RAPID AUTOMATIC INDEX PROFILING OF WHOLE-FIBER SAMPLES .2.

Automatic, nondestructive methods have been developed for measuring and analyzing the refractive index distribution of a fiber that is immersed in index‐matching oil and illuminated transversely to its axis in a single‐pass interference microscope. The output field of the microscope is automatically processed with a video‐digitized, computer‐controlled system, and the profile is determined by the solution of an integral equation that can handle arbitrary variations in the index distribution. The resulting profiles are reproducible to approximately 1 percent and can be determined within a few minutes after fiber fabrication. Details of a rapid video scanning procedure and of error estimates involved in solving the integral equation are presented along with representative profiles. © 1979 The Bell System Technical Journal