PRODUCTION OF PREFORM OF OPTICAL FIBER

摘要

PURPOSE: To enable large change in surface temperature of a porous glass material and to suppress crack/deformation by specifying a mixing ratio of a glass raw material gas and an inert gas in a method for producing an optical fiber preform by a flame hydrolysis method. CONSTITUTION: Glass fine particles produced by jetting a glass raw material gas from a burner 4 and subjecting the gas to flame hydrolysis by a flame 6 are attached to a rotating starting material and grown to give a porous glass material 7. In production of this optical fiber preform, the glass raw material gas is sent to the burner 4 as a mixed gas having a blending ratio of the glass raw material gas and an inert gas to be the flow rate of the inert gas/that of the glass raw material of >=2.0. In order to attain the blending ratio, for example, the inert gas 2 is bubbled in a glass raw material solution 1 to form a mixed gas 3 of the glass raw material gas and the inert gas and the prepared mixed gas 3 is passed through a condenser and the glass raw material is condensed to actualize the blending ratio.