Reflection-mode scanning near-field optical microscopy: Influence of sample type, tip shape, and polarization of light

A reflection-mode aperture-type scanning near-field optical microscope (R-SNOM) based on the external collection of the reflected light is presented. The light detection is based on an elliptical mirror setup, with the tip and sample at one focus, and a photomultiplier tube at the other. Results are presented on the general imaging properties of this microscope. The results presented concentrate on an analysis of the gap-width dependence of the optical signal, on resolution and on the contrast mechanisms which may be used in R-SNOM imaging, including reflectivity, polarization/magneto-optics, and topographic effects. (C) 1998 American Institute of Physics. [S0021-8979(98)09503-6].