| 摘要 |
PURPOSE:To eliminate the generation of air bubbles at the time of melt spinning by adding dopants which increase the melt viscosity of glass to constitute cores, thereby providing the melt viscosity of 80-120% of the melt viscosity of silica to this glass. CONSTITUTION:A clad 1 consists of pure silica and the many cores 2... are dispersed in this clad 1. The cores 2... constitute the picture elements of an image fiber and have about 2-3mum diameter. A jacket 3 consisting of pure silica is provided around the clad 1 and a protective film 4 consisting of a modified silicone resin, etc., is provided on the outside circumference thereof. The cores 2 are formed of the silica glass added with the 1st dopant such as TiO2 or Al2O3 which increases the melting temp. and the 2nd dopant such as GeO2 or P2O5 which increases the refractive index and decreases the melt viscosity so that the melt viscosity of 80-120% of the melt viscosity of the pure silica is provided to the cores at the time of the melt spinning. Since the melt viscosity of the glass to constitute the cores 2 is approximate to the viscosity of the silica, there is no difference in the viscosity between both and the generation of the air bubbles at the time of the melt spinning is obviated.
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