| 摘要 |
PURPOSE:To reduce the variations in the diameter of an optical fiber and eccentricity of a core by providing a specified upper port member for the furnace core tube in the device wherein a preform held by a chuck is introduced into the furnace core tube from the upper part and the chuck is positioned. CONSTITUTION:The chuck 6 holding the preform 5 is connected to the preform positioning device 4 provided at the upper part of the furnace core tube 2, and the upper port member 8 is hung from the chuck 6 by the right and left braces 7. The upper port member 8 having an opening for forming the upper port 9 of the furnace core tube 2, is closely attached to the upper end face of the furnace core tube 2, and can be moved in the horizontal plane along with the chuck 6 under such conditions. When the preform 5 is introduced into the furnace core tube 2 and drawn, the passing position of the optical fiber 11 is detected by a position detector 10, and the signal corresponding to the deviation from a specified position is transmitted to the device 4. The chuck 6 and the upper port member 8 are correctively moved by the device 4 in the horizontal direction based on the signal. |
