Overview paper scanning near-field microscopies

Optical images whose resolution is not limited by diffraction can be created by recording the radiation from a point-like (subwavelength size) probe light source, while raster scanning it across an object in immediate proximity. An imaging capability with resolution in the range from 1 to 50 nm has been demonstrated with various types of light sources, including luminescence from an STM junction, in transmission, as well as in reflection, emission and in a topographic mode. This paper gives a brief overview of the underlying principles, followed by a discussion of a few selected results.