Patent ID: 6646267
Filing Date: 2003-11-11
Classification: H01J

Abstract:
A method for eliminating an axial image deformation in electron optical systems with the axial image deformation being proportional to &agr;n or &agr;nÂ·{overscore (&agr;)}nâˆ’N, comprising the steps of:measuring a beam angle of a beam path with respect to an an optical axis as a complex number by a magnitude and azimuth with n representing an order of the axial image deformation wherein an off-axial image deformation of an order n+m has the same behavior in &agr;n, thereby having a form of &agr;n &ggr;m or &agr;N{overscore (&agr;)}nâˆ’N&ggr;M&ggr;mâˆ’M; and, modifying via shifting or tilting the beam path with respect to the optical axis until a compensation of the axial image deformation has been achieved, wherein &ggr; describes image coordinates as a complex number.