| 摘要 |
PURPOSE:To prevent the cracking of a preform for an optical fiber by using a starting member having a specified coefft. of thermal expansion when a base material for an optical fiber is formed on a starting member by a vapor axial deposition method. CONSTITUTION:SiCl4, GeCl4 for a dopant, He as a carrier gas, H2 and O2 for generating an oxyhydrogen flame are blown on a starting rod 4 rotating in a reactor 6 from a burner 1 to form a porous base material 2 for an optical fiber on the rod 4 by hydrolysis in a flame, and the base material 2 is made transparent to manufacture a preform for an optical fiber. At this time, the starting rod 4 is made of quartz or SiC contg. a dopant such as GeO2 so that the coefft. of thermal expansion is made higher than or equal to that of the base material formed by deposition, and the tip of the rod 4 is made conic. Cracking is prevented when the porous base material 2 is made transparent by heating to manufacture a preform. |
