PROCESS FOR MAKING CORE HOLE IN CAST PREFORM FOR OPTICAL FIBER AND APPARATUS THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a process and an apparatus for forming 21 small hole in the cast clad glass for preparing a preform of single-mode and multimode optical fibers. SOLUTION: This process is for forming a core hole in the cast clad glass for forming the optical fiber preform making single mode and multiple mode optical fibers. Liquefied clad glass 30 is poured into the cast mold 15 having a metallic wire 20. The wire is allowed to move through the liquefied glass 30 during the cooling so that the wire may cut out a smooth cylindrical core hole 16 along the axis of the cylinder of the cooled clad glass. This process for forming a core hole can essentially reduce the surface staining on the interface between the core hole and the clad glass, because any liquefied glass contacting with the metallic wire is removed during the process and the surface of the original glass (or fresh surface) always remains.