Principles and Theory of Electron Holography

Electron holography was conceived as a means for overcoming the limitation of the resolution of electron microscopes due to the unavoidable presence of aberrations of electromagnetic lenses.129,130 The essential means for doing this was the formation of an interference pattern between the electron wave scattered by the specimen and a reference wave of known form. The practical realization of this aim had to await the technological developments of smaller, brighter electron sources to give greatly improved coherence of the illumination and more effective, quantitative recording media. With the advent of these aids, rapid progress is now being made toward realization of the potential of electron holography for providing important advances in the power and range of applications of electron microscopy.