Abstract: Provided are a substrate for epitaxially growing a diamond crystal, having at least a surface made of a metal, in which the above surface made of the metal is a plane having an off angle ? of more than 0°, and the full width at half maximum of the X-ray diffraction peak from the (002) plane by the X-ray rocking curve measurement at the above surface made of the metal is 300 seconds or less; and a method of manufacturing a diamond crystal, including epitaxially growing a diamond crystal on the above surface made of the metal of the above substrate.

Abstract: There is room for improvement in the quality of diamond crystals used in radiation detectors produced using the conventional hetero-epitaxial method. The diamond crystal used for the radiation detector according to the present invention: is heteroepitaxially grown by means of chemical vapor deposition on a substrate comprising a material other than the diamond and having a plane orientation inclined by a predetermined off-angle from a just plane orientation; and has a crystallinity such that the full width half maximum of the diffraction peak of the (004) plane of the X-ray diffractometry represents a value shorter than or equal to 200 seconds.

Abstract: A clutch device includes: an input disk; an output disk; and a biasing member configured to press the input disk and the output disk against each other, the input disk and the output disk contact or separate from each other in an axial direction, and at opposing surfaces thereof, respectively have tooth portions engageable with or disengageable from each other, at each tooth portion, recessed and raised portions extending in a radial direction are alternately provided in a circumferential direction, each of the recessed and raised portions is formed so that a width in the circumferential direction may outwardly expands in the radial direction, and engagement force in the axial direction is greater on an inside of the tooth portions in the radial direction than on the outside when the tooth portions of the input disk and the output disk pressed by the biasing member are fitted in each other.

Abstract: An optical coupling device including multiple optical fibers each of which includes at least one core; and a self-forming optical waveguide, wherein the optical fibers are arranged facing each other, and the self-forming optical waveguide is provided between the optical fibers, an end portion of the self-forming optical waveguide is optically connected to the core of each optical fiber, the cores of the optical fibers arranged facing each other are optically connected to each other through the self-forming optical waveguide in a linear shape, optical axis directions of the optical fibers optically connected to each other through the self-forming optical waveguide are parallel with each other, and an end portion of each core is diagonally formed with an inclination angle according to a refractive index of each core and a refractive index of the self-forming optical waveguide.

Abstract: A method for polishing a diamond crystal includes preparing a diamond crystal having a main surface having a plane orientation of (100). Mechanical polishing is performed on the main surface using a polishing wheel such that: a tangent contacts a curve extending in a rotation direction of the wheel and contacting a contact position between the diamond crystal and the wheel that is rotating; and a tangent direction of the tangent at the contact position is within a range of ±10 degrees relative to a <110> direction of the diamond crystal, thereby causing an affected region to appear such that the affected region is parallel to a direction of a plane orientation (111) of the diamond crystal and penetrates the diamond crystal onto the main surface. Chemical mechanical polishing is performed on the main surface to remove the affected region, thereby removing the affected region from the main surface.

Abstract: A method for polishing a diamond crystal includes preparing a diamond crystal having a main surface having a plane orientation of (100). Mechanical polishing is performed on the main surface using a polishing wheel such that: a tangent contacts a curve extending in a rotation direction of the wheel and contacting a contact position between the diamond crystal and the wheel that is rotating; and a tangent direction of the tangent at the contact position is within a range of ±10 degrees relative to a <110> direction of the diamond crystal, thereby causing an affected region to appear such that the affected region is parallel to a direction of a plane orientation (111) of the diamond crystal and penetrates the diamond crystal onto the main surface. Chemical mechanical polishing is performed on the main surface to remove the affected region, thereby removing the affected region from the main surface.

Abstract: An optical connector includes multiple optical fibers; a single multicore fiber; and multiple self-forming optical waveguides, wherein the total number of cores of the multiple optical fibers and the total number of cores of the multicore fiber are identical to each other, the multiple optical fibers and the multicore fiber are arranged facing each other, the self-forming optical waveguides are provided among the multiple optical fibers and the multicore fiber, end portions of the self-forming optical waveguides are optically connected to the cores of the multiple optical fibers and the cores of the multicore fiber, and either the multiple optical fibers or the multicore fiber contacting the end portions of the self-forming optical waveguides is detachable from the self-forming optical waveguides.

Abstract: As the diamond crystal, a diamond crystal in a bulk form including dislocation concentration regions is formed. An interval between each of the dislocation concentration regions is from 10 nm to 4000 nm. The crystal orientation of crystal main face at the surface of the diamond crystal is any one of (100), (111), or (110). An external shape of the diamond crystal in a surface direction is a rectangle, a circle, or a circle having an orientation flat plane. The rectangle is set to have a side length of not less than 8.0 mm. The circle is set to have a diameter of not less than 8.0 mm.

Abstract: An optical coupling device including multiple optical fibers each of which includes at least one core; and a self-forming optical waveguide, wherein the optical fibers are arranged facing each other, and the self-forming optical waveguide is provided between the optical fibers, an end portion of the self-forming optical waveguide is optically connected to the core of each optical fiber, the cores of the optical fibers arranged facing each other are optically connected to each other through the self-forming optical waveguide in a linear shape, optical axis directions of the optical fibers optically connected to each other through the self-forming optical waveguide are parallel with each other, and an end portion of each core is diagonally formed with an inclination angle according to a refractive index of each core and a refractive index of the self-forming optical waveguide.

Abstract: A zirconia material manufacturing method includes: dispersing hydroxyapatite powder in water to prepare a slurry having a hydroxyapatite powder concentration of 1%; and dipping zirconia in the slurry to form, on the zirconia, a coating layer containing hydroxyapatite.

Abstract: Provided are a substrate for epitaxially growing a diamond crystal, having at least a surface made of a metal, in which the above surface made of the metal is a plane having an off angle ? of more than 0°, and the full width at half maximum of the X-ray diffraction peak from the (002) plane by the X-ray rocking curve measurement at the above surface made of the metal is 300 seconds or less; and a method of manufacturing a diamond crystal, including epitaxially growing a diamond crystal on the above surface made of the metal of the above substrate.

Abstract: The Ga2O3-based single crystal substrate has an amount of warpage of ?50 ?m or more and 50 ?m or less (including 0 ?m) on a main surface. The method of manufacturing a Ga2O3-based single crystal substrate includes processing a substrate from a Ga2O3-based single crystal grown according to an induction heating type single crystal growth method to have an amount of warpage of ?50 ?m or more and 50 ?m or less (including 0 ?m) on a main surface.

Abstract: An optical connector includes: at least a ferrule and n self-forming optical waveguides, wherein the ferrule includes n optical fiber insertion holes, and optical fibers are each inserted into and included in the optical fiber insertion holes, the number n indicates a natural number not including zero, there are variations in an angle of each optical fiber in a core axial direction and a core gap between adjacent ones of the optical fibers, an end surface of the ferrule is formed with roundness, and end portions of the self-forming optical waveguides are each optically connected to the optical fibers.