| 摘要 |
PURPOSE:To manufacture a glass base material for an optical fiber having high transmission characteristics by heat treating an aggregate of fine silicon oxide particles to remove impurities, heat treating it in an atmosphere of a gas contg. fluorine, and converting it into transparent glass by heating. CONSTITUTION:An aggregate of fine quartz glass particles (sootlike base material) is put in the core tube of a furnace made of pure quarts or Al, and it is sintered. At this time, the 1st-step heat treatment mainly for dehydrating the sootlike base material and removing impurities is carried out at 800-1,200 deg.C, and the 2nd-step heat treatment mainly for adding fluorine is carried out at 1,100-1,400 deg.C in an atmosphere of gaseous fluorine or an inert gas contg. a fluorine compound. The 3rd-step heat treatment mainly for converting the base material into transparent glass is then carried out at >=1,400 deg.C for >=1hr. |
