| 摘要 |
PURPOSE:To obtain the titled base material having a desired refractive index distribution for optical communication by carrying out flame treatment to form a porous glass preform while controlling the temp. of a reactor as well as the inflow vol. and temp. of a gas for exhausting an excess reaction product and exhaust gas. CONSTITUTION:When an optical fiber base material is manufactured by a vapor phase axial deposition method, glass starting materials and various kinds of gases are blown off from flame burner 4 while rotating and moving rodlike substrate 3, upward, inserted into reactor 2 of flame treatment apparatus 1, and flame treatment is carried out to form porous glass preform 5. A dry gas for exhausting an excess reaction product and exhaust gas is allowed to flow into reactor 2 while controlling the inflow vol. and temp., and it is exhausted from exhaust pipe 6. The flame treatment is carried out while controlling the temp. of reactor 2. Thus, the flame reaction part can be kept stable, and an optical fiber base material having a desired refractive index distribution is obtd. easily. |
