PRODUCTION OF POROUS GLASS PREFORM

摘要

PURPOSE:To stably obtain a porous glass preform even at a high dopant concentration, by shifting and adjusting a burner for glass synthesis in a direction crossing with an axial line of a porous glass preform and forming the preform in the above state. CONSTITUTION:A state that a target 1 and a burner 3 are aligned on a Y-axis is defined as X=0, i.e. the origin and an X-axis is set as a direction perpendicular to the center axis of an exhaustion pipe 4. The burner 3 is set in such a manner as to get the X at a certain value alpha. Glass soot of doped quartz is blasted from the burner 3 by the flame hydrolysis reaction of each gaseous component and deposited on a target 1 attached to a rotating supporting rod 2. A porous glass preform 5 is formed by this process and, at the same time, the supporting rod 2 is pulled up along the Y-axis at a speed synchronized with the growing speed of the preform 5. A preform 5 having a desired length can be produced without forming a dent at the lower face of the preform 5 by continuing the deposition of the glass soot in a state that the burner 3 is shifted by a certain distance from the center axis of the target 1 along the direction of the X-axis perpendicularly crossing with the center axis.