Optical fiber profiles using the refracted near-field technique: a comparison with other methods

Multimode fiber profiles by the refracted near-field method (RNF) agree to within +/-0.5% with profiles obtained by the highly accurate interferometric slab technique in regions of adequate resolution of the latter. Nineteen multimode fiber profiles by the RNF and transverse interferometric methods differ in Delta and alpha on the average by 4% and 3%, respectively. The precision of a refractive-index determination by the RNF technique is 4 x 10(-5). A rapid method of calibrating the profiles by measuring the liquid temperature is presented, and the effect of foreign matter on the fiber face is discussed.