| 摘要 |
PURPOSE:To obtain a large-sized preform in a state without fluctuation in composition, by adopting a constitution for pressurizing and controlling a glass melt so as to provide a constant pulling up speed in pulling up a preform upward from a nozzle of a crucible and forming the melt. CONSTITUTION:An apparatus for producing a preform for fluoride glass optical fiber provided with a crucible 1, having an upwardly opened nozzle 2 to be a taking outlet of the preform for the optical fiber and filled with a fluoride glass melt (A) therein; a heating means 8 for heating the fluoride glass melt (A) so as to keep a molten state; a pulling up rod 6, placed so as to face the nozzle 2 of the nozzle 1 and continuously pulling up the preform for the optical fiber while upwardly moving; a cooling means 9 for quenching the fluoride glass melt (A) near the nozzle 2 of the crucible 1 and growing the preform for the optical fiber on the pulling up rod 6 and a pressurizing means 3 for pressurizing and controlling the fluoride glass melt (A) so as to provide a constant pulling up speed of the preform for the optical fiber to be pulled up from the nozzle 2 of the crucible 1. |
