METHOD OF MANUFACTURING DOPED QUARTZ GLASS TUBE, DOPED QUARTZ GLASS TUBE AND QUARTZ GLASS PREFORM FOR OPTICAL FIBER MANUFACTURED FROM THE DOPED QUARTZ GLASS TUBE

摘要

PROBLEM TO BE SOLVED: To clarify a manufacturing condition of a quartz glass porous body deposit capable of easily pulling the quartz glass porous body deposited on a rod-like target.;SOLUTION: The method comprises a process of depositing the quartz glass porous body on the rod-like target, a process of pulling the rod-like target from the deposited quartz glass porous body, and a process of transparently vitrifying the quartz glass porous body from which the rod-like target is pulled in a dopant-gas atmosphere, where an average density of the quartz glass porous body is controlled to be 0.3-0.5 g/cm³. In the process of depositing the quartz glass porous body, an initial and steady depositing conditions are set so as to reduce an H₂ quantity of the initial condition by 15% vs. that of the steady condition and contain a raw material gas of 30% in the initial condition vs. in the steady condition. At least 3 steps or more changes of the gas condition are preferable in transferring from the initial condition to the steady condition.;COPYRIGHT: (C)2004,JPO