| 摘要 |
PROBLEM TO BE SOLVED: To provide an aberration corrector capable of correcting chromatic aberration of an electronic optical system of a transmission type electron microscope by a comparatively simple and convenient system and capable of achieving high resolution observation. SOLUTION: Excessive two astigmatisms remain even if a concave lens effect is generated by a first quadrupole field generating multipole 21. These excessive two astigmatisms are removed by inserting a second quadrupole field generating multipole 23 such as the second quadrupole field. The polarity of the second quadrupole field generating multipole 23 is made reverse from the first quadrupole field generating multipole 21. In other words, by combining the first and second quadrupole field generating multipoles, the two-astigmatisms are offset, and the chromatic aberration caused by the concave lens effect is corrected against a cylindrically symmetrical electron beam having a spread. COPYRIGHT: (C)2008,JPO&INPIT
|
