METHOD OF OBSERVING THE CORE REGION OF OPTICAL FIBERS AND PREFORMS

摘要

METHOD OF OBSERVING THE CORE REGION OF OPTICAL FIBERS AND PREFORMS A method of observing the core region of optical fibers and fiber preforms is disclosed comprising the step of inducing fluorescence in at least one of the indexmodifying dopants present in the core being observed by illuminating said fiber/preform with radiation at the peak absorption wavelength for said dopant, and observing the region between the fluorescing edges of said fiber/preform. The core diameter can be determined by measuring the distance between said edges. This technique can be utilized to control the fiber pulling rate during fabrication.