| 摘要 |
PURPOSE:To prevent the title glass from reducing its transmission zone width when converted into a fiber by feeding two or more kinds of glass starting materials different in dopant concn. to a rotating starting member so that they are not contacted to each other with combustion gases including hydrogen. CONSTITUTION:The first glass starting material gas contg. a refractive index raising dopant is fed toward rotating starting member 7 such as quartz glass rod through central tube 2 of concentric quintuple burner 1, hydrogen through second layer tube 3, glass starting material whose refractive index is made lower than that of a central portion through third layer tube 4, inert gas through 4th layer tube 5, and O2 through 5th layer tube 6. They are subjected to flame hydrolysis to attach glass fine particles to member 7, and the paticles are grown to fine particle body 8 and sintered. Since the first starting material gas and the second gas are separated with hydrogen gas, central glass particles do not spread to the periphery. Thus, the title glass tube is obtd. which is converted into a fiber without making a difference in sectional refractive index and reducing the transmission zone width. |
