| 摘要 |
PURPOSE:To obtain the titled base material having a core glass layer of uniform thickness in depositing a glass layer on the inner surface of a reactor tube by the modified (internal) CVD method, by heating a gas with perforated plates for heating the gas provided at a gas introductory end of the reactor tube and an auxiliary heat source. CONSTITUTION:Plural perforated plates 26 for heating a raw material gas are provided in an introductory end 27 for a raw material forming glass of a reactor tube 25, and a fixed auxiliary heating burner 24 for heating the zone of the perforated plates 26 from the outside of the reactor tube 25 is provided. The introductory end 27 for the raw material gas is constantly heated at about 700-800 deg.C by te auxiliary heating burner 24, and the raw material gas for forming glass is then introduced from the introductory end 27 into the reactor tube 25 to reciprocate a main heating burner 23 and heat the reactor tube 25. The raw material gas is reacted chemically to deposit a glass layer on the inner surface of the reactor tube 5. Thus, the raw material gas is heated efficiently by the perforated plates 26 to form the glass layer of uniform thickness on the inner surface of the reactor tube 25. |
