| 摘要 |
PURPOSE:To draw a fluoride optical fiber having excellent mechanical strength by heating a rod-shaped fluoride glass base material by the title drawing furnace provided with a furnace core tube made of high-purity aluminum and coaxially arranged with the heater. CONSTITUTION:The rod-shaped fluoride glass base material 1 is introduced through an O ring 3a into the drawing furnace obtained by providing a furnace core tube 6 between upper and lower casings 3 and 4, and partially heated by a heater 5. A gas contg. a fluoride compd. such as HF is simultaneously sent into the furnace from a gas inlet 7 toward an outlet 8. Under such conditions, the base material 1 is drawn into a fiber 2. In the drawing furnace, the furnace core tube 6 coaxially arranged with the heater 5 is made of aluminum having >=99.9% purity. Consequently, the crystallization of the base material 1 is controlled, the corrosion of the furnace core tube 6 is prevented, and a fluoride optical fiber having a low loss and high strength can be drawn. |
