| 摘要 |
PURPOSE:In drawing an optical fiber in a carbon cylindrical pipe kept hermetically in a furnace, to prepare the continuous high-strength fiber with keeping an atmosphere in the furnace clean, by making an Ar gas containing a specific amount of He flow in it. CONSTITUTION:In the furnace body 1, the inside 9 of the carbon cylindrical pipe 8 in the furnace is kept hermetically from the outside 10, and the pipe 8 in the furnace is heated by the heater 11. The bar fiber parent material 6 consisting essentially of quartz glass is suspended from the top opening 3 into the pipe 8 in the furnace, drawn, and taken out as the fiber 7 from the bottom opening 5. In the operation, a mixed gas obtained by mixing an He gas of the bomb 12 with an Ar gas from the bomb 13 by the blender 14 is made to flow from the gas inlet 15 of the bottom protrusion chamber 4 to the inside of the pipe 8 in the furnace, and discharged from the gas outlet 16, so that the inside of the pipe 8 in the furnace is kept clean. A ratio of flow rate of He to Ar is regulated at 0.05-0.6. |
