| 摘要 |
PURPOSE:To greatly improve the radiation resistant characteristic of an optical fiber and to inexpensively obtain the optical fiber which is usable for a long period of time in a high radiation atmosphere by subjecting the optical fiber to a heating treatment in a hydrogen atmosphere. CONSTITUTION:The optical fiber 1 is heated by a mantle heater 5 in the state of maintaining the hydrogen atmosphere in a pressure vessel 2 in which the optical fiber 1 is housed by replacing the air in the vessel 2 with hydrogen. The heating treatment temp. is preferably >=150 deg.C, more preferably >=200 deg.C. The radiation resistant characteristic of the optical fiber is greatly improved and the optical fiber which is usable for a long period of time in the high radiation atmosphere is provided. In addition, the radiation resistant characteristics of the optical fibers added with F and B2O3 are also improved according to this treatment method and, therefore, the use of the wide band G.I. type optical fiber, which is produced by adding F, etc., thereto, in the high radiation atmosphere is also permitted. |
