| 摘要 |
A system of investigating aberrations in a charged-particle lens system, which lens system has an object space comprising an object plane and an image space comprising an image plane, includes: Selecting a fixed pivot point on said object plane; Directing a charged-particle beam through said pivot point, entrance pupil and lens system and onto said image plane, said beam having a relatively small cross-sectional area relative to the area of the entrance pupil; Changing the orientation of said beam through said pivot point, so as to trace out an entrance figure on said entrance pupil and a corresponding image figure on said image plane; Registering said image figure; Repeating this procedure at a series of different focus settings of the lens system, thus acquiring a set of registered image figures at different focus settings; Analyzing said set so as to derive lens aberrations therefrom. |
