Imaging simulation of near-field optical scanning microscope: Comparison between dielectric probe and metal-coated aperture probe

In this paper, a simulation code for a two-dimensional photon scanning tunneling microscope (PSTM) is created by using the boundary element method based on the guided-mode extracted integral equation. Imaging simulation is carried out for the cases of a dielectric probe or a metal-coated probe and observation objects that are multiple dielectrics or metals. In the simulation, the transmission coefficient of the guided mode in a collection mode probe with an incident TE wave (s polarization) and the reflection coefficient of the illumination mode for the incident fundamental TE mode are derived. By a probe scan, the relationship between the output image and the observation object is studied. It is shown that the output image contrast decreases and the effect of interference pattern increases with a metal-coated aperture probe, whereas the image characteristics on the output image are improved relative to those obtained with a dielectric probe. (C) 2002 Wiley Periodicals.