It is necessary to adjust the position of the electron beam as the voltage is varied. It is worthwhile to contrast the diffraction of electrons with the diffraction of light by a two dimensional grid.

The first reference to diffraction phenomena appears in the work of Leonardo da Vinci (1452–1519). Such phenomena were, however, first accurately described by Grimaldi in a book, published in 1665, ...

In 1873, the German physicist Ernst Abbe realized that the resolution of optical imaging instruments, including telescopes and microscopes, is fundamentally limited by the diffraction of light.