| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical fiber preform that can manufacture an optical fiber preform of stable quality by avoiding dilation of a quartz tube caused by a pressure rise in the quartz tube and preventing a backflow of gas in the quartz tube.SOLUTION: A method for manufacturing an optical fiber preform includes a deposition step for depositing glass on the inner surface of a quartz tube 2 while a raw material gas supplied from a gas feed pipe 3 flows in the quartz tube 2, and a collapse step for heating the quartz tube 2 to make the quartz tube 2 solid while supplying the gas to the quartz tube 2 from the gas feed pipe 3 to obtain an optical fiber preform, after the deposition step. In blocking at least a part of the quartz tube 2 in the collapse step, a part of the gas in the gas feed pipe 3 is made flow to the gas discharge side through a by-pass pipe 7 and the pressure in the quartz tube 2 is set lower than outside pressure. |
