Abstract: A method for evaluating a quartz glass crucible constituted by an outer layer formed of an opaque quartz glass containing a bubble, and an inner layer formed of a transparent quartz glass. The method includes steps of preparing a quartz glass crucible to be evaluated, irradiating the quartz glass crucible to be evaluated with ultraviolet rays as an excitation light, detecting a blue fluorescence emitted from the quartz glass crucible irradiated with the ultraviolet rays, and evaluating a state of oxygen deficiency defects in the outer layer of the quartz glass crucible on the basis of existence or non-existence of the blue fluorescence. The method allows hydrogen doping and water vapor introduction to attain nondestructive and easy evaluation on the state of the oxygen deficiency defects generated in the quartz glass crucible.

Abstract: A quartz glass plate has a quartz glass plate body and a quartz glass member adhered to the quartz glass plate body through an adhesive layer, where the adhesive layer contains silica, and a sum of concentrations of Li, Na, and K ions, being alkali metal ions and Ca ions, being alkaline earth metal ions contained in the adhesive layer is 10 ppm by mass or less. Consequently, a step with a uniform thickness can be formed, and a quartz glass plate is not easily damaged by irradiation with a light containing an ultraviolet ray.

Abstract: Provided is a silica glass member for hermetic sealing of an ultraviolet SMD LED element to be suitably used for hermetic sealing of, and as a transmission window material for, a surface mount-type package (SMD) having an ultraviolet LED mounted thereon and configured to emit ultraviolet light in a wavelength range of from 200 nm to 350 nm.

Abstract: Provided is a silica glass member for hermetic sealing of an ultraviolet SMD LED element to be suitably used for hermetic sealing of, and as a transmission window material for, a surface mount-type package (SMD) having an ultraviolet LED mounted thereon and configured to emit ultraviolet light in a wavelength range of from 200 nm to 350 nm.

Abstract: Provided is a silica glass member for hermetic sealing of an ultraviolet SMD LED element to be suitably used for hermetic sealing of, and as a transmission window material for, a surface mount-type package (SMD) having an ultraviolet LED mounted thereon and configured to emit ultraviolet light in a wavelength range of from 200 nm to 350 nm.

Abstract: A quartz glass plate has a quartz glass plate body and a quartz glass member adhered to the quartz glass plate body through an adhesive layer, where the adhesive layer contains silica, and a sum of concentrations of Li, Na, and K ions, being alkali metal ions and Ca ions, being alkaline earth metal ions contained in the adhesive layer is 10 ppm by mass or less. Consequently, a step with a uniform thickness can be formed, and a quartz glass plate is not easily damaged by irradiation with a light containing an ultraviolet ray.

Abstract: Provided are a sizing agent for quartz glass fibers capable of suppressing charging of quartz glass fibers, and suppressing generation of fluff in a production process for quartz glass fibers and a weaving process for a quartz glass cloth, a quartz glass fiber or a quartz glass yarn having applied thereonto the sizing agent, a quartz glass cloth, a prepreg for a printed circuit board, and a product using the quartz glass fiber. The sizing agent for quartz glass fibers includes an aqueous solution containing: a cationic vinyl acetate copolymer emulsion in which a cationic vinyl acetate copolymer having a weight average molecular weight of from 5,000 to 500,000 is dispersed in water; and starch, in which emulsion particles of the cationic vinyl acetate copolymer emulsion have a 50% diameter on a volume basis of from 0.1 ?m to 5 ?m.

Abstract: Provided are a sizing agent for quartz glass fibers capable of suppressing charging of quartz glass fibers, and suppressing generation of fluff in a production process for quartz glass fibers and a weaving process for a quartz glass cloth, a quartz glass fiber or a quartz glass yarn having applied thereonto the sizing agent, a quartz glass cloth, a prepreg for a printed circuit board, and a product using the quartz glass fiber. The sizing agent for quartz glass fibers includes an aqueous solution containing: a cationic vinyl acetate copolymer emulsion in which a cationic vinyl acetate copolymer having a weight average molecular weight of from 5,000 to 500,000 is dispersed in water; and starch, in which emulsion particles of the cationic vinyl acetate copolymer emulsion have a 50% diameter on a volume basis of from 0.1 ?m to 5 ?m.