ABSTRACT
For imaging, and for electron microscopy in particular, the use of a reference wave was introduced by Gabor (2,3) who proposed a scheme for the enhancement of the resolution of electron microscopes by the correction of the image wave for
the phase changes due to the spherical aberration of the objective lens. He coined the term "hologram" for the interference pattern formed by the reference wave and the wave scattered by the object and thus laid the basis for the development of the field of holography with a broad range of applications with visible light and other forms of radiation as well as electrons.
