PURPOSE: Preparation of a parent material for optical fiber of fluoride glass, wherein a core-clad interface is formed smoothly, every layer is deposited one by one by every drop, quenching effect can be expected, infrared rays with short wavelength can be transmitted, and extreme reduction in loss is possible.
CONSTITUTION: While a metallic or semimetallic template having a cylindrical hollow part and a structure capable of being split into plural parts in the longitudinal direction is being rotated, droplets of glass melt are made to fall on the hollow part of the template, the composition of the glass melt is changed, so that refractive index of glass made during solidification of the droplets is changed, to give a parent material for optical fiber having a core-clad wave transmission structure. The cover 2 is put on the crucible 1 made of gold (platinum), the crucible 1 is evacuated, and the droplets 8 glass for clad are dropped at a proper speed. The template 9 of three split parts is fastened, and fixed to the rotary stand 13 by the template holder 12. A thin film of glass forced up to the wall face of the template by centrifugal force is gradually piled to form the glass raw film 20.
OOISHI YASUTAKE
MIYASHITA TADASHI
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