| 摘要 |
<p>The invention provides a method for automatically aligning a beam of charged particles with an aperture. Thereby, the beam is defelcted to two edges of the aperture. From the signals required to obtain an extinction, a correction deflection field is calculated. Furter, a method for automatically aligning a beam of charged particles with an optical axis is provided. Thereby a defocusing is introduced and a signal calculated based on an introduced image shift is applied to a deflection unit. Further, a method for correction of the astigmatism is provided. Thereby the sharpness is evaluated for a sequence of frames measured whilst varying the signals to a stigmator.</p> |
