| 摘要 |
PURPOSE:To stably grow a porous glass sintered body while preventing consumption of a torch for synthesizing glass fine particles by surrounding torch holes for spouting a glass forming raw material gas and a combustible gas by holes for spouting an inert gas and a combustion improving gas. CONSTITUTION:A mixed gas of a glass raw material gas such as SiCl4 and a combustible gas such as H2 is spouted from spouting holes 41, 42 of a torch for synthesizing glass fine particles. An inert gas such as Ar or He is spouted from spouting hole 43 surrounding holes 41, 42, and a combustion improving gas such as O2 from spouting hole 44 surrounding hole 43. Thus, the raw material gas is hydrolyzed or thermally decomposed in an oxyhydrogen flame to form a round-rodlike porous glass sintered body as an optical fiber base material. By this torch form the flame is formed from an position several mm or more away from the torch tip, so consumption of partition wall 45 due to high temp. is prevented, thereby stabilizing the dimensional accuracy and refractive index distribution of the sintered body. |
