Theoretical comparison of illumination and collection mode images of magneto‐optical dots

Abstract

We compare theoretical images of the same sample obtained with two different scanning near-field optical microscopes. The sample is a two-dimensional periodic array of magnetic sub-micrometric dots. The magnetization is perpendicular to the sample plane (polar magnetization). The first configuration is a scanning tunnelling optical near-field microscope (STOM) where the tip is used in the detection mode and the sample is illuminated by total internal reflection. The second configuration is an inverted STOM: the tip is used in the emission mode and the diffracted field is far-field detected in one direction. We present the models used to describe the two configurations and then explain the main lines of the formalism used to calculate the diffracted fields by a magneto-optical sample.