PRODUCTION OF SYNTHETIC QUARTZ PREFORM

摘要

PURPOSE:To obtain a high-quality preform in the absence of bubbles in a transparent material by surrounding a burner flame stream with a sealing gas stream and controlling fine glass particles in an atmosphere between the flame stream and the sealing gas stream so as to provide a specific value or below of concentration thereof in producing a synthetic quartz preform by a vapor axial deposition method. CONSTITUTION:A synthetic quartz preform 5 is produced by a vapor axial deposition method. In the process, the following constitution is adopted. That is a flame stream 4 of a burner 3 arranged under a reaction vessel 1 is surrounded with a sealing gas stream 13 (jetted from a nozzle 11) and the flow rate of the sealing gas stream 13 or feed rate of a glass raw material fed from the burner 3 is regulated to control the concentration of fine glass particles suspended in the atmosphere between the flame stream 4 and the sealing gas stream 13 to <=10g/Nm<3>.