| 摘要 |
A chromatic aberration corrector (14) is offered which has a relatively simple correction system capable of correcting the electron optical system of a transmission electron microscope for chromatic aberration. Furthermore, high-resolution imaging is enabled. The correction system uses a first multipole element (21) for producing a quadrupole field to produce a concave lens effect. However, surplus two-fold astigmatism is left behind. This two-fold astigmatism is removed by inserting a second multipole element (23) for producing a second quadrupole field. The first andsecondmultipoleelementsare set tomutuallyopposite polarities. That is, the two-fold astigmatism is canceled out by combining the first and second multipole elements. A cylindrically symmetrical electron beam having spread can be corrected for chromatic aberration by the concave lens effect. |
