Influence of the probe-sample interaction angle on image formation in apertureless scanning near field optical microscope

Abstract

Using the two-dimensional finite difference time domain method, we report on the image formation of an apertureless scanning near field optical microscope. It is found that the obtained images are influenced by the angle at which the probe interacts with a dielectric sample under total internal reflection illumination. The scanning probe is assumed to be a sharp silver tip with similar shape to those used in atomic force microscopy. We show that the near-field optical response produced by semi-circular and square imperfections are significantly affected with small (0°–10°) variations of the probe-sample interaction angle.