The manner null which produces the optical fiber whose mechanical resistance is large by stretching doing by big pulling power

摘要

PURPOSE: To make it possible to produce a high mechanical strength fiber by subjecting the completely solidified fiber reheating under specific conditions before the application of a protective coating thereon at the time of applying the protective coating on the fiber obtd. by continuous drawing of a preform. ;CONSTITUTION: Part at the bottom end of the preform 1 consisting of a cylindrical body of silica having the rule of a suitable internal compsn. according to its radius is heated in a furnace 2 and is softened down to its core to form a viscoelastic body 20. Next, the glass of this viscoelastic body 20 is elongated to a fiber F under high tension while the rule described above is maintained. After the surface thereof is slowly cooled, the fiber is subjected to supplementary cooling until the fiber F is completely solidified. The surface of the fiber F is then reheated by a reheating torch 14 over the thickness of 5 to 10 μm in average while the tension is acted thereon to locally form the softened surface layer and thereafter, the fiber is subjected to second cooling and the org. protective coating is applied on its circumference by a coating device 4. The fiber having the reduced risk of the fiber breaking in the presence of tensile stresses or bending stresses is obtd. by the method.;COPYRIGHT: (C)1989,JPO