Near-Field Scanning Optical Microscopy

The spatial resolution of most of the imaging or microcharacterization methods presently in use are fundamentally limited by the wavelength of the exciting or the emitted radiation being used. In general, the smaller the wavelength of the exciting probe, the greater the structural damage to the sample under study. Thus, the requirements of minimal sample alteration and high spatial resolution seem to be at odds with one another.However, the reason for this wavelength resolution limit is due to the far field methods for producing or detecting the radiation of interest. If one does not use far field optics, but rather the method of near field imaging, the spatial resolution attainable can be much smaller than the wavelength of the radiation used. This method of near field imaging has a general applicability for all wave probes.