| 摘要 |
PURPOSE:To obtain a preform for an optical fiber transmitting infrared rays by fixing a fluoride glass rod at the center of the cylindrical hollow part of a mold splittable into a plurality of segments, pouring molten fluoride glass in the gap between the outer frame of the mold and the rod, and slowly cooling the glass after annealing. CONSTITUTION:A fluoride glass rod 7 is fixed at the center of the cylindrical hollow part 6 of the mold formed with an outer frame 1 vertically splittable into a plurality of segments and forming the part 6, and after preheating the rod 7 at a temp. below the transition temp. of fluoride glass, molten fluoride glass having a lower refractive index than the rod 7 is poured in the gap between the frame 1 and the rod 7. The mold is then maintained at a temp. below the transition temp. of the fluoride glass to anneal the glass, and it is slowly cooled. After the cooling the frame 1 is detached to obtain a preform for an optical fiber transmitting infrared rays. |
