Abstract: According to one embodiment, a write-once type information storage medium comprises an organic dye based recording material having sensitivity at a wavelength of 405 nm and at a recording wavelength in the range of 600 nm to 700 nm, wherein, when absorbance of a maximum absorption wavelength in the vicinity of 405 nm is defined as 1, the absorbance is 5% or more at any wavelength in the range of 600 nm to 700 nm.

Abstract: According to one embodiment, a write-once type information storage medium comprises an organic dye based recording material having sensitivity at a wavelength of 405 nm and at a recording wavelength in the range of 600 nm to 700 nm, wherein, when absorbance of a maximum absorption wavelength in the vicinity of 405 nm is defined as 1, the absorbance is 5% or more at any wavelength in the range of 600 nm to 700 nm.

Abstract: According to one embodiment, an information recording medium has a plurality of recording layers, and records and reproduces information by using a semiconductor layer of 450 nm or less. When reproducing information, letting x be the frequency of repetitive recording of a shortest mark length and shortest space length of the information, the ratio of the value of a highest level to the value of a level at x/190 of a sum signal detected within the frequency range of x/3240 to x/190 is lower than 32 dB, or the ratio of the average value of the amplitudes of signals of repetitive recording of the shortest mark length and shortest space length to the value of the highest level within the frequency range of x/3240 to x/190 is higher than 10 dB.

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, 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 second light reflecting layer is larger than the thickness of the first light reflecting layer.

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, 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 second light reflecting layer is larger than the thickness of the first light reflecting layer.

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 recordable information recording medium includes an organic dye layer contains an organic dye including a cation portion having monomethinecyanine and an anion portion having an azo metal complex, and a quencher having a formazan metal complex.

Abstract: According to one embodiment, a write-once information recording medium includes a transparent resin substrate having concentric or spiral grooves and lands, and a recording film formed on the grooves and lands of the transparent resin substrate, wherein the recording film includes an organic dye layer containing a metal complex monomer and a metal complex polymer, a recording mark is formed in the organic dye layer by emission of a short-wavelength laser beam, and a light reflectance of the recording mark formed by emission of the short-wavelength laser beam is higher than that before emission of the short-wavelength laser beam, and the grooves wobble within a predetermined amplitude range.

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: According to one embodiment, an information recording medium includes a transparent resin substrate having concentric grooves and concentric lands or a spiral groove and spiral land, and a recording layer formed on the groove and land, and capable of recording and reproducing information by using a semiconductor laser of 450 nm or less. When reproducing recorded information, the information recording medium satisfies the following formula (1) 0.87?M4×/M1×?1.

Abstract: According to one embodiment, an information recording medium including a recording film using an organic recording material recorded by recording light having a wavelength of 405 nm and an organic recording material whose light reflection quantity varies by reproducing light having a wavelength of 650 nm for a recording layer and an optical reflection layer and a land sandwiched between a pre-groove having an irregular shape and an adjoining pre-groove is provided on an interface between the recording layer and the optical reflection layer.

Abstract: In an optical disk system using a PRML identification system, a method for deriving an optimum recording wave in a short period of time is provided. Parameters of the recording wave are adjusted by using an evaluation value obtained by a signal evaluation method which is suitable for the PRML identification system as an index. In this case, as a parameter adjusting method, a plurality of adjusting methods are utilized.

Abstract: According to one embodiment, an information recording medium has a plurality of recording layers, and records and reproduces information by using a semiconductor layer of 450 nm or less. When reproducing information, letting x be the frequency of repetitive recording of a shortest mark length and shortest space length of the information, the ratio of the value of a highest level to the value of a level at x/190 of a sum signal detected within the frequency range of x/3240 to x/190 is lower than 32 dB, or the ratio of the average value of the amplitudes of signals of repetitive recording of the shortest mark length and shortest space length to the value of the highest level within the frequency range of x/3240 to x/190 is higher than 10 dB.

Abstract: According to one embodiment, when recording information by using a semiconductor laser at 450 nm or less, an information recording medium satisfies 9.5×10?8??/(X*NA)?4.6×10?8 (where X is the linear recording velocity, ? is the laser wavelength, and NA is the numerical aperture).

Abstract: According to one embodiment, an apparatus which records a signal in a recording medium in which information is written by using a first laser having a first wavelength and from which information is read by using a second laser having a second wavelength longer than that of the first laser, a signal is recorded in the recording medium by using the first laser, and a control section reproduces the signal recorded with the first laser and measures a first amount that is used to calculate a target value for optimization of recording conditions, reproduces a signal recorded with the second laser and measures a second amount for optimization of a reproduction signal, compares the first amount with the second amount, and determines the first amount under the recording conditions where the second amount becomes optimum as a target value for optimization of the recording conditions.

Abstract: According to one embodiment, an optical head device provides a signal processing circuit which sets a control amount to move an objective lens so that a distance between the objective lens and a given recording layer of the an optical disc coincides with a focal position, an optical path length correction mechanism which corrects an influence of an aberration component producing an error in the focal distance, a thickness difference detection circuit which finds an amount of correction to be made by the optical path length, and an aberration correction circuit which generates a correction signal to correct the influence of the aberration component producing the error in the focal distance detected by the thickness difference detection circuit, and supplies the correction signal to the optical path length correction mechanism.

Abstract: An optical disk according to the present invention has a guide groove formed with a width which is not less than 80 nm and not more than 170 nm in terms of a half-value width. A depth of the guide groove is formed within a range in which (n1?n2)·d1+n2·d2=(2m?1)·?/4 is ±15%, wherein n1 is a refractive index of a substrate, n2 is a refractive index of a recording film, ? is a wavelength of light beams used for recording and reproduction of information, d1 is a depth of the guide groove, d2 is a depth of the recording film positioned on the guide groove, and m is an integer (m=1, 2, 3, 4 . . . ).

Abstract: According to one embodiment, an information storage medium has a substrate, a first recording layer containing an organic dye material, a first barrier layer, a spacer layer, a second recording layer, a second barrier layer, and a protective layer formed on the second barrier layer. The angle that the outer side surface and inner side surface of the protective layer make with a direction parallel to the surface of the second barrier layer is 30° to 150°, at least one of the first and second barrier layers has lands and grooves on its two major surfaces and the depth of the lands on one major surface is smaller than that of the lands on the other major surface close to the substrate, or the first and second barrier layers are made of a material formable by coating.