| 摘要 |
The present invention provides an aberration correction device ( 100 ). The aberration correction device comprises a Wien filter element ( 110 ), a quadrupole element ( 310 ) for compensating a focusing property of the Wien filter element ( 110 ), and at least one multipole element ( 410 ) for spherical aberration correction. The Wien filter element ( 110 ) and said quadrupole element ( 310 ) are adapted to generate, in combination, an astigmatic image. Furthermore, the at least one multipole element ( 410 ) is adapted to act essentially in a plane of sagittal or meridional focus of the astigmatic image. Thereby, chromatic aberration is reduced as well as spherical aberration can be corrected.
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