Patent ID: 7282722

Claim:
A charged particle beam apparatus comprising: a charged particle source and a charged particle optical system which focuses a charged particle beam emitted from the charge particle source and scans the charged particle beam onto a sample, the apparatus further comprising: an objective lens which focuses the charged particle beam onto the sample, a deflector which deflects the charged particle beam away from an optical axis of the charged particle beam such that the charged particle beam traverses an off-axis of the objective lens, an aberration correction lens adapted to produce a first coma aberration and a first chromatic aberration by an aperture making the charged particle beam pass through an off-axis of the aberration correction lens, thereby correcting a second coma aberration and a second chromatic aberration produced in a plane of the sample surface, the second coma aberration and the second chromatic aberration is produced by the charged particle beam traversing the off-axis of the objective lens.