Methods for Improving Spatial Resolution in EMs
- 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.


Many different methods can be used to improve the spatial resolution or to increase the amount of useful information obtained from an EM image:
         i) The spatial resolution can be increased with the accelerating voltage of the electron beam;
         ii) Image simulation can be applied to obtain images with very high spatial resolution;
         iii) The spatial resolution can be improved using aberration correction significantly;
         iv) Image series reconstruction can be used to extract high spatial resolution information. The advantage of this technique is that it can be applied on any microscopes;
         v) Information at high spatial resolution can also be obtained by electron holography. The drawback for this technique is that specially designed microscopes and computer processing of the images are needed;
         vi) Monochromator can be applied to the electron sources. This method additionally benefits to EELS energy-resolution.

In the future, all microscopes probably will have aberration correctors. However, the combination of the different methods can still benefit to the extraction of structural information from the TEM samples. For instance, by reducing the main aberrations the corrector enables the image series reconstruction to deal with the higher order aberrations instead as well as perform beam tilts at higher angles for tilt series reconstruction. Moreover, the image series reconstruction can further compensate for any residual aberrations from the corrector, improve signal to noise ratio and do quantitative comparisons with the object wave function. [1] The combination of image series reconstructions and aberration corrected microscopy would also facilitate correction of local variations of the aberrations over the field of view. [2]



[1] S. Haigh, Super Resolution Tilt Series Exit Wave Restoration from Aberration Corrected Images. PhD thesis, Oxford University, 2008.
[2] A. I. Kirkland, R. R. Meyer, and L. Y. S. Chang, “Local measurement and computational refinement of aberrations for HRTEM,” Microscopy and Microanalysis, vol. 12, pp. 461–468, 2006.




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