| 摘要 |
PURPOSE:To clean a glass surface by feeding a specified gas into the gap between a quartz glass tube and a quartz glass rod at a high temp. before they are united by melting. CONSTITUTION:A tube and a rod kept at a high temp. are surface treated by feeding a fluorine compound such as a fluorocarbon compound into the gap between them. The fluorine content of the compound is adjusted to <=10wt%. A glass surface treating agent and oxygen gas are then fed to carry out finish treatment. A substance formed at this time by heating at a high temp. in the presence of oxygen gas has a b.p. or a subliming point lower than a temp. required to unite the tube and rod by melting. The surface treating agent is a substance contg. at least one of B, P, As, Sb and Se, and halides of the element may be used. Thus, the corroded traces of the fluoride are retreated with the nonfluorine substance and oxygen gas to remove voids and foreign matter in the resulting optical fiber base material. |
