| 摘要 |
PURPOSE:To stabilize inner pressure of a furnace core tube during the sintering and vitrification of a porous preform for an optical fiber and to eliminate the disturbance of refractive index distribution of an optical fiber preform, by placing a partition member to control the flow rate of gas at a downstream side of a target holding the porous preform based on a He+Cl2 gas stream in the furnace core tube. CONSTITUTION:A He+Cl2 gas is introduced into a furnace core tube 5 from its bottom 6 and exhausted from its top 7. A target 4 holding a porous preform 3 is inserted from above into the core tube 5 against the gas stream to effect the sintering of the preform. A partition member 11 to control the flow rate of the gas is placed in the furnace core tube 5 at the downstream side of the target 4 based on the above gas stream. The flow rate of the He+Cl2 gas in the furnace core tube 5 can be maintained at a nearly definite level by the gap formed between the partition member 11 and the inner wall of the furnace core tube 5. The flow rate is independent upon the position or volume change of the porous preform 3. |
