Abstract: A method of measuring the bending performance of an optical fiber in a simple manner is provided. Power P1 of light emitted from one end of the optical fiber when light is incident onto the other end of the optical fiber is measured under conditions where the optical fiber 1 is wound at a constant pitch by one layer on the circumferential side of a mandrel 2 and the overall circumference of the optical fiber 1 thus wound is covered with an index matching sheet 5. The refractive index of the index matching sheet 5 substantially matches with the refractive index of resin of the outermost layer of the optical fiber 1.

Abstract: An anti-seizure agent for hot steel working that exhibits excellent wettability and surface film-adherability comprises: an inorganic component (first component); sodium hydroxide (second component); water-soluble resins and/or water-soluble surfactants (third component); and water. With the mass of the sum of the first component, the second component, and the third component as 100 mass %, the anti-seizure agent contains: 96.5 mass % or more and 99.98 mass % or less of the first component; 0.01 mass % or more and 2.0 mass % or less of the second component; and 0.01 mass % or more and 1.5 mass % or less of the third component, and the inorganic component is one or more selected from a group consisting of Al2O3, SiO2, CaO, B2O3, K2O, and Na2O. A coating layer formed after application solidly adheres to the steel and does not come off in the environment of both cold and hot working.

Abstract: An optical fiber that has a small bending loss can be securely prevented from being fractured due to accidental bending during installation or other operations, and is compliant with the G. 652 standard. The optical fiber includes a core, a first cladding, a second cladding and a third cladding. The relative refractive index difference ?1 of the core is in the range of 0.3% to 0.38%, the relative refractive index difference ?2 of the first cladding is equal to or smaller than 0%, and the relative refractive index difference ?3 of the second cladding is in the range of ?1.8% to ?0.5%. The inner radius r2 and the outer radius r3 of the second cladding satisfy the expression “0.4r2+10.5<r3<0.2r2+16”, and the inner radius r2 of the second cladding is equal to or greater than 8 ?m.

Abstract: A method includes a first step of joining a multimode fiber to a first end of an optical fiber being a specimen, allowing light to propagate from the multimode fiber to the specimen, measuring an intensity of light from a second end of the specimen, and determining a first power spectrum; a second step of joining the multimode fiber to a first end of a reference fiber having bending loss higher than that of the specimen, allowing light to propagate from the multimode fiber to the reference fiber, measuring an intensity of light from a second end of the reference fiber, and determining a second power spectrum; a third step of determining a difference spectrum by subtracting the second power spectrum from the first power spectrum; and a fourth step of determining a higher-order mode cutoff wavelength of the specimen on the basis of a shape of the difference spectrum.

Abstract: An optical fiber that has a small bending loss can be securely prevented from being fractured due to accidental bending during installation or other operations, and is compliant with the G. 652 standard. The optical fiber includes a core, a first cladding, a second cladding and a third cladding. The relative refractive index difference ?1 of the core is in the range of 0.3% to 0.38%, the relative refractive index difference ?2 of the first cladding is equal to or smaller than 0%, and the relative refractive index difference ?3 of the second cladding is in the range of ?1.8% to ?0.5%. The inner radius r2 and the outer radius r3 of the second cladding satisfy the expression “0.4r2+10.5<r3<0.2r2+16”, and the inner radius r2 of the second cladding is equal to or greater than 8 ?m.

Abstract: Provided is an optical fiber that has a small bending loss, can be securely prevented from being fractured due to accidental bending during installation or other operations, and is compliant with the G. 652 standard. An optical fiber 1 includes a core 11, a first cladding 12, a second cladding 13, and a third cladding 14. The relative refractive index difference ?1 of the core 11 is in the range of 0.3% to 0.38%, the relative refractive index difference ?2 of the first cladding 12 is equal to or smaller than 0%, and the relative refractive index difference ?3 of the second cladding 13 is in the range of ?1.8% to ?0.5%. The inner radius r2 and the outer radius r3 of the second cladding 13 satisfy the expression “0.4r2+10.5<r3<0.2r2+16”, and the inner radius r2 of the second cladding 13 is equal to or greater than 8 ?m. The bending loss at a wavelength of 1550 nm and at a radius of curvature of 7.5 mm is smaller than 0.

Abstract: Provided is an optical fiber that has a small bending loss, can be securely prevented from being fractured due to accidental bending during installation or other operations, and is compliant with the G. 652 standard. An optical fiber 1 includes a core 11, a first cladding 12, a second cladding 13, and a third cladding 14. The relative refractive index difference ?1 of the core 11 is in the range of 0.3% to 0.38%, the relative refractive index difference ?2 of the first cladding 12 is equal to or smaller than 0%, and the relative refractive index difference ?3 of the second cladding 13 is in the range of ?1.8% to ?0.5%. The inner radius r2 and the outer radius r3 of the second cladding 13 satisfy the expression “0.4r2+10.5<r3<0.2r2+16”, and the inner radius r2 of the second cladding 13 is equal to or greater than 8 ?m. The bending loss at a wavelength of 1550 nm and at a radius of curvature of 7.5 mm is smaller than 0.

Abstract: A novel phosphorous-containing epoxy resin having a naphthalene skeleton is suitable as an insulating material, such as a copper-clad laminate used in an electronic circuit board, and a sealing material, molding material, casting material, adhesive or film material used in an electric component. Furthermore, this epoxy resin is suitable as a material for an electrically insulating coating.

Abstract: In a glass processing method according to the invention, in the case of performing chemical vapor deposition or diameter shrinkage of a substrate glass tube G by relatively moving a heating furnace 20 comprising a heating element 21 for annularly enclosing the circumference of the substrate glass tube in a longitudinal direction of the substrate glass tube G with respect to the substrate glass tube G in which an outer diameter is 30 mm or more and a wall thickness is 3 mm or more and is less than 15 mm and an ovality of the outer diameter is 1.0% or less using a glass processing apparatus 1, a temperature of at least one of the heating element 21 and the substrate glass tube G is measured and the amount of heat generation of the heating element 21 is adjusted based on the measured temperature.

Abstract: Provided is an optical fiber that has a small bending loss, can be securely prevented from being fractured due to accidental bending during installation or other operations, and is compliant with the G. 652 standard. An optical fiber 1 includes a core 11, a first cladding 12, a second cladding 13, and a third cladding 14. The relative refractive index difference ?1 of the core 11 is in the range of 0.3% to 0.38%, the relative refractive index difference ?2 of the first cladding 12 is equal to or smaller than 0%, and the relative refractive index difference ?3 of the second cladding 13 is in the range of ?1.8% to ?0.5%. The inner radius r2 and the outer radius r3 of the second cladding 13 satisfy the expression “0.4r2+10.5<r3<0.2r2+16”, and the inner radius r2 of the second cladding 13 is equal to or greater than 8 ?m. The bending loss at a wavelength of 1550 nm and at a radius of curvature of 7.5 mm is smaller than 0.

Abstract: In a glass processing method according to the invention, in the case of performing chemical vapor deposition or diameter shrinkage of a substrate glass tube G by relatively moving a heating furnace 20 comprising a heating element 21 for annularly enclosing the circumference of the substrate glass tube in a longitudinal direction of the substrate glass tube G with respect to the substrate glass tube G in which an outer diameter is 30 mm or more and a wall thickness is 3 mm or more and is less than 15 mm and an ovality of the outer diameter is 1.0% or less using a glass processing apparatus 1, a temperature of at least one of the heating element 21 and the substrate glass tube G is measured and the amount of heat generation of the heating element 21 is adjusted based on the measured temperature.

Abstract: To provide phosphorus-containing epoxy resins and phosphorus-containing epoxy resin compositions having high levels of appearance, yield and economic efficiency and cured products thereof that are used for various applications. A phosphorus-containing phenol compound represented by Formula (3) obtained by reacting a compound represented by Formula (2) with a compound represented by Formula (1), wherein in the peak area (A) of the component represented by Formula (1) on a chromatogram measured under specific conditions by gel permeation chromatography, peak area (B) on the high-molecular-weight side of the component of Formula (1), and total area (C) of peak area (A) and peak area (B), the value obtained by dividing peak area (B) by total area (C) is 8 area % or less, and epoxy resin compositions and cured products comprising the phosphorus-containing phenol compound as an essential ingredient.

Abstract: To provide a lubricant for hot plastic working which is excellent in lubricating properties, feedability and operability and will produce no adverse affects on the corrosion resistance of the products. A lubricant for hot plastic working which is characterized in that the composition is comprised of, in an anhydrous condition, 50 to 80% by mass of iron oxide, 20 to 50% by mass of sodium silicate and 1 to 20% by mass of calcium oxide and that the total content of the impurities of zinc oxide, lead oxide and copper oxide is not higher than 5% by mass, where the content of the stabilizer is not counted. This lubricant is suited for use in lubricating guide shoes in piercing-rolling of high-Cr steel species.

Abstract: A photoelectric conversion unit in which efficiency of optical coupling and stability of mechanical coupling improve is obtained. The photoelectric conversion unit includes a light density conversion element 11 which changes at an output end face the density of light that has impinged on an incident end face and outputs the light, and a photoelectric conversion element 13. The photoelectric conversion element 13 is arranged closely to a high light-density side of the light density conversion element 11, and integrated with this light density conversion element 11. The photoelectric conversion element 13 can be a solar cell or a light emission medium. In the light density conversion element 11, it is preferable that a refractive index profile in the radial direction in a section becomes a square distribution. Further, the light density conversion element 11 uses silica glass in a base member, and by changing the addition amount of impurity added in this glass, a refractive index profile is formed.

Abstract: An optical fiber having excellent strength that can be manufactured at low cost, as well as a method for making such optical fiber, is provided. An optical fiber 1 is a silica-based optical fiber comprising a core 11, an optical cladding 12 surrounding the core 11, and a jacketing region 13 surrounding the optical cladding 12 and having a uniform composition throughout from the internal circumference to the outer circumference. A compressive strained layer having a residual compressive stress is provided at the outermost circumference of the jacketing region 13.

Abstract: Glass can be synthesized and deposited at a high rate by the inside CVD method using a plasma burner in a manner such that unconsolidated portions or bubbles are little generated. The method includes a step of depositing a glass film on the inner wall surface of a starting pipe. In a first aspect, temperature the pipe is controlled not to exceed (1800 +100xd)° C., a temperature of (1100 +100xd)° C. or higher being continued for 20 seconds or more at each point of the pipe, where d (mm) represents the wall thickness of the pipe. In a second aspect, the burner includes at least two inlets and has an inner diameter of 80 mm or more, and the deposition step is performed in the relationship, 150 mm/s <(Total flow rate of the gases introduced into the burner)/(Sectional area of the burner) <600 mm/s.

Abstract: A method includes a first step of joining a multimode fiber to a first end of an optical fiber being a specimen, allowing light to propagate from the multimode fiber to the specimen, measuring an intensity of light from a second end of the specimen, and determining a first power spectrum; a second step of joining the multimode fiber to a first end of a reference fiber having bending loss higher than that of the specimen, allowing light to propagate from the multimode fiber to the reference fiber, measuring an intensity of light from a second end of the reference fiber, and determining a second power spectrum; a third step of determining a difference spectrum by subtracting the second power spectrum from the first power spectrum; and a fourth step of determining a higher-order mode cutoff wavelength of the specimen on the basis of a shape of the difference spectrum.

Abstract: In a glass processing method according to the invention, in the case of performing chemical vapor deposition or diameter shrinkage of a substrate glass tube G by relatively moving a heating furnace 20 comprising a heating element 21 for annularly enclosing the circumference of the substrate glass tube in a longitudinal direction of the substrate glass tube G with respect to the substrate glass tube G in which an outer diameter is 30 mm or more and a wall thickness is 3 mm or more and is less than 15 mm and an ovality of the outer diameter is 1.0% or less using a glass processing apparatus 1, a temperature of at least one of the heating element 21 and the substrate glass tube G is measured and the amount of heat generation of the heating element 21 is adjusted based on the measured temperature.

Abstract: An optical fiber and a broadband light source that can generate SC light having a broader bandwidth. A broadband light source 1 is equipped with a seed light source 11 and an optical fiber 12. The seed light source 11 outputs light having a central wavelength in the wavelength range of 1500 nm to 1650 nm. The optical fiber 12 outputs supercontinuum light a result of input of the light output from the seed light source. The optical fiber 12, which has a zero dispersion wavelength in the wavelength range of 1300 nm to 1500 nm and an effective area of 12 ?m2 or less at the central wavelength, outputs supercontinuum light having a wavelength bandwidth expanded to 1000 nm or more.

Abstract: A core part of a multimode optical fiber including the core part and a cladding part has a structure composed of a plurality of concentric layers in which a refractive index is decreased stepwise from a first core layer as an innermost layer to a third core layer as an outermost layer. The structure having the plurality of layers is formed by adjusting a quantity of addition of fluorine to silica glass. Fluorine is added to the cladding part so that a refractive index is lower than that of the third core layer as the outermost layer of the core part.