Patent ID: 6584808
Filing Date: 2003-07-01
Classification: C03B

Abstract:
A method of making an optical fiber preform, comprising the steps of:centrally positioning a rod within a tube, providing an annular gap between the outer surface of the rod and the inner surface of the tube; mechanically forming a seal between one end of said tube and said rod, while aligning said tube with said rod with respect to each of their longitudinal axes; thermally collapsing a first section of the tube onto the rod by traversing a heat source along said first section of the tube at a predetermined collapse speed, said section being located at an end of said tube opposite from the mechanically formed seal, in order to sealingly close said opposite end of said tube onto said rod; applying a force for biasing the tube inwardly towards the rod; moving the heat source towards a second section of the tube, located in the proximity of the mechanically formed seal, by traversing said heat source at a predetermined traverse speed, so to avoid any collapsing of the tube onto the rod between the first and second sections and to avoid any thermal cracking of the preform; thermally collapsing said second section of the tube onto the rod by traversing said heat source along said second section of the tube at substantially said predetermined collapse speed.