FABRICATION METHOD OF POROUS GLASS PREFORM FOR OPTICAL FIBER, AND GLASS PREFORM FABRICATED THEREBY

摘要

A method for producing a porous glass base material wherein a raw material for glass is flame-hydrolyzed in an oxyhydrogen flame and resultant fine glass particles are deposited, characterized in that a central rod is raised at a nearly constant rate with the deposition of fine glass particles, and a flame flow containing fine glass particles synthesized by a burner for deposition is sprayed to a fine glass particle deposition face from diagonally below, to form a concave portion on the under deposition face of a deposited article and deposit fine glass particles; and a glass base material produced by the method. The above method allows the enhancement of the proportion of the attachment of fine glass particles onto a deposition face, the reduction of the soot floating in a reaction vessel, and the prevention of the generation of bubbles in the resultant product.