| 摘要 |
PURPOSE:To stabilize the quality of the titled base material and to improve yield by specifying the ratio of the maximum diameter of a starting member to be deposited with fine glass particles by flame hydrolysis to the maximum diameter of the obtained porous base material for an optical fiber. CONSTITUTION:The inside of a reaction vessel 5 is evacuated through an exhaust pipe 6. Starting materials, O2, H2, gaseous Ar, etc., are introduced into a burner 1 from gas inlet pipes 7, and flame hydrolysis is carried out in the reaction vessel to deposit fine glass particles on the starting member 3 being rotated by a lifting device 2. The porous base material 4 for an optical fiber is thus produced by the above-mentioned VAD method. The relation of the maximum diameter D of the obtained porous base material 4 to the maximum diameter (d) of the starting member 3 is limited to conform to the equation, 0.2D<=d<=0.5D. Consequently, the base material 4 is not cracked, the fine glass particles are surely deposited, and the flowing out of the particles into the exhaust pipe 6 is prevented. |
