Abstract: An optical information recording medium (1) includes on a substrate (50), a ROM layer (20), a RE layer (40), an intermediate layer (30) separating the ROM layer (20) and the RE layer (40), and a light transmitting layer (10) provided farthest from the substrate (50). The RE layer (40) is an information recording layer provided most farthest from the light transmitting layer (10), and is a recording layer of BCA recorded in a format easily determinable as compared to an information recording format used in the ROM layer (20), and antifouling property of a surface of the light transmitting layer (10) is set based on the RE layer (40). This makes it easy for the recording and reproducing apparatus to confirm a disc type, allows for sharing one recording and reproducing apparatus with other types of optical discs, and simplifies the disc production.

Abstract: A method for copy protection includes providing audiovisual or audio data stored in sectors of a record carrier having a file system, and providing additional or modified data to be stored in further sectors. The method includes generating a first file of the file system referencing at least a part of the sectors and none of the further sectors, so when the first file is rendered by a playback device, the data is reproduced which is included in the part of the sectors. The method also includes generating a second file of the file system being another file than the first file and referencing at least a part of the sectors and further referencing at least one of the further sectors, such that when the second file is rendered by the playback device the part of the sectors and the at least one of the further sectors are reproduced.

Abstract: Disclosed is an optical disc with a first area to store data for playback and that is reflective or opaque to visible light, and a second area that is transparent to visible light and includes first and second concentric rings. In one embodiment, a method of printing information on the optical disc includes: printing an inverse first text pattern in the first ring during a first printing on a first side, where the first text pattern is formed in reverse as viewed from the first side; printing a second text pattern in the second ring during a second printing on the first side, where the second text pattern is correctly visible from the first side; and printing, during the second printing, a first solid pattern to overlay at least a portion of the first text pattern, where the first text pattern is correctly visible as viewed from a second side.

Abstract: Shape-wise thicknesses of a cover layer and first through (N?1)th intermediate layers of an optical recording medium having refractive indexes nr1, nr2 are converted into thicknesses t1, t2 of the respective layers having a predetermined refractive index which makes a divergent amount equal to a divergent amount of a light beam resulting from the thicknesses tr1, tr2, 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 are calculated by products of a function f(n) expressed by the following formula (1), and the thicknesses tr1, tr2: f(n)=?1.088n3+6.1027n2?12.042n+9.1007 ??(1) in the formula (1), n=nr1, nr2, . . . , and nrN.

Abstract: A recording apparatus includes a rotation driving portion that rotates and drives an optical disc master; and a recording portion that performs an information recording on the optical disc master, by performing a laser beam irradiation on the optical disc master, based on a recording waveform which has a land pulse of a first power, a recording waveform portion having a recording pulse of a second power higher than the first power, and a cooling pulse which has a third power lower than the first power and is inserted between the land pulse and the recording waveform portion.

Abstract: A manufacturing method of an optical information recording medium includes forming a substrate which has a first main surface and a second main surface, forming a first information signal layer on the first main surface of the substrate, forming an intermediate layer on the first information signal layer, forming a second information signal layer on the intermediate layer, irradiating light from the second main surface side of the substrate and recording identification information on a first region out of the first region and a second region, and forming a barrier layer with regard to the second main surface in the second region which excludes the first region where the identification information is recorded before the recording of the identification information.

Abstract: An optical disc has a data layer including a data-layer substrate made of a transparent material and a data-layer reflection film formed on an upper side of the data-layer substrate, a display layer including a display-layer substrate having a display pattern and a display-layer reflection film formed on a lower side of the display-layer substrate, and an intermediate layer made of a transparent material provided between an upper side of the data layer and a lower side of the display layer. The data- and display-layer reflection films exhibit specific reflectivity to allow the display pattern to be visible from a lower side of the data-layer substrate through the data-layer reflection film.

Abstract: There is provided a method of initializing a recording medium having a first surface and a second surface which face to each other with a recording layer in between. The method includes forming interference patterns to have a pitch wider than ?r/2N by applying initializing light of a plane wave with a wavelength ?f to the recording layer from both of the first surface side and the second surface side, where ?r is a wavelength of reproducing light applied to the recording layer at the time of reproducing recorded information, and N is an average refractive index of the recording layer.

Abstract: To provide an information recording medium which is capable of reducing damage to a recording layer while improving environmental resistance of the recording layer and which enables information to be recorded or reproduced at a high density and a high sensitivity, an optical information recording and reproducing apparatus, an optical information recording and reproducing method, and a manufacturing method of an information recording medium.

Abstract: The present techniques provide methods and systems for recording micro-holograms on a holographic disk using a plurality of counter-propagating light beams in parallel. The parallel counter-propagating light beams overlap to form interference patterns on a data layer and over multiple data tracks in the holographic disk. Rotating the disk enables the parallel recording of micro-holograms over multiple data tracks, thus reducing recording time. Further, the illumination pattern may include illuminated spots and non-illuminated regions, such that each illumination spot may cover a relatively small fraction of the data layer plane, possibly controlling the depth spread of the recorded micro-hologram. In some embodiments, data in the parallel signal beams may be retrieved from a master holographic disk or may be modulated into the parallel signal beams.

Abstract: An optical recording medium includes a recording layer in which recording of a mark is selectively performed in a depth direction by irradiation of first light, and the mark is formed in multilayer form; and a reflection film reflecting second light of a wavelength different from a wavelength of the first light, and provided on a lower layer side of the recording layer.

Abstract: The present invention provides a multilayer optical disc and an optical disc drive which can identify recording layers without performing tracking servo control or changing the structure of the disc. In a multilayer optical disc 100, the recording layer includes a layer identification region 101 having a recording pattern for layer identification, the layer identification region 101 including a layer specific region 102 having a specific pattern and a common region 103 having a common pattern different from the specific pattern, the layer specific region 102 being provided at a different radial position in each of the recording layers. The optical disc drive detects the layer specific region 102 having the specific pattern from the layer identification region 101 of the multilayer optical disc 100, and identifies the current layer based on the radial position of the layer specific region.

Abstract: An optical recording medium (disk) capable of preventing a back focus at a face thereof and reducing the interference between beams reflected by each recording surface, thereby improving a quality of a servo signal and a reproductive signal. In a disk having (N?1) layers, if N is a natural number (more than three), and if a cover-layer thickness and intermediate-layer thicknesses are d1, d2, . . . dN, then a difference of 1 ?m or above is set between the sum of di to dj and the sum of dk to dm for arbitrary natural numbers i, j, k, m (i?j?k?m?N). If refractive indexes are different from a standard value or different for each layer, then the thickness of each layer is converted based on a spread width of light according to the thickness.

Abstract: An information storage medium having a plurality of recording layers is provided. The information storage medium including a physical ADIP address (PAA) which corresponds to an address recorded on the information storage medium. In the case in which an address of a layer i to which a pickup will move corresponds to PAAi, an address of a layer j in which the pickup is currently located corresponds to PAAj, and n corresponds to the number of the recording layers, the PAAi and the PAAj satisfy the equation PAAi= PAAj+(7?(i+j))*40 00 00h+00 00 01h(i+j=odd and i,j=0,1,2, . . . ,n?1) in response to the pickup moving from an even layer to an odd layer or from an odd layer to an even layer, and satisfy the equation PAAi=PAAj+(i?j)*40 00 00h(i+j=even and i,j=0,1,2, . . . ,n?1) in response to the pickup moving from an even layer to another even layer or from an odd layer to another odd layer.

Abstract: Provided is an information storage medium that has a plurality of recording layers, a recording/reproducing method, and a recording/reproducing apparatus. In the information storage medium, each of the plurality of recording layers includes an inner circumference zone and a data zone, and at least one of the recording layers includes, in the inner circumference zone, a temporary disc management area (TDMA) for recording information about a defect detected in the data zone, wherein a size of a TDMA allocated on an upper layer is greater than a size of a TDMA allocated on a lower layer.

Abstract: An optical information recording medium (1) includes, on a substrate (50), a ROM layer (20), a RE layer (40), an intermediate layer (30) separating the ROM layer (20) and the RE layer (40), and a cover layer (10) provided in a position farthest from the substrate (50). The RE layer (40) is an information recording layer provided in a position farthest from the light transmitting layer and also is a recording layer of disc type identification information and an individual identification number recorded in a format allowing easier determination as compared to an information recording format used in the layer allowing only readout of information by use of light irradiation. Therefore, it becomes easy to check a disc type in a recording/reproducing device and one recording/reproducing device can be shared with other types of optical disks. Further, disk production becomes easy.

Abstract: An optically writable holographic card, an optically writable holographic media, and a method of making the media are herein described. The card has a media region that includes an optically writable material. The optically writable material has an holographic embossment such that an holographic image is producible by the optically writable material. The media includes an holographically embossed first layer. An optically writable, optically readable second layer conforms to the embossment. The holographic image is generable by the second layer. The method includes producing an holographic embossment associated with an holographic image. An optically writable layer is conformed to the holographic embossment. The holographic image is viewable in response to illuminating the optically writable layer. The optically writable layer is optically readable.

Abstract: A method by which depressions and projections (pit pattern) can be formed directly and easily in a substrate made of inorganic material is provided. A method for forming a medium on which information is recorded in a pit pattern comprises the steps of: forming a recording material layer (21) over a substrate (11) made of inorganic material wherein the recording material layer is of a thermally deformable heat mode recording material; forming a plurality of holes 15 by application of condensed light to the recording material layer (21); and forming a plurality of pits (16) in the substrate wherein the plurality of pits corresponding to the plurality of holes (15) are etched by using as a mask the recording material layer (21) in which the plurality of holes are formed.

Abstract: Manufacturing of a higher quality write-once type multilayer optical disc is facilitated. The optical disc includes a plurality of recording layers in which recording or reproduction is carried out by a blue or blue-violet laser beam of a wavelength of about 405 nm. Each of the recording layers includes a recording layer which uses an organic dye. The plurality of recording layers includes a layer in which a groove pattern around a recording mark is deformed when information is recorded, and a layer in which the groove pattern around the recording mark is not deformed when information is recorded.

Abstract: A recording layer for an optical information recording medium, which has a high reflectance (initial reflectance) and excellent recording characteristics; an optical information recording medium comprising the recording layer; and a sputtering target useful for forming the recording layer. The recording layer for an optical information recording medium, on which recording is performed by irradiation of laser light, is characterized by containing indium (In) oxide and palladium (Pd) oxide which includes palladium monoxide and palladium dioxide. The recording layer for an optical information recording medium is also characterized in that the ratio of Pd atoms contained in the recording layer relative to the total of In atoms and Pd atoms contained therein is 6-60 atom %.

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: The present invention provides an optical information recording medium (2) capable of shortening a time from acquiring identification information to starting a program etc. recorded on an ROM layer. The optical information recording medium (2) includes two or more information recording layers, information of each of the two or more information recording layers is readable by emitting reproducing light thereto, at least one of said two or more information recording layers is an RE/R layer (4), at least another one of said two or more information recording layers is an ROM layer (5), and the RE/R layer (4) includes an identification information recording region (41), and an interlayer-movement Flag is recorded on the identification information recording region (41).

Abstract: A radio frequency transponder for use with a disc, such as a CD or DVD has an antenna formed by depositing a conductive solution on a surface of disc outside at adjacent to its outer periphery outside of the disc storage area to yield at least one conductive region. A transponder circuit is coupled to the antenna for supplying an RF signal to the antenna in response to a signal received from the antenna.

Abstract: Disclosed is a digital information media having an adhesion promotion layer supported on a dummy (L1) substrate that enables secure bonding of the L1 layer, directly or indirectly, to the rest of the stack of layers in the digital information media. Certain materials including metals, metal alloys, or metalloids enhance adhesion between the adhesive layer and the L1. By applying an adhesion promotion layer of such materials on an inner surface of the L1, the bond between the adhesive and the adhesion promotion layer improves bonding and reduces a tendency for the L1 to delaminate from the rest of the stack. The tendency for breakage of the media at the juncture between the adhesion promotion layer and the adhesive is reduced, and incursion of moisture or oxygen through the interface between the adhesion promotion layer and the adhesive is inhibited.

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

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: 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: 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: 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: 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: A method of recording content comprising the steps of: providing a content storage medium comprising a pre-recorded grating or hologram; and illuminating a pre-recorded grating or hologram with a single recording beam to record content in the grating or hologram. The recording beam may increase the diffraction efficiency of the pre-recorded grating or hologram. Alternatively, the recording beam may form a new grating or hologram in close proximity to a pre-recorded grating or hologram.

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 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: 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: The invention relates to a master device which can be used in a method for producing a recording medium, a substantially spirally or concentrically running main track structure and at least one substantially spirally or concentrically running secondary track structure being formed on the master device, the secondary track structure being arranged on at least one side of the main track structure, the secondary track structure having discontinuities varying an optically detectable surface texture of the recording medium in such a way that at least first auxiliary information is represented on the recording medium.

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: A data storage assembly is presented. The data storage assembly comprises a bi-layered antireflective coating. An inner layer of the antireflective coating comprises diamond like carbon. An outer layer is disposed over the inner layer.

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: An optical disc recording apparatus (10) is provided with a tracking servo (13) for tracking a spiral track of concave and convex marks, an analog signal processor (14) for extracting a reproduction signal corresponding to the concave and convex marks, a digital signal processor (15) for extracting a channel clock synchronized with a channel bit length of the concave and convex marks, and a sub-information recording section (30) for recording sub-information by irradiating laser light based on the tracking to the spiral track. The sub-information recording section (30) records all the sub-information by repeating a process of recording a part of the sub-information by discretely irradiating laser light at a specified interval and with a specified frequency in synchronism with a channel clock by one tracking to form recordable marks on a reflective film a plurality of times.

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: [Object] A recoding playback apparatus and an optical disk are provided that allows reduction of a low frequency noise at a time of playback of a super resolution optical disk including small record marks whose size is below the diffractive limitation, to enhance quality of a playback signal. [Means for Solution] The reflective beams from the optical disk are received by dividing into outer portion beams and a center portion beam, and a playback signal is created by combining such beams based on respective different gains. Based on received amounts of light or amounts of low frequency noise in respective light receiving regions, adjustment or determination of gain values is made, or the optical head apparatus is optically adjusted, whereby the low frequency noise is optimally suppressed. Further, a specific region is provided on the optical disk for making the foregoing adjustment.

Abstract: An information recording medium, comprising N number (N is an integer fulfilling N?3) of information layers on which information is recordable, and allowing information to be recorded on each of the information layers and allowing information recorded on each of the information layers to be reproduced by being irradiated with laser light. The N number of information layers include an N'th information layer, an (N?1)th information layer, an (N?2)th information layer, . . . a second information layer and a first information layer sequentially located from a laser light incidence side. A reflectance of the N'th information layer is RN, and a reflectance of an M'th information layer (M refers to every integer fulfilling N>M?1) is RM.