Microscope, Near‐Field Scanning Optical

Near-field scanning optical microscopy (NSOM) is a relatively new technique that provides optical resolution below 100 nm. The development of the NSOM, also frequently termed scanning near-field optical microscopy, has been stimulated by the need for an imaging technique that retains the various contrast mechanisms offered by optical microscopy methods while spatial resolution is beyond the standard optical diffraction limit. There are two fundamental differences between near-field and far-field conventional optical microscopies: the size of the specimen area that is illuminated, and the separation distance between the source of radiation and the specimen. The primary components of an NSOM are the light source, feedback mechanism, the scanning tip, the detector, and the piezoelectric sample stage. The technique is ideally suited in nanotechnology research for drug distribution and product homogeneity investigations; imaging of cells, tissues, and biofilms; monitoring of metabolic activities and high resolution fluorescence imaging; and nanobiomedical studies.