JP4844759B2 - Recording medium, optical information recording method, optical information recording apparatus, optical information reproducing method, optical information reproducing apparatus, and recording medium manufacturing method - Google Patents

Description

  The present invention relates to a recording medium on which interference fringes of information light and recording reference light are recorded on a hologram recording layer, a method for manufacturing the same, an optical information recording method for recording interference fringes on a hologram recording layer of a recording medium, and an optical information recording apparatus The present invention also relates to an optical information reproducing method and an optical information reproducing apparatus for reproducing information from a hologram recording layer on which interference fringes are recorded.

  Holographic recording in which information is recorded on a recording medium using holography is generally performed by superimposing information light having image information and reference light inside the recording medium, and forming interference fringes generated at that time. Is done by writing to At the time of reproducing the recorded information, the image information is reproduced by diffraction by interference fringes by irradiating the recording medium with reference light.

  In recent years, volume holography, particularly digital volume holography, has been developed and attracted attention in practical areas in order to achieve ultra-high data density in holographic recording. Volume holography is a method of writing interference fringes three-dimensionally by actively utilizing the thickness direction of the recording medium. Digital volume holography is a recording medium and recording method similar to those used for volume holography. The image information to be recorded is a computer-oriented holographic recording method limited to a binarized digital pattern. In this digital volume holography, for example, image information such as an analog picture is once digitized, developed into two-dimensional digital pattern information, and recorded as image information. At the time of reproduction, the digital pattern information is read and decoded so that the original image information is restored and displayed. As a result, even if the S / N ratio (signal to noise ratio) is somewhat poor at the time of reproduction, the original information is reproduced very faithfully by performing differential detection or encoding binary data and performing error correction. It becomes possible.

  An example of recording on the hologram recording layer by volume holography is that the information light carrying the information to be recorded and the recording reference light simultaneously form a thickness direction interference fringe in the hologram recording layer for a predetermined time from the transparent substrate side. The information is recorded as a three-dimensional hologram by irradiating and fixing the interference fringe pattern three-dimensionally in the hologram recording layer (Patent Document 1).

  FIG. 8 is a schematic configuration diagram of a conventional hologram recording / reproducing apparatus 1. The optical information recording / reproducing apparatus 1 in FIG. 8 includes a recording / reproducing light source 35, a beam expander 34, a polarization beam splitter 32, a spatial light modulator 33, a beam splitter 31, first and second relay lenses 29 and 30, and a dichroic. A mirror 28, an objective lens 26, a projection lens 36, a photodetector 37, and a servo reading element 24 are provided. Then, the disk-shaped recording medium 25 is rotated by the driving means 27.

  FIG. 9 is an enlarged schematic view of the vicinity of the recording medium 25. The recording medium 25 reflects the reflective layer 20, the gap layer 19, and the recording / reproducing light 14 onto the substrate 21 on which pits are recorded as servo information. A wavelength selective reflection film 18 that transmits the servo light 15, a hologram recording layer 17, and a protective layer 16 are provided. FIG. 9 shows a state in which the recording / reproducing light 14 and the servo light 15 are irradiated onto the recording medium 25 while converging in a conical shape by an objective lens 26 (not shown).

  FIG. 10 is a schematic plan view of the recording medium 25 irradiated with the recording / reproducing light 14 and the servo light 15. FIG. 10 shows the pit 3 for specifying the irradiation position of the recording / reproducing light 14 and the servo light 15, the irradiation area (beam spot) 4 of the servo light 15 in the pit 3 and the hologram recording layer of the recording / reproducing light 14. An irradiation area (beam spot) 22 at the bottom of 17 is shown.

  In the operation of the optical information recording / reproducing apparatus 1, first, the servo light 15 is emitted from the servo reading element 24. The dichroic mirror 28 has a wavelength selective reflection surface that transmits the recording / reproducing light 14 emitted from the recording / reproducing light source 35 and reflects the servo light 15. The recording medium 25 is irradiated by the objective lens 26. Then, as shown in FIG. 9, the servo light 15 passes through the protective layer 16, the hologram recording layer 17, the wavelength selective reflection film 18, and the gap layer 19, and the beam spot 4 (see FIG. 10) passes through the reflection layer 20. Formed, modulated by the pits 3 of the substrate 21 and reflected. The reflected servo light 15 passes again from the gap layer 19 to the protective layer 16, passes through the objective lens 26, is reflected by the dichroic mirror 28, and is detected by the servo reading element 24. The beam spot 4 of the servo light 15 follows the row of the pits 3, and the tracking and focusing of the irradiation position are controlled by the information of the pits 3 detected by the servo reading element 24.

  The optical information recording / reproducing apparatus 1 reads the address to be recorded or reproduced based on the information of the pit 3 detected by the servo reading element 24 and irradiates the recording or reproducing position with the recording / reproducing light source 35. S-polarized recording / reproducing light 14 is emitted. The recording / reproducing light 14 has its beam diameter enlarged by the beam expander 34 and reflected by the polarization beam splitter 32 toward the spatial light modulator 33. At the time of recording, a two-dimensional pattern in which information to be recorded is encoded and a two-dimensional pattern of reference light are displayed on the spatial light modulator 33, and information light and recording reference light are generated and reproduced as recording / reproducing light 14. Sometimes, a two-dimensional pattern of reference light is displayed on the spatial light modulator 33 to generate reproduction reference light. The recording / reproducing light 14 is converted into P-polarized light by the spatial light modulator 33, passes through the polarization beam splitter 32 and the beam splitter 31, and the pupil plane of the objective lens 26 by the first and second relay lenses 29 and 30. The image of the two-dimensional pattern displayed on the spatial light modulator 33 is transferred.

  Further, the recording / reproducing light 14 passes through the dichroic mirror 28 and is irradiated onto the recording medium 25 by the objective lens 26. The recording / reproducing light 14 passes through the protective layer 16 and the hologram recording layer 17 of the recording medium 25, and forms a beam spot 22 (see FIG. 10) on the bottom surface of the hologram recording layer 17. The recording / reproducing light 14 is reflected by the wavelength selective reflection film 18 and passes through the hologram recording layer 17 and the protective layer 16 again. At the time of recording, interference fringes formed by interference between the information light that is the recording / reproducing light 14 and the recording reference light are recorded on the hologram recording layer 17 of the recording medium 25, and at the time of reproduction, the reproduction is the recording / reproducing light 14. The reference light for use interferes with the interference fringes recorded on the hologram recording layer 17 of the recording medium 25 to generate reproduction light. During reproduction, the reproduction light generated from the hologram recording layer 17 passes through the objective lens 26 and the dichroic mirror 38, and is formed on the pupil plane of the objective lens 26 by the first and second relay lenses 29 and 30. The two-dimensional pattern image is transferred, reflected by the beam splitter 31, projected onto the photodetector 37 by the projection lens 36, and the two-dimensional pattern image of the reproduction light is detected by the photodetector 37.

JP 11-311938 A

  A hologram recording layer having a sufficiently large thickness compared to the interval between interference fringes is called a thick hologram, and is distinguished from a thin hologram having the same properties as a diffraction grating. In principle, a thick hologram can be reproduced only by a reproduction reference beam under the same conditions as the recording reference beam used at the time of recording. If the conditions are different, the reproduction efficiency rapidly decreases. That is, the reference light for reproduction is not only the two-dimensional pattern and irradiation position of the reference light displayed on the spatial light modulator 33, but also the angle of incidence on the recording medium, the magnification in the hologram recording layer, and the rotation direction about the optical axis. The positional relationship at is also preferably the same as the recording reference light at the time of recording.

  As described above, the irradiation position of the recording / reproducing light 14 is determined by reading the pit 3 with the servo light 15. Incidentally, the diameter (φD) of the beam spot 22 of the recording / reproducing light 14 is several hundred μm, whereas the diameter of the beam spot 4 of the servo light 15 is several μm (FIGS. 9 and 10 are described). It is a schematic diagram for the purpose, and does not accurately indicate the ratio of the spot diameters). In this way, the beam diameter of the recording / reproducing light 14 is remarkably wider than the beam diameter of the servo light 15, and the beam spot 22 of the recording / reproducing light 14 and the beam spot 4 of the servo light 15 overlap. However, the positional relationship is not the same. Since the recording / reproducing light 14 and the servo light 15 are irradiated to the recording medium from different light sources through different optical systems, strictly speaking, the light of the recording / reproducing light 14 as shown in FIG. The axis 12 and the optical axis 13 of the servo light 15 cannot be completely matched, and a difference of Δθ occurs. For this reason, the center of the irradiation position of the recording / reproducing light 14 on the recording medium 25 and the center of the irradiation position of the servo light 15 are displaced in the order of submicrons. 9 and 10, the center of the recording / reproducing light 14 and the center of the servo light 15 are displaced by Δr in the X direction and Δt in the Y direction.

  Further, the arrangement of the optical system, the magnification of the lens, and the like cannot be completely the same for each optical information recording / reproducing apparatus 1, and have a certain error range. For example, if the recording / reproducing light source 35 is slightly tilted, the incident angle and irradiation position of the recording / reproducing light 14 on the recording medium 25 are shifted, and if the servo reading element 24 is slightly tilted, The irradiation position and incident angle of the servo light 15 are shifted. Further, if the arrangement and focal length of the pair of relay lenses 29 and 30 and the objective lens 44 are slightly different, the magnification of the Fourier transform image of the recording / reproducing light 14 in the hologram recording layer is shifted, and the spatial light modulator 33 is connected to the optical axis. Is slightly rotated, the Fourier transform image of the recording / reproducing light 14 is rotated about the optical axis.

  For this reason, in the conventional optical information recording / reproducing apparatus using interference fringes, the recording / reproducing state of the recording / reproducing light and the servo light differs in a strict sense between different apparatuses. Since it affects the efficiency, the device dependency is high and the versatility between devices is low. The present invention provides a novel recording medium, an optical information recording method, an optical information recording device, an optical information reproducing method, and an optical information reproducing device for the purpose of enhancing versatility between devices in the optical information recording / reproducing device.

  The recording medium of the present invention is a recording medium on which information is recorded by interference fringes, a hologram recording layer on which interference fringes are recorded, a control information layer on which control information reproduced by control light is recorded, A plurality of reference fringes that can be detected by the control light, and a plurality of interference fringes in which recording conditions are changed in association with the reference marks are recorded on the hologram recording layer.

  Furthermore, in the recording medium, it is preferable that the reference mark is a part of control information recorded in the control information layer.

  Further, in the recording medium, the plurality of interference fringes may be arranged by changing a relative positional relationship between each interference fringe and a reference mark associated with the interference fringe. In this case, each interference fringe preferably has a direction dependency in diffraction efficiency in the plane direction of the recording medium. The plurality of reference marks may be arranged by changing the positional relationship of the reference marks with respect to the normally recorded interference fringe arrangement.

  Further, the magnification of the recording light recording each interference fringe in the hologram recording layer may be changed, and the rotation angle about the optical axis of the recording light recording each interference fringe may be changed. Also good.

  Furthermore, in the recording medium, it is preferable that the plurality of interference fringes are recorded in a partial area of the recording medium.

  Furthermore, in the recording medium, it is preferable that the plurality of interference fringes can be reproduced by reproduction reference light having the same spatial modulation pattern.

  The optical information recording method of the present invention is an optical information recording method for recording information on a recording medium on which information is recorded by interference fringes, the recording medium comprising a hologram recording layer on which interference fringes are recorded, A control information layer on which control information reproduced by the control light is recorded; and a plurality of reference marks detectable by the control light; and a plurality of interferences by changing recording conditions in association with the reference marks Stripes are recorded on the hologram recording layer.

  Furthermore, in the optical information recording method, it is preferable that the reference mark is a part of control information recorded in the control information layer.

  Further, in the optical information recording method, the plurality of interference fringes may change a relative positional relationship between each interference fringe and a reference mark associated with the interference fringe. In this case, it is preferable to record each interference fringe so that the diffraction efficiency in the plane direction of the recording medium has direction dependency. Further, the recording medium is arranged by changing the positional relationship of the reference marks with respect to the normally recorded interference fringe arrangement, and does not completely follow the displacement of the arrangement of the plurality of reference marks. The plurality of interference fringes may be recorded.

  The magnification of the recording light in which each interference fringe is recorded in the hologram recording layer may be changed, and the rotation angle about the optical axis of the recording light in which each interference fringe is recorded may be changed.

  Further, in the optical information recording method, it is preferable that the plurality of interference fringes are recorded in a partial area of the recording medium.

  The optical information reproducing method of the present invention is an optical information reproducing method for reproducing information from a recording medium on which information is recorded by interference fringes, and the recording medium includes a hologram recording layer on which interference fringes are recorded, A control information layer on which control information reproduced by the control light is recorded; and a plurality of reference marks detectable by the control light; a plurality of interference fringes in the hologram recording layer in association with the reference mark The plurality of interference fringes are arranged by changing a relative positional relationship between each interference fringe and a reference mark associated with the interference fringe, and the control light and the reference mark are arranged. The recording medium is irradiated with reproduction light for reproducing the interference fringes recorded in association with the control mark, the reference mark is detected by the control light, and the reproduction light is generated from the interference fringes. Raw light is detected, a relative positional relationship between the control light and the reproduction light is detected from the detected reference mark and the detected reproduction light, and the relative relationship between the control light and the reproduction light is detected. It is characterized by controlling the general positional relationship.

  Further, in the optical information reproduction method, the control light and the reproduction light are controlled relative to each other by controlling the timing of irradiating the control light or the reproduction light or position information in the reproduced control information. The positional relationship may be controlled.

  Another optical information reproducing method of the present invention is an optical information reproducing method for reproducing information from a recording medium on which information is recorded by interference fringes, the recording medium comprising a hologram recording layer on which interference fringes are recorded. A control information layer on which control information reproduced by the control light is recorded, and a plurality of reference marks detectable by the control light, and a hologram recording layer of the recording light in association with the reference marks A plurality of interference fringes are recorded on the hologram recording layer by changing the magnification in the recording medium, and reproduction light for reproducing the interference fringes recorded in association with the control light and the reference mark is recorded on the recording medium. Irradiating, detecting the reference mark with the control light, detecting reproduction light generated from the interference fringe with the reproduction light, and detecting the reference mark and the detected reproduction light Detecting a magnification of hologram recording layer of the reproducing light, and controls the magnification in the hologram recording layer of the reproducing light.

  Another optical information reproducing method of the present invention is an optical information reproducing method for reproducing information from a recording medium on which information is recorded by interference fringes, the recording medium comprising a hologram recording layer on which interference fringes are recorded. A control information layer in which control information reproduced by the control light is recorded, and a plurality of reference marks that can be detected by the control light, and an optical axis of the recording light is associated with the reference mark. A plurality of interference fringes are recorded on the hologram recording layer while changing the rotation angle around the center, and the reproduction light for reproducing the interference fringes recorded in association with the control light and the reference mark is Irradiating the recording medium, the reference mark is detected by the control light, the reproduction light generated from the interference fringe is detected by the reproduction light, and the reproduction mark is detected from the detected reference mark and the detected reproduction light. Detecting a rotation angle around the optical axis of the use light, and controlling the rotation angle around the optical axis of the reproduction light.

  Further, in the optical information reproducing method, it is preferable that the reference mark is a part of control information recorded in the control information layer.

  Further, in the optical information reproducing method, the plurality of interference fringes are recorded in a partial area of the recording medium, and after reproducing the plurality of interference fringes in a part of the recording medium, Information is preferably reproduced in other areas.

  Further, the optical information reproducing apparatus of the present invention comprises means for generating reproduction light for reproducing the interference fringes recorded on the recording medium, and for reproducing the control information and the reference mark recorded on the recording medium. Means for generating control light; a reproduction optical system for irradiating the recording medium with the reproduction light; a control optical system for irradiating the recording medium with the control light; and the interference by the reproduction light. Detected by the first detection means for detecting the reproduction light generated from the stripes, the second detection means for detecting the control information and the reference mark reproduced by the control light, and the second detection means A relative positional relationship between the control light and the reproduction light is detected from a reference mark and the reproduction light detected by the first detection means, and the relative relationship between the control light and the reproduction light is detected. To control general positional relationship And having a stage.

  Furthermore, in the optical information reproducing apparatus, the control means is configured to position the control light and the reproduction light relative to each other by means of a displacement means for displacing the reproduction optical system or a part of the control optical system. The relationship may be controlled, and the relative position of the control light and the reproduction light by controlling the position information in the timing of irradiating the control light or the reproduction light or the reproduced control information The relationship may be controlled.

  Further, another optical information reproducing apparatus of the present invention reproduces means for generating reproduction light for reproducing interference fringes recorded on a recording medium, and control information and reference marks recorded on the recording medium. Means for generating control light, an optical system for irradiating the recording medium with the reproduction light, an optical system for irradiating the recording medium with the control light, and the interference fringes by the reproduction light. First detection means for detecting the generated reproduction light, second detection means for detecting the control information and reference mark reproduced by the control light, and the reproduction light in the hologram recording layer of the recording medium The magnification of the reproduction light in the hologram recording layer is detected from the displacement means for changing the magnification of the light, the reference mark detected by the second detection means, and the reproduction light detected by the first detection means. And characterized by a control means for changing the magnification in the hologram recording layer of the reproducing light by said displacement means.

  Further, another optical information reproducing apparatus of the present invention reproduces means for generating reproduction light for reproducing interference fringes recorded on a recording medium, and control information and reference marks recorded on the recording medium. Means for generating control light, an optical system for irradiating the recording medium with the reproduction light, an optical system for irradiating the recording medium with the control light, and the interference fringes by the reproduction light. First detection means for detecting the generated reproduction light, second detection means for detecting the control information and reference mark reproduced by the control light, and rotation about the optical axis of the reproduction light A rotation angle around the optical axis of the reproduction light is detected from the displacement means for changing the angle, the reference mark detected by the second detection means, and the reproduction light detected by the first detection means. And by the displacement means And having a control means for varying the rotation angle around the optical axis of the reproduction light Te.

  The optical information recording method of the present invention is an optical information recording method for recording information on a recording medium on which information is recorded by interference fringes, the recording medium comprising a hologram recording layer on which interference fringes are recorded, A control information layer on which control information reproduced by the control light is recorded; and a plurality of reference marks detectable by the control light; a plurality of interference fringes in the hologram recording layer in association with the reference mark The plurality of interference fringes are arranged by changing a relative positional relationship between each interference fringe and a reference mark associated with the interference fringe, and the control light and the reference mark are arranged. The recording medium is irradiated with reproduction light for reproducing the interference fringes recorded in association with the recording medium, the reference mark is detected by the control light, and the reproduction light generated from the interference fringes by the reproduction light is reproduced. Light is detected, a relative positional relationship between the control light and the reproduction light is detected from the detected reference mark and the detected reproduction light, and the control light or the relative light of the reproduction light is detected. After controlling the positional relationship, the recording light is irradiated using the same optical system as the reproducing light to record interference fringes on the hologram recording layer.

  The optical information recording method of the present invention is an optical information recording method for recording information on a recording medium on which information is recorded by interference fringes, the recording medium comprising a hologram recording layer on which interference fringes are recorded, A control information layer in which control information reproduced by the control light is recorded, and a plurality of reference marks detectable by the control light, and a magnification of the recording light in the hologram recording layer in association with the reference mark And a plurality of interference fringes are recorded on the hologram recording layer, and the recording medium is irradiated with reproduction light for reproducing the interference fringes recorded in association with the control light and the reference mark. The reference mark is detected by the control light, the reproduction light generated from the interference fringe is detected by the reproduction light, and the reproduction is performed from the detected reference mark and the detected reproduction light. After detecting the magnification of the light in the hologram recording layer and controlling the magnification of the reproduction light in the hologram recording layer, the recording light is irradiated using the same optical system as the reproduction light to interfere with the hologram recording layer It is characterized by recording stripes.

  The optical information recording method of the present invention is an optical information recording method for recording information on a recording medium on which information is recorded by interference fringes, the recording medium comprising a hologram recording layer on which interference fringes are recorded, A control information layer on which control information reproduced by the control light is recorded; and a plurality of reference marks that can be detected by the control light; and the optical axis of the recording light is centered in association with the reference mark A plurality of interference fringes are recorded on the hologram recording layer by changing the rotation angle of the recording medium, and the recording light is reproduced to reproduce the interference fringes recorded in association with the control light and the reference mark. , The reference mark is detected by the control light, the reproduction light generated from the interference fringe is detected by the reproduction light, and the reproduction light is detected from the detected reference mark and the detected reproduction light. After detecting the rotation angle around the optical axis and controlling the rotation angle around the optical axis of the reproduction light, the hologram is irradiated with the recording light using the same optical system as the reproduction light. Interference fringes are recorded on the recording layer.

  Furthermore, in the optical information recording method, it is preferable that the reference mark is a part of control information recorded in the control information layer.

  Further, in the optical information recording method, the plurality of interference fringes are recorded in a partial area of the recording medium, and after reproducing the plurality of interference fringes in a part of the recording medium, It is preferable to record interference fringes in other areas.

  Further, the optical information recording apparatus of the present invention records an interference fringe on a recording medium, generates a recording / reproducing light for reproducing the interference fringe recorded on the recording medium, and recorded on the recording medium Means for generating control light for reproducing the control information and the reference mark, a recording / reproducing optical system for irradiating the recording medium with the recording / reproducing light, and control for irradiating the recording medium with the control light Optical system, first detection means for detecting reproduction light generated from the interference fringes by the recording / reproducing light, and second detection for detecting the control information and the reference mark reproduced by the control light The relative positional relationship between the control light and the recording / reproducing light is detected from the means, the reference mark detected by the second detecting means, and the reproduction light detected by the first detecting means. And the control light And having a control means for controlling the relative positional relationship between the recording and reproducing light.

  Further, in the optical information recording apparatus, the control means may be configured to cause the control light and the recording / reproduction light to move relative to each other by a displacement means that displaces the recording / reproduction optical system or a part of the control optical system. The positional relationship between the control light and the recording / reproducing light may be controlled by controlling the position information in the timing of irradiating the control light or the recording / reproducing light or the reproduced control information. The relative positional relationship may be controlled.

  Also, the optical information recording apparatus of the present invention records interference fringes on a recording medium, generates recording / reproducing light for reproducing the interference fringes recorded on the recording medium, and recorded on the recording medium Means for generating control light for reproducing control information and reference marks; an optical system for irradiating the recording medium with the recording / reproducing light; and an optical system for irradiating the recording medium with the control light; First detection means for detecting reproduction light generated from the interference fringes by the recording / reproducing light, second detection means for detecting the control information and reference mark reproduced by the control light, and the recording From the displacement means for changing the magnification of the recording / reproducing light in the hologram recording layer of the medium, the reference mark detected by the second detecting means, and the reproducing light detected by the first detecting means, the recording Detecting the magnification in the hologram recording layer of the raw light, and having a control means for changing the magnification in the hologram recording layer of the recording light by the displacement means.

  Also, the optical information recording apparatus of the present invention records interference fringes on a recording medium, generates recording / reproducing light for reproducing the interference fringes recorded on the recording medium, and recorded on the recording medium Means for generating control light for reproducing control information and reference marks; an optical system for irradiating the recording medium with the recording / reproducing light; and an optical system for irradiating the recording medium with the control light; First detection means for detecting reproduction light generated from the interference fringes by the recording / reproducing light, second detection means for detecting the control information and reference mark reproduced by the control light, and the recording From the displacement means for changing the rotation angle around the optical axis of the reproduction light, the reference mark detected by the second detection means, and the reproduction light detected by the first detection means, the recording and reproduction The optical axis of the light Detecting the angle of rotation, and having a control means for varying the rotation angle around the optical axis of the recording reproducing light by said displacement means.

  In the recording medium manufacturing method of the present invention, a plurality of interference fringes are recorded in a predetermined arrangement on the hologram recording layer, and the hologram recording layer on which the plurality of interference fringes are recorded has a plurality of reference marks. The information layer is characterized in that each of the plurality of reference marks and each of the plurality of interference fringes are associated and coupled.

  Further, in the method for manufacturing a recording medium, when recording the plurality of interference fringes, a temporary control information layer having a plurality of reference marks having the same arrangement as the predetermined arrangement is coupled to the hologram recording layer. Preferably it is.

  According to the recording medium of the present invention, since the plurality of interference fringes whose recording conditions are changed in association with the reference mark are recorded on the hologram recording layer, in the optical information recording / reproducing apparatus using the recording medium, the recording / reproducing conditions The conditions can be determined. For this reason, it is possible to unify the recording / reproducing conditions between different devices, and the versatility between the devices can be improved.

  According to the optical information recording method of the present invention, it is possible to record a plurality of interference fringes on the hologram recording layer by changing the recording condition in association with the reference mark, and the recorded recording medium is recorded and reproduced as described above. Conditioning can be performed and versatility between apparatuses can be enhanced.

  According to the optical information reproducing method or the optical information reproducing apparatus of the present invention, even when reproducing a recording medium recorded in a different apparatus, the condition for reproducing conditions is determined from the interference fringes recorded in association with the reference mark. It is possible to increase the versatility between apparatuses.

  According to the optical information recording method or the optical information recording apparatus of the present invention, it is possible to determine the recording conditions from the interference fringes recorded in association with the reference mark, and it is possible to always record under constant conditions. The versatility between apparatuses can be improved.

  Further, according to the recording medium manufacturing method of the present invention, after recording a plurality of interference fringes, the control information layer having a plurality of reference marks is combined with each of the plurality of reference marks in association with each other. A recording medium having a plurality of interference fringes associated with a plurality of reference marks can be easily obtained. Other effects of the present invention will be described in the embodiments.

(A) is a schematic plan view of the recording medium of the present invention, and (B) is a schematic cross-sectional view. (A) thru | or (C) is a schematic sectional drawing which shows one of the embodiment of the control information layer in the recording medium of this invention, respectively. Diagram explaining the effects caused by changes in recording conditions Schematic plan view of a recording medium on which interference fringes are recorded by changing the positional relationship with respect to a reference mark Schematic sectional view of a recording medium recorded by changing the focal position of the recording light in the thickness direction of the recording medium The figure which shows the change of the reproduction light when reproducing the plural interference fringes Schematic configuration diagram of an optical information recording / reproducing apparatus of the present invention Schematic configuration diagram of a conventional optical information recording / reproducing apparatus Schematic diagram enlarging the vicinity of the recording medium Schematic plan view of a recording medium irradiated with recording / reproducing light and servo light (A) And (B) is a schematic plan view of a recording medium showing an arrangement in which the positional relationship between a reference mark and an interference fringe is changed in an oblique direction. (A) to (C) are schematic plan views of a recording medium in which the positional relationship of the reference marks is changed. (A) thru | or (D) is a figure explaining the interference fringe in which diffraction efficiency has direction dependence. (A) and (C) are diagrams showing spatial modulation patterns of information light and recording reference light for forming interference fringes whose diffraction efficiency has direction dependence, and (B) is direction dependence of diffraction efficiency. Illustration showing sex The figure which shows one embodiment of the manufacturing method of a recording medium

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 7 and FIGS. 11 to 15.

  FIG. 1A is a schematic plan view of a recording medium 101 of the present invention, and FIG. 1B is a schematic cross-sectional view thereof. The recording medium 101 includes a hologram recording layer 107 on which interference fringes are recorded, a control information layer 103 on which control information is recorded, and a plurality of reference marks 109a to 109h. A plurality of interference fringes 110a to 110h in which the recording conditions are changed in association with the reference marks 109a to 109h are recorded. Further, the recording medium 101 in FIG. 1 includes a substrate 102, a first gap layer 104, a wavelength selective reflection layer 105, a second gap layer 106, and a protective layer 108.

  Although the disc-shaped recording medium 101 is shown in FIG. 1, it is not limited to the disc shape, and may be a rectangular card shape, for example. If it is disk-shaped, information can be recorded and reproduced efficiently by being driven to rotate.

  The hologram recording layer 107 records interference fringes between information light and a recording reference wave, and is particularly preferably a material that is sensitive to recording / reproducing light and not sensitive to control light. As the hologram recording layer 107, for example, a photopolymer material can be used. If a photopolymer material having sensitivity to green and blue light is used as the material of the hologram recording layer 107, green or blue light is used as recording / reproducing light, and other wavelengths are used as control light. Light, such as red light, may be used. In the present invention, the hologram recording layer 107 is not limited to a photopolymer material.

  In the control information layer 103, control information reproduced by the control light is recorded. The control information layer 103 may be dedicated to reproduction in which information is recorded in advance or information can be recorded and reproduced. Examples of the control information include servo address information for recording / reproducing light, recording medium identification information indicating the capacity and structure of the recording medium, and the like.

  2A to 2C are schematic cross-sectional views of the recording medium 101 when a layer in which pits are formed in advance is used as the reproduction-only control information layer 103. FIG. As shown in FIGS. 2A to 2C, information can be reproduced by changing the reflectance or transmittance of the control light 15 due to the unevenness of the pits. It is preferable to form a reflective layer as a part of the control information layer 103 when reproducing information by a change in reflectance or detecting a change in transmittance on the incident surface side. Concavities and convexities are formed on the surface of the substrate 102, and if necessary, a reflective layer may be formed on the uneven surface to form pits. Alternatively, a pit-forming layer may be formed on the substrate 102, and the concavo-convex portions may be formed thereon by etching or the like. The structure etc. which formed and formed the reflection layer in the uneven | corrugated surface as needed can also be used. By using the pits, servo address information, identification information of the recording medium 101, and the like can be recorded in advance.

  FIG. 2A is a schematic cross-sectional view of a hologram recording medium 101 in which a concavo-convex shape is formed on the surface of the substrate 102 and a reflective layer 111 is formed on the concavo-convex surface to form a reflective control information layer 103. FIG. 2B is a schematic cross-sectional view of the hologram recording medium 101 in which the control information layer 103 is formed by forming the metal layer 112 on the substrate 102 and etching by photolithography to form the holes 112a. The control information layer 103 including the metal layer 112 and the hole 112a shown in FIG. 2B can be used as both the reflective control information layer 103 and the transmissive control information layer. FIG. 2C is a schematic cross-sectional view of a hologram recording medium 101 in which a concavo-convex shape is formed on the surface of the substrate 102 to form a transmission type control information layer 103. In FIG. 2C, the surface of the substrate 102 functions as the control information layer 103.

  In this specification, the case of the reflective control information layer 103 will be described, but in the case of the transmissive control information layer 103, a photodetector for detecting control light is arranged on the back side of the recording medium 101. .

  As the control information layer 103 that can be recorded and reproduced, an organic dye layer, a phase change layer, or the like can be used. When the control information layer 103 is an organic dye layer, information can be recorded only once, and pits can be formed by decomposing the dye with laser light. Information can be reproduced from the formed pits by changing the reflectance or transmittance of the pits as in the reproduction-only layer.

  In the case where the control information layer 103 is a phase change layer, information can be rewritten and the crystal portion is formed by changing the crystal structure of the phase change layer by heating with a laser beam to form a crystalline portion and an amorphous portion. Information can be recorded according to the difference in reflectance or transmittance between the amorphous part and the amorphous part.

  The reference marks 109a to 109h serve as a reference for specifying the position on the recording medium 101, and may be any marks that can be detected by the control light. It is preferable to use a part of the control information recorded in the control information layer 103 as the reference marks 109a to 109h. For example, the control information recorded in the system area provided separately from the area where the normal information of the recording medium 101 is recorded or the interference fringes are recorded in association with the pit using the pit as the address information as a reference mark. As a reference mark, interference fringes may be recorded in association with the pit. In this case, a plurality of interference fringes 110 for determining conditions can be recorded without reducing the recording capacity of normal information. Further, an identifier that can be detected by the control light may be provided separately from the control information. For example, a pit as a reference mark is separately formed on the control information layer 103, a reference mark layer is provided, or a seal that selectively reflects control light on the protective layer 108 is used as a reference mark. Alternatively, the reference mark may be printed by selectively printing ink that reflects the control light.

  The plurality of interference fringes 110a to 110h are provided for determining the conditions related to the recording reference light or the reproduction reference light of the recording / reproducing apparatus, and change the recording conditions related to the reference light when recording each interference fringe. ing. The plurality of interference fringes 110a to 110h are formed by interference of information light and recording reference light.

  The spatial modulation patterns of information light for recording each interference fringe are preferably the same, and the spatial modulation patterns of recording reference light for recording each interference fringe are preferably the same. By doing so, it is not necessary to consider the influence on the reproduction light due to the difference in the spatial modulation pattern of the information light or the recording reference light, and the influence on the reproduction light due to the change of the recording condition can be detected more accurately. You can make conditions. Furthermore, if the recording modulation reference light has the same spatial modulation pattern, it can be reproduced by the reproduction reference light having the same spatial modulation pattern, so that there is no limitation on the switching time of the spatial modulation pattern, and conditions are determined more quickly. be able to.

  As will be described in detail with reference to FIGS. 13 and 14, when the irradiation position of the control light and the irradiation position of the recording / reproducing light in the plane direction are changed as the recording conditions of the plurality of interference fringes 110a to 110h, each interference fringe 110a. ˜110h, it is preferable that the diffraction efficiency in the plane direction of the recording medium 101 has direction dependency. For this reason, it is preferable to use a spatial modulation pattern of information light or a spatial modulation pattern of recording reference light whose diffraction efficiency has direction dependency.

  The fact that the interference fringe 110 is recorded in association with the reference mark 109 means that the interference fringe 110 is positioned by the reference mark 109 detected by the control light 15.

  For example, if the interference light 110a is recorded by irradiating the recording light 14 when the control light detects the reference mark 109a, the interference fringe 110a is recorded in association with the reference mark 109a. After the control light detects the reference mark 109a, the time when the recording medium reaches the position again is calculated, and the recording light 14 is irradiated to the position of the reference mark 109a to record the interference fringe 110a. The interference fringe 110a is recorded in association with the reference mark 109a. Even when the control light detects the reference mark 109a and irradiates the recording light 14 after a specific time and records the interference fringe 110a, the interference fringe 110a is recorded in association with the reference mark 109a. Will be. Furthermore, even when a plurality of interference fringes 110 are recorded by irradiating the recording light 14 at regular intervals after the control light detects the reference marks 109a, the plurality of interference fringes are recorded in association with the reference marks 109a. Will be. Therefore, even if the reference mark 109a is not located in the area of the interference fringe 110, the interference fringe 110 may be recorded in association with the reference mark 109a. Alternatively, as described in detail in the description of FIG. 15, after recording the interference fringes 110, the reference marks may be associated afterwards.

  As a recording condition to be changed in a plurality of interference fringes, it is better to consider an error between apparatuses. For example, a relative positional relationship between the interference fringes and a reference mark associated with the interference fringes (recording / reproduction) (Relative positional relationship between the irradiation position of the control light and the irradiation position of the control light), the magnification of the recording light for recording the interference fringes in the hologram recording layer, and the optical axis of the recording light for recording the interference fringes The rotation angle, the wavelength of the recording / reproducing light, the incident angle of the recording / reproducing light with respect to the recording medium, and the like.

  FIG. 3 is a diagram for explaining a part of the influence caused by the change of the recording condition. FIG. 3A shows an ideal relationship between the recording / reproducing light and the control light, and the control light 115 for detecting the center of the interference fringe 110a formed and reproduced by the recording / reproducing light and the reference mark 109a. The center of is consistent. In the interference fringe 110, bright spots 116 are generated at equal intervals from the center due to diffraction caused by the spatial modulation pattern of the recording / reproducing light.

  FIG. 3B shows a case where the irradiation position of the control light and the irradiation position of the recording / reproducing light in the plane direction of the recording medium are changed. The interference fringe 110b is displaced from the position of the ideal interference fringe 110a (dotted line), and the relative positional relationship between the interference fringe 110b and the reference mark 109b changes. This can be changed, for example, by tilting the optical axis of the recording / reproducing light or control light emitted from the light source. Further, the relationship between the relative irradiation positions can also be changed by controlling the timing at which light is emitted from the light sources of the recording / reproducing light and the control light or the position information in the reproduced control information.

  FIG. 3C shows a case where the magnification of the recording light in the hologram recording layer is changed, and the magnification of the interference fringe 110c changes. This can be changed, for example, by changing the magnification by the pair of relay lenses.

  FIG. 3D shows a case where the rotation angle around the optical axis of the recording light is changed, and the bright spot 116 in the interference fringe 110d is rotated and recorded by rotating the spatial modulation pattern. . This can be changed, for example, by rotating the spatial light modulator with respect to the optical axis of the recording / reproducing light.

  FIG. 3E shows a case where the position of the spatial modulation pattern in the recording light changes, and the position of the bright spot 116 in the interference fringe 110d changes. This can be changed, for example, by translating the spatial light modulator in a direction orthogonal to the optical axis of the recording / reproducing light.

  FIG. 4 is a schematic plan view of a recording medium on which the interference fringes 110 are recorded by changing the positional relationship in the plane direction of the recording medium with respect to the reference mark 109. In FIG. 4, a plurality of reference marks 109 are arranged on a straight line for explanation, but the reference marks 109 are not necessarily arranged on a straight line, and may be arranged on a circular or spiral track. It may be arranged in a way.

  In FIG. 4, since the interference fringes 110a to 110g are shifted in the arrangement direction (the horizontal direction of the paper) with respect to the arrangement 117 of the plurality of reference marks 109a to 109g, the upper stage shows the recording / reproducing light and control light in the horizontal direction. It is possible to detect a shift in the positional relationship between Since the lower stage shifts the interference fringes 110h to 110n in the direction orthogonal to the upper stage (vertical direction on the paper surface) with respect to the arrangement 117 of the plurality of reference marks 109h to n, the recording / reproducing light and the control light in the vertical direction are shifted. A positional shift can be detected. It is preferable to use both the upper stage and the lower stage because a positional deviation in the plane direction of the recording medium can be grasped in a certain area. Note that if the positional relationship between the recording / reproducing light and the control light is expected to shift in a wider range, it is possible to change the positional relationship between the reference mark and the interference fringe only in one of the two orthogonal directions. It is not possible to record interference fringes in various arrangements by changing both orthogonal directions.

  For example, if the recording medium is a disk, the horizontal direction can be the circumferential direction and the vertical direction can be the radial direction. In this case, the circumferential direction is the direction that advances when the recording medium rotates during recording or reproduction. When the interference fringes are continuously recorded, the interference fringes are arranged in the circumferential direction and are reproduced. The interference fringes arranged in the circumferential direction are sequentially reproduced.

  Further, as shown in FIGS. 11A and 11B, each interference fringe 110a-n is recorded with respect to the reference mark 109a-n associated with the interference fringe using the array 117a of a plurality of reference marks as a reference. You may arrange | position by changing a relative positional relationship about the diagonal direction (direction of a dotted line) in the plane direction of a medium. In FIG. 11A, the interference fringes 110a-g are shifted in the diagonally left direction with respect to the arrangement 117a of the reference marks 109a-g, and FIG. 11B shows the right side of the arrangement 117a of the reference marks 109h-n. The interference fringes 110h to 110n are shifted in an oblique direction. In FIGS. 11A and 11B, the arrangement 117a of the reference marks 109a to 109n is linear, but it may be curved corresponding to a track on a disk-shaped recording medium. In this case, the reference marks may be arranged obliquely with respect to the tangent line at the position of each reference mark.

  In FIG. 4, a plurality of reference marks 109a to 109n are arranged at regular intervals, and a plurality of interference fringes 110a to 110n are recorded with the positional relationship changed. On the contrary, as shown in FIGS. 12A and 12B, a plurality of interference fringes 110a to 110n are arranged at regular intervals, and the positions of the reference marks 109a to 109n are arranged with respect to this arrangement. The relationship may be changed, and as shown in FIG. 12C, any of the plurality of reference marks 109a to 109g and the plurality of interference fringes 110a to 110g may be normally recorded. The positional relationship may be changed with respect to the arrangement.

  12A and 12B, an array 117b (shown by a one-dot chain line in the figure) of a plurality of interference fringes 110a to 110n is a straight line at a constant interval, similarly to the arrangement of a plurality of normally recorded interference fringes. Alternatively, they are arranged on an arc. In FIG. 12A, the positional relationship of the array 117c (shown by dotted lines in the figure) of the plurality of reference marks 109a to 109g is changed in the orthogonal direction with respect to the array 117b of the plurality of interference fringes. In FIG. 12B, the plurality of reference marks 109h to 109i are arranged with the positional relationship changed in the arrangement direction with respect to the arrangement 117b of the plurality of interference fringes.

  In FIG. 12C, the plurality of interference fringes 110o-u and the plurality of reference marks 109o-u are orthogonal to a plurality of interference fringe arrays 117b (indicated by alternate long and short dash lines) that are normally recorded. They are arranged by changing the positional relationship with respect to each direction. However, the amount of displacement differs between the plurality of interference fringes 110o-u and the plurality of reference marks 109o-u. In FIG. 12C, an array 117c of the plurality of reference marks 109o to 109u is indicated by a dotted line, and an array 117d of the plurality of interference fringes 110o to u is indicated by a broken line.

  In FIGS. 12A to 12C, when the positional deviation is detected by the plurality of interference fringes 110a to 110u, the recording and reproduction light 114 is reproduced by reproducing along the arrangement of the reference marks 109a to 109u. The relative positional relationship between the irradiation position and the irradiation position of the control light 115 can be detected. In FIG. 12, the positional relationship of the reference marks in the plane direction of the recording medium is changed. However, the positional relationship of the reference marks may be changed in the thickness direction of the recording medium.

  A plurality of interference fringes are recorded along the reference marks of FIGS. 12A to 12C, and at the time of reproduction, reproduction reference light is irradiated along the array 117b of the plurality of interference fringes that are normally recorded. In addition, the relative positional relationship between the irradiation position of the recording / reproducing light 114 and the irradiation position of the control light 115 can be detected.

  In addition, when the interference fringes 110 are recorded with the positional relationship in the plane direction of the recording medium changed with respect to the reference mark 109, each interference fringe 110 has direction dependency in the diffraction efficiency in the plane direction of the recording medium. It is preferable. FIGS. 13A to 13D show the reproducible range 119 of each interference fringe when the interference fringe 110 is recorded with the positional relationship in the plane direction of the recording medium changed with respect to the reference mark 109. FIG. FIGS. 13A and 13B show an isotropic case where the diffraction efficiency has no direction dependency, and FIGS. 13C and 13D show different cases where the diffraction efficiency has a direction dependency. This is the case of a direction. 13A to 13D, the interference fringes 110a to 110g (shown by dotted lines) are recorded with being shifted in the arrangement direction with respect to the arrangement 117 of the plurality of reference marks 109a to 109g as in the upper part of FIG. Has been.

  As shown in FIG. 13A, when the diffraction efficiency is isotropic, the reproducible ranges 119a to 119g of each interference fringe are circular. FIG. 13B is a collection of the reproducible ranges 119a to 119g of FIG. 13A with the reference mark 109 as a reference, and a set portion 119X (a hatched area) is shown in FIG. This is a region in which the positional deviation between the reproduction light and the control light can be grasped by the plurality of interference fringes 110a to 110g in A). That is, when the collection portion 119X is irradiated with the reproduction light, at least one of the interference fringes 110a to 110g is reproduced, and based on the reproduced information, the positional relationship shift in the arrangement direction is grasped and controlled. can do. However, in FIG. 13B, even when the reproduction light is irradiated to the position X where the reproduction light and the control light are shifted in the direction orthogonal to the arrangement direction, the interference fringes cannot be reproduced and the positional deviation cannot be grasped. For this reason, it is necessary to record a plurality of interference fringes in which the positional relationship in the arrangement direction is changed while being shifted in a direction orthogonal to the arrangement direction, and widen the reproducible area 119Y (indicated by a dotted line).

  As shown in FIG. 13C, when the diffraction efficiency is anisotropic, the reproducible ranges 119a to 119g of the interference fringes are not circular but deformed. In FIG. 13C, the reproducible ranges 119a to 119g are vertically long ellipses, and have high selectivity in the arrangement direction and low selectivity in the direction orthogonal to the arrangement direction. In other words, the diffraction efficiency of the interference fringes in FIG. 13C decreases steeply in the arrangement direction and gradually decreases in the direction orthogonal to the arrangement direction.

  FIG. 13D is a collection of the reproducible ranges 119a to 119g of FIG. 13C using the reference mark 109 as a reference, and a set portion 119Z (a hatched area) is shown in FIG. This is a region in which the positional deviation between the reproduction light and the control light can be grasped by the plurality of interference fringes 110a to 110g in C). That is, when the collection portion 119Z is irradiated with reproduction light, at least one of the interference fringes 110a to 110g is reproduced, and based on the reproduced information, the positional relationship shift in the arrangement direction is grasped and controlled. can do. And since each reproducible range 119a-g has low selectivity in the direction orthogonal to the arrangement direction, the positional relationship in the arrangement direction can be grasped in a wider range. For example, even when the reproduction light is irradiated to the position X that could not be grasped in FIG. 13B, it is possible to grasp the positional relationship shift in the arrangement direction.

  In this way, if the selectivity in the direction for confirming misalignment is increased and the selectivity in other directions is decreased, the time required for alignment can be shortened while ensuring the alignment accuracy. Can do.

  In order to form an interference fringe whose diffraction efficiency has direction dependency, the interference itself between the information light for recording the interference fringe and the recording reference light may have direction dependency. For example, as for the spatial modulation pattern of information light or the spatial modulation pattern of recording reference light, the spatial frequency is not uniform or uniform in the plane direction, but may be different in frequency components in a specific direction.

  FIGS. 14A and 14C are examples of embodiments of the spatial modulation pattern of information light and the spatial modulation pattern of recording reference light, respectively, and FIG. 14B shows the information light of FIG. 4 is a reproduced image when the interference fringes recorded by the recording reference beam are reproduced while shifting the position. Note that X and Y in FIG. 14B are coordinate axes shown on the right side of FIG.

  As shown in FIG. 14A, the spatial modulation pattern 140 of information light has five squares arranged at the center so as to intersect with each other, and four squares separated from each other by the same distance in four directions in the XY direction. Is a shape in which is arranged. For this reason, the spatial modulation pattern 140 of information light is symmetrical with respect to the X direction and the Y direction, and the frequency components in the X direction and the Y direction are equal. The spatial modulation pattern 141 of the recording reference light has a shape extending linearly from the center in the Y direction around the information light, and has a high frequency component in the X direction and a low frequency component in the Y direction.

  As shown in FIG. 14B, the interference fringes recorded by the information light and the recording reference light in FIG. 14A are reproduced even if the irradiation position of the reproduction light is moved by 9 μm in the X direction. Spatial modulation pattern of light, that is, 5 squares crossed at the center and 4 squares spaced apart from each other can be reproduced, but when moved 9 μm in the Y direction, spatial modulation of the reproduced light The pattern cannot be confirmed and cannot be played back. As described above, the interference fringes recorded by the information light and the recording reference light in FIG. 14A have low selectivity in the X direction and high selectivity in the Y direction. Has dependency. The interference fringes are preferably recorded with the positional relationship shifted in the Y direction.

  Furthermore, if the spatial modulation pattern 142 of the recording reference light as shown in FIG. 14C is used, the frequency component in the X direction is higher than that of the spatial modulation pattern 141 in FIG. Therefore, the selectivity in the Y direction can be further increased. Note that the interference fringes reproduced in FIG. 14B are interference fringes when the information light and the recording reference light in FIG. 14A are irradiated onto the recording medium by the objective lens so as to converge. This is due to interference between images obtained by Fourier transform of the spatial modulation pattern shown in A).

  FIG. 5 is a schematic cross-sectional view of a recording medium recorded by sequentially changing the focal position 114a of the recording light 114 in which the interference fringes 110o to 110q are recorded in the thickness direction of the recording medium. Each interference fringe 110o-q is associated with each reference mark 109o-q, respectively. A shift between the focal position 114a of the recording / reproducing light 114 and the focal position 115a of the control light 115 can be detected from the plurality of interference fringes 110o to 110q in FIG.

  When detecting the relative positional relationship between the recording / reproducing light 114 and the control light 115, it is preferable to associate the reference mark 109 with each interference fringe 110 because the detection accuracy is improved.

  Further, as shown in FIG. 3C, if the interference fringes are sequentially recorded by gradually changing the magnification of the recording light in the hologram recording layer, the magnification of the recording / reproducing light 114 in the hologram recording layer can be detected. As shown in FIG. 3D, if the interference fringes are sequentially recorded by gradually changing the rotation angle around the optical axis of the recording light, the rotational direction of the spatial modulation pattern with respect to the optical axis can be detected. As shown in FIG. 3E, if the interference fringes are sequentially recorded by gradually changing the position of the spatial modulation pattern in the recording light, the position in the direction orthogonal to the optical axis of the spatial modulation pattern is detected. it can. Furthermore, if the interference fringes are sequentially recorded by changing the wavelength of the recording light, it is possible to detect the wavelength error of the light source. Further, if the interference fringes are sequentially recorded by changing the incident angle of the recording light, an error in the incident angle of the recording light in each apparatus can be detected.

  The plurality of interference fringes 110 are recorded for condition determination, and may be recorded in a partial area of the recording medium. In particular, if recording is performed in an area (for example, a system area) provided separately from an area for recording normal information, a plurality of interference fringes 110 for recording conditions are recorded without reducing the recording capacity of normal information. be able to.

  Also, when rotating a disk-shaped recording medium, if a plurality of interference fringes are arranged on the same track provided in the circumferential direction of the recording medium, the irradiation position of the reproduction light is fixed and the recording is performed. A plurality of interference fringes can be reproduced simply by rotating the medium, which is efficient. For example, if interference fringes are recorded without overlapping on a circle having a radius of 23 mm, since the diameter of the interference fringes is 200 μm, 722 interference fringes can be recorded. Therefore, conditions can be determined 722 times in one round, and can be performed in a short time and reliably.

  In FIG. 1, a plurality of interference fringes 110a to 110h are arranged at equal intervals on the same track in the system region 101a near the center, and conditions are determined by making one rotation while reproducing under the same irradiation conditions. be able to.

  FIG. 6 is a diagram illustrating a change in reproduction light when a plurality of interference fringes are reproduced under the same reproduction condition. In FIG. 6, the horizontal axis 6 is related to the reference mark, and the vertical axis 9 is an amount related to the reproduction level of the interference fringes, for example, the light amount, SNR, error rate, and the like. Curves 7 and 8 were taken with different devices. From the curve 7 and the curve 8, the tendency in the reproduced device can be grasped. That is, in the curves 7 and 8, the playback level gradually increases from the reference mark whose playback level is almost zero, the playback level becomes maximum at a certain reference mark, and then the playback level gradually decreases. Therefore, it can be seen that the condition for recording the interference fringes recorded in association with the reference mark having the maximum reproduction level is closest to the irradiation condition of the recording / reproducing apparatus.

  Furthermore, it becomes clear that there is a difference in irradiation conditions by Δ for the apparatus of curve 7 and the apparatus of curve 8. Therefore, if the conditions of the apparatus of curve 7 or the apparatus of curve 8 are changed by Δ, the same conditions can be recorded or reproduced by the apparatus of curve 7 and the apparatus of curve 8, and versatility is improved.

  Assuming that the relationship between the recording / reproducing light and the control light is the relationship between the reference mark 109d and the interference fringe 110d in FIG. 4 (the relationship between the reference mark 109k and the interference fringe 110k is the same), The reproduction light will be described with reference to FIG. First, even when the reproduction light is irradiated when the control light detects the reference marks 109a and 109h, the reproduction is hardly reproduced from the interference fringes 110a and 110h, and the reproduction level becomes almost zero. Next, when the reproduction light is irradiated when the control light detects the reference marks 109b and 109i, the interference fringes 110b and 110i increase interference more than the interference fringes 110a, so that the reproduction level increases. Further, if the reproduction light is irradiated when the control light detects the reference marks 109c and 109j, the interference fringes 110c and 110j further interfere with each other, and the reproduction level increases. When the reproduction light is emitted when the control light detects the reference marks 109d and 109k, the reproduction light is emitted in the same state as during recording, so that the reproduction level generated from the interference fringes 110d and 110k is maximized. . Thereafter, since the interference decreases again, the reproduction level gradually decreases.

  The correspondence between the change in the recording conditions of the plurality of interference fringes 110 and the reference mark may be input to the control means in advance, or may be recorded as control information on the recording medium 110 and reproduced by the control light. May be. Furthermore, if the plurality of interference fringes 110 are recorded by supporting the information light with the change in the recording conditions of the plurality of interference fringes 110 and the correspondence between the reference marks as information, the plurality of interference fringes 110 are reproduced to obtain the most suitable recording condition. While specifying the near interference fringes, the correspondence between the change in the recording conditions of the plurality of interference fringes 110 and the reference marks can be obtained from the information of the reproduction light obtained from the interference fringes with the closest recording conditions. Further, a non-volatile memory such as an EPROM may be installed in the cartridge that accommodates the recording medium, and the correspondence between the change in the recording condition of the plurality of interference fringes 110 and the reference mark may be recorded in the memory. In addition, it is preferable that the cartridge can block light having a wavelength at which the hologram recording layer is exposed to prevent the recording medium from being exposed to photosensitive light.

  As described above, in the recording medium of the present invention, the irradiation condition of the recording / reproducing apparatus can be detected. If the irradiation condition of the recording / reproducing apparatus is adjusted based on the detection result, the irradiation condition between the recording / reproducing apparatuses can be changed. Since they are unified, recording can be performed under the same conditions regardless of which apparatus is used, and even interference fringes recorded by different apparatuses can be reproduced. The irradiation condition of the recording / reproducing apparatus may be automatically adjusted to a specific condition from the detected irradiation condition of the recording / reproducing apparatus.

  As the recording medium of the present invention, all the recording media may be provided with a reference mark for determining the condition and a plurality of interference fringes. However, the recording medium may be used as a reference medium for determining the condition of adjustment and maintenance of the apparatus. Good.

  In the recording medium 101 of FIG. 1, as the substrate 102, a plastic substrate such as polycarbonate, a glass substrate, a metal substrate, or the like can be used. When a plastic substrate is used, pits can be easily formed as a control information layer by forming a concavo-convex shape on the surface by pressing. In addition, the glass substrate has high strength and smoothness, and can reduce the influence of inclination due to the bending of the substrate. The metal substrate can also serve as a reflection layer for the control light. The shape of the substrate 102 may be a disk shape or a card shape.

  Further, the thickness of the substrate 102 is not particularly limited. However, if the recording medium 101 as a whole has a thickness of 1.2 to 2.4 mm, a currently used CD (Compact Disc) or DVD is used. (Digital Versatile Disc) can be made compatible.

  The wavelength selective reflection layer 105 reflects the recording / reproducing light and transmits the control light. As the wavelength selective reflection layer 105, a dichroic mirror layer or a cholesteric liquid crystal layer in which a high refractive index substance and a low refractive index substance are alternately laminated can be used. The reflection surface of the wavelength selective reflection layer 105 for the first wavelength light 2 is preferably flat so that information can be recorded and reproduced stably.

  The first gap layer 104 and the second gap layer 106 are formed by applying a resin material, for example, a material such as UV resin, by spin coating or by attaching a resin sheet such as a polycarbonate sheet. The gap layer protects the hologram recording layer 107 and the control information layer 103 and adjusts the size of the hologram generated in the hologram recording layer 107 and the interval between the focal lengths of the recording / reproducing light and control light. Is also effective. Further, since the second gap layer 106 can prevent the position near the focal point where the interference fringes are concentrated in the hologram recording layer 107, the photosensitive material of the hologram recording layer 107 is determined by the portion near the focal point where the interference fringes are concentrated. Can be alleviated, and the phenomenon that the multiplicity (the amount by which multiple holograms can be recorded at the same location) is reduced can be alleviated. The thickness of the second gap layer 106 is preferably in the range of 10 to 100 μm.

  The protective layer 108 is formed on the surface on the incident surface side of the recording medium 101 and protects the recording medium 101. The protective layer 108 is formed by applying a resin material such as a UV resin on the hologram recording layer 107 by spin coating or pasting a resin sheet such as a polycarbonate sheet.

  The recording medium 101 in FIG. 1 has a structure in which the wavelengths of the control light and the recording / reproducing light are different, and the wavelength selective reflection layer 105 transmits the control light and reflects the recording / reproducing light. However, it is not limited to this configuration.

  The recording medium of the present invention may be recorded by changing the recording conditions in the optical information recording apparatus as will be described later. However, a plurality of interference fringes are recorded on the hologram recording layer, and the positional relationship is later determined. It may be manufactured by combining control information layers having fiducial marks arranged in a varied manner.

  FIG. 15 is a diagram illustrating a method for manufacturing a recording medium. First, a plurality of interference fringes 110 are recorded on a recording medium 101 a having at least the hologram recording layer 107. In FIG. 15A, the recording medium 101 a includes not only the hologram recording layer 107 but also a protective layer 108, a gap layer 106, and a wavelength selective reflection layer 105.

  In the step of recording the plurality of interference fringes 110, the interference fringes may be recorded by transferring from the master hologram substrate. The master hologram substrate is a substrate on which interference fringes due to interference between virtual information light obtained by combining information light and recording reference light and virtual recording reference light are recorded. When the master hologram substrate is reproduced with the virtual recording reference light, the virtual information light that combines the information light and the recording reference light is reproduced. Therefore, if the reproduced virtual information light is irradiated to the hologram recording layer of another recording medium Interference fringes due to interference between the information light in the virtual information light and the recording reference light can be recorded. That is, if a master hologram substrate is used, a replica can be easily produced. In particular, if a plurality of virtual information lights are reproduced from the master hologram substrate at a time, a plurality of interference fringes can be formed at a time, so that productivity can be improved.

  As shown in FIGS. 12A and 12B, in the case where the plurality of interference fringes 110 are arranged on a straight line or an arc at regular intervals, similarly to the arrangement of a plurality of interference fringes that are normally recorded, A plurality of interference fringes 110 may be recorded mechanically on the hologram recording layer 107 at regular intervals.

  Further, as shown in FIG. 15B, if a temporary control information layer 203 is coupled to the hologram recording layer 107, a plurality of interference fringes 110 are aligned while being aligned with the control information of the temporary control information layer 203. Can be recorded. The temporary control information layer 203 is formed on, for example, another substrate 202, and the recording medium 101a may be bonded by fixing or temporarily bonding, or in the process of FIG. In the optical information recording apparatus to be used, the optical information recording apparatus may be formed on a holder in which the recording medium 101a is disposed, and may be coupled by holding the recording medium 101a in the holder. In FIG. 15B, a temporary control information layer 203 and a second gap layer 204 are formed on another wide substrate 202.

  The provisional control information layer 203 is preferably provided with a plurality of reference marks 209 having the same arrangement as the arrangement of the plurality of interference fringes 110 to be recorded. In this case, for example, FIG. 4, FIG. 5, FIG. 11 (A), (B) or FIG. 12 (C) only needs to record the plurality of interference fringes 110 following the reference mark 209 of the temporary control information layer 203. As described above, a plurality of interference fringes having a complicated arrangement can be recorded in a predetermined arrangement compared to the arrangement of interference fringes normally recorded. After recording a plurality of interference fringes, the temporary control information layer 203 may be removed. If the control information layer is rewritable, the first reference mark 209 is recorded as a temporary control information layer, and after recording the plurality of interference fringes 110, the first reference mark 209 is erased. The second reference mark 109 may be recorded as the control information layer.

  Next, as shown in FIG. 15C, a plurality of control information layers 103 having a plurality of reference marks 109 arranged in a predetermined arrangement are arranged on a hologram recording layer 107 on which a plurality of interference fringes 110 are recorded. Each of the reference marks 109 and each of the plurality of interference fringes 110 are associated and combined. In FIG. 15C, not only the control information layer 103 but also the substrate 102 and the gap layer 104 are simultaneously bonded to complete the recording medium 101. For example, reference information having a predetermined arrangement may be formed in advance on the substrate 102 to form the control information layer 103, and the gap layer 104 may be laminated and bonded to the hologram recording layer 107 side.

  In order to associate the reference marks with the interference fringes, for example, if a plurality of interference fringes are recorded in a predetermined area of the recording medium, a plurality of reference marks are arranged in an area corresponding to the predetermined area. What is necessary is just to combine so that two area | regions may overlap. For this purpose, since precise alignment is required, it is preferable to provide alignment marks on the hologram recording layer side 101a and the control information layer side.

  Next, a recording / reproducing apparatus and a recording / reproducing method capable of producing the above-described recording medium 101 and correcting recording / reproducing conditions using the above-described recording medium 101 will be described.

  FIG. 7 is a schematic configuration diagram of the optical information recording / reproducing apparatus 120. The optical information recording / reproducing apparatus 120 in FIG. 7 includes a recording / reproducing light source 135, a beam expander 134, a first displacement unit 141, a polarization beam splitter 132, a spatial light modulator 133, a fourth displacement unit 144, and a beam splitter 131. , First relay lens 129, third displacement means 143, dichroic mirror 128, objective lens 126, projection lens 136, photodetector 137, control element 124, and second displacement means 142. Then, the disk-shaped recording medium 101 is rotated by the driving unit 127.

  The optical information recording / reproducing apparatus 120 shown in FIG. 7 is different from the conventional recording / reproducing apparatus in that first to fourth displacement means 141 to 144 are provided.

  The first displacing means 141 changes the irradiation position of the recording / reproducing light 114 on the recording medium 101 to change the relative positional relationship between the irradiation position of the control light 115 and the irradiation position of the recording / reproducing light 114. It is something to change. As the first displacing means 141, the recording / reproducing light source 135 itself may be moved, but the direction of the optical axis of the recording / reproducing light 114 may be changed. For example, as shown in FIG. 7, an element for changing the light path, such as a mirror or a prism, may be provided in the optical path of the recording / reproducing light 114, and the element may be moved, or the already disposed polarized beam. A mirror such as the splitter 132 may be rotated. Further, when a spatial light modulator is used as means for generating recording / reproducing light described later, the spatial light modulator may be tilted. When changing the direction of the optical axis of the recording / reproducing light 114, it is preferable to be able to change the direction in two orthogonal directions because it can cope with all the positional deviations in the plane direction of the recording medium. A plurality of displacement means may be used in combination as the first displacement means 141.

  The second displacement means 142 changes the relative position relationship between the irradiation position of the control light 115 and the irradiation position of the recording / reproducing light 114 by changing the irradiation position of the control light 115 on the recording medium 101. It is something to be made. As the second displacement means 141, the control element 124 itself may be moved, but the direction of the optical axis of the control light 115 may be changed. For example, as shown in FIG. 7, an element for changing the light path, such as a mirror or a prism, may be provided in the optical path of the control light 115, and the element may be moved, or the dichroic mirror 128 already arranged. A mirror such as the above may be rotated. When the direction of the optical axis of the control light 115 is changed, it is preferable that the direction of the optical axis can be changed with respect to two orthogonal directions, since all the positional deviations in the plane direction of the recording medium can be handled. A plurality of displacement means may be used in combination as the second displacement means 142.

  In FIG. 7, both the first displacement means 141 and the second displacement means 142 are provided. However, either one of the displacements in the plane direction of the recording medium may be used.

  Further, instead of the first displacement means 141 and the second displacement means 142, the control light is controlled by controlling the timing of irradiating the control light 115 or the recording / reproducing light 114 or the position information in the reproduced control information. The relative positional relationship between 115 and the recording / reproducing light 114 may be controlled. When recording / reproducing while moving the recording medium 101 relative to the irradiation position, the irradiation timing is taken by PLL (Phase Lock Loop) control, but the recording / reproducing light 114 is emitted from the recording / reproducing light source 135. By adjusting the timing and the timing at which the control light 115 is emitted from the control element 124, the irradiation position in the traveling direction (circumferential direction when the recording medium is rotated in a disk shape) can be controlled. . Further, an offset may be added to the position information detected from the control information reproduced by the control light 115 to bias the tracking servo control or the focus servo control. For example, normally, the control light 115 is positioned so as to irradiate the center of the reference mark, but a bias can be applied to the tracking servo control to intentionally align the position with a position deviated from the center of the reference mark. Compared with the irradiation position of the recording / reproducing light 114 when the control light 115 irradiates the center of the reference mark, the irradiation position of the reproducing light 114 can be moved. The relative positional relationship with the recording / reproducing light 114 can be changed.

  The third displacing means 143 changes the magnification of the recording / reproducing light 114 in the hologram recording layer 107 of the recording medium 101. As the third displacing means 143, for example, in order to change the focal length of the relay lens optical system of the recording / reproducing light 114, the focal length of at least one of the pair of relay lenses may be changed. By changing the focus of at least one of the pair of relay lenses, the magnification of the image of the spatial modulation pattern displayed on the spatial light modulator on the pupil plane of the objective lens 126 can be changed. The magnification of the Fourier transform image in the hologram recording layer of the recording / reproducing light 14 can also be changed. In FIG. 1, a lens capable of changing the focal point is employed as the second relay lens. As the third displacing means 143, the magnification of the display itself of the image of the spatial modulation pattern displayed on the spatial light modulator may be changed to change the magnification in terms of information processing. A plurality of displacement means may be used in combination as the third displacement means 143.

  The fourth displacement means 144 changes the rotation angle around the optical axis of the recording / reproducing light and the position of the spatial modulation pattern in the recording / reproducing light by changing the arrangement of the spatial modulation pattern of the recording / reproducing light. (FIGS. 3D and 3E). As the fourth displacing means 144, the means for spatially modulating the light in the means for generating the recording / reproducing light is rotated about the optical axis or translated in the direction perpendicular to the optical axis. . As a means for spatially modulating, a transmissive or reflective spatial light modulator having a large number of pixels arranged in a grid and capable of modulating the phase or / and intensity of emitted light for each pixel. For example, a DMD (digital micromirror device) or a matrix type liquid crystal element can be used. When the spatial modulation pattern of the reference light is a constant pattern, a mask in which an opening of the spatial modulation pattern is formed can be used. As the fourth displacement means 144, the rotation angle about the optical axis of the recording / reproducing light can be changed even if the arrangement of the recording medium is rotated.

  Further, as the fourth displacement means 144, the display itself of the image of the spatial modulation pattern displayed on the spatial light modulator may be translated or rotated. A plurality of displacement means may be used in combination as the fourth displacement means 144. When the display of the spatial light modulator is moved or rotated, the moving distance and the rotation amount depend on the pixel pitch of the spatial light modulator. When the pixel pitch of the spatial light modulator is larger than the required alignment accuracy, not only the display of the spatial light modulator is moved or rotated but also other displacement means may be used together.

  Further, if the interference fringes are sequentially recorded by changing the incident angle of the recording light, an error in the incident angle of the recording light in each apparatus can be detected. In order to change the incident angle, for example, the objective lens may be translated perpendicularly to the optical axis.

  The optical information recording / reproducing apparatus 120 in FIG. 1 includes all of the first to fourth displacing means 141 to 144, but only one of them may be provided. Further, as another displacement means, a means capable of changing the wavelength of the recording / reproducing light may be provided. In addition, the drive means itself in the 1st thru | or 4th displacement means 141-144 may be the structure installed only at the time of condition setting, removed at the time of normal use, and the arrangement | positioning of an optical system being fixed.

  The recording / reproducing light source 135 emits light that becomes the recording / reproducing light 14. For example, a coherent linearly polarized light beam is generated using a semiconductor laser. As the recording / reproducing light source 135, a shorter wavelength is advantageous in order to perform high-density recording, and it is preferable to employ a blue laser or a green laser. As described above, the first displacement means 141 may be movable.

  The beam expander 134 is formed so that the beam diameter of the light emitted from the recording / reproducing light source 135 can be used as recording / reproducing light. A collimator lens may be used as long as it is diverging light.

  The polarization beam splitter 132 has a semi-reflective surface that reflects or transmits linearly polarized light (for example, P-polarized light) and transmits or reflects linearly polarized light (for example, S-polarized light) perpendicular to the polarized light. In FIG. 7, the polarization beam splitter 132 reflects the light beam generated from the recording / reproducing light source 135 toward the spatial light modulator 133, and the information light whose polarization direction is rotated by 90 degrees by the spatial light modulator 133. The reference light for recording or the reference light for reproduction is transmitted. The polarization beam splitter 132 may be rotatable as the first displacement unit 141.

  The spatial light modulator 133 has a large number of pixels arranged in a lattice pattern, and uses a transmissive or reflective spatial light modulator capable of modulating the phase or / and intensity of the emitted light for each pixel. can do. As the spatial light modulator, a DMD (digital micromirror device) or a matrix type liquid crystal element can be used. DMD can modulate the intensity of incident light by changing the reflection direction for each pixel, or spatially modulate the light intensity by changing the reflection position of incident light for each pixel. The liquid crystal element can spatially modulate the polarization state, intensity, phase, or the like of incident light by controlling the alignment state of the liquid crystal for each pixel. For example, the phase of the light can be spatially modulated by setting the phase of the emitted light for each pixel to one of two values that differ from each other by π radians. Further, in FIG. 7, the spatial light modulator rotates the polarization direction of the outgoing light by 90 ° with respect to the polarization direction of the incident light.

  Information light carrying the spatial modulation pattern as information can be generated by spatially modulating the light from the light source 135 with the spatial modulation pattern displayed on the display surface of the spatial light modulator 133.

  In FIG. 7, the spatial light modulator 133 also functions as means for generating, from the light from the light source 135, recording reference light at the time of recording and reference light for reproduction at the time of reproduction. As shown in FIG. 7, when information light and reference light are formed by one spatial light modulator, two regions are provided in the spatial light modulator, information light is formed in one region, and the other region is formed. In this case, reference light may be formed. Therefore, in FIG. 7, the light source 135 and the spatial light modulator 133 are recording light generating means and reproducing light generating means.

  The means for generating the reference light can be provided separately from the spatial light modulator 133. For example, the light from the light source 135 may be divided, one light may be generated by the spatial light modulator 133, and the other light may be used as the reference light. In this case, the optical system that propagates the other light including the optical element that divides the light from the light source 133 serves as reference light generation means, and the reproduction apparatus serves as reproduction light generation means. Further, another spatial light modulator may be provided in the optical system that propagates the other light to spatially modulate the reference light. In this case, since the spatial modulation pattern of the reference light needs to be imaged on the entrance pupil plane of the objective lens 126 as in the case of the information light, the spatial light modulator that generates the information light and the spatial light that generates the reference light. The modulator is a conjugate relationship.

  During reproduction, the beam splitter 131 transmits the reproduction reference light and reflects the reproduction light generated from the recording medium 101 by the reproduction reference light toward the detection unit 137.

  The first relay lens 129 in FIG. 7 is arranged between the spatial light modulator 133 and the objective lens 126 together with the third displacing means 143, and the image displayed on the spatial light modulator 133 is converted into the objective lens. It arrange | positions so that it may image on 126 entrance pupil planes. In FIG. 7, the first relay lens 129 and the third displacement means 14 are disposed between the objective lens 126 and the detection means 137, and are generated from the hologram recording layer of the recording medium 101 by the reproduction light. The image of the reproduced light on the exit pupil plane of the objective lens 126 is again formed as a real image by the detection means 137. In FIG. 7, an image is formed by the detection unit 137 via the projection lens 136 disposed in front of the detection unit 137.

  The dichroic mirror 128 has a wavelength selective reflection surface that transmits the recording / reproducing light 114 emitted from the recording / reproducing light source 135 and reflects the servo light 115. The dichroic mirror 128 may be rotatable as the second displacement means 142.

  The objective lens 126 irradiates the recording medium 101 with information light and recording reference light imaged on the entrance pupil plane at the time of recording, and causes the hologram recording layer to interfere and record, and at the time of reproduction. The reproduction reference light imaged on the entrance pupil plane is irradiated onto the recording medium 101, and the reproduction light generated from the recording medium 101 is imaged on the exit pupil plane.

  The projection lens 136 projects the reproduction light generated from the recording medium 101 onto the photodetector 137 during reproduction. With the projection lens 136, the spatial modulation pattern displayed on the spatial light modulator 133 can be enlarged and reproduced, and information can be reproduced more accurately.

  The photodetector 137 has a large number of pixels arranged in a lattice pattern, and can detect the intensity of light received for each pixel. As the photodetector 137, a CCD solid-state image sensor or a MOS solid-state image sensor can be used. Further, as the photodetector 137, a smart optical sensor in which a MOS type solid-state imaging device and a signal processing circuit are integrated on one chip (for example, a document “O plus E, September 1996, No. 202, Nos. 93 to 93). (See page 99). Since this smart optical sensor has a high transfer rate and a high-speed calculation function, it is possible to perform high-speed reproduction by using this smart optical sensor, for example, reproduction at a transfer rate on the order of G (giga) bits / second. Can be performed.

  The control element 124 reproduces control information recorded on the recording medium 101, and includes a light source that generates control light, such as a semiconductor laser, and a photodetector that receives light returned from the recording medium 101. It has. The control light 115 emitted from the control element 124 preferably does not affect the hologram recording layer of the recording medium 101, and preferably has a wavelength different from that of the recording / reproducing light 114.

  Furthermore, the optical information recording / reproducing apparatus 120 has a control means (not shown). The control means controls the operation of the optical information recording / reproducing apparatus 120 including the first to fourth displacement means 141 to 144.

  As a method of recording the interference fringes for determining the conditions on the recording medium 101, a plurality of interference fringes may be recorded on the hologram recording layer by changing the recording conditions in association with the reference mark of the recording medium 101.

  First, the control light 115 is emitted from the control element 124, and the emitted control light 115 is reflected by the second displacement unit 142, reflected by the dichroic mirror 128, and applied to the recording medium 101 by the objective lens 126. Irradiated and reflected by the recording medium 101. The reflected return light of the control light is detected by the control element 124 along the reverse path. The reference mark on the recording medium 101 is detected by the control light 115.

  Next, when the reference mark by the control light 115 is detected, the recording / reproducing light 114 is emitted from the recording / reproducing light source 135 in association with the reference mark. The recording / reproducing light 114 is enlarged in beam diameter by the beam expander 134, reflected by the first displacement means 141, and reflected by the polarization beam splitter 132 toward the spatial light modulator 133. The spatial light modulator 133 displays a spatial modulation pattern of information light and recording reference light, and generates information light and recording reference light as recording / reproducing light 114. The recording / reproducing light 114 is converted to P-polarized light by the spatial light modulator 133, passes through the polarization beam splitter 132 and the beam splitter 131, and is output from the objective lens 126 by the first relay lens 129 and the third displacement unit 143. The image of the two-dimensional pattern displayed on the spatial light modulator 133 is transferred to the pupil plane.

  Further, the recording / reproducing light 114 passes through the dichroic mirror 128 and is irradiated onto the recording medium 101 by the objective lens 126. The recording / reproducing light 114 interferes with the hologram recording layer of the recording medium 101 to form interference fringes.

  For example, when the irradiation position of the recording / reproducing light 114 on the recording medium 101 is changed as the recording condition, the recording / reproducing light can be changed by sequentially changing the angle of the first displacement means 141 in one direction for each reference mark. Since the irradiation position 114 changes in one direction, the positional relationship between the interference fringes 110a to 110n and the reference marks 109a to 109n in the plane direction of the recording medium is changed and recorded as shown in the upper or lower part of FIG. .

  As shown in the upper or lower part of FIG. 4, when changing the positional relationship between the interference fringes 110a to 110n and the reference marks 109a to 109n in the plane direction of the recording medium, the angle of the second displacing means 142 is used as a reference. You may change sequentially for every mark.

  Further, a part of the recording condition can be controlled by changing the irradiation condition and the display condition by the control means without using the physical displacement means. Note that in order to control the recording conditions by the control means, changing the irradiation conditions and display conditions may adversely affect the original recording or reproducing operation. Therefore, in addition to the control by the control means, the above physical You may utilize combining a displacement means and some control.

  For example, by gradually shifting the irradiation timing of the control light 115 and the recording / reproducing light 114, the positional relationship between the reference marks and the interference fringes in the traveling direction can be changed as shown in the upper part of FIG. it can. Furthermore, the relative positional relationship between each reference mark and the interference fringes can be changed by gradually changing the offset added to the position information detected from the control information.

  Also, as shown in FIGS. 12A to 12C, the plurality of reference marks 109 are not aligned at regular intervals, and the positional relationship changes with respect to the array 117b of the plurality of interference fringes that are normally recorded. When the plurality of interference fringes are recorded without causing the control light 114 to completely follow the displacement of the arrangement of the plurality of reference marks, the positional relationship between each reference mark and the interference fringes can be changed. it can. For example, when performing tracking servo control, PLL (Phase Lock Loop) control for irradiation timing, or focus servo control based on the information of the reference mark detected by the control light 114, a notch filter or LPF (Low Pass Filter) is used. By removing the high-frequency components, the displacement of the interference fringe array can be moderated with respect to the reference mark arrangement (FIG. 12C), or the displacement can be eliminated and the interference fringe array can be made linear ( FIG. 12 (A) and (B)).

  Further, when changing the magnification of the recording / reproducing light 114 in the hologram recording layer 107 of the recording medium 101 as the recording condition, the magnification of the recording / reproducing light 114 is sequentially changed for each reference mark by the third displacing means 143. Just do it. When changing the rotation angle about the optical axis of the recording / reproducing light or the position of the spatial modulation pattern in the recording / reproducing light as the recording condition, the fourth displacement means 144 centers the optical axis of the recording / reproducing light. If the rotation angle and the position of the spatial modulation pattern in the recording / reproducing light are sequentially changed for each reference mark, the bright spot 116 in the interference fringe 110d rotates (FIG. 3D), or the bright spot in the interference fringe 110d. The position of the point 116 changes (FIG. 3E).

  Further, the optical information recording / reproducing apparatus 120 can adjust the recording / reproducing conditions by using the recording medium 101 on which the interference fringes for condition determination are recorded.

  First, as described above, the reference mark of the recording medium 101 is detected by the control light 115 emitted from the control element 124. Next, in order to reproduce the interference fringes recorded in association with the reference mark, the recording / reproducing light 114 is emitted from the recording / reproducing light source 135. The recording / reproducing light 114 is enlarged in beam diameter by the beam expander 134, reflected by the first displacement means 141, and reflected by the polarization beam splitter 132 toward the spatial light modulator 133. A spatial modulation pattern of reproduction reference light is displayed on the spatial light modulator 133, and reproduction reference light is generated as recording / reproduction light 114. The recording / reproducing light 114 is converted to P-polarized light by the spatial light modulator 133, passes through the polarization beam splitter 132 and the beam splitter 131, and is output from the objective lens 126 by the first relay lens 129 and the third displacement unit 143. The image of the two-dimensional pattern displayed on the spatial light modulator 133 is transferred to the pupil plane.

  Further, the recording / reproducing light 114 passes through the dichroic mirror 128 and is irradiated onto the recording medium 101 by the objective lens 126. The recording / reproducing light 114 interferes with interference fringes recorded on the hologram recording layer of the recording medium 101 to generate reproducing light. The reproduction light generated from the hologram recording layer passes through the objective lens 126 and the dichroic mirror 138, and has a spatial modulation pattern formed on the pupil plane of the objective lens 126 by the first relay lens 129 and the third displacement means 143. While the image is transferred to the pupil plane of the projection lens, it is reflected by the beam splitter 131. Thereafter, the reproduction light is projected onto the photodetector 137 by the projection lens 136, and an image of the spatial modulation pattern of the reproduction light is detected.

  A curve as shown in FIG. 6 is obtained by performing the reproduction operation on a plurality of interference fringes for determining conditions while the first to fourth displacement means 141 to 144 are fixed. Here, if the curve 8 in FIG. 6 is the detection result of the optical information recording / reproducing apparatus 120, and the curve 7 is the detection result of the optical information recording / reproducing apparatus in which a plurality of interference fringes are recorded, there is a deviation of Δ between them. Exists. Therefore, the first to fourth displacement means 141 to 144 are driven to correct the deviation of Δ.

  For example, when adjusting the relative positional relationship between the irradiation position of the recording / reproducing light 114 and the irradiation position of the control light 115 on the recording medium 101, the angle of the first displacement means 141 or the second displacement means 142 is adjusted. Can be changed.

  Further, instead of the first displacing means 141 and the second displacing means 142, the timing of irradiating the control light 115 or the recording / reproducing light 114 or the position information in the reproduced control information may be controlled. When recording / reproduction is performed while moving the recording medium 101 relative to the irradiation position, timing for emitting the recording / reproduction light 114 from the recording / reproduction light source 135 and timing for emitting the control light 115 from the control element 124. And the irradiation position in the traveling direction (circumferential direction when the recording medium is rotated in a disk shape) can be controlled. In addition, an offset may be added to the position information detected from the control information reproduced by the control light 115 to bias the tracking servo or the focus servo by the control light 115.

  Further, when the magnification of the recording / reproducing light 114 in the hologram recording layer of the recording medium 101 is adjusted, the magnification of the recording / reproducing light 114 may be changed by the third displacing means 143.

  Further, when adjusting the rotation angle around the optical axis of the recording / reproducing light or the position of the spatial modulation pattern in the recording / reproducing light, the fourth displacing means 144 makes the optical axis of the recording / reproducing light as the center. The position of the spatial modulation pattern in the rotation angle or recording / reproducing light may be changed.

  Note that the information used as a reference for adjustment (in the above example, the curve 7 which is the detection result of the optical information recording / reproducing apparatus in which a plurality of interference fringes are recorded) may be recorded as control information of the recording medium 101. Alternatively, it may be recorded as information of a plurality of interference fringes for condition determination.

  In this way, if the interference fringes are recorded with the recording / reproducing light after adjusting the recording / reproducing conditions, the interference fringes are recorded under the standard recording / reproducing conditions. Interference fringes with the same recording and playback conditions are recorded. It can be played back on multiple devices. Further, if playback is performed after adjusting the recording / playback conditions, playback can be performed at a higher playback level. Changes caused by long-term use of the device can be corrected.

The adjustment may be performed every time, but may be performed only at an appropriate adjustment or maintenance time. Moreover, although it is preferable to carry out automatically by a control apparatus, it can also adjust manually.

Claims (40)

A recording medium on which information is recorded by interference fringes,
A hologram recording layer on which interference fringes are recorded, a control information layer on which control information reproduced by the control light is recorded, and a plurality of reference marks detectable by the control light,
A recording medium, wherein a plurality of interference fringes whose recording conditions are changed in association with the reference mark are recorded on the hologram recording layer.   The recording medium according to claim 1, wherein the reference mark is a part of control information recorded in the control information layer.   3. The recording according to claim 1, wherein the plurality of interference fringes are arranged by changing a relative positional relationship between each interference fringe and a reference mark associated with the interference fringe. Medium.   The recording medium according to claim 3, wherein each of the interference fringes has a direction dependency in diffraction efficiency in a plane direction of the recording medium.   The recording medium according to claim 3, wherein the plurality of reference marks are arranged by changing a positional relationship of the reference marks with respect to an array of interference fringes that are normally recorded.   The recording medium according to claim 1, wherein the plurality of interference fringes change a magnification in a hologram recording layer of recording light on which the interference fringes are recorded.   7. The recording according to claim 1, wherein the plurality of interference fringes change a rotation angle about the optical axis of the recording light on which the interference fringes are recorded. Medium.   The recording medium according to claim 1, wherein the plurality of interference fringes are recorded in a partial area of the recording medium.   9. The recording medium according to claim 1, wherein the plurality of interference fringes can be reproduced by a reproduction reference beam having a spatial modulation pattern having the same shape. An optical information recording method for recording information on a recording medium on which information is recorded by interference fringes,
The recording medium includes a hologram recording layer on which interference fringes are recorded, a control information layer on which control information reproduced by control light is recorded, and a plurality of reference marks that can be detected by the control light. ,
An optical information recording method comprising: recording a plurality of interference fringes on the hologram recording layer by changing a recording condition in association with the reference mark.   11. The optical information recording method according to claim 10, wherein the reference mark is a part of control information recorded in the control information layer.   12. The optical information recording method according to claim 10, wherein the plurality of interference fringes change a relative positional relationship between each interference fringe and a reference mark associated with the interference fringe.   13. The optical information recording method according to claim 12, wherein the interference fringes are recorded so that diffraction efficiency in the planar direction of the recording medium has direction dependency. The recording medium is arranged by changing the positional relationship of the reference marks with respect to the array of interference fringes that are normally recorded,
13. The optical information recording method according to claim 12, wherein the plurality of interference fringes are recorded without completely following the displacement of the arrangement of the plurality of reference marks.   The optical information recording method according to claim 10, wherein the plurality of interference fringes change a magnification in a hologram recording layer of recording light on which the interference fringes are recorded. .   The light according to any one of claims 10 to 15, wherein the plurality of interference fringes change a rotation angle about an optical axis of recording light on which the interference fringes are recorded. Information recording method.   The optical information recording method according to claim 10, wherein the plurality of interference fringes are recorded in a partial region of the recording medium. An optical information reproducing method for reproducing information from a recording medium on which information is recorded by interference fringes,
The recording medium includes a hologram recording layer on which interference fringes are recorded, a control information layer on which control information reproduced by control light is recorded, and a plurality of reference marks that can be detected by the control light. A plurality of interference fringes are recorded in the hologram recording layer in association with the reference mark, and the plurality of interference fringes have a relative positional relationship between each interference fringe and the reference mark associated with the interference fringe. It is arranged with changes,
Irradiating the recording medium with reproduction light for reproducing the control light and the interference fringes recorded in association with the reference mark;
Detecting the reference mark by the control light;
Detecting reproduction light generated from the interference fringes by the reproduction light;
The relative positional relationship between the control light and the reproduction light is detected from the detected reference mark and the detected reproduction light, and the relative positional relationship between the control light and the reproduction light is controlled. An optical information reproducing method comprising:   The relative positional relationship between the control light and the reproduction light is controlled by controlling the timing of irradiating the control light or the reproduction light or the positional information in the reproduced control information. The optical information reproducing method according to claim 18. An optical information reproducing method for reproducing information from a recording medium on which information is recorded by interference fringes,
The recording medium includes a hologram recording layer on which interference fringes are recorded, a control information layer on which control information reproduced by control light is recorded, and a plurality of reference marks that can be detected by the control light. A plurality of interference fringes are recorded on the hologram recording layer by changing the magnification of the recording light in the hologram recording layer in association with the reference mark,
Irradiating the recording medium with reproduction light for reproducing the control light and the interference fringes recorded in association with the reference mark;
Detecting the reference mark by the control light;
Detecting reproduction light generated from the interference fringes by the reproduction light;
An optical information reproducing method comprising: detecting a magnification of the reproduction light in the hologram recording layer from the detected reference mark and the detected reproduction light, and controlling the magnification of the reproduction light in the hologram recording layer. An optical information reproducing method for reproducing information from a recording medium on which information is recorded by interference fringes,
The recording medium includes a hologram recording layer on which interference fringes are recorded, a control information layer on which control information reproduced by control light is recorded, and a plurality of reference marks that can be detected by the control light. A plurality of interference fringes are recorded on the hologram recording layer by changing a rotation angle around the optical axis of the recording light in association with the reference mark,
Irradiating the recording medium with reproduction light for reproducing the control light and the interference fringes recorded in association with the reference mark;
Detecting the reference mark by the control light;
Detecting reproduction light generated from the interference fringes by the reproduction light;
A rotation angle around the optical axis of the reproduction light is detected from the detected reference mark and the detected reproduction light, and the rotation angle around the optical axis of the reproduction light is controlled. Optical information reproduction method.   The optical information reproducing method according to any one of claims 18 to 21, wherein the reference mark is a part of control information recorded in the control information layer. The plurality of interference fringes are recorded in a partial area of the recording medium,
The optical information according to any one of claims 18 to 21, wherein information is reproduced in another area of the recording medium after reproducing the plurality of interference fringes in a part of the recording medium. Playback method. Means for generating reproduction light for reproducing the interference fringes recorded on the recording medium;
Means for generating control light for reproducing the control information and the reference mark recorded on the recording medium;
A reproducing optical system for irradiating the recording medium with the reproducing light;
A control optical system for irradiating the recording medium with the control light;
First detection means for detecting reproduction light generated from the interference fringes by the reproduction light;
Second detection means for detecting the control information and the reference mark reproduced by the control light;
A relative positional relationship between the control light and the reproduction light is detected from the reference mark detected by the second detection means and the reproduction light detected by the first detection means, and the control is performed. An optical information reproducing apparatus comprising control means for controlling a relative positional relationship between the light for reproduction and the light for reproduction.   The control means controls a relative positional relationship between the control light and the reproduction light by a displacement means for displacing the reproduction optical system or a part of the control optical system. The optical information reproducing apparatus according to claim 24.   The control means controls a relative positional relationship between the control light and the reproduction light by controlling timing information of the control light or the reproduction light or position information in the reproduced control information. 25. The optical information reproducing apparatus according to claim 24. Means for generating reproduction light for reproducing the interference fringes recorded on the recording medium;
Means for generating control light for reproducing the control information and the reference mark recorded on the recording medium;
An optical system for irradiating the recording medium with the reproducing light;
An optical system for irradiating the recording medium with the control light;
First detection means for detecting reproduction light generated from the interference fringes by the reproduction light;
Second detection means for detecting the control information and the reference mark reproduced by the control light;
Displacement means for changing the magnification of the reproduction light in the hologram recording layer of the recording medium;
The magnification of the reproduction light in the hologram recording layer is detected from the reference mark detected by the second detection means and the reproduction light detected by the first detection means, and the reproduction light is detected by the displacement means. And a control means for changing the magnification of the hologram recording layer. Means for generating reproduction light for reproducing the interference fringes recorded on the recording medium;
Means for generating control light for reproducing the control information and the reference mark recorded on the recording medium;
An optical system for irradiating the recording medium with the reproducing light;
An optical system for irradiating the recording medium with the control light;
First detection means for detecting reproduction light generated from the interference fringes by the reproduction light;
Second detection means for detecting the control information and the reference mark reproduced by the control light;
Displacement means for changing a rotation angle about the optical axis of the reproduction light;
A rotation angle around the optical axis of the reproduction light is detected from the reference mark detected by the second detection means and the reproduction light detected by the first detection means, and the displacement means detects the rotation angle. An optical information reproducing apparatus comprising: a control unit that changes a rotation angle about the optical axis of reproduction light. An optical information recording method for recording information on a recording medium on which information is recorded by interference fringes,
The recording medium includes a hologram recording layer on which interference fringes are recorded, a control information layer on which control information reproduced by control light is recorded, and a plurality of reference marks that can be detected by the control light. A plurality of interference fringes are recorded in the hologram recording layer in association with the reference mark, and the plurality of interference fringes have a relative positional relationship between each interference fringe and the reference mark associated with the interference fringe. It is arranged with changes,
Irradiating the recording medium with reproduction light for reproducing the control light and the interference fringes recorded in association with the reference mark;
Detecting the reference mark by the control light;
Detecting reproduction light generated from the interference fringes by the reproduction light;
The relative positional relationship between the control light and the reproduction light is detected from the detected reference mark and the detected reproduction light, and the relative positional relationship between the control light or the reproduction light is controlled. An optical information recording method characterized in that an interference fringe is recorded on the hologram recording layer by irradiating recording light later using the same optical system as the reproducing light. An optical information recording method for recording information on a recording medium on which information is recorded by interference fringes,
The recording medium includes a hologram recording layer on which interference fringes are recorded, a control information layer on which control information reproduced by control light is recorded, and a plurality of reference marks that can be detected by the control light. A plurality of interference fringes are recorded on the hologram recording layer by changing the magnification of the recording light in the hologram recording layer in association with the reference mark,
Irradiating the recording medium with reproduction light for reproducing the control light and the interference fringes recorded in association with the reference mark;
Detecting the reference mark by the control light;
Detecting reproduction light generated from the interference fringes by the reproduction light;
After detecting the magnification of the reproduction light in the hologram recording layer from the detected reference mark and the detected reproduction light, and controlling the magnification of the reproduction light in the hologram recording layer, the same optical system as the reproduction light is used. And recording the interference fringes on the hologram recording layer by irradiating recording light. An optical information recording method for recording information on a recording medium on which information is recorded by interference fringes,
The recording medium includes a hologram recording layer on which interference fringes are recorded, a control information layer on which control information reproduced by control light is recorded, and a plurality of reference marks that can be detected by the control light. A plurality of interference fringes are recorded on the hologram recording layer by changing a rotation angle around the optical axis of the recording light in association with the reference mark,
Irradiating the recording medium with reproduction light for reproducing the control light and the interference fringes recorded in association with the reference mark;
Detecting the reference mark by the control light;
Detecting reproduction light generated from the interference fringes by the reproduction light;
A rotation angle about the optical axis of the reproduction light is detected from the detected reference mark and the detected reproduction light, and the rotation angle about the optical axis of the reproduction light is controlled. An optical information recording method comprising recording an interference fringe on the hologram recording layer by irradiating recording light using the same optical system as the light.   32. The optical information recording method according to claim 29, wherein the reference mark is a part of control information recorded in the control information layer. The plurality of interference fringes are recorded in a partial area of the recording medium,
33. The light according to claim 29, wherein the interference fringes are recorded in another area of the recording medium after reproducing the plurality of interference fringes in a part of the recording medium. Information recording method. Means for recording interference fringes on a recording medium and generating recording / reproducing light for reproducing the interference fringes recorded on the recording medium;
Means for generating control light for reproducing the control information and the reference mark recorded on the recording medium;
A recording / reproducing optical system for irradiating the recording medium with the recording / reproducing light;
A control optical system for irradiating the recording medium with the control light;
First detection means for detecting reproduction light generated from the interference fringes by the recording and reproduction light;
Second detection means for detecting the control information and the reference mark reproduced by the control light;
Detecting a relative positional relationship between the control light and the recording / reproducing light from the reference mark detected by the second detecting means and the reproducing light detected by the first detecting means; An optical information recording apparatus comprising: control means for controlling a relative positional relationship between the control light and the recording / reproducing light.   The control means controls a relative positional relationship between the control light and the recording / reproducing light by a displacing means for displacing the recording / reproducing optical system or a part of the control optical system. An optical information recording apparatus according to claim 34.   The control means controls the relative positional relationship between the control light and the recording / reproducing light by controlling the timing information of the control light or the recording / reproducing light or the positional information in the reproduced control information. The optical information recording apparatus according to claim 34, wherein the optical information recording apparatus is controlled. Means for recording interference fringes on a recording medium and generating recording / reproducing light for reproducing the interference fringes recorded on the recording medium;
Means for generating control light for reproducing the control information and the reference mark recorded on the recording medium;
An optical system for irradiating the recording medium with the recording / reproducing light;
An optical system for irradiating the recording medium with the control light;
First detection means for detecting reproduction light generated from the interference fringes by the recording and reproduction light;
Second detection means for detecting the control information and the reference mark reproduced by the control light;
Displacement means for changing the magnification of the recording / reproducing light in the hologram recording layer of the recording medium;
The magnification in the hologram recording layer of the recording / reproducing light is detected from the reference mark detected by the second detecting means and the reproducing light detected by the first detecting means, and the recording / reproducing is detected by the displacing means. An optical information recording apparatus comprising: control means for changing the magnification of the light in the hologram recording layer. Means for recording interference fringes on a recording medium and generating recording / reproducing light for reproducing the interference fringes recorded on the recording medium;
Means for generating control light for reproducing the control information and the reference mark recorded on the recording medium;
An optical system for irradiating the recording medium with the recording / reproducing light;
An optical system for irradiating the recording medium with the control light;
First detection means for detecting reproduction light generated from the interference fringes by the recording and reproduction light;
Second detection means for detecting the control information and the reference mark reproduced by the control light;
Displacement means for changing a rotation angle about the optical axis of the recording / reproducing light;
A rotation angle about the optical axis of the recording / reproducing light is detected from the reference mark detected by the second detecting means and the reproduction light detected by the first detecting means, and the displacement means An optical information recording apparatus comprising: control means for changing a rotation angle about the optical axis of the recording / reproducing light. A plurality of interference fringes are recorded in a predetermined arrangement on the hologram recording layer,
A method for manufacturing a recording medium, wherein a control information layer having a plurality of reference marks is associated with each of the plurality of reference marks and the plurality of interference fringes in association with the hologram recording layer on which the plurality of interference fringes are recorded Because
The recording is characterized in that the plurality of reference marks are arranged by changing a relative positional relationship between each interference fringe of the plurality of interference fringes and the reference mark associated with the interference fringe. A method for manufacturing a medium.   40. The provisional control information layer having a plurality of reference marks arranged in the same arrangement as the predetermined arrangement is coupled to the hologram recording layer when the plurality of interference fringes are recorded. The manufacturing method of the recording medium as described.

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