PRODUCTION OF BASE MATERIAL FOR OPTICAL FIBER

摘要

PURPOSE:To obtain a high-quality base material for optical fiber little in OH group content in case of producing the base material for optical fiber in a rode-in-tube method by decompressing and exhausting the inside of a glass pipe and also melting the glass pipe and a glass rod to make them to one body while allowing gaseous chloride to flow through the pipe. CONSTITUTION:A quartz glass rod 1 becoming a core is inserted into the inside of a high-purity quartz glass pipe 2 and fitted on a glass lathe 4. Then the inside of the quartz glass pipe 2 is decompressed and exhausted by a vacuum pump 5 and also a gaseous mixture of gaseous chlorine and gaseous oxygen is introduced into the inside of the glass pipe 2 via a gas sealed box 11, and both the glass pipe 2 and the glass rod 1 are successively melted from an end part and made to one body by heating them with a burner 3 while rotating the glass pipe 2. In such a way, moisture content namely OH group can be prevented from being mixed from outside air because the gaseous mixture contg. gaseous chlorine excellent in dehydration effect is continuously allowed to flow between both till the glass rod 1 and the glass pipe 2 are completely melted and fused in an integral body.