Theoretical Considerations Associated with Near-Field Scanning by Subwavelength Apertures

Abstract

Various theoretical aspects of image formation and positioning constraints in near-field scanning aperture microscopies are considered in this paper. As well as a study of the way evanescent radiation fields behave immediately behind a subwavelength aperture, it includes a preliminary study of the role that the polarization of the illuminating radiation plays in the quality of the image obtained. In particular, three different models are used to explore specific aspects of SNOM: coupling of light through a subwavelength circular aperture, coupling of light into a tapered conical structure (to model commonly used probes), the effect on images produced by the illumination parameters and interactions between the detector itself and the structure under observation.