| 摘要 |
PURPOSE:To reduce consumption of expensive heavy hydrogen gas and to obtain a perform with low transmission loss, by depositing glass fine particles from hydrogen flame through glass fine particle piled layer from a heavy hydrogen flame on a glass rod and making the prepared preform transparent. CONSTITUTION:A multiple burner 3 is charged with a glass raw material gas such as SiCl4, etc., an oxygen gas and a hydrogen gas or a heavy hydrogen as fuel gases, the glass raw material gas is subjected to flame hydrolysis reaction and thermal oxidation reaction into glass fine particles in flame obtained by burning the fuel gas and the glass fine particles are attached and piled on the peripheral surface of a glass rod 1. In the operation, the heavy hydrogen gas as the fuel gas is fed to the burner 3 from the first reciprocation of the burner 3 to given times of reciprocations and the hydrogen gas is used as the fuel gas in reciprocations after that. The glass rod having formed a porous preform 4 to become clad is heat-treated to give optical fiber preform. |
