Nondestructive interferometric measurement of the delta and alpha of clad optical fibers.

It is shown that interferograms generated by passing light perpendicular to the axis of a fiber can be used to obtain the maximum refractive index difference and the index profile shape to better than +/-10% accuracy in regions of the core where alpha is constant. This technique avoids the time consuming sample preparation required for the slab method, the propagation problems associated with the near-field technique, and the surface quality problem associated with the reflection technique.