| 摘要 |
PURPOSE:To manufacture a large-sized base material for an optical fiber free from eccentricity and deformation by moving a porous base material obtd. with a burner for flame hydrolysis upward in a heating furnace to reduce the outside diameter and by moving the material downward in the furnace to convert it into transparent glass. CONSTITUTION:A flame 5 contg. fine glass particles is generated from a burner 1 for flame hydrolysis in a reactor 6, and the particles are sprayed on a target to grow a porous base material 2. While moving the material 2 upward, the outside diameter is reduced by several -60% by a zone melting method in a heating furnace 3. At this time, the material 2 is prevented from being thoroughly converted into transparent glass. The material 2 is then moved downward in the furnace 3, whereby it is thoroughly converted into transparent glass to obtain a base material for an optical fiber. By feeding gaseous He 11' contg. Cl2 when the material 2 is moved upward in the furnace 3, the OH content of the material 2 is reduced, and the quality can be enhanced. |
