| 摘要 |
PURPOSE:To adjust stream of air flow in a pipe at the center of a furnace and to draw extremely uniform optical fiber from preform, by setting an inert gas reservoir at an upper opening and/or lower opening of the furnace for drawing optical fiber. CONSTITUTION:In a furnace for drawing optical fiber wherein a preform of optical fiber is heated, melted, and processed into thin fiber, the box-shaped inert gas reservoir 12 to be filled with pressurized inert gas is set at the upper opening of the pipe 5 at the center of the furnace 3 for drawing optical fiber. By setting the inert gas reservoir 12 between the pipe 15 at the center of the furnace and atmosphere like this, gas pressure is always lowered stepwise in the order of interior of the pipe 5 at the center of the furnace, interior of the inert gas reservoir, and atmosphere at the outside of the furnace for drawing optical fiber. Consequently, variability of gas flow at the thin diameter part 11 of the preform is suppressed, and variability of diameter of the optical fiber 2 to be drawn is lessened. The inert gas reservoir 12 may be set at the lower part of the furnace 3 for drawing optical fiber or at both the upper and lower parts. |
