| 摘要 |
PURPOSE:To realize uniform local heating within a narrow range in the lengthwise direction of an optical fiber by providing a primary heater for optical fiber work and a secondary heater for the local heating therein. CONSTITUTION:In a box 1 which is made of a heat insulating material and has insertion openings 2 and 3, the annular primary heater 4 and the secondary heater 5 arranged in the heater 4 to heat the optical fiber 6 within a cencentric narrow range are provided. In this case, the primary heater 4 is selected to have heat capacity up to a temperature close to the softening point of a multicomponent glass fiber, e.g. about 900 deg.C and the secondary heater 5 is selected to have heat capacity up to a temperature high enough to soften the fiber, i.e. about 1,200 deg.C. Consequently, the optical fiber 6 is heated by the primary heater up to a temperature at which the fiber is almost softened, and then heated locally by the secondary heater 5. Thus, the optical fiber is heated uniformly and locally within the narrow range in its lengthwise direction. |
