Interlaboratory measurement comparison to determine the radiation angle (N.A.) of graded-index optical fibers

A procedure for determining the radiation angle (N.A.) of graded-index optical fibers was tested by an inter-laboratory measurement comparison among six fiber manufacturers and the National Bureau of Standards (NBS). Radiation angle was determined using the 5% intensity points on an exit far-field radiation pattern. Measurements on five fibers representing low-to-high N.A. values show standard deviations of 2.9, 2.4, 2.0, 1.5, and 0.9%. The overall average, 2.0%, is close to the one standard deviation measurement precision reported by most participants.