Method of observing the core region of optical fibers and preforms

摘要: A method of observing the core region optical fibers and fiber preforms is disclosed comprising step inducing fluorescence in at least one index-modifying dopants present being observed by illuminating said fiber/preform with radiation peak absorption wavelength for dopant, between fluorescing edges fiber/preform. The diameter can be determined measuring distance edges. This technique utilized to control pulling rate during fabrication.