| 摘要 |
PURPOSE:To produce the title base material having an excellent transmission characteristic by dehydrating the SiO2 glass particles synthesized by a vapor- phase reaction, adding fluorine to the particles, sintering the particles, forming the particles into a tube, etching the inside of the tube, and depositing a synthetic glass film on the inner wall. CONSTITUTION:The soot 5 synthesized from the glass material introduced into the flame of a burner 4 is deposited on a starting material 7 being pulled up while rotating to obtain a pure SiO2 soot body 6. The soot body is heated in a heating furnace in the atmosphere contg. gaseous F or a vaporized fluoride and He, dehydrated, added with F, and sintered to obtain an F-SiO2 transparent glass body having <=1ppm residual OH. The glass body is formed into a tube, a vaporized fluoride is supplied into the tube, hence the tube is etched in the vapor phase. The glass contg. at least the glass material and a vaporized oxidizing agent is introduced into the tube to deposit a synthetic glass on the inner wall of the tube, and the tube is then heated to a high temp. to form a massive solid. |
