Calculation of Refractive Index Distribution from Interferograms Using the Born and Rytov's Approximation

Discussion is made of calculational reconstruction of refractive index distribution from "multidirectional interferograms." Two approximate calculation formulae are given for two-dimensional case. One is derived using the Born approximation and corresponds to a generalization of the formula in X-ray structure analysis. The other is obtained using Rytov's approximation and a generalization of straight path approximation.