ABSTRACT
In conventional (far-field) acoustic microscopy, Rayleigh’s criterion gives the result that the spatial resolution is limited by the wavelength. However, this condition can be circumvented by using the principle of near-field imaging in which a probe or pinhole is placed very close to the surface. The importance of the probe microscopies cannot be exaggerated, for they are the techniques which really opened the door to all of the different forms of nanoscience and nanotechnology. The actual instrument has to be set up with care as it is sensitive to vibrations, surface imperfections, and so on. Tips were originally made of tungsten or platinum–iridium, whereas today almost all scanning probes are made from micromachined silicon. Even with the spectacular success of the scanning tunneling microscope, there remained one major problem and that was that it could not be used to study surfaces of insulating materials.
