| 摘要 |
PURPOSE:To enhance the building-up velocity of the fine silica particles without the loss thereof by building up a mixture of the fine silica particles contg. the dopants having various concn. so that the refractive index of light becomes large in accordance with proceeding to the center of the inside of a vessel. CONSTITUTION:A mixture of the fine silica particles contg. dopants having various concn. is independently prepared. This mixture of the fine silica particles is discharged through each guide pipe 4 and built up in a vessel 1. The vessel 1 or each guide pipe 4 is rotated and the vessel 1 slowly descended or each guide pipe 4 is slowly ascended. Thereby the mixture of the fine silica particles having various concn. is built up so that the refractive index of light becomes large in accordance with proceeding to the center part of the center part of the vessel 1. This built-up material is vitrified by a conventional method to make it a preform of optical fiber. By this method, high-speed building-up is enabled and the preform can be inexpensively produced in large amounts. |
