Abstract: A dielectric multilayer film-attached substrate including a substrate and a dielectric multilayer film provided thereon, in which the dielectric multilayer film includes a first dielectric laminated film and a second dielectric laminated film laminated in this order from a substrate side, the first dielectric laminated film includes a first high refractive index film layer containing TiO2 and a first low refractive index film layer containing SiO2 laminated alternately in this order from the substrate side with an equal number, the second dielectric laminated film includes a second high refractive index film layer containing Ta2O5 or Nb2O5 and a second low refractive index film layer containing SiO2 laminated alternately in this order from the substrate side with an equal number, and a first low refractive index film layer located farthest from the substrate in the first dielectric laminated film has a thickness of 30 nm or more.

Abstract: An optical filter, including: a substrate; and a dielectric multilayer film laid on or above at least one major surface of the substrate, the dielectric multilayer film including at least two different layers, where: the dielectric multilayer film includes four or more films having a spin density of 5.0×1010/nm·cm2 or larger, each of the four or more films has a minimum thickness of 1.5 nm to 5 nm, a maximum transmittance at an incident angle of 0° in a wavelength range of 400 nm to 680 nm is 6% or lower, a maximum reflectance at an incident angle of 5° in the wavelength range is 20% or lower, and an average transmittance at an incident angle of 0° in at least one wavelength range having a width of 40 nm included in a wavelength range of 800 nm to 1570 nm is 90% or higher.

Abstract: An anti-reflective film-attached transparent substrate includes: a transparent substrate having two main surfaces; and a diffusion layer and an anti-reflective film in this order from a transparent substrate side on one main surface of the transparent substrate. When reflection on the other main surface of the transparent substrate is eliminated and a light source is incident on the one main surface at an incident angle of 45°, a* and b* of diffusely reflected lights at angles of ?15°, 15°, and 25° with respect to a specularly reflected light under a D65 light source satisfy formulas (1) ?5?a*??1 and (2) 0?b*?9.

Abstract: An anti-reflective laminate includes: a substrate; and an anti-reflective layer having a four-layer structure including a first refractive index layer, a second refractive index layer, a third refractive index layer, and a fourth refractive index layer. The first refractive index layer has a refractive index of 1.25 to 1.50, the second refractive index layer has a refractive index of 1.50 to 2.40, the third refractive index layer has a refractive index of 2.25 to 2.45, and the fourth refractive index layer has a refractive index of 1.25 to 1.50. The first refractive index layer has a thickness of 40 to 105 nm, the second refractive index layer has a thickness of 60 to 90 nm, the third refractive index layer has a thickness of 80 to 110 nm, and the fourth refractive index layer has a thickness of 70 to 100 nm.

Abstract: An antiglare layer-attached transparent substrate includes: a transparent substrate comprising two main surfaces; and an antiglare layer and an anti-reflective layer in this order on at least one main surface of the transparent substrate. The antiglare layer-attached transparent substrate has a haze value of 30% or more, and a skewness Ssk of 0.4 or less on a surface having the antiglare layer, and the antiglare layer contains fine particles, and a difference between a thickness of the antiglare layer and an average particle diameter of the fine particles is 4 ?m or less.

Abstract: An anti-reflective film-attached transparent substrate includes: a transparent substrate comprising two main surfaces; and a diffusion layer and an anti-reflective film in this order from a transparent substrate side on one main surface of the transparent substrate. When reflection on the other main surface of the transparent substrate is eliminated and a light source is incident on the one main surface at an incident angle of 45°, a* and b* of diffusely reflected lights at angles of ?15°, 15°, 25°, 45°, 75°, and 110° with respect to a specularly reflected light under a D65 light source satisfy formulas (1) ?6?a*?2, (2) ?1?b*?12 (3) b*??2a*+4, and (4) b*??2a*?5.

Abstract: An anti-reflective film-attached transparent substrate includes a transparent substrate and an anti-reflective film. The anti-reflective film has a laminated structure in which at least two layers having different refractive indices are laminated, at least one layer is mainly formed of a Si oxide, at least another layer is a mixed oxide layer mainly formed of a mixed oxide containing Mo and Nb, the mixed oxide layer contains an oxide of at least one high hardness metal element selected from the group consisting of W, Cr, Mn, Ni, Zr, Ta, and Be, a proportion of Mo to a total of Mo and Nb in the mixed oxide layer is 60 at % or less, and a proportion of a total of the high hardness metal element to a total of metal elements in the mixed oxide layer is 12 at % or more.

Abstract: An anti-reflective film-attached transparent substrate includes: a transparent substrate including two major surfaces; and a diffusion layer and an anti-reflective film on one major surface of the transparent substrate, which are provided in this order. (A) A luminous reflectance SCI Y of an outermost surface of the anti-reflective film-attached transparent substrate is 1% or lower. (B) The anti-reflective film has a lamination structure in which at least two dielectric layers having different refractive indices are laminated. (C) A ratio (SCE Y)/(SCI Y) of a diffuse reflectance SCE Y of the outermost surface of the anti-reflective film-attached transparent substrate to the luminous reflectance SCI Y of the outermost surface of the anti-reflective film-attached transparent substrate is 0.15 or higher.

Abstract: An optical filter including: a substrate; and a dielectric multilayer film laid on or above at least one major surface of the substrate as an outermost layer, in which: the dielectric multilayer film is a laminate including a low refractive index film and a high refractive index film laid on each other; the low refractive index film or the high refractive index film satisfies the spectral characteristics (i-1) and (i-2); the optical filter satisfies all of the spectral characteristics (ii-1) to (ii-3); and the optical filter has a nanoindentation hardness of 5.5 GPa or higher when a measurement load is 1 mN.

Abstract: An optical filter including: a substrate; and a dielectric multilayer film laid on or above at least one major surface of the substrate as an outermost layer, in which: the dielectric multilayer film is a laminate including a low refractive index film and a plurality of high refractive index films laid on each other; the dielectric multilayer film comprises four or more high refractive index films that are 15 nm or smaller in thickness; the high refractive index films have a minimum thickness of 1.5 to 5 nm; the high refractive index films have a minimum thickness of 100 nm or smaller; the high refractive index films satisfy the following spectral characteristics (i-1) and (i-2); and the optical filter satisfies all of the following spectral characteristics (ii-1) to (ii-4).

Abstract: An optical filter includes a substrate and a dielectric multilayer film laid as an outermost layer on at least one major surface of the substrate. The dielectric multilayer film includes a low-refractive index film and a high-refractive index film provided alternately. At least one film selected from the group consisting of the low-refractive index film and the high-refractive index film satisfies the following optical characteristics (i-1) and (i-2A): (i-1) an extinction coefficient k600 at a wavelength of 600 nm is 0.12 or larger; and (i-2A) a minimum extinction coefficient k1530-1570MIN in a wavelength range of 1530 to 1570 nm is 0.01 or smaller; and the optical filter satisfies the following optical characteristic (ii-1A): (ii-1A) light in a wavelength range of 400 to 680 nm is blocked and light in the wavelength range of 1530 to 1570 nm is transmitted.

Abstract: A magnetic recording medium may have a stacked structure including a first soft magnetic layer, an orientation control layer, a lower recording layer, an intermediate layer, and an upper recording layer that are sequentially stacked, and a second soft magnetic layer provided between the lower recording layer and the intermediate layer.

Abstract: A magnetic recording medium may include a stacked structure of orientation control, lower recording, intermediate, and upper recording layers. The lower recording layer has a coercivity higher than that of the upper recording layer. The lower recording layer includes a first layer with a granular structure that includes magnetic particles including Co, Cr, and Pt, and an oxide covering a periphery of the magnetic particles, and a second layer with a non-granular structure that includes magnetic particles including Co, Cr, and Pt. The lower recording layer includes columnar crystals continuous with crystal particles forming the orientation control layer in a stacking direction of the stacked structure.

Abstract: A magnetic recording medium may include an orientation control layer, a lower recording layer, an intermediate layer, and an upper recording layer that are stacked. The lower recording layer may have a coercivity higher than that of the upper recording layer, and the intermediate layer may include a layer including a magnetic material and having a saturation magnetization of 50 emu/cc or higher. The upper recording layer may include columnar crystals continuous with crystal particles forming the intermediate layer in a direction in which the layers are stacked.

Abstract: A servo information recording method continuously records servo information in a radial direction of a magnetic disk on a plurality of concentric tracks or on a single spiral track of a first recording layer that forms a magnetic layer of the magnetic disk together with a second recording layer to which data are recorded and from which data are reproduced, wherein the first recording layer has a coercivity higher than that of the second recording layer, and partially overlaps two mutually adjacent tracks when continuously recording the servo information on an entire surface of the first recording layer.

Abstract: A servo information recording method continuously records servo information in a radial direction of a magnetic disk on a plurality of concentric tracks or on a single spiral track of a first recording layer that forms a magnetic layer of the magnetic disk together with a second recording layer to which data are recorded and from which data are reproduced, wherein the first recording layer has a coercivity higher than that of the second recording layer, and partially overlaps two mutually adjacent tracks when continuously recording the servo information on an entire surface of the first recording layer.

Abstract: A magnetic recording medium may have a stacked structure including a first soft magnetic layer, an orientation control layer, a lower recording layer, an intermediate layer, and an upper recording layer that are sequentially stacked, and a second soft magnetic layer provided between the lower recording layer and the intermediate layer.

Abstract: A magnetic recording medium may include a stacked structure of orientation control, lower recording, intermediate, and upper recording layers. The lower recording layer has a coercivity higher than that of the upper recording layer. The lower recording layer includes a first layer with a granular structure that includes magnetic particles including Co, Cr, and Pt, and an oxide covering a periphery of the magnetic particles, and a second layer with a non-granular structure that includes magnetic particles including Co, Cr, and Pt. The lower recording layer includes columnar crystals continuous with crystal particles forming the orientation control layer in a stacking direction of the stacked structure.

Abstract: A perpendicular magnetic recording medium that is excellent in terms of electromagnetic conversion characteristics and can achieve the demand for the recording density growth, and a magnetic recording and reproducing apparatus provided with the perpendicular magnetic recording medium are provided. The perpendicular magnetic recording medium has at least a backing layer, an underlayer, an intermediate layer, and a perpendicular magnetic recording layer sequentially laminated on a non-magnetic substrate, in which the backing layer includes at least a soft magnetic film having an amorphous structure; the underlayer includes a first underlayer and a second underlayer laminated from the non-magnetic substrate side; the first underlayer is an fcc-structured alloy layer including an fcc-structured element and a bcc-structured element, the second underlayer includes a NiW alloy; and the intermediate layer includes Ru or a Ru alloy.

Abstract: A magnetic recording medium may include an orientation control layer, a lower recording layer, an intermediate layer, and an upper recording layer that are stacked. The lower recording layer may have a coercivity higher than that of the upper recording layer, and the intermediate layer may include a layer including a magnetic material and having a saturation magnetization of 50 emu/cc or higher. The upper recording layer may include columnar crystals continuous with crystal particles forming the intermediate layer in a direction in which the layers are stacked.