Computer modeling wave propagation with a variation of the Helmholtz-Kirchhoff relation.

We have employed a variation of the Helmholtz-Kirchhoff equation to computer model a wide range of diffracting systems. The equation leads to a straightforward, easily understood and implemented simulation. It is shown to work as well in the Fresnel as in the Fraunhofer limits and is used to model a wide variety of aperture shapes and incident wavefronts.