| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for manufacturing an optical fiber preform on which an external deposition layer can be applied in a high external deposition ratio by reducing the concentration of the hydroxy groups that exist in the neighborhood of the interface of the core rod and the external deposition layer. SOLUTION: In a flame polishing step of a process for manufacturing an optical fiber preform which is provided with a flame polishing step that is performed by heating the surface of a core rod 10 with an oxyhydrogen flame blowing out from a burner 11 while moving the burner 11 along the length of the core rod 10, the flame polishing step comprises cooling the surface of the core rod 10 immediately after heating with the oxyhydrogen flame blowing out from the burner 11 by a cooling means 12. The cooling is performed on an area where the surface temperature is 1,500°C or higher and 1,700°C or lower when the cooling is not performed. When cooling the surface of the core rod 10, the cooling is performed such that the maximum difference of the temperature distribution at each position when the cooling is not performed is 50°C or higher and 400°C or lower. The cooling is performed on an area where the distance from the hottest area of the surface temperature along the length of the core rod 10 is 300 mm or shorter. COPYRIGHT: (C)2006,JPO&NCIPI
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