Nano-Optical Microscopy Techniques

A variety of techniques have been developed in recent years for optical imaging with sub-wavelength spatial resolution: confocal techniques record farfield properties only. Their resolution limit is usually given by the Abbe or "diffraction" limit. An interesting novel approach is stimulated emission depletion (STED) and related techniques, which take advantage of a priori knowledge of luminescent samples to push the resolution to ~10nm. Nearfield detection utilize probes that approach the sample to ~nm distances and thus can reach corresponding spatial resolution in principle. Aperture techniques suffer from throughput problems and are limited in ultimate resolution by the skin depth in the aperture forming material. Apertureless techniques provide lateral resolution of about the sharpness of the probe. However, great care must be taken in parasitic background signal reduction.

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