MANUFACTURE OF PREFORM FOR OPTICAL TRANSMISSION

摘要

PURPOSE:To form glass of low transmission loss by depositing glass fine powder while maintaining a hot oxygen atmosphere to prevent pollution due to impurities when a perform for optical transmission is manufactured by an outside vapor phase oxidation method. CONSTITUTION:While rotating starting member 41 with a carbon coat formed in the arrow direction, hot oxygen-contg. gas 42 is sprayed from many gas spraying nozzles 43a, 43b arranged along the longitudinal direction of member 41 to envelop the glass depositing part of member 41. Starting material gases such as SiCl4 and GeCl4 are fed into gas-oxygen flame 46 spouting from burner 45 and flame-oxidized. The resulting glass fine powder is sprayed on member 41 while reciprocating burner 45 in the arrow direction to form glass deposit 44. After pulling out member 41 by a known method, deposit 44 is converted into transparent glass by heating, and the hollow is removed by collapsing to obtain a preform.