| 摘要 |
PURPOSE:To stabilize a plasma flame and produce an optical fiber preform at a high speed, by supplying a reaction gas for forming a glass through a gap between layers of a high-frequency coil toward a plasma flame and synthesizing a glass on a target rod placed at downstream side of the plasma flame. CONSTITUTION:A multi-layered high-frequency coil 2 is provided at the outer circumference of a plasma oscillation tube 1. A plasma gas is introduced into the oscillation tube 1 from its top and the gas stream is discharged with the high-frequency coil 2 to generate a plasma flame 9. A reaction gas is supplied through a reaction gas inlet tube to the plasma flame 9 and, at the same time, a target rod 6 is horizontally transferred while revolving with a glass lathe 5 to form a glass film 10 having a desired refractive index on the outer circumference of the target rod 6. The reaction gas inlet tube 3 is preferably positioned at the position B between the first layer and the second layer of the high-frequency coil 2. The reaction efficiency of the reaction gas can be improved and a high-quality optical fiber preform can be produced by this process. |
