Achromaticity Correction in EFTEM
- Practical Electron Microscopy and Database -
- An Online Book -  

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


Figure 2665 shows an example on how to correct the achromaticity in EFTEM mode. In this process, an energy offset is applied to the electron beam by changing the accelerating voltage at the electron gun of the TEM. The differences between the current positions of the hole centers of the mask and those measured before the change in beam energy are determined. The net average displacement is taken as a measure of the departure of the energy filtering system from the true achromatic imaging. If the net average displacement is not within the operator-specified tolerance, the effect on the average displacement to the changes in the current of a chromatic adjustment quadrupole lens of post-slit electron optics of the energy filtering system is assessed. These operations are iteratively performed if more precise achromatic adjustment is required or until the measured average displacement is within the specified tolerance.

example on how to correct the achromaticity

Figure 2665. An example on how to correct the achromaticity.




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