Imaging optically thick objects in scanning microscopy: perfectly conducting surfaces

A rigorous numerical simulation of imaging in an optical scanning microscope is described. The sample is assumed to be a perfectly conducting one-dimensional surface-relief object. The approach is capable of taking into account multiple interactions between the illuminating field and the surface and is also valid for optically thick objects. The results are compared with those obtained by use of the Kirchhoff approximation and the thin-phase-screen model. We find that for the structures considered, the Kirchhoff approximation is adequate for describing the process of image formation, except in those cases in which the surface leads to significant amounts of multiple scattering.