METHOD OF AND APPARATUS FOR MANUFACTURING AN OPTICAL FIBER PREFORM

摘要

Optical fibers are produced by means of a direct sleeving technique that allows the collapsing of the outer jacket tube onto the inner core rod to be achiev ed directly during the drawing phase of optical fiber manufacture. In the course of the optical fiber manufacturing process, a preform having an enclosed annular gap/cavity is produced. The preform is produced by first aligning a rod within a sleeve tube using a centering device which also creates an air-tight seal. A vacuum may be maintained in the annular gap/cavity of this assembly. A heat source is then applied in order to collapse the extreme ends of said tube onto the respective extreme ends of the rod, the traverse speed of said heat source moving from one end to the other being controlled so to avoid any cracking i n the final preform. The obtained preform is then mounted onto a drawing tower where the fiber is drawn while simultaneously collapsing the remaining portion of the tube onto the rod. A device for aligning a rod within a tube, such as used in the preform manufacturing process, is also disclosed and comprises a threated body and rings, o-rings and splitrings.