The maximum resolution of a conventional optical microscope is limited by the optical diffraction limit. It is roughly equal to half of the wavelength of the incident light and generally measures hundreds of nanometers (1 nanometer = 10−9 of a meter). In addition, optical microscopes cannot achieve high resolution in all three dimensions simultaneously. Scanning electron microscopes generate a data type that reveals contrast information about a sample surface but it does not accurately measure the height of a given data point.
To continue reading this paper please follow link to full paper in related links.