The physical process of the electron diffraction is described mathematically by a Fourier transform and is fully reversible. In other words, the diffraction pattern is a reciprocal space representation of the atomic lattice. Electrons are scattered at the energy distribution of electrostatic potential within the unit cell. This distribution peaks are at the positions of atoms.
Figure 2718 shows the schematic illustration of the incident electron beam scattered by a set of lattice planes, forming a diffraction pattern.
Figure 2718. The relationship between the real space atomic lattice and reciprocal space diffraction pattern. The process can be undertaken mathematically by a Fourier transform.
For instance, the Fourier transform of the two-dimensional (2-D) exit wave from a TEM specimen is given by,