INTENT

This test procedure describes a useful working method for the determination of near-field radiation patterns for the purpose of measuring the core diameter of multimode optical fibers with a near-parabolic index profile. The accuracy and precision (typical 1 sigma less than or equal to 0.5 micro m) are sufficient for many purposes. Refer to FOTP-58 (EIA-455-58), Core Diameter Measurement of Graded-Index Optical Fibers, for the determination of core diameter from the results of this measurement procedure.

This procedure can also provide the general output near-field distribution for many types of optical fibers. These patterns may not be free of leaky modes or other effects, but relative distribution comparisons can still be made.