Patent ID: 7807965

Claim:
A corrector for axial and off-axial beam paths of a particle-optical system, the corrector comprising: a first correction piece; a second correction piece disposed behind said first correction piece in a beam path on an optical axis, wherein each of said first and said second correction pieces comprises four successive multipole elements disposed symmetrically with respect to a center plane, wherein a first and a fourth multipole element of each of said first and said second correction pieces generate quadrupole fields and a second and a third multipole element of each of said first and said second correction pieces generate superposed magnetic and electric octupole fields and quadrupole fields, wherein quadrupole fields of all four multipole elements are successively rotated from one to the next through 90° to enable chromatic aberration correction using astigmatic intermediate images in said second and third multipole elements through interaction of said magnetic and electric fields as well as aperture aberration correction using said quadrupole fields and said octupole fields; and a central multipole element disposed in said center plane, said central multipole element generating an octupole field for eliminating an astigmatism of third order.