INFLUENCE OF DIELECTRIC CONTRAST AND TOPOGRAPHY ON THE NEAR-FIELD SCATTERED BY AN INHOMOGENEOUS SURFACE

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 Geld 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. (C) 1995 Optical Society of America.