| 摘要 |
PURPOSE:To improve mechanical strength and uniformity of outer diameter of optical fiber by equipping an upper inert gas feed part, a storage chamber of parent material, a furnace core tube provided with a small chamber opening downward at an extended part and a specific gas blowing tool and carrying out melt spinning in an inert gas atmosphere. CONSTITUTION:A fixed amount of inert gas is always sent from an upper inert gas feed part 6 to a high-temperature storage chamber 9 of parent material having stored an optical fiber preform 1, flows downward along the outside of the optical fiber preform 1 and the inert gas is gradually expanded by a small chamber 10 opening downward at an extended part 8 of furnace core tube having an inner diameter l2 smaller than an inner diameter l1 of the stor age chamber 9 of parent material and a throttling part 11 having an inner diameter l3 smaller than l2 set between the storage chamber of parent material and the small chamber. An inert gas is introduced upward from an inert gas blowing tool 12 below the extended part 8 of furnace core tube at a given interval so that a fiber drawing furnace to seal an optical fiber 5 sent from the small chamber 10 from the open air until the optical fiber is solidified is constituted to give an optical fiber having small diameter variability. |
