided.

  Further, the hologram master 17 may be a relief type computer generated hologram, which is sensitive to interference fringes caused by divergent light emitted from the position of point 2 shown in FIG. 1 and divergent lights emitted from points 5 and 8. A volume phase hologram produced by two-beam interference exposure that exposes a material may be used, or a hologram duplicated by the above-described hologram duplication method using a computer generated hologram as a master. In the case of a relief-type computer generated hologram, a hologram interference pattern having a diffraction action necessary for the hologram master 17 is calculated by the computer, and the hologram master 17 is produced by electron beam lithography or photolithography. Free setting is easy. In the case of a relief hologram, it is desirable that only one diffracted light (for example, + 1st order diffracted light) is generated in addition to the transmitted light. Specifically, for example, the diffraction grating shape may be a blazed shape or a staircase shape. When the hologram master 17 is a volume phase hologram, the completed hologram master 17 is adjusted by adjusting the thickness of the photosensitive material, the refractive index of the material, and the exposure conditions at the time of manufacture. The intensity ratio between the transmitted light and the diffracted light generated from 17 can be adjusted, and as a result, it is possible to set the exposure conditions for hologram replication. Further, when the hologram master 17 is a hologram that is duplicated by the above-described hologram replication method using a computer generated hologram as a master, it takes time and effort to produce the hologram master 17, but a volume phase type It is possible to take advantage of both of the advantages realized by using the holograms.

  Various photosensitive materials such as a photopolymer, dichromated gelatin, and a photoresist can be used as the photosensitive material in the duplicate hologram 18 or the hologram master 17 described above, but a holographic polymer dispersion containing a liquid crystal material can be used. By using a liquid crystal (HPDLC: Holographic Polymer Dispersed Liquid Crystal), a photocurable liquid crystal (PPLC: Photo Polymerized Liquid Crystal), or the like, it is possible to obtain a hologram exhibiting polarization (polarization hologram).

  In the former HPDLC, a liquid crystal is dispersed in a polymer monomer to form a photosensitive material. When an interference fringe is exposed to this, the bright part of the interference fringe moves and cures. The liquid crystal remains in the dark part of the interference fringes and is pulled by the polymer cured in the bright part, and the liquid crystal is oriented in a specific direction. Because of this orientation, for orthogonal incident polarized light, one is made to diffract by observing the periodic refractive index change by making it coincide with the direction in which the refractive index due to the liquid crystal orientation is large, and the other hardly feels the refractive index change. Make it transparent. Therefore, when HPDLC is a photosensitive material, it can function as a polarization hologram.

  The latter PPLC is a liquid crystal with a photopolymerizable sensitive group sealed between a transparent substrate (ITO, etc.) and a transparent substrate having an alignment film for aligning the liquid crystal, and the liquid crystal is horizontally aligned. When the interference fringes are exposed, the liquid crystal molecules are polymerized and cured in the bright portions of the interference fringes. On the other hand, the liquid crystal molecules remain uncured in the dark part of the interference fringes. Next, when light is irradiated while applying a voltage between the transparent electrodes sandwiching the liquid crystal layer, the dark portion of the liquid crystal is aligned and cured in a direction perpendicular to the substrate by applying the voltage. Accordingly, the alignment of the liquid crystal has a horizontal / vertical periodic structure corresponding to the bright and dark interference fringes. Because of this orientation, the incident light is perpendicular to the direction of the minor axis of the horizontally aligned liquid crystal molecules, and the refractive index does not change. Is diffracted by feeling a periodic refractive index change. Therefore, when PPLC is used as a photosensitive material, it can function as a polarization hologram.

  Next, FIGS. 3 to 9 are views for explaining a hologram duplication method used in the optical pickup device according to the second embodiment of the present invention. The schematic diagram of the optical system of the optical pickup device is the same as that of FIG. 18, but the polarization hologram 42 is replaced with the polarization hologram 42 'according to the present invention. FIG. 3 is a partially enlarged view including the light source 41, the polarization hologram 42 ', and the photodetector 47 in FIG. That is, the reflected light from the optical disc that has been converged by the coupling lens is divided and diffracted into three optical paths by the hologram regions 42-1 to 42-3 in the polarization hologram 42 ', and each diffracted light is detected by a photodetector. 47-1 to 47-3. Information signals and servo signals are detected from the photodetectors 47-1 to 47-3. For example, a focus error signal based on the knife edge method is detected from the difference signal in the two-divided photodetector 47-1. The track error signal based on the push-pull method is detected from the difference signal of 2 and 47-3, and the information signal is detected from the sum signal of the photodetectors 47-1 to 47-3. The configuration of the polarization hologram 42 ′ shown in FIG. 3 and the signal detection method in this embodiment are an example of a detection system in the optical pickup device, and the present invention is not limited to this configuration.

  4 to 6, the converging light 1 that is condensed at a position 2 equivalent to the light emitting point of the light source in the optical pickup device is incident on the hologram master 17, and the diffracted light and the transmitted light from the hologram master 17 are passed through the photosensitive material 11. FIG. 4 is an explanatory diagram of the case where a duplicate hologram 42 ′ is to be obtained by interfering with each other, and the boundary lines 20 to 22 of the three hologram regions 42-1 to 43-3 in the duplicate hologram 42 ′ in FIG. It is the figure seen from the viewpoint 23 or 24 so that it may become a perpendicular direction.

  In FIG. 4, the hologram master 17 detects light in the optical pickup device (FIG. 3) when the converging light 1 condensing at a position 2 equivalent to the light emitting point 41 of the light source in the optical pickup device (FIG. 3) is incident. Diffracting action such that convergent lights 26-1 and 26-2 that are condensed at positions equivalent to the light receiving points 25-1 and 25-2 corresponding to the detectors 47-1 and 47-2 are generated as diffracted lights, respectively. Different hologram regions 17-1 and 17-2 are provided via a gap 27.

  Further, in FIG. 5, the hologram original plate 17 is used in the optical pickup device (FIG. 3) when the converging light 1 condensing at a position 2 equivalent to the light emitting point 41 of the light source in the optical pickup device (FIG. 3) is incident. Diffraction so that convergent lights 26-1 and 26-3 that are condensed at positions equivalent to the light receiving points 25-1 and 25-3 corresponding to the photodetectors 47-1 and 47-3 are generated as diffracted lights, respectively. The hologram regions 17-1 and 17-3 and the overlap 28 have different functions.

  Further, in FIG. 6, the hologram original plate 17 is used in the optical pickup device (FIG. 3) when the converging light 1 condensing at a position 2 equivalent to the light emitting point 41 of the light source in the optical pickup device (FIG. 3) is incident. Diffraction so that convergent lights 26-2 and 26-3 are respectively collected as diffracted lights at positions equivalent to the light receiving points 25-2 and 25-3 corresponding to the photodetectors 47-2 and 47-3. Hologram areas 17-2 and 17-3 having different functions are provided.

  4 to 6, the duplicate hologram 42 ′ is arranged such that the photosensitive material 11 is arranged at a position where the two diffracted lights are substantially in contact with each other on a plane perpendicular to the paper surface including the optical axis. Thus, each of the diffracted light and the transmitted light by the hologram master 17 is caused to interfere with each other to duplicate the duplicate hologram 42 '.

  4 to 6, the positions and sizes of the hologram regions 17-1 to 17-3 in the hologram master 17 and the hologram regions 42-1 to 42-3 in the duplicate hologram 42 ′ to be obtained. The relationship is approximately as shown in FIG. As shown in FIG. 5, the hologram regions 17-1 and 17-3 in the hologram master 17 are overlapped. Therefore, the overlapping regions are subjected to multiple exposure when the hologram master is manufactured, or for example, FIGS. It is necessary to provide them on separate hologram masters as shown in FIG. When separate hologram masters as shown in FIGS. 8 and 9 are used, the hologram copy exposure may be performed twice using each hologram master.

  Also, the position of the light source, the position of the photodetector, and the angle and position of the light beam incident on or emitted from the hologram are maintained at the time of hologram duplication, when the duplicate hologram is used in an optical pickup device, and at the time of producing a hologram master. It is preferable to provide means for this. This is because the light beam is refracted at the interface between the transparent substrate and the air in the duplicate hologram or hologram master, and the angle and position of the light beam are shifted. Specifically, for example, after a duplicate hologram is manufactured, a dummy transparent substrate having a thickness equivalent to that of a hologram original plate used for hologram replication may be attached to the duplicate hologram and used for the optical pickup device. The same applies to the production of the hologram master. As a result, a substantially aberration-free wavefront that is the same as that at the time of hologram duplication is reproduced from the duplication hologram, and an offset due to aberration can be prevented from occurring in signal detection in the photodetector of the optical pickup device.

  According to the above, since the plurality of hologram regions of the polarization hologram are adjacent to each other without being overlapped with each other, there is a concern that the light use efficiency is reduced near the boundary between the hologram regions, and the occurrence of flare light may occur. It is possible to realize an optical pickup device having high light utilization efficiency.

  Next, FIGS. 10 to 15 are diagrams for explaining a hologram duplication method used in the optical pickup device according to the third embodiment of the present invention. The schematic configuration diagram of the optical system of the optical pickup device and the duplicate hologram to be obtained are the same as those in the second embodiment, as shown in FIGS.

  10 to 12, diverging light 1 ′ emitted from a position 2 equivalent to the light emitting point of the light source in the optical pickup device is incident on the hologram master 17 ′, and the diffracted light and transmitted light from the hologram master 17 ′ are used as the photosensitive material 11. FIG. 4 is an explanatory diagram when a duplicate hologram 42 ′ is to be obtained by interfering with each other, and boundary lines 20 to 22 of three hologram regions 42-1 to 42-3 in the duplicate hologram 42 ′ in FIG. It is the figure seen from the viewpoint 23 or 24 so that it may become a paper surface perpendicular | vertical direction.

  In FIG. 10, the hologram master 17 ′ receives light from the optical pickup device (FIG. 3) when diverging light 1 ′ emitted from a position 2 equivalent to the light emitting point 41 of the light source in the optical pickup device (FIG. 3) is incident. Diffraction so that diverging lights 26-1 'and 26-2' respectively emitted from positions equivalent to the light receiving points 25-1 and 25-2 corresponding to the detectors 47-1 and 47-2 are generated as diffracted light. Hologram areas 17-1 ′ and 17-2 ′ having different functions are provided via an overlap 29.

  Further, in FIG. 11, the hologram master 17 ′ is arranged such that the diverging light 1 ′ emitted from the position 2 equivalent to the light emitting point 41 of the light source in the optical pickup device (FIG. 3) is incident on the optical pickup device (FIG. 3). The divergent lights 26-1 'and 26-3' emitted from the positions equivalent to the light receiving points 25-1 and 25-3 corresponding to the photodetectors 47-1 and 47-3 in FIG. The hologram regions 17-1 ′ and 17-3 ′ having different diffractive effects are provided via the gap 30.

  Also, in FIG. 12, the hologram master 17 ′ has an optical pickup device (FIG. 3) when diverging light 1 ′ emitted from a position 2 equivalent to the light emitting point 41 of the light source in the optical pickup device (FIG. 3) is incident. The divergent lights 26-2 'and 26-3' emitted from the positions equivalent to the light receiving points 25-2 and 25-3 corresponding to the photodetectors 47-2 and 47-3 in FIG. The hologram regions 17-2 ′ and 17-3 ′ have different diffraction effects.

  10 to 12, the duplicate hologram 42 ′ is arranged such that the photosensitive material 11 is arranged at a position where the two diffracted lights are substantially in contact with each other on a plane perpendicular to the paper surface including the optical axis. Thus, each of the diffracted light and the transmitted light from the hologram master 17 ′ is caused to interfere with each other to replicate the duplicate hologram 42 ′.

  As described above, considering FIGS. 10 to 12, the positions of the hologram regions 17-1 ′ to 17-3 ′ in the hologram master 17 ′ and the hologram regions 42-1 to 42-3 in the duplicate hologram 42 ′ to be obtained. The size relationship is approximately as shown in FIG. As shown in FIG. 10, the hologram regions 17-1 ′ and 17-2 ′ in the hologram master 17 ′ are overlapped, so that the overlapping regions are subjected to multiple exposure when the hologram master is manufactured, or, for example, As shown in FIGS. 14 and 15, it is necessary to provide them on separate hologram masters. When separate hologram masters as shown in FIGS. 14 and 15 are used, the hologram copy exposure may be performed twice using each hologram master.

  Also in the present embodiment, as in the case of the second embodiment, the position of the light source, the position of the photodetector, and the hologram are respectively obtained when the hologram is duplicated, when the duplicate hologram is used in the optical pickup device, and when the hologram master is produced. It is preferable to provide means for maintaining the angle and position of the light beam incident on or emitted from the hologram.

  According to the above, since the plurality of hologram regions included in the polarization hologram are adjacent to each other so as not to overlap each other, there is a concern that the light use efficiency is reduced near the boundary between the hologram regions, and flare light is generated. It is possible to realize an optical pickup device with high light utilization efficiency that has no light.

  16 and 17 are diagrams for explaining a hologram duplication method used in the optical pickup device according to the fourth embodiment of the present invention. The schematic configuration diagram of the optical system of the optical pickup device and the duplicate hologram to be obtained are the same as those in the second embodiment, as shown in FIGS.

  FIG. 16 shows that the converging light 1 collected at the position 2 equivalent to the light emitting point of the light source in the optical pickup device is incident on the hologram master 17, causing the diffracted light and transmitted light from the hologram master 17 to interfere with each other in the photosensitive material 11. Further, divergent light 1 ′ emitted from a position 2 equivalent to the light emission point of the light source in the optical pickup device is incident on the hologram master 17 ′, and the diffracted light and transmitted light from the hologram master 17 ′ interfere with each other in the photosensitive material 11 to be duplicated. It is explanatory drawing at the time of trying to obtain hologram 42 ', Comprising: The boundary line 20 of the hologram area | regions 42-1 and 42-2 in the duplicate hologram 42' in FIG. 3, and the hologram area | regions 42-1 and 42-3 It is the figure seen from the viewpoint 24 so that the boundary line 21 may become a paper surface perpendicular | vertical direction.

  In FIG. 16, the hologram master 17 detects light in the optical pickup device (FIG. 3) when the converged light 1 is incident on the position 2 equivalent to the light emitting point 41 of the light source in the optical pickup device (FIG. 3). Diffracting action such that convergent lights 26-1 and 26-2 that are condensed at positions equivalent to the light receiving points 25-1 and 25-2 corresponding to the detectors 47-1 and 47-2 are generated as diffracted lights, respectively. Different hologram regions 17-1 and 17-2 are provided with a gap.

  Further, the hologram master 17 ′ is a photodetector in the optical pickup device (FIG. 3) when diverging light 1 ′ emitted from a position 2 equivalent to the light emitting point 41 of the light source in the optical pickup device (FIG. 3) is incident. It has a hologram region 17-3 ′ where divergent light 26-3 ′ emitted from a position equivalent to the light receiving point 25-3 corresponding to 47-3 is generated as diffracted light.

  In consideration of the above, the hologram regions 17-1 and 17-2 in the hologram master 17 and the hologram region 17-3 'in the hologram master 17', and the hologram regions 42-1 to 42 in the duplicate hologram 42 'to be obtained. The relationship between the position and the size of −3 is as shown in FIG. It should be noted that the hologram replication by the hologram master 17 and the hologram replication by the hologram master 17 'need not be performed at the same time but in two steps.

  Also in the present embodiment, as in the case of the second embodiment, the position of the light source, the position of the photodetector, and the hologram are respectively obtained when the hologram is duplicated, when the duplicate hologram is used in the optical pickup device, and when the hologram master is produced. It is preferable to provide means for maintaining the angle and position of the light beam incident on or emitted from the hologram.

  According to the above, since the plurality of hologram regions of the polarization hologram are adjacent to each other without being overlapped with each other, there is no concern about a decrease in light use efficiency near the boundary between the hologram regions and generation of flare light. An optical pickup device with high light utilization efficiency can be realized.

  According to the optical disc apparatus including the optical pickup apparatus as described above and a processing apparatus that performs at least one of recording, reproduction, and erasing of information using an output signal from the optical pickup apparatus, the optical pickup apparatus can It is possible to provide an optical disc apparatus that can stably perform the above access.

Here, an embodiment of an optical disc apparatus equipped with the optical pickup device according to the present invention will be described.
Since the optical pickup device according to the present invention uses the polarization hologram produced by the above-described method, the light use efficiency is high, and a highly reliable signal suitable for high-speed recording / reproduction can be obtained. Further, when the light utilization efficiency is high, the gain of the optical integrated circuit (OPIC) of the signal detection system can be reduced, which can contribute to the high-speed response of OPIC. If the diffraction efficiency does not change depending on the incident angle, a signal with a small offset can be obtained. Therefore, it is possible to increase the recording / reproducing speed of the optical disc apparatus and achieve stable servo control.
Furthermore, in the optical pickup device according to the present invention, it is possible to reduce the size and thickness of the optical pickup device by using a polarization hologram and integrating it with a unit in which a light source and a light detector are arranged as in FIG. For example, it can be suitably used as an optical pickup device of an optical disk device mounted on a notebook personal computer.

  FIG. 22 shows an example of an optical disk device. This optical disc 120 includes a spindle motor 122 for rotating and driving an optical disc 117 as an information recording medium, an optical pickup device 123, a laser control circuit 124, an encoder 125, a motor driver 127, a reproduction signal processing circuit 128, a servo controller 133, a buffer. A RAM 134, a buffer manager 137, an interface 138, a read-only memory (ROM) 139, a central processing unit (CPU) 140, a random access memory (RAM) 141, and the like are provided. Note that the arrows in FIG. 22 indicate the flow of typical signals and information, and do not represent the entire connection relationship of each block.

  As the optical disc 117, a CD (compact disc) optical disc (CD, CD-R, CD-RW), a DVD (digital versatile disc) optical disc (DVD, DVD-R, DVD-RW), There are DVD + Blue, etc., but if the optical pickup device 123 includes a plurality of light sources having different wavelengths and the light source is selectively driven according to the type of the optical disk 117, a plurality of types of optical disks can be used. Thus, an optical disc apparatus capable of recording and reproducing can be configured.

In FIG. 22, an optical pickup device 123 irradiates a recording surface on which a spiral or concentric track of an optical disk 117 is formed with laser light and receives reflected light from the recording surface to record or reproduce information. This is an apparatus for erasing, and has the configuration as described above.
The reproduction signal processing circuit 128 converts a current signal that is an output signal of the optical pickup device 123 into a voltage signal, and based on the voltage signal, a wobble signal, an RF signal including reproduction information, and a servo signal (focus signal, tracking signal). Etc. are detected. Then, the reproduction signal processing circuit 128 extracts address information, a synchronization signal, and the like from the wobble signal. The address information extracted here is output to the CPU 140, and the synchronization signal is output to the encoder 125. Further, the reproduction signal processing circuit 128 performs error correction processing or the like on the RF signal and then stores it in the buffer RAM 134 via the buffer manager 137. The servo signal is output from the reproduction signal processing circuit 128 to the servo controller 133. The servo controller 133 generates a control signal for controlling the optical pickup device 123 based on the servo signal and outputs it to the motor driver 127.

  The buffer manager 137 manages input / output of data to / from the buffer RAM 134 and notifies the CPU 140 when the amount of accumulated data reaches a predetermined value. The motor driver 127 controls the optical pickup device 123 and the spindle motor 122 based on a control signal from the servo controller 133 and an instruction from the CPU 140. The encoder 125 retrieves data stored in the buffer RAM 134 via the buffer manager 137 based on an instruction from the CPU 140, adds an error correction code, etc., creates write data to the optical disc 117 and reproduces it. Write data is output to the laser control circuit 124 in synchronization with the synchronization signal from the signal processing circuit 128. The laser control circuit 124 controls the laser light output from the optical pickup device 123 based on the write data from the encoder 125.

The interface 138 is a bidirectional communication interface with a host (for example, a personal computer) and conforms to a standard interface such as ATAPI (AT Attachment Packet Interface) and SCSI (Small Computer System Interface).
The ROM 139 stores a control program written in a code readable by the CPU 140. The CPU 140 controls the operation of each unit according to the program stored in the ROM 139 and temporarily holds data necessary for control in the RAM 141.

The configuration example of the optical disc apparatus has been described above. However, the configuration of FIG. 22 is an example, and the configuration is not limited thereto. Various configurations can be applied as long as the optical disc apparatus is equipped with the optical pickup device 123.
In the present invention, an optical pickup device using a polarization hologram having a high diffraction efficiency is mounted as the optical pickup device 123. Therefore, the light utilization efficiency is high, a highly reliable signal is obtained, and the recording / reproducing speed is high. Can be achieved. Furthermore, in the present invention, by providing a plurality of light sources having different wavelengths in the optical pickup device 123, recording, reproduction, or erasure is performed on a plurality of standard optical discs having different wavelengths such as a CD system, a DVD system, and DVD + Blue. It is possible to realize an optical disc apparatus capable of performing the above.

  As described above, the hologram replication method according to the present invention is such that a plurality of hologram regions having different diffraction effects are substantially in contact with each other even when a gap exists between both holograms in hologram replication using a hologram master. Since it can be duplicated, it can be suitably used for producing a hologram with high diffraction efficiency and low cost, each having a plurality of hologram regions that are different in diffraction action and substantially in contact with each other. The hologram duplicated by the hologram duplicating method according to the present invention can be suitably used for an optical pickup device, and there is a concern that the light use efficiency is lowered near the boundaries of a plurality of hologram regions of the hologram and flare light is generated. It is possible to realize an optical pickup device with high light utilization efficiency that is free of light. The optical pickup apparatus can be suitably used for an optical disk apparatus, and an optical disk apparatus that can stably perform access at a high speed can be realized. The optical disk apparatus according to the present invention can be suitably used for an information recording / reproducing apparatus built in (or connected to) a personal computer or the like, a DVD recorder that has become widespread in recent years, and the like.

It is explanatory drawing of the hologram replication method which concerns on the 1st Example of this invention. FIG. 2 is a diagram illustrating transmitted light outside a hologram region that contributes to replication in the replication method of FIG. 1. It is a figure which shows the relationship between the hologram of the optical pick-up apparatus which concerns on the 2nd Example of this invention, and a photodetector. It is explanatory drawing of the hologram replication method which concerns on the 2nd Example of this invention. It is explanatory drawing of the hologram replication method which concerns on the 2nd Example of this invention. It is explanatory drawing of the hologram replication method which concerns on the 2nd Example of this invention. It is a figure which shows the relationship between each hologram area in the hologram original plate based on the 2nd Example of this invention, and the position and magnitude | size of each hologram area in the replication hologram to be obtained. It is a figure which shows the relationship between each hologram area in the hologram original plate based on the 2nd Example of this invention, and the position and magnitude | size of each hologram area in the replication hologram to be obtained. It is a figure which shows the relationship between each hologram area in the hologram original plate based on the 2nd Example of this invention, and the position and magnitude | size of each hologram area in the replication hologram to be obtained. It is explanatory drawing of the hologram replication method which concerns on the 3rd Example of this invention. It is explanatory drawing of the hologram replication method which concerns on the 3rd Example of this invention. It is explanatory drawing of the hologram replication method which concerns on the 3rd Example of this invention. It is a figure which shows the relationship between each hologram area in the hologram original plate based on the 3rd Example of this invention, and the position and magnitude | size of each hologram area in the replication hologram to be obtained. It is a figure which shows the relationship between each hologram area in the hologram original plate based on the 3rd Example of this invention, and the position and magnitude | size of each hologram area in the replication hologram to be obtained. It is a figure which shows the relationship between each hologram area in the hologram original plate based on the 3rd Example of this invention, and the position and magnitude | size of each hologram area in the replication hologram to be obtained. It is explanatory drawing of the hologram replication method which concerns on the 4th Example of this invention. It is a figure which shows the relationship between each hologram area in the hologram original plate concerning the 4th Example of this invention, and the position and magnitude | size of each hologram area in the replication hologram to be obtained. It is a schematic block diagram which shows an example of the optical system of the optical pick-up apparatus using a polarization hologram. It is a schematic sectional drawing which shows the prior art example of the polarization hologram used for the optical pick-up apparatus shown in FIG. It is a schematic sectional drawing which shows an example of the hologram unit used for an optical pick-up apparatus. It is explanatory drawing of the hologram replication method using the hologram original plate. FIG. 25 is a block diagram illustrating an example of a configuration of an optical disc device.

Explanation of symbols

1: Convergent light 3, 6: Hologram area with different diffraction action 4.7: Diffracted light 9: Condensing lens 10: Hologram area 11: Photosensitive material 12, 13: Transparent substrate 14, 15: Transparent substrate 16: Gap 17: Hologram master 18: Duplicated hologram 41: Light emitting point of light source 42 ': Polarization hologram 42-1 to 42-3: Hologram area 47-1 to 47-3: Photo detector 117: Optical disk 123: Optical pickup device

Claims (10)

Diffracted light from a hologram master having a plurality of hologram areas respectively corresponding to the plurality of hologram areas, and having a hologram having at least two hologram areas having different diffraction effects and intersecting the diffracted light with respect to a light beam having an arbitrary wavelength. And a hologram duplicating method in which the transmitted light interferes in the photosensitive material and is duplicated.
A hologram duplicating method, wherein a gap is provided between a plurality of hologram regions in the hologram master, and the photosensitive material is disposed at a position where diffracted light from each region is substantially in contact with each other. The hologram replication method according to claim 1, wherein
The hologram original plate is provided with a region in which a hologram including gaps between a plurality of hologram regions in the hologram original plate is not provided, and a hologram with respect to the intensity of transmitted light by the hologram original plate that interferes in the photosensitive material. A hologram duplication method comprising means for making the area substantially equal to each other. The hologram duplication method according to claim 1 or 2,
The hologram replicating method, wherein the hologram master comprises a computer generated hologram. The hologram duplication method according to claim 1 or 2,
The hologram replication method according to claim 1, wherein the hologram master comprises a volume phase hologram manufactured by causing interference between a light beam corresponding to the diffracted light and the transmitted light. The hologram duplication method according to claim 1 or 2,
The hologram master is a computer-generated hologram or a hologram duplicated by a hologram master made of a volume phase hologram made by causing interference between the diffracted light and the light beam corresponding to the transmitted light. . A hologram having at least two hologram regions each having a different diffracting action with respect to a light beam having an arbitrary wavelength and intersecting with diffracted light,
A hologram produced by the hologram duplication method according to claim 1. The hologram according to claim 6, wherein
The hologram is a polarization hologram. An optical pickup device that irradiates light onto a recording surface of an information recording medium and receives reflected light from the recording surface,
A light source; an objective lens that condenses the light beam emitted from the light source on a recording surface of the information recording medium; and a plurality of photodetectors that receive the reflected light beam from the recording surface. An optical pickup device using the hologram according to claim 6 or 7 as a means for guiding to a container. The optical pickup device according to claim 8, wherein
The optical pickup, wherein the hologram is set so that the diffracted light and the transmitted light incident on the hologram master incident upon duplication substantially coincide with the diffracted light generated from the hologram and the reflected light beam from the recording surface, respectively. apparatus. An optical disc apparatus that performs at least one of recording, reproduction, and erasing of information on an optical disc that is an information recording medium,
10. An optical pickup device according to claim 8 or 9, and a processing device that performs at least one of recording, reproducing, and erasing information using an output signal from the optical pickup device. Optical disk device to perform.

Images