| 摘要 |
PURPOSE:To prepare a parent material for optical fiber having high numerical aperture in high productivity inexpensively, by melting two kinds of fine powder of glass under heating in such a way that fine powder of high-purity glass having relatively high refractive index becomes a core and fine powder of high-purity glass having low refractive index becomes a skin, so that they are integrated. CONSTITUTION:The fine powder 2 of high-purity glass having relatively high refractive index and the fine powder 3 of high-purity glass having relatively low refractive index are prepared from a glass raw material by flame hydrolysis method. They are dividedly put in the glass container 1 in such a way that the fine powder 2 of glass will become a core and the fine powder 3 of glass will become a skin, and dropped through the regulating mechanism 4 for a dropped amount on the revolving heat-resistant base material 7, respectively. The carbonic acid gas laser beam 9 is condensed through the lens 10 and the movable reflecting mirror 11, the fine powder 2 and 3 of glass is heated by the laser beam, melted, processed into transparent glass, to give a parent material for optical fiber having high numerical aperture consisting of the core 5 having high refractive index and the skin 6 having low refractive index. |
