INTENT

The intent of this test method is to establish procedures to be followed to determine the refractive index profile n(r) of an optical fiber sample by transverse interferometry. Using an interference microscope, the fiber sample is illuminated perpendicular to its axis to generate a fringe pattern. The refractive index profile is obtained from video detection and digitization of the interference fringes under computer control.

Determination of core diameter may also be made from the results of this test procedure. Refer to FOTP-58 (EIA-455-58), "Core Diameter Measurement of Graded-Index Optical Fibers."

Determination of numerical aperture may also be made from the results of this test procedure. Refer to FOTP-177 (EIA/TIA-455-177), "Numerical Aperture Measurement of Graded Index Optical Fibers."