| 摘要 |
PURPOSE:To prevent the crystallization of a fiber material contg. a halide, to increase the strength of a drawn optical fiber, and to reduce the transmission on the lower end of a preform at the insulating part of the title drawing furnace for a halide-contg. optical fiber preform. CONSTITUTION:The lower end C of the preform contg. the halide glass A to give a core at the inner part and the halide glass B to give a clad having a lower refractive index than the inner part at the outer part to form a waveguide structure is heated by the heating part 8 and insulating part 9 of the drawing furnace, and pulled to draw on optical fiber. In this case, the insulating part 9 is allowed to contain the control means for controlling the temp. distribution of the lower end C (e.g., a refrigerant supply means 9d and a refrigerant flow control means 9c). The symbol 9a shows an insulating material, and the symbol 9b denotes a refrigerant pipe. |
