A method for the flaming polishing a preform made of glass

摘要

PURPOSE: To prevent the cracking of a glass preform in the cooling stage by carrying out the flame-polishing of a glass preform with an oxyhydrogen flame in a preheated state. ;CONSTITUTION: SiO₂ glass soot is deposited on a rotating quartz rod and sintered by heating in a vacuum furnace to form a transparent optical fiber preform having prescribed diameter and length. Supporting rods 2 are attached to both ends of the optical fiber preform 1 and the preform is preheated at a prescribed temperature in an N₂ atmosphere with an electric resistance furnace 3 furnished with a carbon heater. The preform is moved downward and subjected to flame-polishing with an oxyhydrogen flame burner 4 under rotation before the preform 1 is cooled. The oxyhydrogen flame burner 4 is extinguished and the preform is allowed to cool to room temperature without generating craze and crack. An optical fiber having smoothed surface is produced by this process.;COPYRIGHT: (C)1994,JPO&Japio