| 摘要 |
PURPOSE:To eliminate disadvantages such as limitation in the material on the outermost side of the preform, easy evaporation of dopant, low accuracy of the outside diameter of the preform, low yield, etc. by depositing soot within circular tube, then sintering and vitrifying the same. CONSTITUTION:Source gases such as SiCl4, POCl3 and O2 are blown upward from the source introduction tube 39 heated by an electric furnace 38. The soot formed through CVD reaction is cooled by the air blown out from a blower 37 and soot preform 36 deposits on the inside wall of a quartz tube 32. Since the tube 32 ascends slowly, the preform 36 is heated by the electric furnace 35 and shrinks. As a result, the preform 36 separates from the tube 32. The preform 34 having been sintered ascends further and is heated by the electric furnace 33 to become a transparent glass rod 31. |
