| 摘要 |
PURPOSE:To manufacture a high-strength optical fiber in high efficiency, and to elongate the life of the heating furnace, by feeding an inert gas containing chlorine atom into the heating furnace, and drawing an optical fiber preform in the gas atmosphere. CONSTITUTION:A core tube 11 is inserted into the furnace 10, and a carbon heater 12 is placed around the core tube 11. The inside of the core tube 11 is heated with the heater 12. Nitrogen gas is introduced into the core tube 11 through the inlet 13, and at the same time, a mixture of nitrogen gas and chlorine gas is introduced through the inlet 13. The flow ratio of chlorine gas to nitrogen gas is preferably about 1 to 10-1,000. A glass preform is molten in the mixed gas atmosphere, and drawn to a fiber. The life of the carbon heater can be elongated by this arrangement, and at the same time, the OH-group of the optical fiber can be eliminated by the action of chlorine atom resulting in the improvement of the strength of the optical fiber. |
