Thesis defense of Matthias Gianfelice

Holography, introduced by Dennis Gábor in 1948, was intended to contribute to a better resolution of the electron microscope. However, its use with electron waves still required further research at the time. The first experimental implementation was light holography, in the context of which the holographic idea could be substantially further developed. By generating a phase contrast, the phase information is stored in a two-dimensional image in addition to the amplitude information. This allows for the reconstruction of the original object wave and a three-dimensional image reproduction under a different perspective from any viewing point. In accordance with Gábor’s first idea, electron holography pursues the goal of resolving atomic structures. By using of computer holography the reconstruction of crystals can be made visible. In this work, simulations of electron holography using Electron Backscatter Diffraction (EBSD) on a planar screen will demonstrate that successful reconstruction of a tungsten single crystal is achievable with equipment currently available. For this purpose, a theoretical foundation is firstly prepared. Based on the screen size and resolution, it is determined under which conditions a holographic reconstruction is possible. The computed limit values are explained quantitatively. By defining a fitting criterion it is possible to evaluate the reconstructions automatically. With the introduction of the addition method the original limitations are improved and the reconstruction is significantly stabilized. Finally, the experimental feasibility is discussed.

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