Near-field optical random mapping (NORM) microscopy

Abstract

In recent years several methods to overcome diffraction limit in the far field microscopy have been demonstrated. Still the problem of superresolution is reliably solved only for fluorescent microscopy, giving a resolution of up to 20-30nm. Obtaining the optical resolution lower than 100nm without fluorescent dyes requires using rather slow and complicated technique of scanning near filed optical microscope (SNOM). We propose and demonstrate a method of optical near field acquisition by far-field microscope through observation of nanoparticles Brownian motion in immersion liquid. The resolution of the method is restricted only by the size of nanoparticles that can be registered (detected) by a given far field microscope. From this point of view this resolution can achieve up to 10-20nm. Up to now we achieved a resolution of about 140nm observing 120nm particles through an objective with N.A.=0.4. The resolution is thus improved by factor of five for a given microscope objective.