APPARATUS FOR PRODUCING OPTICAL FIBER PREFORM

摘要

PROBLEM TO BE SOLVED: To provide an apparatus for producing an optical fiber preform where in the sealability of a vitrifying furnace having a furnace core tube is improved, and to provide an apparatus for producing an optical fiber preform wherein the He concentration can be raised by improving the sealability of the vitrifying furnace to thereby suppress an increase in the flow rate of He gas passed through the furnace core tube.

SOLUTION: The apparatus for producing an optical fiber preform having the vitrifying furnace that dehydrates and vitrifies the porous optical fiber rod by passing a dehydrating and sintering gas and discharging the gas, wherein a cover (11) in the furnace core tube has a through-hole through which a supporting rod (1) for the rod passes, and a ring (18) having opposed multistage grooves (18a) is fitted on the wall of the through-hole.

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