Abstract: An information storage medium and a recording/reproducing apparatus and method are provided with the ability to extend at least one middle area of an information storage medium comprising two or more recording layers so as to ensure optimal data recording/reproduction. The information storage medium comprises a plurality of recording layers, each including a user data area for recording user data and at least one middle area used by a recording/reproducing apparatus that records/reproduces data on the information storage medium to move among two recording layers, wherein the at least one middle area is extended when the information storage medium is finalized. As a result, when an information storage medium that contains an OPC area for obtaining optimum recording conditions (such as recording power) in an outer circumference thereof is finalized, and if a middle area of the disk is not large enough, the middle area can flexibly be extended.

Abstract: According to one embodiment, an information storage medium in which layer 0 and layer 1 are arranged from a read surface, a system lead-in area, data lead-in area, data area, and middle area are arranged from an inner circumference of the layer 0, and a system lead-out area, data lead-out area, data area, and middle area are arranged from an inner circumference of the layer 1. A guard track zone is arranged on a side of the data area in the data lead-out area, and a reference code zone, R physical format information zone, recording management zone, and drive test zone are arranged in the data lead-in area of the layer 0 and padding of the guard track zone of the data lead-out area is performed after padding of the drive test zone of data lead-in area and recording of the recording management zone.

Abstract: An optical data storage system and method with non-destructive multiple readout of 3-D data stored in multiple layers uses two-photon induced fluorescence modulation. The novel system uses the photochromic properties of the open and closed form of diarylethene in the two-photon energy transfer-based read-out method of a 3-D optical data storage system, providing more than 10,000 readout cycles without significantly compromising the stored data. The system of the present invention can be recorded and read out using the same wavelength simply by changing the intensities. Also, since the incident intensity used in two-photon readout is low due to the efficient absorption of the two-photon absorbing fluorene dye, a less expensive, nanosecond laser diode can be used, making this two-photon 3-D data storage system less expensive, stable, highly responsive, and reliable. This photochromic system is capable of either write-once read many (WORM) or erasable and rewritable 3D optical data storage.

Abstract: An optical information recording and reproducing device 1 irradiates initialization light L1 to an optical information recording medium 100 having a recording layer 101 made of photopolymerization-type photopolymer in advance to bring about the photopolymerization or the photocrosslinking to perform the initialization processing, and condenses a recording light beam L2c having a comparatively strong light intensity to a target position in the recording layer 101 and increases the temperature thereof to transubstantiate the target position to record a recording mark RM at the time of recording information, and condenses a reading light beam L2d having a comparatively weak light intensity to the target position and receives a returned light beam L3 having a sufficient light amount reflected by the recording mark RM at the time of reproducing information, which makes it possible to reliably record the recording mark RM and stably read out the recording mark RM.

Abstract: An information recording medium 1 at least comprises a substrate 13 having a microscopic pattern 20, which is constituted by a shape of continuous substance of approximately parallel grooves formed with a groove section G and a land section L alternately, a recording layer 12 formed on the microscopic pattern 20 and a light transmission layer 11 formed on the recording layer. The microscopic pattern 20 is formed so as to satisfy a relation of P<?<NA and a thickness of the light transmission layer 11 is within a range of 0.07 to 0.12 mm, wherein P is a pitch of the groove section G or the land section L, ? is a wavelength of reproducing light beam and NA is a numerical aperture of an objective lens. Further, there provided an information recording medium, which is improved in cross erase and recorded in high density, and a reproducing apparatus and a recording apparatus for the information recording medium.

Abstract: The present invention relates to an optical disc for use as a recording medium in an optical disc drive, which has a transparent protection film (120) formed on a recording layer on one plane of the disc substrate (110) and a printing label film 130 being of approximately the same film quality and film structure as the transparent protection film (120) formed on the other plane thereof. The printing label film (130) is a synthetic resin film made mainly of polycarbonate and formed on the disc substrate by screen printing, etc. Thus, the optical disc has the same film quality and film structure on the respective one and the other planes, which prevents occurrence of skew caused by the deformation due to the asymmetry of the structure along the thickness direction of the optical disc. The optical disc has a function to present contents of information recorded therein with the printing label film provided on the other plane of the disc substrate.

Abstract: According to one embodiment, a write-once type information storage medium using a recording material which has a low to high characteristic that a light reflectivity in a recording mark increases with respect to a non-recording area and which has a recording characteristic in accordance with a principle of recording without substrate deformation, wherein the recording material includes at least an organic metal complex, and wherein the organic metal complex includes a center metal.

Abstract: An optical recording medium driving apparatus includes an optical pickup which irradiates first and second laser lights from one object lens with respect to an optical recording medium having a bulk layer and a tilt detection surface; a focus control portion that performs the focus control relative to each predetermined position of the optical recording medium in regard to each of the first and second laser lights; a tracking control portion that controls the position of the object lens to perform the tracking control of the first and second laser lights relative to the optical recording medium; and a tilt control portion.

Abstract: The present invention relates to a recording apparatus, record carrier and method of recording data on at least two layers of a recording medium by using a radiation power, wherein individual recording speeds are determined for respective ones of the at least two layers at different values of the radiation power. A recording speed to be used for recording on an individual one of the at least two recording layers is selected based on a maximum radiation power specified for the recording operation, and the speed of the recording operation is controlled individually for each of the at least two layers based on the selected recording speed. The determination of the individual recording speeds at different radiation power values may be written or embossed on the record carrier. Furthermore, a recording sequence used for recording on the recording layers can be set based on the sensitivities and thus recording speeds. Thereby, total recording time can be minimized for multi-layer recording media.

Abstract: An optical recording medium and a method of recording and reproducing of the optical recording medium are provided, which are capable of recording and reproducing data with reliability even when blue or blue violet laser light is used as irradiation light. The optical recording medium has a recording layer in which a recording mark composed of a plurality of cavities is formed by irradiation of the laser light. The recording layer is configured so that, in a plan view taken in a direction of irradiation of the laser light, cavities lying in an area of the center and its vicinities of the recording mark, out of the plurality of cavities, include cavities greater than ones lying around the area.

Abstract: An optical read/write apparatus causes a read/write light beam from illuminating means to strike only one side of an optical storage medium including stacked data storage layers each of which is readable/writeable separately from the other layers. In this case, the optical read/write apparatus operates so that data is read/written from/into a second data storage layer after fully recording a recordable area of a first data storage layer. Thus, light can be shone with uniform intensity across the substantially entire recordable area of the second data storage layer without using a complex read/write system even under such conditions that the transmittance to light of the first data storage layer in the recordable area may vary depending on whether any data is recorded in the recordable area.

Abstract: An optical read/write apparatus causes a read/write light beam from illuminating means to strike only one side of an optical storage medium including stacked data storage layers each of which is readable/writeable separately from the other layers. In this case, the optical read/write apparatus operates so that data is read/written from/into a second data storage layer after fully recording a recordable area of a first data storage layer. Thus, light can be shone with uniform intensity across the substantially entire recordable area of the second data storage layer without using a complex read/write system even under such conditions that the transmittance to light of the first data storage layer in the recordable area may vary depending on whether any data is recorded in the recordable area.

Abstract: An optical read/write apparatus causes a read/write light beam from illuminating means to strike only one side of an optical storage medium including stacked data storage layers each of which is readable/writeable separately from the other layers. In this case, the optical read/write apparatus operates so that data is read/written from/into a second data storage layer after fully recording a recordable area of a first data storage layer. Thus, light can be shone with uniform intensity across the substantially entire recordable area of the second data storage layer without using a complex read/write system even under such conditions that the transmittance to light of the first data storage layer in the recordable area may vary depending on whether any data is recorded in the recordable area.

Abstract: A super-resolution optical recording medium includes a reflective layer formed on a substrate, a recording layer for recording information thereon, a super-resolution layer made of a chalcogenide semiconductor material, and a first and a second dielectric layers laminated on upper and lower surfaces of the super-resolution layer. The recording layer is made of a material that has a decomposition temperature higher than an information reproduction temperature and does not form bubble recording marks during recording, and the super-resolution layer contains one or more elements selected from the group consisting of nitrogen, oxygen, carbon, and boron.

Abstract: An optical disk is provided that includes a face carrying information that is readable by a laser while the disk is being driven in rotation, the face being defined by a flexible structure; a support stiffening the flexible structure and including at least one fiber layer having a thickness; and an identification and/or authentication element carried by the support, the identification and/or authentication element being configured to emit a detectable signal on being illuminated by the laser that is used for reading the information present on the face, the identification and/or authentication element being inside and/or outside the support.

Abstract: An information recording medium according to the present invention includes three or more information recording layers. Each of the plurality of information recording layers includes a test recording area usable for adjusting a recording condition. One of the plurality of information recording layers includes a reproduction-only management data area in which management data usable for managing the information recording medium is pre-recorded. One information recording layer includes a recordable management data area in which management data usable for managing the information recording medium is newly writable. Each of the other two or more information recording layers among the plurality of information recording layers includes a test recording area at a radial position overlapping the radial position of a part of the reproduction-only management data area. In the one recording layer including the recordable management data area, the recordable management data area is provided at two positions, i.e.

Abstract: Each layer includes a data recording area and a test writing area divided into a plurality of small areas, wherein the small areas of the test writing area are recorded in advance so that other each layer can make a combination of recorded and unrecorded states with respect to the small area, where OPC is carried out, in a layer where OPC is carried out. Moreover, OPC is carried out to each small area, where a combination of recorded/unrecorded states of other each layer differs from each other, to thereby calculate, as the optimum power, an average value of the result of each OPC or a central value of the dispersion thereof.

Abstract: An optical recording medium includes a recording layer in or on a substrate, a light-transmitting cover layer over said recording layer, and a disc rib over an outer periphery of a first side of the substrate and delimiting an outer diameter of the cover layer.

Abstract: An optical read/write apparatus causes a read/write light beam from illuminating means to strike only one side of an optical storage medium including stacked data storage layers each of which is readable/writeable separately from the other layers. In this case, the optical read/write apparatus operates so that data is read/written from/into a second data storage layer after fully recording a recordable area of a first data storage layer. Thus, light can be shone with uniform intensity across the substantially entire recordable area of the second data storage layer without using a complex read/write system even under such conditions that the transmittance to light of the first data storage layer in the recordable area may vary depending on whether any data is recorded in the recordable area.

Abstract: A multi-layered information recording medium including a plurality of recording layers, the multi-layered information recording medium comprising: a user data area for recording user data; and a plurality of spare areas including at least one replacement region, wherein when the user data area includes at least one defect region, the at least one replacement region may be used in place of the at least one defect region, wherein a first spare area of the plurality of spare areas is positioned so as to be contiguous to a first user data area of a first recording layer, a second spare area of the plurality of spare areas is positioned so as to be contiguous to a second user data area of a second recording layer, and the first spare area and the second spare area are positioned approximately at the same radial position on the multi-layered information recording medium.

Abstract: In a recording disc, a straight groove (31) and a position determining pit (33) are formed in an inner circumference area (21), and a straight groove (34) and an over-run preventing pit (36) are formed in an outer circumference area (22), and only a straight groove (37) is formed over the entire middle area (23).

Abstract: Imaging layers, optical disks, and methods of preparation of each, are disclosed.

Abstract: Disclosed is a sheet for producing a multilayer optical recording medium having a repeating structure wherein a plurality of optical recording layers are laminated. The sheet for a multilayer optical recording medium has a structure having a unit wherein an optical recording layer and an adhesive layer are laminated, or a structure having a unit wherein an optical recording layer, a barrier layer and an adhesive layer are laminated in this order. The maximum height roughness (Rz) of the optical recording layer or the barrier layer is not more than 500 nm. A multilayer optical recording medium is produced by using the sheet for a multilayer optical recording medium. Also disclosed is a sheet for producing, with high precision, a high-quality multilayer optical recording medium having a repeating unit wherein a plurality of optical recording layers containing a multiphoton absorbing material are laminated. A multilayer optical recording medium is also produced by using this sheet.

Abstract: Imaging layers, optical disks, and methods of preparation of each, are disclosed.

Abstract: An information storage medium according to the present invention has n information storage layers (where n is an integer and n?3), on which data can be written with a laser beam and which are stacked one upon the other. Each of the n storage layers has a test write zone for determining the recording power of the laser beam. When those n layers are counted from the one that is located most distant from the surface of the medium on which the laser beam is incident, there is a bigger radial location difference between the outer peripheral end of the inner one of the test write zones of ith and (i+1)th information storage layers (where i is an integer that satisfies 2?i?n?1) and the inner peripheral end of the other outer test write zone than between the outer peripheral end of the inner one of the test write zones of jth and (j+1)th information storage layers (where j is an integer that satisfies 1?j?i?1) and the inner peripheral end of the other outer test write zone.

Abstract: An information recording medium is provided, which comprises a plurality of recording layers and a first disc information area for storing parameters relating to access to the plurality of recording layers and formats relating to the plurality of recording layers. The first disc information area is provided in a first recording layer which is one of the plurality of recording layers.

Abstract: An optical information recording medium comprises: a recording layer capable of recording and reproducing information by irradiation with a laser light; and an image recording layer capable of recording a visible image and containing a dye as a major component.

Abstract: A sheet for producing a multilayer optical recording medium having a repeated structure in which a plurality of optical recording layers are laminated, wherein the sheet has a structure such that a unit comprising at least a release assisting layer, an optical recording layer having a thickness of 1 to 1,000 nm and a pressure sensitive adhesive layer are disposed on a process film, the release assisting layer is disposed on the surface of the process film, and a pressure sensitive adhesive layer is disposed as the outermost layer, and an absolute value of difference between refractive indices of the release assisting layer and the pressure sensitive adhesive layer at a wavelength of 660 nm is 0.11 or smaller; and a multilayer optical recording medium obtained by using the sheet. The sheet enables to release the process film and transfer the optical recording layer while the condition of the surface of the optical recording layer is kept excellent.

Abstract: According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the first light reflecting layer is smaller than the thickness of the second light reflecting layer.

Abstract: According to one embodiment, a write-once type information storage medium comprises a recording layer which is formed by mixing a plurality of organic dye based recording materials whose molecular weights are different from each other, and wherein a mixture ratio of organic dye based recording materials whose molecular weight is small is larger than a mixture ratio of organic dye based recording materials whose molecular weight is large.

Abstract: To provide a dye to be used for an optical recording medium excellent in both high speed recording characteristics and reproduction durability. A dye having an azo compound represented by the following formula coordinated to a metal ion: wherein the ring A represents a nitrogen-containing heteroaromatic ring containing a carbon atom and a nitrogen atom; X represents C—R1R2, an oxygen atom, a sulfur atom or N—R3, wherein each of R1, R2 and R3 which are independent of one another, represents a hydrogen atom, a linear or branched alkyl group, an aralkyl group, a cycloalkyl group, a linear or branched alkenyl group, an aryl group or an acyl group represented by —COR4, wherein R4 is a hydrocarbon group or a heterocyclic group which may be substituted; and the benzene ring B represents a benzene ring which may have a substituent(s), provided that adjacent substituents in the benzene ring B may be mutually bonded to form a ring.

Abstract: The invention provides a multilayer information recording medium manufacturing method, a multilayer information recording medium manufacturing apparatus, and a multilayer information recording medium that enable to make a distance from a light incident surface of the multilayer information recording medium to a farthest information recording layer thereof uniform within a plane of the medium.

Abstract: An optical information recording and/or reproducing apparatus comprises: a focusing unit (11) which collects generated near-field light on an optical disc (1); a first detector (17) which receives light reflected by the optical disc (1) and outputs an electric signal according to the quantity of the received light; and a distance control circuit (22) which controls the distance between the focusing unit (11) and a light entrance surface of the optical disc (1), using the electric signal that is output from the first detector (17), and the optical disc (1) has at least N (N is an integer of 2 or greater) number of information layers, and a distance d0 from the light entrance surface to a first information layer which is most distant from the light entrance surface and a distance dn from the light entrance surface to an Nth information layer which is closest to the light entrance surface satisfy the relationship of dn?d0×(1/25).

Abstract: A production method for an optical recording medium including a substrate, an information recording layer, and a light transmission layer, includes: molding the substrate; forming on the substrate the information recording layer so as to have a multilayer structure including a layer that has been sputtered under a first deposition condition and a layer that has been sputtered under a second deposition condition with use of targets of the same composition; and forming the light transmission layer on the information recording layer.

Abstract: An optical read/write apparatus causes a read/write light beam from illuminating means to strike only one side of an optical storage medium including stacked data storage layers each of which is readable/writeable separately from the other layers. In this case, the optical read/write apparatus operates so that data is read/written from/into a second data storage layer after fully recording a recordable area of a first data storage layer. Thus, light can be shone with uniform intensity across the substantially entire recordable area of the second data storage layer without using a complex read/write system even under such conditions that the transmittance to light of the first data storage layer in the recordable area may vary depending on whether any data is recorded in the recordable area.

Abstract: A method for manufacturing an optical recording medium includes forming a light-transmitting cover layer over an information layer by depositing a predetermined volume of a liquid resin on the information layer. The method may further include forming a disc rib over an outer periphery of the information bearing side of the substrate, to stop flow of the deposited resin beyond the outer disc periphery. An optical recording medium formed through such a method includes a disc rib delimiting an outer diameter of the light-transmitting cover layer.

Abstract: In a single-sided incident type optical recording medium having a plurality of dye containing recording layers, sufficient reflectance and excellent recording characteristics necessary to record or read information in or from a dye containing recording layer positioning farther from a side from which a light beam comes in can be obtained. The optical recording medium has a first substrate (21) having a guide groove, a first dye containing recording layer (22), a semitransparent reflective layer (23), an intermediate layer (24), a second dye containing recording layer (25), a reflective layer (26) and a second substrate (27) having a guide groove. Information is recorded or read in or from the first dye containing recording layer (22) and the second dye containing recording layer (25) by irradiating the light beam from the first substrate's side. The depth of the guide groove on the second substrate is within a range from 1/100×? to ?×? where ? represents the recording/reading wavelength.

Abstract: An optical information recording medium (100) of the present invention includes an information layer (011) that allows information to be recorded thereon and reproduced therefrom by irradiation with a laser beam (040). The information layer (011) includes a reflective layer (002), a first dielectric layer (003), a recording layer (005) capable of undergoing a phase change by the irradiation with the laser beam (040) and a second dielectric layer (007) formed in this order from a side opposite to a laser beam incident side. The recording layer (005) contains Ge, Sb and Te. When Ge, Sb and Te contained in the recording layer (005) are represented by GexSbyTez in atomic number ratio, x, y, and z satisfy 0.39?x?0.48, 0.02?y<0.11, 0.40?z<0.56, and x+y+z=1. The recording layer (005) has a thickness of at least 10 nm but not more than 15 nm.

Abstract: An irreversible optical recording medium comprises at least an active layer presenting a rear face and a front face designed to receive at least an optical writing radiation. The optical writing radiation enables gas bubbles forming write marks to be formed locally in said active layer by means of a layer forming a gas source arranged on the rear face of the active layer. The layer forming the gas source moreover has a thickness less than or equal to 100 nm so as to limit the height of the bubbles formed in the active layer and therefore to improve tracking when read operations are performed. The layer forming the gas source is preferably made of carbon-doped hydrogenated amorphous silicon oxide.

Abstract: An object of the invention is to improve the quality of a servo signal and a reproduction signal. Shape-wise thicknesses tr1, tr2, . . . , and trN of a cover layer and first through (N?1)-th intermediate layers of an optical recording medium having refractive indexes nr1, nr2, . . . , and nrN are converted into thicknesses t1, t2, . . . , and tN of the respective layers having a predetermined refractive index “no” which makes a divergent amount equal to a divergent amount of a light beam resulting from the thicknesses tr1, tr2, . . . , and trN, a difference DFF between the sum of a thickness “ti” through a thickness “tj”, and the sum of a thickness “tk” through a thickness “tm” is set to 1 ?m or more (where i, j, k, and m are each any positive integer satisfying i?j<k?m?N), and the thicknesses t1, t2, . . . , and tN are calculated by products of a function f(n) expressed by the following formula (1), and the thicknesses tr1, tr2, . . . , and trN: f(n)=?1.088n3+6.1027n2?12.042n+9.

Abstract: An optical information storage medium according to the present invention has at least one information storage layer. The optical information storage medium has a management area that stores at least one unit containing control information about the optical information storage medium. The control information includes a format number, which provides information about at least a write strategy type and a write pre-compensation type, and a write strategy parameter, which provides information about the magnitude of shift in an edge position, or variation in the pulse width, of a write pulse train to form a recording mark. And the value of the format number changes according to a combination of the write strategy type and the write pre-compensation type.

Abstract: An optical information recording medium including a recording layer that can record a large amount of information is manufactured using a simple system. A single recording layer is formed by bonding two optically transparent substrates on which the first photosensitive polymer and the second photosensitive polymer are spread such that the layers of the photosensitive polymers face each other. Furthermore, since the absorptivity of light in the recording layer increases as the focal point of light for information recording moves in a depth direction, information can be recorded without decreasing the recording transfer rate of the information.

Abstract: An optical recording medium includes: a substrate; an information recording layer that is formed on the substrate and that has a recording film, which contains Zn or Al, Pd, and oxygen and in which the amount of oxygen is larger than that in a stoichiometric composition when Zn or Al is completely oxidized to become ZnO or Al2O3; and a light transmissive layer formed on the information recording layer.

Abstract: In a conventional multilayer optical disc, management information needs to be retrieved from the control area of its reference layer to find how many information layers there are in the optical disc. A multilayer optical disc according to the present invention has multiple information layers that are stacked one upon the other. The information layers include at least one layer on which layer number information, indicating its own place in the multiple information layers, and information about the total number of information layers included are both stored.

Abstract: An information recording medium according to the present invention includes a plurality of recording layers, and a test area for determining a recording power of a laser light for each of the plurality of recording layers, in which a first test area of a first layer and a second test area of a second layer adjacent to the first layer are provided at different radial positions.

Abstract: An information recording medium according to the present invention includes at least three information recording layers. If the readout power of a laser beam in reading information from an information recording layer L(n) is identified by Pw(n), and if the readout power of the laser beam in reading information from an information recording layer L(n+a) is identified by Pw(n+a), then a base thickness between the information recording layers is determined so that the intensity of the light when the information recording layer L(n+a) is irradiated with a laser beam having the readout power Pw(n) becomes equal to or lower than that of the light when the information recording layer L(n+a) is irradiated with a laser beam having the readout power Pw(n+a).

Abstract: A dual sided optical storage medium which comprises a substrate disk having a first information layer readable from one side of the medium through the substrate disk and one or more information layers formed on the non-read side of the first information layer and configured to be read from the other side of the medium.

Abstract: An optically-readable disk includes a device that disrupts readability of the disk when the disk is spun at an angular velocity substantially greater than required to play the disk in its intended playing device, or when a defined integral of velocity and time is exceeded. The device may include a fluid container that disperses a data-disruptive fluid. The device may include a membrane or layer that is disrupted when the disk is rotated above a defined angular velocity, or when a defined integral of velocity and time is exceeded. The device may include an electro-optical material that is activated by an electrical signal from a controller in response to an input from a sensor responsive to motion of the disk.

Abstract: Phase-change type, reversible optical information recording medium, being possible for recording, reproducing, erasing, and rewriting of information, by use of a laser beam. This invention, consists of recording thin film of ternary elements, for example, containing Ge, Te, Sb/or Bi or quaternary elements containing the fourth element of Se with which a part of Te is replaced, which is established on such surface—flat substrates as glass or plastics. In this case, the component ratio of Te and Se is selected not to be excess for other elements, such as Ge, Sb/or Bi so as to be fixed as stable compounds of stoichiometric compositions of GeTe, Sb2Te3/or Bi2Te3, or GeSe, Sb2Se3/Bi2Se3 when crystallized. Strictly speaking, a concentration of each component is selected to have proper ratio of the number of atoms each other so as to represent whole composition as the sum of each component. By this treatment, it is possible to have high crystallization speed and long cyclability of recording/erasing.

Abstract: An optical disk has a first substrate having a recording layer thereon, information to be recorded on the recording layer being reproducible with irradiation of a laser beam, a reflective layer formed on the recording layer, and a second transparent substrate, the laser beam being incident to the second substrate in reproduction. The first and the second substrates are bonded to each other by a bonding layer via the reflective layer. The bonding layer includes ultraviolet-hardened resin and at least one type of photochromic dye that is stable against the laser beam. In another type, the first substrate maybe transparent. Instead of the second substrate, this type has a hardcoat layer formed on a surface of the first substrate opposite to another surface thereof having the recording layer thereon, the laser beam being incident to the hardcoat layer in reproduction. The hardcoat layer includes ultraviolet-hardened resin and at least one type of photochromic dye that is stable against the laser beam.