Fresnel coefficients for weak reflection, and the scattering potential forthree-dimensional imaging

The Fresnel coefficients for reflection from a planar interface between two dielectrics are investigated for the case when the change in refractive in dex is small. Approximate expressions, in which the effects of refractive i ndex and angle of incidence are separated, are obtained. These can be used as the basis for developing a scattering potential for three-dimensional im aging based on a generalization of the Kirchhoff approximation. It is shown how for scalar waves this reduces to the usual expression for the scatteri ng potential in the Born approximation. (C) 1999 Published by Elsevier Scie nce B.V. All rights reserved.