| 摘要 |
PURPOSE:To obtain an optical fiber having high strength in rapid exclusion of dust generated in a furnace center tube, by constituting an apparatus so that the upper end side of the furnace center tube has double structure and inert gas fed to the furnace tube is forced to be exhausted from the aperture of the upper end side. CONSTITUTION:The titled apparatus is so constituted that a preform 9 is introduced from the upper end of a furnace core tube 1 to the inner part thereof, drawn while being heated to send out an optical fiber 10 from the lower end of the tube, and at the same time an inert gas is fed from the lower part of the tube 1 to the upper part thereof in order to exclude dust generated in the core tube 1. An aperture-forming furnace core tube 4 is provided in the upper side in the furnace core tube 1 so as to form an aperture 5 between the tube 1 and the preform 9 and an exhaust means 7 for exhausting above-mentioned inert gas fed into the furnace core tube 1 through the aperture 5. |
