Abstract: According to one embodiment, a first encoder encodes main information, a second encoder encodes sub-information, a first modulator modulates a carrier based on an output of the first encoder, a duplicating module duplicates an output of the second encoder to generate encoded sub-information units, and a second modulator amplitude-modulates an output of the first modulator based on the encoded sub-information units. The second modulator amplitude-modulates with ?/(?×(2N)1/2) being 0.4 or less, wherein a noise power of a transmission path or a storage medium is ?2, a number of the encoded sub-information units is N, signal levels after amplitude modulation, which correspond to bit 1 and bit 0 of the encoded sub-information units, are A and B, and a level difference A?B is ?.

Abstract: According to one embodiment, a first encoder encodes main information, a second encoder encodes sub-information, a first modulator modulates a carrier based on an output of the first encoder, a duplicating module duplicates an output of the second encoder to generate encoded sub-information units, and a second modulator amplitude-modulates an output of the first modulator based on the encoded sub-information units. The second modulator amplitude-modulates with ?/(?×(2N)1/2) being 0.4 or less, wherein a noise power of a transmission path or a storage medium is ?2, a number of the encoded sub-information units is N, signal levels after amplitude modulation, which correspond to bit 1 and bit 0 of the encoded sub-information units, are A and B, and a level difference A?B is ?.

Abstract: The present invention relates to an optical recording media including two or more information layers, at least one of the information layers including a writable recording film. In the optical recording media, at least one information layer has protrusions and recesses that permit tracking and at least another one information layer is substantially flat.

Abstract: According to one embodiment, an optical disc is the following the distance between a light incidence plane and the first recording layer is a minimum of 550 ?m. The distance between the first and the third recording layer is a maximum of 72 ?m. The distance between the second and the third recording layer is a minimum of 15 ?m. The distance between the first and the second recording layer is about 31 to 40 ?m. The reflectivities of the first and the second recording layer with respect to the first laser beam range from 18 to 27%, and the ratio therebetween is about 1.1 or less. The reflectivity of the third recording layer is below about 6%. The areal recording density of the third recording layer is three times or more as high as that of the first recording layer and the second recording layer.

Abstract: An optical disc of this invention is configured to be capable of dealing with both information in HD DVD and information in DVD.

Abstract: According to one embodiment, an optical information recording medium includes pre-grooves with an irregular shape and lands each of which is sandwiched between the pre-grooves adjacent to each other, where the pre-grooves and lands are defined on an interface between a recording layer and a light reflection layer in a recording film, where the recording film includes a light reflectivity that enables reproduction with light of 650±5 nm, the recording layer includes a recording sensitivity with respect to light by a wavelength shorter than 650±5 nm, and a recording mark can be formed on the pre-groove by using light with a wavelength shorter than 650±5 nm.

Abstract: In an optical disk of the invention composed of two substrates bonded to each other, the level of double refraction is set to 60 nm or less in a read-only disk, to 60 nm or less in a write-once type disk, and to 40 nm or less in a rewritable type disk, respectively.

Abstract: According to one embodiment, in a single-sided, triple-layered optical disk, at least a first reflecting layer on the light incident side is made of silicon or a silicon compound, and has a recording density lower than those of second and third reflecting layers.

Abstract: An optical disc is provided which realizes desired optical properties, which has a transmissive reflection layer causing no deformation and the like of minute convex pits, and which can realize superior reproduction properties even when high density recording is performed. The above optical disc has at least three information layers independent with respect to a light incident surface, and a reflection layer formed on an information layer other than the layers most close to and most far from the light incident surface has a thickness of 5 to 20 nm and has a refractive index of 3.0 or more and an extinction coefficient of 0.6 or less with respect to the wavelength of incident laser light. This reflection layer is preferably composed of at least one material selected from the group consisting of Si, a SiCr alloy, a SiNb alloy, a SiW alloy, and SiC.

Abstract: According to one embodiment, disclosed is an optical disc in which information is recorded by a pit pattern and which includes a reflection membrane. When concavities and convexities of the pits are opposite to those of a usual case, the reflection membrane is formed on the pits in the form of a two-layer membrane of silver or a silver alloy and aluminum or an aluminum alloy. The reflection membrane is formed with a two-layer structure including a first layer and a second layer different from the first layer. The material of the first layer is aluminum, an aluminum alloy or aluminum oxide. The second layer contacts the first layer and its material is silver or a silver alloy.

Abstract: A phase-change optical recording medium includes a phase-change optical recording film that permits reversible phase change between a crystalline phase and an amorphous phase upon irradiation with light, and an interface film formed of hafnium oxide, or a mixture of hafnium oxide and at least one oxide selected from the group consisting of cerium oxide, titanium oxide and zirconium oxide, and formed in contact with at least one surface of the phase-change optical recording film.

Abstract: According to one embodiment, a single-sided, multilayered optical disc which performs recording and playback when irradiated with a laser beam having a predetermined wavelength, and has at least two recording layers that are independent of each other with respect to the light incident surface, a reflecting layer farthest from the light incident surface contains an Ag alloy, and has a light absorbance of 20% (inclusive) to 50% (inclusive) to a laser beam and/or a thermal conductivity of 50 (inclusive) to 250 (inclusive) W/m·K.

Abstract: According to one embodiment, a write-once optical disc which uses a short-wavelength laser allows BCA information recording even using a long-wavelength laser. To this end, a groove is cut in advance on a BCA part on a molded substrate of the optical disc to store a dye. In this way, the sensitivity of the dye in the BCA increases, to allow a laser having a wavelength other than the wavelength corresponding to information recording of the dye to record a barcode pattern on the BCA.

Abstract: According to one embodiment, a multilayer optical disk includes three or more recording layers, and one of conditions (1) Rn/((Rn?1+Rn?2)/2)>0.6, and (2) Rn×(100?Rn?1)2/(Rn?2×Rn?1×Rn?1)>30 is satisfied, where Rn(%) is a reflectivity of an nth layer (n>2) when seen from a surface on which a reproducing light is incident.

Abstract: According to one embodiment, there is provided an optical disk including a photopolymer layer including a recording pattern formed by concave pits, and a reflecting film formed on the photopolymer layer. The depth direction of the concave pits is opposite to the direction in which the reflecting film is formed.

Abstract: An embodiment of the invention, an information recording medium has a first recording layer, a second recording layer which is provided with respect to the first recording layer through a first space layer with a first thickness, a third recording layer which is provided with respect to the second recording layer through a second space layer whose thickness is different from the first space layer and is set to a predetermined magnitude with respect to the thickness of the first space layer, a first substrate which supports the first recording layer, and a second substrate which supports the third recording layer, and it is possible to manufacture with high productivity an information recording medium having three or more recording layers hard to cause interlayer crosstalk.

Abstract: According to one embodiment, an optical disc is the following the distance between a light incidence plane and the first recording layer is a minimum of 550 ?m. The distance between the first and the third recording layer is a maximum of 72 ?m. The distance between the second and the third recording layer is a minimum of 15 ?m. The distance between the first and the second recording layer is about 31 to 40 ?m. The reflectivities of the first and the second recording layer with respect to the first laser beam range from 18 to 27%, and the ratio therebetween is about 1.1 or less. The reflectivity of the third recording layer is below about 6%. The areal recording density of the third recording layer is three times or more as high as that of the first recording layer and the second recording layer.

Abstract: An optical disc comprising three or more of a predetermined number of information recording layers between a first molding disc and a second molding disc, each of which has an incident face, is featured in that a distance between the incident face and each of the information recording layers is within the range of 600±55 ?m.

Abstract: An optical disc of this invention is configured to be capable of dealing with both information in HD DVD and information in DVD.

Abstract: According to this invention, an information recording medium has the first and second sides. The information recording medium includes the first information recording layer which includes the first reflecting layer reflecting incident light with a predetermined intensity from the first side, the second information recording layer which includes a second reflecting layer reflecting incident light with a predetermined intensity from the second side, an adhesion layer which adheres the first information recording layer and the second information recording layer, and a unique information recording area which is formed by burst-cutting the first reflecting layer and the second reflecting layer in correspondence with medium unique information, using incident light with an intensity higher than the predetermined intensity from one of the first side and the second side.