| 摘要 |
PURPOSE:To produce an optical fiber parent material stably and at high yield without causing foam generation nor stripping by controlling partly the surface temp. of deposit of fine glass particles formed at the external periphery of a cylindrical starting material. CONSTITUTION:An ejecting port 4 for cooling gas is provided to a foot of a burner 3 for synthesizing fine glass particles. Measurement of temp. of the part A where the fine glass particles begin to deposit to the rod 1 of the starting glass and the part B near the boundary between the rod 1 and the burner are executed with a temp. measuring sensor 51. Then, the flow rate of the cooling gas from an ejecting port 4 is increased in accordance with the result of this temp. measurement if it is higher than specified temp., or it is decreased if it is lower than the specified temp. Further, the part A is heated if necessary by providing another heat source to the foot of the ejecting port 4, whereby the temp. of the parts A, B, are controlled by cooling the part B. It is preferred that the temp. difference between the part A and the part B is within 200 deg.C and the temp. of the part A is >=600 deg.C. |
