| 摘要 |
<p>When manufacturing an optical fiber preform by feeding at least glass raw material, dopant material and oxygen gas to a high frequency induction thermal plasma torch to synthesize glass particles in plasma therein, a glass rod (6) is rotated and reciprocated relative to the plasma torch (1) to deposit the synthesized glass particles onto the glass rod (6). The fluctuation of the relative refractive-index difference in the longitudinal direction of the optical fiber preform is suppressed and the average value of the relative refractive-index difference in the longitudinal direction is enhanced. The glass raw material is fed to the plasma torch (1) in a forward direction of the reciprocating motion of the glass rod, and a feeding amount of the glass raw material in the backward direction of the reciprocating motion is reduced relative to the feeding amount in the forward direction.
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