METHODS OF AND APPARATUS FOR HEATING A PREFORM FROM WHICH LIGHLGUIDE FIBER IS DRAWN

摘要

A glass preform (22) was vertically appended to a chuck, and was protected by protecting wall (76), from which light-guide fiber was drawn. Flames from nozzles (47) were made to face the neck-down of the preform with an angle of 10 - 50≦̸C. While the light-guide fiber was drawn, the preform was moved down-ward. An iris diaphragm(80) was equipped to prevent a upward current of air.