| 摘要 |
PURPOSE:To obtain the titled base material for an optical fiber 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 an introductory end for a raw material gas with an auxiliary heating burner provided separately from a main heating burner for heating the reactor tube. CONSTITUTION:An auxiliary heating burner 12 is provided and fixed at an introductory end 2 for a raw material gas of a reactor tube 5 separately from a main heating burner 11 to be transferred from the introductory end 2 for the raw material forming glass to a gas discharge end 6. The raw material for forming glass is then introduced from the gas introductory end 2 into the reactor tube 5, and only the main heating burner 11 is reciprocated from the gas introductory end 2 to the gas discharge end 6. The heating power of the auxiliary heating burner 12 is weakened on transferring the main heating burner 11 from the gas introductory end 2 to the gas discharge end 6, and the heating power of the auxiliary heating burner 12 is increased on returning the main heating burner 11 from the gas discharge end 6 to the gas introductory end 2 to form a glass layer of uniform thickness on the inner surface of the reactor tube 5. |
