Fresnel Fringes in TEM Images
- Practical Electron Microscopy and Database -
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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.


Fresnel fringes are produced along the edges of TEM objects when the objects are out of focus under a coherent illumination. For instance, the edge between the carbon film and vacuum, or the aperture edges in the TEM present such fringes.

Figure 1949 shows the TEM images of 1-nm He (helium) bubbles in palladium tritides when the specimen is oriented far from any Bragg conditions of the matrix of the palladium tritides [1]. For negative defocus (underfocus), the bubbles appear as white dots surrounded by a dark fringe, while for positive defocus (overfocus), the dots are black with white fringe.

TEM images of 1-nm He (helium) bubbles in palladium tritides: (a) Underfocus and (b) Overfocus

Figure 1949. The TEM images of 1-nm He (helium) bubbles in palladium tritides: (a) Underfocus and (b) Overfocus. The insets present theoretically simulated TEM contrasts of centered He bubbles in 6.5 nm thick TEM specimen. Adapted from [1]








[1] S. Thiébaut, B. Décamps, J. M. Pénisson, B. Limacher, A. Percheron Guégan, TEM study of the aging of palladium-based alloys during tritium storage, Journal of Nuclear Materials 277 (2000) 217-225.



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