| 摘要 |
PURPOSE:To obtain the title optical fiber of little absorption loss by inserting a fluoride glass into a tube to be a clad, depressurizing the tube while heating to temperatures enough to evaporate the moisture contained, allowing a dry, inert gas to flow into the tube to effect dehydration and cleanness followed by wire drawing. CONSTITUTION:A fluoride glass rod 1 to be an optical transmission part is set up within a furnace core tube 10 in such a state as to be inserted into a fluororesin tube or fluoride glass tube 2 (e.g. polytetrafluoroethylene tube) to be a clad. Thence, the tube 2 is depressurized, using a vacuum pump 5, while heating, by a heater 7, to temperatures below the glass transition temperature of the fluoride glass but >= 100 deg.C followed by allowing a dry, inert gas to flow into the tube at least once to effect dehydration and cleanness and then heating to such temperatures as to bring the viscosity of the fluoride glass to 10<4>-10<6> poise followed by wire drawing, thus obtaining the objective optical fiber 11. |
