Patent ID: 8841630

Claim:
A corrector for correcting axial aberrations of a particle-optical lens, the corrector to be irradiated with a beam of charged particles, the corrector comprising: a first multipole for generating a first hexapole field; a second multipole substantially aligned with the first multipole for generating a second hexapole field substantially aligned with the first hexapole field; an optical system for imaging the first multipole on the second multipole and for forming a cross-over of the beam between the multipoles, the optical system having a negative magnification; and at least one additional multipole for generating at least one additional hexapole field, wherein the at least one additional multipole is located between the first multipole and the second multipole and is not imaged on the first and the second multipole, wherein the at least one additional hexapole field is suited for correcting the six-fold astigmatism A5 of the corrector or sixth-order three-lobe aberration D6 of the corrector, wherein the at least one additional hexapole field is positioned at or symmetric around the beam cross-over, and wherein the strength of the at least one additional hexapole field is less than the strength of the first and second hexapole fields.