Producing titanium dioxide-containing quartz glass body doped with fluorine, comprises adjusting concentrations of titanium dioxide and fluorine and fictive temperature, and depositing glass particles on substrate to form porous glass body

摘要

Producing titanium dioxide-containing quartz glass body doped with fluorine, comprises (a) adjusting a concentration of titanium dioxide, fluorine concentration and a fictive temperature, (b) depositing and growing fine glass particles obtained by flame hydrolysis of a glass-forming raw material containing a silica precursor and a titania precursor on a substrate to form a porous glass body, and (c) doping the porous glass body with fluorine to obtain a fluorine-containing porous glass body and then subjecting to a compression treatment to obtain a dense body. Producing titanium dioxide-containing quartz glass body doped with fluorine, comprises (a) adjusting a concentration of titanium dioxide, fluorine concentration and a fictive temperature according to a given predictive equation so that a given linear thermal expansion coefficient (CTE) at a given temperature (Tx[deg] C) of 15-60[deg] C and increasing a temperature of CTE (CTE i n c r e a s e ) consisting of a target value of a temperature at which the CTE 0 ppb/[deg] C (COT) is determined and a target value from a zero expansion temperature range (delta T), which is a temperature range in which CTE 0 +- 5 part per billion/[deg] C is sufficient to be achieved, (b) depositing and growing fine glass particles obtained by flame hydrolysis of a glass-forming raw material containing a silica precursor and a titania precursor on a substrate to form a porous glass body, (c) doping the porous glass body with fluorine to obtain a fluorine-containing porous glass body, (d) subjecting the fluorine-containing porous glass body to a compression treatment to obtain a dense body, (e) measuring the concentration of titanium dioxide, porous glass body and/or dense body and optionally re-setting the fictive temperature, (f) measuring the concentration of fluorine of the dense body, (g) determining the fictive temperature in which, when COT and delta T predicted to the predictive equation by applying a measured value of the concentration of titanium dioxide are obtained in the last step, measuring the concentration of titanium dioxide in the step (e) and a measured value of the fluorine concentration obtained in the step (f), the fluoride concentrations in permissible ranges of the respective targets are measured and the fictive temperature in the step (e) is considered as a predetermined value, and in which when COT and delta T predicticted to the predictive equation are exceed the allowable ranges of the respective target values, the fictive temperature is further set according to the predictive equation and a new set value is considered as the predetermined value, (h) subjecting the dense body to a transparent glass to obtain a transparent glass body, and annealing the transparent glass body in the step (g) to achieve certain fictive temperature.