| 摘要 |
PURPOSE:To produce a parent material for optical fiber having superior strength by forming a layer of porous glass by depositing the porous glass to the external periphery of a glass rod comprising core glass and clad glass, and converting the layer to transparent body by heating without performing dehydration. CONSTITUTION:SiCl4 as raw material gas, H2 as combustion gas, O2 as combustion suporting gas, and inert gas as buffer gas are fed from a burner 14 moving reciprocally in the longitudinal direction of a glass bar 1 while rotating the glass bar comprising core glass 2 and clad glass 3 by supporting both ends of the glass bar 1 with a chuck 15 is a vessel 11. Fine glass particles formed by the flame hydrolysis of the gases are deposited on the external periphery of the glass bar 1 to form a porous glass layer 4. Clean air contg. <=1,000 dust particles having >=0.3mum particle size per 1l air or inert gas, etc. is introduced as the atmosphere in the vessel 11. the porous glass layer 4 is heated at 1,300-1,600 deg.C to convert it to a transparent glass layer 5, thus, a parent material for producing optical fiber having superior strength is obtd. |
