On near-field scanning optical microscopy homogeneous and evanescent radiation

A field propagator, which describes field propagation stemming from a dipole site to a point in the space, is decomposed exactly into two parts: homogeneous and inhomogeneous field propagators. The dipole radiation can be then described separately for both the propagating (homogeneous) waves and the evanescent (inhomogeneous) field. The resulting formulae have been incorporated in a microscopic theory for near-field scanning optical microscopy. Two numerical outputs are presented: (1) separate total, propagating and evanescent intensity distributions near a sample surface (a group of silver spheres on a silver surface); (2) influence of the incident field polarization at the probe tip in reflection near-field scanning optical microscopy. The numerical results are accompanied by discussions regarding the resolution and imaging properties of the microscopy.