FURNACE FOR DRAWING OPTICAL FIBER AND METHOD FOR DRAWING OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To reduce the variation of the fiber diameter of an optical fiber in drawing a large-scale optical fiber preform as much as possible. SOLUTION: This furnace for drawing an optical fiber is equipped with a tubular pipe body 4. An optical fiber preform 1 whose upper part is supported by a dummy rod 3 is arranged in the pipe body 4 so as to drop the preform together with the dummy rod 3. The optical fiber preform 1 is heated through the pipe body 4 by a heater 9 and melted to draw an optical fiber 10 from the bottom of the optical fiber preform 1. In this case, the furnace is provide with a pressure monitoring means 5 for watching an internal pressure of the pipe body 4, a gas blowing port 8 attached to the wall face of the pipe body 4 and a gas flow rate control means 6 for regulating the gas flow rate of the gas blowing port 8. The gas flow rate of the gas blowing port 8 is controlled by the gas flow rate control means 6 based on an order from the pressure monitoring means 5.