| 摘要 |
PURPOSE:To provide the subject method for producing a preform of an optical fiber so that the amount of residual dehydrating gas in the preform may be uniformly distributed in the longitudinal direction, in clarification of a porous preform. CONSTITUTION:When clarifying a glass by heating and sintering a porous preform (M), a dehydrating gas is supplied from a dehydrating-gas supply unit 5 into a muffle 2 while controlling a flow control device 4 based on a concentration signal sent from a concentration sensor 7 till completion of clarification of the glass by connecting, at least, the dehydrating-gas supply unit 5 filled with the dehydrating gas through the flow control device 4 to the muffle 2, equipping the concentration sensor 7 for detecting the concentration of the dehydrating gas in the muffle 2 and watching the concentration of the dehydrating gas in the muffle 2. Thereby, the concentration of the dehydrating gas is gradually increased and the amount of the residual dehydrating gas in the preform (M) is uniformly distributed in the longitudinal direction. |
