| 摘要 |
PURPOSE:To produce a preform for optical fiber so as to have uniform optical properties. CONSTITUTION:When glass fine particles are formed from burners 21-23 and stuck on the lower end of a target bar 12 to form a cylindrical glass fine particle deposited body 11, a gaseous starting material of a dope material for increasing the refractive index is fed into the burner 21 for sticking a core part. The temperature of the deposited surface on which the core part is deposited is monitored by a radiation thermometer 41 and the measured temperature data are taken in a computer 42. The computer 42 obtains the flow conditions that determine the required dopant concentration from the measured temperature data, based on the relationship between the existence ratio of the dope material previously obtained and the temperature, and gives a command to a mass flow controller 31 to adjust the flow rate of the gaseous starting material for the doping material. |
