Optimisation of near-field optical probes

The most important part of a scanning near-field optical microscope (SNOM) is an optical probe that is scanned along the object at a very small distance. The probe tip is usually the tapered end of an optical monomode fiber. In various types of SNOM tips with and without metal coating are: utilized. In the aperture SNOM (a-SNOM) the tip is overcoated by a metal except for a small aperture at the apex. In the photon scanning tunneling microscope (PSTM) the bare quartz tip is used to detect the evanescent field near the sample.