Doing the production mannered null medial axis

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a porous preform for an optical fiber to improve the deposition efficiency of glass soot by controlling the flow rate of gaseous starting material for glass and additive gas jetted from a jet port of a burner during depositing and by controlling the flow rate ratio of the gaseous starting material for glass to the additive gas to an optimum state, and to provide a burner device for manufacture of an optical fiber porous preform.;SOLUTION: The flow velocity of the gaseous mixture of the gaseous starting material for glass and the additive gas jetted from a first jet port 21 or a second jet port 22 of a burner 10 is changed once or more during depositing the glass soot. The total flow rate V1 l/min of the gaseous starting material for glass and the total flow rate V2 l/mini of the additive gas jetted from the two jet ports are controlled to satisfy the relation of 0.25≤Rb/Rf≤4.0, where Rb=V1/V2 in the initial stage of deposition of the glass soot and Rf=V1/V2 in the terminating stage of deposition of the glass soot.;COPYRIGHT: (C)2004,JPO