| 摘要 |
PURPOSE:To obtain preform for optical fiber having small transmission loss, by inserting a rod for core comprising SiO2 glass into a hallow part of a specific pipe for clad and heating the pipe using a heating source except hydrogen- containing flame. CONSTITUTION:In production of preform for optical fiber by inserting a rod for core comprising SiO2 glass into a pipe for clad having difference in specific refractive index >=0.5 smaller than that of the SiO2 glass and heating to fuse and to integrate both the rod and the pipe, a fluorine-containing SiO2 glass pipe having <=100mm outer diameter is used as the pipe for the clad, a heating source except hydrogen-containing flame is used as in heating and the core diameter A and the clad diameter B after fusing and integration are made to satisfy conditions of A>=3mm, B/A>=4 and 1/2(B-A)>=12mm. Induction heating to carbon zirconia, Co flame, CS2 flame or CN flame may be cited as the heating source except the hydrogen-containing flame to be used. |
