Manufacturing method and manufacturing apparatus of porous glass base material

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for producing a porous glass perform, in which characteristics of the porous glass perform are stable in the longitudinal direction and bubbles are hardly mingled when the porous glass perform for an optical fiber is synthesized by the VAD method. SOLUTION: A reaction gas 15 containing a glass raw material gas and a combustion gas is jetted out from one or more burners 13 installed in a reaction vessel 11, and glass microparticles formed by the reaction of the reaction gas 15 are deposited on a target 17 to fabricate a porous glass perform 19. A clean air jet-out port 27 is disposed on a wall surface 21a of the reaction vessel 11 for the porous glass preform 19 such that the lower end 25 of the jet-out port is installed at a lower position than a lower end 23 of a burner 13 whose raw material charge amount is most. The clean air jet-out port 27 is set upward toward an exhaust port 29 positioned on a wall surface 21b opposing to the burner 13 and opening upward, and clean air 31 is fed from the clean air jet-out port 27 to the reaction vessel 11.

Description

technical field [0001] The present invention relates to a manufacturing method and manufacturing apparatus of a porous glass base material in which air bubbles are less likely to be mixed. Background technique [0002] When using the VAD method to manufacture glass base materials, silicon tetrachloride (raw material), germanium tetrachloride and other dopants, oxygen, hydrogen, etc. are fed into the nozzle for synthesis, and glass particles are synthesized by hydrolysis reaction, and stacked on the standard on target. At this time, since there are also glass particles not stacked on the target, they are exhausted from the exhaust port attached to the reaction container. If the unstacked glass particles are not sufficiently discharged and remain in the reaction vessel, the remaining glass particles may adhere to the porous glass base material being produced, and the subsequent porous glass base material may be vitrified in the sintering furnace , with the attached glass par...

AI Technical Summary

Problems solved by technology

However, in the VAD method, it has not been determined that the characteristics of the porous glass base material can be stabilized in the longitudinal direction and that it is difficult to mix air bubbles into the glass base material at which position or in which direction the clean air ejection port is installed. Description, even when clean air is flowing, bubbles may be generated at the interface of the core and cladding

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