| 摘要 |
The invention relates to a method for detecting geometrical-optical aberrations up to the third order in particle optics systems that use probes, especially in scanning electron microscopes that have a punctiform source, lenses, an object and a detector. The image is detected (6), the process is repeated with an underfocussed or overfocussed beam, and the images (6, 6a, 6b) are subjected to a Fourier transformation. The transformation of the overfocussed as well as of the underfocussed image (7a) is divided (8) by that of the focussed image (7) and the result is subjected to a reverse transformation, thereby detecting the brightness profiles of the probes (5, 5a), that is of the images of the source (1) in the overfocussed and underfocussed state. The asymmetry, the width and/or the curvature of the profile (9, 9a) in the center is determined and aberrations are detected from the differences.
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