PRODUCTION OF TRANSPARENT GLASS PREFORM AND APPARATUS FOR ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To provide a process for efficiently producing a transparent glass preform and an inexpensive apparatus used for the same. SOLUTION: The transparent glass preform is produced by a first stage of housing a porous preform 1 into a furnace core tube 3 composed mainly of carbon while ejecting an inert gas out of a gas ejection port of a sealing mechanism 10 disposed in the inlet port of a furnace body 2, a second stage for hermetically sealing the furnace body 2 by a sealing mechanism, a third stage of forming the porous preform to the transparent glass preform by a heat treatment in the furnace core tube, a fourth stage of releasing the hermeticity of the furnace body and a fifth stage of taking out the transparent glass preform while ejecting the inert gas out of the gas ejection port.