| 摘要 |
The present invention relates to a focussing lens (100) for focussing a charged particle beam (7) onto a specimen (3) at a predetermined landing angle (42; 42'; 42) comprising at least one first electrode (26, 105, 105a) having a first aperture (106) to generate a focussing electric field (110) for focussing the charged particle beam (7) onto the specimen (3); and a correcting electrode having a curved surface (115) to compensate for landing angle dependent distortions of the focussing electric field (110) caused by the specimen (3). With the curved surface (115) of the correcting electrode it is possible to improve the focussing of a charged particle beam at landing angles that differ from the perpendicular landing angle. |
