PRODUCTION OF OPTICAL FIBER PREFORM

摘要

PURPOSE: To obtain an optical fiber preform capable of reducing the bending of an optical fiber preform rod after drawing in a step for drawing an optical fiber preform ingot into a preform rod having a smaller diameter than that of the ingot. CONSTITUTION: A tension is applied to a preform ingot on the side of takeoff until the takeoff of the preform ingot is started and a stress or its elongation caused in the preform ingot at this time is measured to start the takeoff of the preform ingot when the viscosity of the preform ingot calculated from the stress or elongation becomes a constant value, in the method for drawing the preform ingot into a preform rod having a smaller diameter than that of the preform ingot and producing the optical fiber preform.