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In a light information recording apparatus, a hologram pattern diffracts a reference light such that the reference light which is emitted from an objective lens to a recording medium side, is superimposed on a information light which is emitted from the objective lens to the recording medium side in the vicinity of a light condensing point of the information light, and the reference light is condensed at a different point from the light condensing point of the information light. In a light information reproducing apparatus, the hologram pattern diffracts the reference light in a going path such that the reference light which is emitted from the objective lens in a returning path comes off a light path of the reference light in the going path.

The present invention provides an Al-based alloy reflecting film which reduces noise on an optical information recording medium by having a reflecting film surface accurately reproduce grooves, pits and the like formed on a substrate, and has high reflectivity. A sputtering target which is effective for forming such a reflecting film is also provided. The reflecting film to be used for the optical information recording medium is substantially composed of an Al-based alloy containing 2.0-15.0 atm% of a rare-earth element, and has a crystallite size of 30 nm or smaller in the thickness direction of the reflecting film.

A magnetic recording medium including a magnetic recording layer and a substrate that supports the magnetic recording layer is provided. At least two underlayers including a nonmetallic underlayer are placed between the magnetic recording layer and the substrate. The perpendicular magnetic recording medium uses a double-layered or tri-layered underlayer. Accordingly, a perpendicular magnetic recording layer can have a high perpendicular magnetic anisotropic energy constant Ku due to a third underlayer and have small crystal grains and a small exchange coupling due to a second underlayer below the third underlayer. Thus, the perpendicular magnetic recording layer can have a good thermal stability, high-density recording characteristics, and excellent SNR characteristics.

The present invention relates to an optical recording medium. The optical recording medium according to one embodiment of the present invention includes a substrate and an information recording layer located on the substrate. The information recording layer includes a first recording layer containing at least one element selected from the group consisting of Ag, In, Ge, Sb and Te, a second recording layer containing at least one element selected from the group consisting of Si, Sn, Sb and Ge, and a third recording layer containing at least one element selected form the group consisting of Ni, Ag, Au, W, Cr and Mo. Therefore, the optical recording medium of the present invention may reduce the thickness and manufacturing cost by consisting of three recording layers and eliminating the reflective layer and the dielectric layer.

Provided is an optical information recording medium having excellent C / N and reproduction durability and having no inhibition to high density recording. Moreover, the recording and reproducing of high volume and high density information can be done by a blue laser light of short wavelength, and the recording property may have excellent sensitivity and reflectivity. The optical information recording media carry out the recording and reproducing by a laser light of 450 nm or less, wherein grooves having a track pitch of 200 to 400 nm, a groove depth of 50 to 150 nm and a groove half width of 90 to 200 nm are form on the substrate, and a reflective layer, a recording layer and a covering layer are provided thereon. The recording layer comprises an organic substance having maximum absorption at 600 to 800 nm and 300 to 400 nm of more than 1. When a laser light of 380 to 500 nm wavelength is irradiated through a lens with a numerical aperture (NA) of 0.7 or more to a substrate, the recording layer of the optical information media carry out the recording of information. The recording layer contains organic substance and the substrate has a groove depth of 15 to 45 nm, a track pith of 250 to 400 nm and a half width of groove of 60 to 200 nm an oblique angle of the groove of 40 to 80 DEG.

The invention provides an optical information recording medium of a blue light structure which gives play to excellent recording characteristics when recording and with easy manufacturing. The optical information recording medium comprises a reflective layer, a recording layer, a barrier layer, and a cover layer in turn on a surface of a support. The recording layer includes at least an azopigment compound in group selection composed of an azo compound and an azo metal coordination compound including an azo compound and a metal ion or a metal oxide ion, wherein the extinction coefficient of the azopigment compound is in the range of 0.15-0.3 at the wavelength of 405 nm. A layer is formed between the barrier layer and the cover layer, which implements curingprocess on the an ultraviolet radiation-curable composition, having a glass transition temperature of equal to or lower than 25 DEG C.

The present invention provides a hologram recording material which is suitable for volume hologram record and can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low dimensional change (low shrinkage) and high multiplicity in holographic memory record using not only a green laser but also a blue laser; and provides a hologram recording medium having a hologram recording layer comprising the hologram recording material. A hologram recording material comprising a metal oxide matrix and a photopolymerizable compound, wherein the metal oxide matrix comprises at least Si and Ti as metallic elements, and Ti originates from titanium-containing oxide fine particles. A hologram recording medium ( 11 ) having the hologram recording layer ( 21 ) comprising the hologram recording material.

The method of evaluating dye component suitability for optical recording media according to the invention comprises a first step in which the temperature of a sample containing the dye component or the temperature of the atmosphere surrounding the sample is set to two or more different prescribed temperatures, and the absorbance of the sample for light of a prescribed wavelength is measured at each of the prescribed temperatures, and a second step in which the suitability of including the dye component in the recording layer of an optical recording medium is evaluated based on one or more conditions which are set based on correlation between the prescribed temperatures and the absorbance.

An optical recording medium includes a substrate having successively disposed thereon a light-reflecting layer, a recording layer and a cover layer, with recording and playback being effected by irradiating the medium with a laser beam having a wavelength of 450 nm or less from the side disposed with the cover layer, wherein a sputter layer having a thickness of 1 to 80 nm is formed between the recording layer and the cover layer, and the sputter layer and the cover layer are adhered with an adhesive. So a high-density makeup recording type optical recording medium having superior recording characteristics is provided.

An optical storage medium comprising: a substrate; a recording layer for recording a recorded mark representing information to be recorded by irradiating a recording light beam onto the recording layer in accordance with a recording pulse pattern of recording pulses rising from an erasing power and formed between a recording power larger than the erasing power and a bottom power smaller than the erasing power and of erasing pulses rising from the bottom power to the erasing power. The recording layer has been initialized with an initialization laser beam having the erasing power satisfying expressions (1) and (2): 1.000<(R1 / R0)<1.030 (1); 0.030<(R10 / R0)-(R1 / R0)<0.150 (2), in which R0 is a reflectivity exhibited by an un-recorded section of the recording layer, on which no data has ever been recorded, when irradiated with a reproducing light beam, R1 is a reflectivity exhibited by the un-recorded section when irradiated with the reproducing light beam after irradiated once with a light beam having the erasing power, and R10 is a reflectivity exhibited by the un-recorded section when irradiated with the reproducing light beam after irradiated ten times with a light beam having the erasing power.

The optical recording material of the invention is an optical recording material used for an optical recording medium capable of recording information by irradiation of light, the optical recording medium being an optical recording medium which records information at a linear speed of at least 14 m / sec, wherein the dye component in the optical recording material comprises at least one type of chelate compound of an azo compound and a metal, and when the dye component is used as a sample for thermogravimetry in an inert gas atmosphere, the dye component sample exhibits a maximum weight reduction of 0.2-3.0% / DEG C. at 180-250 DEG C.

A polishing pad used in the mirror polishing process of a glass substrate, the polishing pad is characterized by: having a plurality of open pits on the main surface in contact with the glass substrate, one open pit and other open pits adjacent to the open pit Partitioned by a partition wall, an inclined portion is provided on the side of the other opening pit side among the side surfaces of the partition wall, and the inclined portion has a minimum curvature radius of 20-100 μm. According to this polishing pad, it is possible to provide a polishing pad or the like which makes it difficult for polishing liquid components to accumulate in open pits while maintaining the processing rate in the mirror polishing step.

An optical information medium (20) for recording, such as DVR-blue, and a method for manufacturing such a medium (20) is provided. Reading from and recording onto the medium (20) is performed by means of a focused radiation beam (10) having a radiation wavelength » and a numerical aperture NA. Said medium has a substrate (1), and a stack (2) of layers provided thereon. The stack (2) comprises at least a first recording stack (3) and k radiation beam transmissive layers (4, 5). Each transmissive layer (4, 5) has a refractive index n i and an average thickness d i µm and 1 ‰ i ‰ k and k ‰¥ 2. The thickness d k of layer k (5) is determined by a simple formula which depends on the parameters n i for i = 1...k and d i for i = 1...k-1. Such a medium (20) has zero or substantially zero spherical aberration at the focal point, being at the recording layer of the first recording stack (3), of said radiation beam (10).

An optical recording medium includes a disc including a dye layer and a reflecting layer formed on a substrate, a dummy substrate, and an adhesive layer adhering the disc and the dummy substrate.

The present invention relates to an optical recording medium. The optical recording medium according to one embodiment of the present invention includes a substrate and an information recording layer located on the substrate. The information recording layer includes a first recording layer containing at least one element selected from the group consisting of Ag, In, Ge, Sb and Te, a second recording layer containing at least one element selected from the group consisting of Si, Sn, Sb and Ge, and a third recording layer containing at least one element selected form the group consisting of Ni,Ag, Au, W, Cr and Mo. Therefore, the optical recording medium of the present invention may reduce the thickness and manufacturing cost by consisting of three recording layers and eliminating the reflective layer and the dielectric layer.

To provide an optical recording medium which can produce successful recording properties in recording at a high lineal speed, can successfully retain the properties of performing a single round or a plurality of rounds of overwrite, and has high long-term shelf stability. A phase-changing type optical recording medium comprises a substrate 1 and at least a recording layer 3 and a reflective layer 5. A material for the recording layer 3 is a Ge-Sb-In-Sn alloy. When the respective atomic ratio of the constituent elements of the alloy is given as a, b, c and d, the relationship among following formulae (1) to (4) is satisfied: 0.08<=a<=0.20... (1), 0.60<=b<=0.80... (2), 0.05<=c<=0.20... (3), 0.01<=d<=0.15... (4), provided, however, that a+b+c+d=1.

The lower magnetic pole layer has a magnetic pole part layer and a yoke part layer. The upper magnetic pole layer has a magnetic pole part layer and a yoke part layer. The magnetic pole portion layer of the lower magnetic pole layer, the recording gap layer, and the magnetic pole portion layer of the upper magnetic pole layer have the same cross-sectional shape parallel to the upper surface of the substrate. The assembly of the two magnetic pole portion layers and the recording gap layer includes a first portion having a width defining the track width and a second portion having a width greater than the width of the first portion. When the width of the first part is W and the distance from the media facing surface ABS to the boundary position of the first part and the second part is L, L / W is 2 or more and 5 or less. When the area of ​​the cross section of the assembly parallel to the upper surface of the substrate is S, S / (W×L) is 5 or more and 40 or less.

The present invention provides a hologram recording material which is suitable for volume hologram record and can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low dimensional change (low shrinkage) and high multiplicity in holographic memory record using not only a green laser but also a blue laser; and provides a hologramrecording medium having a hologram recording layer comprising the hologram recording material. A hologram recording material comprising a metal oxide matrix and a photopolymerizable compound, whereinthe metal oxide matrix comprises at least Si and Ti as metallic elements, and Ti originates from titanium-containing oxide fine particles. A hologram recording medium ( 11 ) having the hologram recording layer ( 21 ) comprising the hologram recording material.