| 摘要 |
PURPOSE:To obtain quartz glass base material having uniform concn. of oxide and distribution of refractive index by producing porous glass body consisting of SiO2 in advance by heat-treating in an atmosphere contg. raw material gas for forming metal oxide and oxygen and thereafter by vitrifying to transparent glass. CONSTITUTION:The porous glass body 1 consisting of SiO2, produced by VAD method, etc., is supported in a furnace core tube 2 made of quartz glass in freely rotatable and vertically movable state. Then, the raw material gas for forming metal oxide (e.g., GeCl4), oxygen and helium gas are supplied from a gas supply port 3 and uniformly introduced into the porous glass body 1. Then, the raw material gas for forming metal oxide and oxygen are reacted in the porous glass body 1 by heating with heater 6 to produce the metal oxide. Then, the quartz glass base material contg. oxide, suitable for optical fiber, optical lens, etc., is obtd. by terminating the supply of the raw material gas for forming metal oxide and by vitrifying the porous glass body 1 to transparent glass. |
