| 摘要 |
PURPOSE:To obtain the title optical fiber porous base material with reduced residual OH group and transmission loss and coated with a thin deposit by depositing the fine glass particle current distant from a flame on a supporting surface isolated from the flame in the production of an optical fiber base material by VAD. CONSTITUTION:Core materials 4 and 4' for graded index-type fibers, for example, are connected through an intermediate dummy rod 9. One end of a center glass body with a working dummy rod fixed on both ends is fixed to a lifting machine 8 of the reaction vessel 6 of the VAD device, the uppermost part of the core material 4 is placed in front of a burner 1, then the lifting machine 8 is raised while injecting a raw material and combustion gas from the burner 1, and fine glass particles 3 enveloped in the flame 2 are deposited on the core material 4 as the center glass body directly covered with the flame 2 to form a porous glass body 5. Meanwhile, the surplus fine glass particle current 3 not depositing on the core material 4 and distant from the flame 2 is deposited on the core material 4' isolated from the flame 2 to form a porous glass body 5' coated with a thin deposit layer. |
