This test describes a procedure to determine the numerical aperture of step-index, glass core, glass clad and plastic clad optical fibers (Fiber material class 1c, 2a and 2b as listed in EIA 492000-A) from the fiber far-field radiation pattern.
ANSI/TIA/EIA 455-7-1992 history
1992ANSI/TIA/EIA 455-7-1992 Numerical Aperture of Step-Index Multimode Optical Fibers by Output Far-Field Radiation Pattern Measurement