Patent ID: 8405836

Claim:
A method for measuring an optical fiber with a probe beam of a two beam optical interferometer, the method comprising: while illuminating a probe beam arm and a second beam arm of said two beam optical interferometer with broad spectrum, spatially incoherent light, shifting the phase of said broad spectrum, spatially incoherent light of said probe beam relative to the phase of said broad spectrum, spatially incoherent light in said second beam arm of said interferometer in a particular direction, and detecting fringe modulation responsive to said shifting phase using an array detector, wherein pixels in said array detector correspond to a particular spatial region in said optical fiber; performing a spectral decomposition of said detected fringe modulation along said particular direction of phase shift to determine relative phase at constituent optical wavelengths for spatial positions in said optical fiber; and determining a spatial distribution of the real part of a refractive index distribution in said optical fiber at one or more of said constituent optical wavelengths using said relative phase associated with said one or more of said constituent optical wavelengths.