TIA ANSI/TIA/EIA-455-176

This is a procedure that can be used to measure all key parameters of optical fiber cross-sectional geometry, with the exception of core diameter. (Core diameter measurements may be made, however, for fiber classes Ic, IIa, and IIb; for other fiber classes, core diameter measurements may be made for purposes other than establishing firm values of core diameter. See 1.3) Refer to section 6, to the Annex, and