| 摘要 |
PURPOSE:To obtain an ultra high purity quartz glass tube contg. little residual bubbles and having easily adjustable refractive index and softening point by spraying inert gas and glass fine particles upon the tip of a seed rod from a multiple tube burner to accumulation-form a porous glass body. CONSTITUTION:Inert gas is fed to central hole 31 of burner 30 from starting material feeder 14, glass starting material to hole 32 in vapor phase state, H2 gas to hole 33, and O2 gas to hole 34. The material is converted into glass fine particles 15 by hydrolysis and oxidation with an oxyhydrogen flame, and the particles are accumulated on the tip of a seed rod to form porous glass body 13. Body 13 is then heated to a fixed temp. with heating element 17 in electric furnace 18, whereby transparent vitrification occurs from the high density periphery. Vitrification is successively performed toward the center from the transparently vitrified periphery as a nucleus, and a central cavity is left. Quartz glass tube 12 thus formed is continuously pulled up with unit 19 to produce a long-size tube. |
