Nondestructive measurement of index profile of an optical-fibre preform

Abstract

A simple and fast nondestructive method of measuring the index profile of an optical-fibre preform is presented. In this method, a laser beam is shone perpendicularly to the preform axis, and the exit angle of its backscattered ray is recorded as a function of the distance of the incident ray from the horizontal axis. A numerical integration involving these exit angles gives the profile.