The Theoretical Resolution Limit of the Electron Microscope

TLDR

The contrast of an atom’s image increases with defocusing and spherical aberration. The study calculates the resolving power and image contrast of electron microscopes under varying focusing, illumination, aperture, and spherical correction methods. The authors compute resolving power and contrast by modeling different focusing, illumination, and aperture conditions. The resolution limit can vary by a factor of about three, and contrast improves when the aberration constant is reduced, especially with defocusing and spherical aberration.

Abstract

The resolving power of the electron microscope and the contrast in the image are calculated for different conditions of focusing, illumination and aperture. These conditions can change the limit of resolution by a factor of about 3. The contrast in the image of an atom is appreciably increased by defocusing and spherical aberration. Nevertheless, the contrast improves when the numerical value of the aberration constant is diminished. The effect of different methods of spherical correction is discussed briefly.