| 摘要 |
PURPOSE:To prevent a base material from cracking by collapsing a tube to unite the tube and a rod prior to drawing and forming both ends of the resulting base material into needle shape by heat drawing. CONSTITUTION:A column, a cylinder or a column-cylinder composite having a desired refractive index distribution in the radius direction and made of glass or glass particles is heat melted to form a transparent glass column, and both ends of the column are formed into needle shape by heat drawing. Thus, a fiber base material free from cracking for optical communication is obtd. For example, dopant contg. silica glass rod 21 is put into pure quartz tube 22. Tube 22 is fed into heat source 23 at a fixed rate and united with rod 21 by collapsing. Immediately after collapsing the front end, the end alone is formed into needle shape by drawing. The collapsing is then continued, and immediately after collapsing the rear end, the end is similarly formed into needle shape by drawing. |
