| 摘要 |
PURPOSE:To obtain an optical fiber having long length and high strength, by spinning an optical fiber from a preform composed mainly of SiO2 in an inert gas atmosphere using a high-purity carbon as the heating element, and passing the fiber through a hot atmosphere containing oxygen. CONSTITUTION:A gas such as argon gas is introduced into the furnace 1 through the gas inlet 3 to keep the inside of the furnace to the inert gas atmosphere, and the furnace is heated at about 2,000 deg.C with the heating element 2. An optical fiber preform 7a composed mainly of SiO2 is inserted slowly into the heated atmosphere, and the molten lower end of the preform is drawn at a high speed to form an optical fiber (b). An oxygen-containing hot atmosphere is formed just below the furnace 1 with the heater 4, and the spun optical fiber 7b is passed through the atmosphere. Accordingly, the impurities attached to the outer circumference of the optical fiber 7b is burnt and removed in the oxygen-containing hot atmosphere. The lowering of the strength of the optical fiber 7b caused by the deposition of impurities can be solved by this process. |
