| 摘要 |
PURPOSE:To improve the control accuracy of the evaporation of raw materials and to produce base material glass of high quality for optical fibers in the stage of producing the glass for said base material by a CVD method or the like by evaporating liquid raw materials by controlling the rate of evaporation of the liquid contained in a vessel with a thermal mass flow controller. CONSTITUTION:In the stage of producing base materials for optical fibers, base materials for rod lenses, etc. from gaseous raw materials of prescribed components by a CVD method or a VAD method, SiCl4 which is a liquid raw material and GeCl4, 11 which is a doping agents, etc. are put into a vessel 2. The vapor phase space 10 in the vessel 2 is sucked with a pump 9 of a piping 6, the vapor of the above-mentioned raw materials in the space 1 is introduced together with O2, He, Ar as carrier gases from a supply source 10 to a mixing device 3 and is supplied to a receiving part 4 for executing the CVD method and the VAD method. Here, thermal mass controllers 8 are placed in a pipeline 6 for gaseous raw materials and a piping line 5 for carrier gases, and the flow rates thereof are measured and controlled to the adequate rates whereby the base material glass having high component accuracy is produced. |
