WO2004104696A1 - 情報記録媒体およびその記録再生方法、並びに情報記録再生装置 - Google Patents
情報記録媒体およびその記録再生方法、並びに情報記録再生装置 Download PDFInfo
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- WO2004104696A1 WO2004104696A1 PCT/JP2004/007433 JP2004007433W WO2004104696A1 WO 2004104696 A1 WO2004104696 A1 WO 2004104696A1 JP 2004007433 W JP2004007433 W JP 2004007433W WO 2004104696 A1 WO2004104696 A1 WO 2004104696A1
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- recording
- information
- polarization plane
- information recording
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
- G11B7/244—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only
- G11B7/245—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only containing a polymeric component
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
- G03C1/00—Photosensitive materials
- G03C1/72—Photosensitive compositions not covered by the groups G03C1/005 - G03C1/705
- G03C1/73—Photosensitive compositions not covered by the groups G03C1/005 - G03C1/705 containing organic compounds
- G03C1/733—Photosensitive compositions not covered by the groups G03C1/005 - G03C1/705 containing organic compounds with macromolecular compounds as photosensitive substances, e.g. photochromic
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/0045—Recording
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/2403—Layers; Shape, structure or physical properties thereof
- G11B7/24035—Recording layers
- G11B7/24038—Multiple laminated recording layers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/21—Circular sheet or circular blank
Definitions
- the present invention relates to an information recording medium, a recording / reproducing method thereof, and an information recording / reproducing apparatus.
- FIG. 6 shows an information recording medium including a plurality of recording layers. As shown in FIG. 6, separating layers 53 and recording layers 51 that are translucent to recording light and reproduction light are alternately arranged between the protective film 50 and the holding substrate 56. I have.
- information can be recorded on the recording layer 51 (primary light absorption recording) by utilizing the phase transition or deformation caused by the heat generation effect accompanying the absorption of the recording light.
- an information recording medium capable of recording information using multiphoton absorption has attracted attention (see, for example, JP-A-08-228688).
- An example is shown in FIG.
- a recording layer 52 substantially transparent to recording light and reproduction light is used instead of the recording layer 51 of the information recording medium shown in FIG.
- a recording material capable of multiphoton absorption has very little attenuation of light passing therethrough (recording light and reproduction light), and is substantially transparent to recording light and reproduction light.
- reference numeral 10 denotes an objective lens
- reference numeral 11 denotes convergent light.
- the necessary conditions for the recording material include the fact that it is substantially transparent to the recording light and the reproduction light, as well as the following (1) ( 2).
- (1) The focal point of the recording material is deformed into a bit shape by heat.
- (2) The refractive index changes due to heat.
- the recording material is (3) the bit-like deformation is removed by heat due to heat generated by two-photon absorption, or (4) the changed refractive index is changed by heat.
- an information recording medium utilizing a change in refractive index accompanying a phase change between a crystalline phase and an amorphous phase is known, and an oxide such as tellurium oxide is used as a recording material (for example, international Public W ⁇ 0 3/1 0 2
- the phase change from the crystalline phase to the amorphous phase occurs at a practical level, but the phase change from the amorphous phase to the crystalline phase requires a long-term heat action, The rate of change is extremely slow.
- the time required for a phase change from a crystalline phase to an amorphous phase can be on the order of several nanoseconds, but it takes several milliseconds to change the phase from an amorphous phase to a crystalline phase. Heating time is required. Disclosure of the invention
- the information recording medium of the present invention includes a recording layer, and recording light is focused on the recording layer.
- An information recording medium on which two-photon absorption occurs to record information on the recording layer wherein the recording layer comprises: a main chain containing acrylate or methacrylate; and a first side branched from the main chain.
- a photosensitive polymer comprising a chain and a second side chain, wherein the first side chain undergoes a cis-translation isomerization reaction upon absorbing the recording light, and the second side chain comprises The first side chain is characterized in that, when the isomerization reaction is performed, the first side chain is oriented in the same manner as the first side chain.
- the recording / reproducing method of the present invention is a recording / reproducing method for recording or reproducing information on / from the information recording medium of the present invention, comprising the steps of: condensing the recording light on the recording layer to form recording bits; Irradiating the recording bits with reproducing light to reproduce information.
- Another recording / reproducing method is a recording / reproducing method for recording or reproducing information on / from the information recording medium according to the present invention, wherein a step of forming recording bits by converging the recording light on the recording layer. Irradiating the recording bit with reproduction light to reproduce information, wherein the recording light includes a first light and a second light, and a polarization plane direction of the second light is: It is inclined substantially 45 degrees with respect to the direction of the deflection surface of the first light, and one of the direction of the deflection surface of the first light and the direction of the deflection surface of the second light is: The orientation direction of the optical axis of the photosensitive polymer coincides with the orientation direction of the optical axis, and the deflection surface direction of the reproduction light is any one of the deflection surface direction of the first light and the deflection surface direction of the second light.
- An information recording / reproducing apparatus of the present invention is an information recording / reproducing apparatus for recording or reproducing information on / from an information recording medium of the present invention, comprising: a light source for emitting recording light; a light source for emitting reproducing light; A ⁇ wavelength plate through which the recording light and the reproduction light pass, and an objective lens for condensing the recording light and the reproduction light on the information recording medium; 1 wavelength 2 wavelengths 2004/007433
- the direction of the deflection plane of the recording light emitted from the light source is substantially tilted by 45 degrees with respect to the direction of the polarization plane of the predetermined direction.
- the polarization plane direction of the predetermined direction is the W1 direction and the polarization plane direction substantially 45 degrees inclined with respect to the predetermined direction is the Wp2 direction
- the reproduction light emitted from the light source is Is rotatable so that the polarization plane direction can be substantially tilted by 90 degrees with respect to one of the polarization plane directions of the Wp1 direction and the Wp2 direction.
- Another information recording / reproducing apparatus of the present invention is an information recording / reproducing apparatus for recording or reproducing information on / from the information recording medium of the present invention, wherein the light source emits recording light and the reproducing light emits A light source; a 1Z2 wavelength plate through which the recording light and the reproduction light pass; and an objective lens for condensing the recording light and the reproduction light on the information recording medium.
- the polarization plane direction of the recording light that has passed through the wavelength plate is a predetermined direction
- the plate substantially changes the polarization plane direction of the recording light emitted from the light source with respect to the polarization plane direction in the predetermined direction.
- the polarization plane direction in the predetermined direction is defined as Wp1 direction
- the polarization plane direction substantially inclined by 45 degrees with respect to the predetermined direction is defined as Wp2 direction
- the optical axis of the polymer can be made to coincide, the polarization plane direction of the reproduction light emitted from the light source, with respect to any one of the polarization plane direction of the Wp1 direction and the Wp2 direction And can be rotated so that it can be substantially tilted by 90 degrees.
- FIG. 1 is a sectional view showing an example of an information recording medium according to the present invention
- FIG. FIG. 2 is a schematic configuration diagram illustrating an optical head of a recording / reproducing apparatus.
- FIG. 2 is a diagram showing directions of polarization planes of recording light and reproducing light applied to an information recording medium whose optical axes are randomly oriented.
- FIG. 3 is a diagram showing the polarization plane directions of recording light and reproduction light applied to an information recording medium initialized to have an optical axis in a single direction.
- FIG. 4 is a diagram showing the spectral characteristics of the photosensitive polymer constituting the information recording medium shown in FIG.
- FIG. 5 is a diagram showing the relationship between the amount of irradiation of the photosensitive polymer constituting the information recording medium shown in FIG. 1 and the absorptance of the photosensitive polymer with respect to the irradiation light.
- FIG. 6 is a diagram showing a cross-sectional configuration of an example of a conventional information recording medium.
- FIG. 7 is a diagram showing a cross-sectional configuration of an example of a conventional information recording medium.
- the polarization plane direction means the vibration direction of the electric field of light, and the polarization plane direction is in a plane perpendicular to the traveling direction of light.
- the first side chain covalently bonded to the main chain is represented by the following formula (1)
- the second side chain is represented by the following formula (2):
- Oyobi 3 2 is O or S atom or NR 1 group independently of one another
- R 1 is hydrogen, - C 6 - a ⁇ alkyl or phenyl,! ⁇ ⁇
- R 1 is hydrogen, - C 6 - a ⁇ alkyl or phenyl,! ⁇ ⁇
- Q 1 and Q 2 are, independently of each other, one O—, one COO—, ⁇ OC 0—, one CONR 1— , — NR 1 C 0—, — NR 1 —, one O— C 6 H 4 — COO—or one O—C 6 H 4 —CONR 1 —, and additionally, S iRiQ 1 and S 2 T 2 Q 2 are, independently of each other,
- R 2 to R 6 may be, independently of one another, hydrogen, halogen, C x —C 4 monoalkyl, C X —C 4 monoalkoxy, CF 3 , nitro, SO CH 3 , S 0 2 NH 2 or cyano, wherein at least one of the substituents R 2 to R 6 must be other than hydrogen and R 7 to R 9 Independently of hydrogen, ⁇ —C 6 -alkyl, hydroxyl, C ⁇ —Ce-alkoxy, phenoxy, C!
- the photopolymer may be such that at least one of Q 1 and Q 2 is 10—C 6 H 4 —CO— or 10—C 6 H 4 —CONR—.
- photosensitive polymers can be prepared by the method described in JP-A-8-109226.
- FIG. 4 shows the spectral characteristics of the photosensitive polymer used as an example of the information recording medium of the present embodiment.
- a laminate in which a recording layer (1 m thick) containing a photosensitive polymer was laminated on a substrate made of a polymer ponate was used.
- a spectrometer was used to measure the spectral characteristics.
- the recording layer was obtained by applying a photosensitive polymer to the substrate by a spin-coating method so as to have a thickness of about 1 m, and then drying.
- the first side chain has 3-bromo-4- [6- (2-methylpropyl) hexoxy] benzoic acid (the structural formula is shown in the following formula (4)).
- a photosensitive polymer was used.
- this photosensitive polymer is abbreviated as photosensitive polymer A.
- Photopolymer A shows the maximum absorption for light having a wavelength of about 41 O nm. This absorption is due to the first side chain. Photosensitive polymer A has a wavelength of about 655 nm and a wavelength of about 80 O nm. Little absorption. Further, since the photosensitive polymer A does not have a crystal structure, there is almost no light transmission loss due to scattering. The transmittance of a laser beam having a wavelength of 800 nm to the recording layer composed of the photosensitive polymer A is about 100% excluding the reflected light from the recording layer surface.
- Figure 5 shows the results.
- the wavelength of the laser light was 800 nm.
- the pulse width of the laser beam was set to 100 femtoseconds ( 10-13 seconds) in order to suppress the influence of heat generation.
- Figure 5 As shown in, in the irradiation light amount is 1 0 0 n JZ ⁇ m 2 or less, is not observed the absorption of the recording layer light. However, when the light intensity exceeds 100 nJ, the light absorption rate increases sharply.
- Electrons excited by two-photon absorption either (1) change to heat by collision with the lattice and return to the normal non-excited state, or (2) emit light of half the wavelength of the excitation light To return to the non-excited state. If the phenomenon (1) occurs, the light absorption of the recording layer containing the photosensitive polymer A should not change so much even if the wavelength of the laser light changes. But the figure As shown in Fig. 4, the photosensitive polymer A exhibits strong absorption for light having a wavelength of about 400 nm.
- the recording layer when the recording layer is irradiated with, for example, recording light having a wavelength of 800 nm, convergent light having a wavelength of 800 nm (the irradiation light amount exceeds, for example, 100 nJZ HI 2 at the condensing portion of the recording layer) ))
- the first side chain undergoes cis-trans isomerization reaction (morphological change).
- the orientation direction of the first side chain includes a stable direction that does not respond to the optical electric field and an unstable direction that easily reacts to the optical electric field direction.
- the trans-form oriented in the direction that responds to the optical electric field returns to the cis-form over time, and the first side chain returned to the cis-form repeats the cycle of being trans-transformed again by light.
- the orientation direction of the first side chain is aligned in a direction that does not respond to the optical electric field (Weigert effect).
- the major axis of the second side chain is oriented in substantially the same way as the major axis of the first side chain, which is aligned in one direction, due to the shape change of the first side chain. .
- the rate of change from the cis-form to the trans-form of the first side chain is almost equal to the rate of this reverse reaction. Also, these rates are faster than the phase change rate, especially much faster than the change rate from the amorphous phase to the crystalline phase. That is, the information recording medium of the present embodiment using the photosensitive polymer as a recording material has a higher information recording speed and information erasing speed than the phase change type information recording medium. fast.
- less than the irradiation light amount is a predetermined value, if for example it is 1 0 0 n JZ m 2 or less, photopolymers one with respect to light having a wavelength of 8 0 0 nm is substantially transparent (see Figure 3). Therefore, when the recording light having a wavelength of 800 nm is focused on any one of the plurality of recording layers, the recording light is substantially transparent to the recording layers other than the recording layer.
- the information recording medium of the present embodiment can perform three-dimensional recording, and can record and erase information at a higher speed than the phase change type information recording medium.
- the light absorption region (absorption wavelength) of the photosensitive polymer hardly changes before and after recording information. Therefore, the wavelength of the light source that emits recording light and the wavelength of the light source that emits reproduction light may be the same. If the recording light and the reproduction light have the same wavelength, the optical system of the information recording / reproducing apparatus requires only one light source, and the structure of the optical system can be simplified.
- a stilbene compound is bonded to at least one of the first side chain and the second side chain.
- the stilbene compound include XI and X described above. It is preferable that R 2 be bonded to any one of R 1 to R 8.
- the stilbene compounds include, for example, the following formulas (5) to (9)
- these stilbene compounds have a large two-photon absorption coefficient (two-photon absorption cross section), these stilbene compounds are bound to at least one of the first side chain and the second side chain. In this case, the trans-isomerization is likely to occur, and the recording sensitivity is improved.
- the photosensitive polymer does not include the stilbene compounds, for recording information by two-photon absorption is the number m JZ m 2 about light quantity is required, the photosensitive polymer is the stilbene compound as containing, it can record hundreds n JZ m 2 about light quantity.
- stilbene compounds can be prepared by methods described in the literature (for example, see “Photoaddressable Polymers For Rewritable Optical Disc System”, Y. Sabi, M. Yamamoto, H. Watanabe eta proceedings of ISOM 2GQ0). .
- the information recording medium preferably includes a plurality of recording layers, and the plurality of recording layers are stacked via a separation layer substantially transparent to recording light and reproduction light.
- substantially transparent to the recording light and the reproduction light means that the recording light and the reproduction light are transmitted with little absorption except for the scattering component of the recording light and the reproduction light.
- the light transmittance per layer is preferably 95% or more, and more preferably 99% or more.
- the information recording medium of the present invention includes, in its manufacturing process, for example, a step of applying a coating material containing a photosensitive polymer on a substrate.
- the optical axis of the photosensitive polymer (recording layer) is randomly oriented, and the recording layer containing the photosensitive polymer is almost optically isotropic. are doing.
- the information recording medium of the present invention can be used as it is, but the photosensitive polymer may be initialized so as to have uniaxial anisotropy.
- the photosensitive polymer is initialized to have a unidirectional optical axis, a larger recording signal can be obtained than an information recording medium in which the photosensitive polymer is optically almost isotropic. .
- substantially "45 degrees” is intended to include the error range, and specifically means 45 degrees ⁇ 10 degrees. If the error is about ⁇ 10 degrees, this error can be absorbed or corrected by the circuit system of the information recording / reproducing apparatus. Further, “substantially 90 degrees” is intended to include an error range, and specifically means 90 degrees ⁇ 15 degrees. If the error is about ⁇ 15 degrees, this error can be absorbed or corrected by the circuit of the information recording / reproducing apparatus.
- the recording light includes a first light and a second light
- a polarization plane direction of the second light is a polarization plane direction of the first light
- the direction of the plane of polarization of the reproduction light is one of the direction of the plane of deflection of the first light and the direction of the plane of deflection of the second light. Is substantially 90 degrees tilted.
- the wavelength of the recording light and the wavelength of the reproducing light are the same.
- the wavelength of the light source emitting the recording light and the wavelength of the light source emitting the reproducing light are the same.
- One example of the information recording / reproducing apparatus of the present invention preferably includes a light source that emits erasing light.
- Embodiment 1 The information recording medium, its recording / reproducing method, and the information recording / reproducing apparatus of Embodiment 1 will be described with reference to FIGS.
- FIG. 1 shows a cross-sectional configuration showing an example of the information recording medium of the present invention and a schematic configuration of an optical head of an information recording / reproducing apparatus.
- FIG. 2 is a diagram showing the directions of polarization planes of recording light and reproducing light applied to an information recording medium A described later
- FIG. 3 is a diagram illustrating recording light applied to an information recording medium B described later.
- FIG. 4 is a diagram illustrating a polarization plane direction of reproduction light.
- the holding substrate 2 5 6 As shown in FIG. 1, in the information recording medium of the present embodiment, the holding substrate 2 5 6 cooperate ⁇
- the recording section 2 13 and the protective layer 250 are formed thereon.
- the recording section 2 13 includes recording layers 2 1 1 and 2 1 2 and a separation layer 2 53 disposed therebetween, and the recording layers and the separation phases are alternately stacked.
- the information recording medium of the present embodiment includes a plurality of recording layers 2 1 1 and 2 1 2 in the recording section 2 13 to record information in the thickness direction in addition to recording information in a plane. Is possible.
- the protective layer 250 is on the light incident side.
- the laser light is condensed on one of the recording layers 211 and 212 by the objective lens 10 to form convergent light 11 1) and recording bits 2 14.
- the laser light is condensed on a desired recording layer by the objective lens 10 (convergent light 7), and the information is reproduced using the light reflected by the recording bits 214.
- the optical axis or the second side chain of the photosensitive polymer is in a state of random orientation, and the recording layer is optically
- the information recording medium of this embodiment may be substantially isotropic (hereinafter, this type of information recording medium is also referred to as information recording medium A)
- the photosensitive polymer is initialized so as to have a unidirectional optical axis.
- this type of information recording medium is also referred to as information recording medium B.
- the initialization can be performed, for example, by irradiating the recording layer with light in a predetermined polarization plane direction.
- the light whose polarization plane direction is tilted 90 degrees (orthogonal) to the radial direction of the information recording medium is recorded.
- the optical axis can be aligned in the radial direction of the information recording medium.
- the light source 1 for emitting the recording light shown in FIG. 1 has, for example, a wavelength of 800 nm. 7433
- the light source 2 which is a semiconductor laser and emits reproduction light is, for example, a semiconductor laser having a wavelength of 655 nm.
- the recording light (laser light) having a wavelength of 800 nm emitted from the light source 1 is collimated by the collimating lens 3.
- the parallel light passes through a half-mirror 15 and a one-two-wavelength plate (quartz) 4.
- the polarization plane direction of the laser beam whose polarization plane direction is directed to a predetermined direction (for example, the Wpl direction in FIG. 2) and the optical axis of the half-wave plate 4 are matched.
- the half-wave plate 4 does not act on the laser light at all.
- the polarization plane direction of the laser beam Is oriented (coincident) with the optical axis of the half-wave plate.
- the recording light whose polarization plane direction is the Wp l direction (see Fig. 2) is emitted from the light source, and the rotation angle of the 1Z2 wave plate 4 is adjusted so that the polarization plane direction of the laser light is the Wp 2 direction (see Fig. 3).
- information may be recorded using recording light whose polarization plane direction is controlled in the Wp2 direction.
- the polarization plane direction in the Wp2 direction is inclined at an angle of substantially 45 degrees with respect to the polarization plane direction in the Wpl direction (predetermined direction).
- recording is performed on the same recording layer by using both the recording light (first light) having the polarization plane direction of Wp1 and the recording light (second light) having the polarization plane direction of Wp2. If bits are formed, multiplexed recording can be performed, and the recording density can be doubled as compared with the case where information is recorded by one of the first light and the second light.
- the polarization plane direction of the recording light emitted from one light source is set to the Wp1 direction
- the polarization plane direction of the recording light emitted from the other light source is set to Wp1. Two directions.
- the polarization plane direction (Wpl direction) of the recording light coincides with the radial direction A of the information recording medium, but is not limited to this. Also, the direction of the polarization plane of the recording light emitted from the light source 1 does not necessarily have to be aligned with the optical axis of the 1- and 2-wavelength plate. The direction of the polarization plane of the recording light that has passed through may be a predetermined direction, for example, the Wpl direction.
- the incident light is separated into two types of light having different polarization plane directions.
- the polarization beam splitter 6 is arranged so that one output direction of the polarization beam splitter 16 is aligned with the polarization plane direction of one of the first light and the second light,
- the light reflected from the information recording medium is split into light in two directions whose polarization planes are at 90 degrees to each other.
- the direction of the deflection plane of the reproduction light must be the first light.
- the diameter of the light focused on the recording layer 212 is approximately 0.45 m when the numerical aperture (NA) of the objective lens 10 is 0.85, for example. If the interlayer distance between the recording layer 211 and the recording layer 211 is, for example, 5 m, the minimum diameter of light passing through the recording layer 211 is about 16 m. You. Therefore, the amount of light irradiated on the recording layer 211 per unit area is about (0.45 / 16) 2 or less (about 1/1000 or less) that of the recording layer 212. As shown in FIG. 5, if the amount of light applied to the recording layer 212 is, for example, 500 (nJ / urn 2 ), the amount of light applied to the recording layer 211 is about 1/1000 or less thereof.
- the recording bit 2 14 When the recording bit 2 14 (see FIG. 1) is formed with the recording light having the polarization plane direction of Wp 1 direction, as shown in FIG. 2, the recording bit 2 14 has the same direction as the Wp 1 direction before forming the recording bit.
- a part of the aligned photosensitive polymer (second side chain) is oriented in a direction perpendicular to the Wp1 direction, that is, in the Ep direction. Therefore, the refractive index from the Ep direction increases by, for example, ⁇ .
- the photosensitive polymer (second side chain) oriented in the same direction as the Wp 1 direction decreases, the refractive index from the Wp 1 direction decreases by ⁇ ⁇ (in FIG. 2, one ⁇ ⁇ ).
- the difference between the refractive index of the area where the recording bit is formed (recording bit 214) and the refractive index of the area where the recording bit is not formed is, for example, about 0.05 to 0.25.
- the recording bit is a photosensitive polymer (second side chain) that was oriented in the same direction as the Wp 2 direction before forming the recording bit.
- the refractive index from the Rp direction increases by, for example, ⁇ 2.
- the photosensitive polymer (second side chain) oriented in the same direction as the Wp 2 direction decreases, the refractive index from the Wp 2 direction decreases by ⁇ 2 (in FIG. 2,- ⁇ 2).
- the laser light emitted from the light source 2 (oscillation wavelength 655 nm, see FIG. 1) that emits the reproduction light is converted into a parallel light by the collimating lens 3.
- the polarization direction of the reproduction light (laser light) is '45 degrees with respect to the polarization direction of the recording light in the Wpl direction (see Fig. 2), and the recording light in the Wp2 direction (see Fig. 2).
- Rotate the half-wave plate 4 so that it tends to about 90 degrees in the direction of the polarization plane.
- the polarization plane direction of the reproduction light is controlled by rotating the half-wave plate 4 by a predetermined angle, but the present invention is not limited to this.
- the polarization plane direction of the reproduction light can be changed to any one of the Wp1 direction (see FIG. 2) and the Wp2 direction (see FIG. 2). It can be tilted 90 degrees with respect to one of the polarization plane directions.
- the reproduction light is focused on the recording layer 212 by the objective lens 10.
- the reflected light from the recording bit 214 is returned to parallel light by the objective lens 10, and a part of the parallel light is bent in a right angle direction by the half mirror 5, and is guided to the polarization beam splitter 16.
- the reflected light is split by the polarizing beam splitter 16 into light having a polarization plane direction of Wpl and Ep directions, and these lights are guided to the photo editors 7 and 8, respectively.
- the photo editors 7 and 8 are arranged at positions where the polarization plane directions can receive light in the Wpl and Ep directions, respectively.
- the signal output from the photodetector 17 that has received the light having the polarization plane direction of Wp1 direction has the recording bit.
- the refractive index becomes smaller by ⁇ 1 than the light reflected by the non-formed area.
- the signal output from the photo-editor 8 receiving the light in the Ep direction has a refractive index ⁇ n 1 higher than the light reflected in the area where no recording bit is formed. That is, the signal output from the photo editor 7 and the signal output from the photo editor 8 are detected as having opposite phases with respect to the refractive index.
- the photosensitive layer When the recording bit is formed by the recording light with the polarization plane direction of Wp2 direction, in the area of the recording layer where the recording bit was formed, the photosensitive layer was oriented in the same direction as the Wp2 direction before the recording bit was formed.
- a part of the polymer (second side chain) is oriented in a direction perpendicular to the Wp2 direction, that is, in the Rp direction. Therefore, the refractive index from the Rp direction increases by, for example, ⁇ 2.
- the photosensitive polymer (second side chain) oriented in the same direction as the Wp 2 direction decreases, the refractive index from the Wp 2 direction decreases by ⁇ 2.
- the above-mentioned increase or decrease in the refractive index is also separated and detected.
- the refractive index from light with a polarization plane direction of Wp 1 direction ends up being No change is detected.
- the change in the refractive index is detected only from the light whose polarization plane direction is the Ep direction.
- multiplexing is performed using both the first light whose polarization plane direction is the Wp 1 direction and the second light whose polarization plane direction (Wp 2 direction) is inclined by 45 degrees with respect to the Wp 1 direction. From the recorded recording bits, a signal twice as large as the signal obtained from the recording bits recorded by one of the first light and the second light can be obtained.
- Erasing recorded bits can be done by randomly aligning the optical axis of the photosensitive polymer. Therefore, circularly polarized light may be used as the erasing light. When circularly polarized light is used, the direction of the optical axis of the photosensitive polymer is rotated, so that there is no anisotropy as a whole. An amorphous polymer without orientation does not show birefringence, and the recorded bits will be erased. Alternatively, a plurality of recording bits formed on the recording layer at one time may be deleted by using random polarized light as erasing light or by heating.
- the photosensitive polymer has a single-direction optical axis, and the optical axis is oriented, for example, in the Pa direction. Therefore, the optical axis in which the direction of the deflection surface of one of the first light whose deflection surface direction is Wp1 and the second light whose deflection surface direction is Wp2 is oriented in the direction Pa. When this is made to match, the change in the refractive index of the recording layer accompanying the recording can be increased.
- the direction of the deflection plane (Wpl direction) of the first light is made to coincide with the direction of Pa.
- the direction of the deflection surface of the second light is in the Wpl direction. Practically tilted 45 degrees.
- the difference between the refractive index of the area where the recording pits are formed (recording bits 2 14) and the refractive index of the area where no recording bits are formed is, for example, about 0.5.
- This refractive index difference is larger than that of the information recording medium A because the optical axis is oriented in one direction in the initial state.
- both the first light whose polarization plane direction is the Wp1 direction and the second light whose polarization plane direction (Wp2 direction) is inclined by 45 degrees with respect to the Wp1 direction The method of reproducing information from the recording bits multiplex-recorded by using the information recording method is the same as the method of reproducing the information recorded on the information recording medium A, and a description thereof will be omitted.
- Erasing of recorded bits can be performed by orienting the optical axis of the photosensitive polymer in the Pa direction.
- the erasing light laser light whose deflection surface direction is orthogonal to the Pa direction, that is, laser light whose deflection surface direction is the Ep direction may be used. In this way, when the laser beam whose deflection surface direction is orthogonal to the direction of the Pa is irradiated, the optical axis of the photosensitive polymer is aligned with the direction of the Pa, and returns to the initialized state.
- the photosensitive polymer is 3-bromo-1- [6- (2-methylpropynyl) hexoxy] benzoic acid 4′-cyano 2 ′, 6, —dibromophenyl (structure The formula is described in the following formula (10).
- the photosensitive polymer B containing the stilbene compound (5) to (9) of the chemical formula (4) is used.
- the configuration is the same as that of the information recording medium of the first embodiment.
- the maximum absorption wavelength ⁇ max of the photosensitive polymer C containing the stilbene compound (6) is 430 nm.
- the maximum absorption wavelength ⁇ max of the photosensitive polymer B is 380 nm.
- the maximum absorption wavelength ⁇ max of the photosensitive polymer containing the stilbene compound (5) is 400 nm, and the longer the stilbene compound length (the length of the major axis), the longer the maximum absorption wavelength shifts. I found out.
- the two-photon absorption cross section of photosensitive polymer B was 1 GMR.
- the two-photon absorption cross section of photosensitive polymer C containing stilbene compound (5) was 25 GMR
- the stilbene compound (7 ) -Containing photopolymer-C had a two-photon absorption cross section of 150 GMR
- the photopolymer-C containing a stilbene compound (8) had a two-photon absorption cross-section of 250 GMR. From these results, it was found that the two-photon absorption cross section increased as the length of the stilbene compound (the length of the major axis) increased. Note that the larger the two-photon absorption cross section, the higher the recording sensitivity.
- the maximum absorption wavelength of the photosensitive polymer becomes too large.
- the maximum absorption wavelength of the photosensitive polymer containing the stilbene compound (8) is 8 It becomes 00 nm. If the absorption wavelength of the photosensitive polymer is too long, the recording density will decrease. From the viewpoint of high-density recording, Amax is preferably around 400 nm at the maximum.
- the stilbene compound (6) of (3) is bound to either the first side chain or the second side chain. Is preferred.
- the maximum absorption wavelength of photosensitive polymer C containing stilbene compound (6) is Since the wavelength is 43 O nm, the optimal wavelength of the recording light is 860 nm.
- the photosensitive Simulation results by molecular orbit analysis showed that the recording sensitivity of the information recording medium using polymer C was 80 times higher than that of the information recording medium using photosensitive polymer B. Therefore, information can be recorded even if the output of the recording light source (semiconductor laser) is relatively small, about 1.25 W.
- the information recording medium of this invention its recording / reproducing method, and information recording / reproducing apparatus, the information recording medium which can perform high-speed recording and high-speed erasure, its recording / reproducing method, and information recording / reproducing apparatus can be provided.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Nanotechnology (AREA)
- Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Theoretical Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Optical Recording Or Reproduction (AREA)
- Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)
- Optical Record Carriers And Manufacture Thereof (AREA)
- Optical Head (AREA)
Abstract
Description
Claims
Priority Applications (2)
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US10/558,131 US20060246376A1 (en) | 2003-05-26 | 2004-05-25 | Information recording medium, recording/reproducing method for the same, and information recording/reproducing apparatus |
JP2005506437A JPWO2004104696A1 (ja) | 2003-05-26 | 2004-05-25 | 情報記録媒体およびその記録再生方法、並びに情報記録再生装置 |
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JP2003147243 | 2003-05-26 |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009086299A (ja) * | 2007-09-28 | 2009-04-23 | Fujifilm Corp | 重合性基を有する色素を含む2光子吸収光記録媒体 |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
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US20060120256A1 (en) * | 2003-02-25 | 2006-06-08 | Matsushita Electric Industrial Co., Ltd | Optical information recording carrier |
JP2008033991A (ja) * | 2006-07-26 | 2008-02-14 | Konica Minolta Opto Inc | 光ピックアップ装置 |
US11211091B2 (en) | 2011-06-09 | 2021-12-28 | Case Western Reserve University | Optical information storage medium |
WO2012170992A2 (en) * | 2011-06-09 | 2012-12-13 | Case Western Reserve University | Optical information storage medium |
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DE4431823A1 (de) * | 1994-09-07 | 1996-03-14 | Bayer Ag | Verfahren zur Verstärkung von Information in photoadressierbaren Seitenkettenpolymeren |
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US20030052311A1 (en) * | 2001-07-06 | 2003-03-20 | Yoshio Inagaki | Two-photon absorption composition |
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2004
- 2004-05-25 JP JP2005506437A patent/JPWO2004104696A1/ja not_active Withdrawn
- 2004-05-25 WO PCT/JP2004/007433 patent/WO2004104696A1/ja active Application Filing
- 2004-05-25 US US10/558,131 patent/US20060246376A1/en not_active Abandoned
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US20060246376A1 (en) | 2006-11-02 |
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