| 摘要 |
PURPOSE:To prevent bubbles from occurring in a transparent glass preform in producing porous glass preform for optical fiber by gas-phase axial deposition method, by making a gas heated to a high temperature flow along the inner wall of a reactor on the outer peripheries of the porous glass preform and a combustion burner. CONSTITUTION:A gas glass raw material is sprayed from a combustion burner 2, hydrolyzed by flame, and glass fine particles formed thereby are deposited on the periphery of a rotating starting material or the shaft 9 to produce a porous glass preform 1. In the operation, a gas (gas heater 6, gas nozzle 7) heated to a high temperature is made to flow along the inner wall of a reactor 4 on the outer peripheries of the porous glass preform 1 and the combustion burner 2 to produce the porous glass preform 1. It is especially preferable that the gas is heated at the high temperature of >=100 deg.C and is made to flow along the jetting direction of the combustion burner 2. |
