Theory and computation for imaging in scanning transmission microscopy considering partial coherence in illumination

Abstract

Based on the theory of wave electron optics, algebra for calculating wave intensities at various planes along the optical axis and the image on the screen of the display tube in a real scanning transmission microscope is introduced. Partial coherence in illumination, aberration of lenses, defocus, aperture, detector systems and signal manipulation in scanning transmission electron microscopy (STEM) are taken into account. The equations are normalized to minimize computation time by the use of Fourier transform and the relevant theorems. Furthermore, some important points in the calculation are discussed.