| 摘要 |
<p>PURPOSE:To prevent the overheating damage, etc., at the front ends of nozzles by ejecting an oxygen-contg. inert gas from the nozzle between the glass raw material supply nozzle and gaseous hydrogen supply nozzle of a multipipe burner in external deposition CVD method, etc. CONSTITUTION:The gaseous glass raw material (e.g.; silicon tetrachloride) is ejected from the multipipe burner and is oxidized and hydrolyzed in an oxyhydrogen flame. The formed glass particulates are deposited on a starting material under rotation to form a porous base material. This base material is sintered to transparent glass, by which the preform for an optical fiber is produced. The oxygen-contg. inert gas (e.g.; gaseous argon) is ejected from the nozzle provided between the glass raw material supply nozzle and gaseous hydrogen supply nozzle of a multipipe burner at this time. As a result, the overheating damage, the deposition of reaction products, etc., at the front ends of the nozzles are prevented and, therefore, the production of the preform for the optical fiber is executed stably over a long period of time.</p> |
