Influence of dielectric contrast and topography on the near field scattered by an inhomogeneous surface

Abstract

The influence of topography and variations of optical properties on the near field scattered by an inhomogeneous sample is analyzed. A perturbative expression of the near field is derived and its range of validity is investigated. This expression shows quantitatively how dielectric contrast and topography modulate the near-field distribution close to a surface. It is shown that the near-field images, produced by conventional near-field optical devices, are sensitive to the integral of the dielectric contrast along the vertical direction across the sample. This point is illustrated by a numerical simulation of the near field scattered by surfaces exhibiting submicronic asperities and subsurface structures.