| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing an optical fiber preform, by which the front edge position of a soot core can be kept constant and the characteristics of the optical fiber preform can be stabilized during depositing glass fine particles. SOLUTION: In the method for manufacturing the optical fiber preform 2 by a VAD method, a process for discretely recognizing the front edge position 3 of the soot core by a digital treatment, a process for averaging the recognized front edge positions 3 with a predetermined time, and a process for regulating the manufacturing conditions of the soot core so that the averaged front edge position 3 becomes constant are included, and the manufacturing conditions are regulated successively so that the difference between the averaged front edge position and the target position set between adjacent two positions to be previously recognized discretely becomes zero. The target position exists in an internally dividing point of 0.4-0.6 of the adjacent two positions to be discretely recognized, and as the manufacturing conditions to be regulated successively, the pulling velocity or the flow amount of a raw gas used for the deposition of the soot core is cited. COPYRIGHT: (C)2006,JPO&NCIPI
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