Patent ID: 6836372
Filing Date: 2004-12-28
Classification: H01J

Abstract:
An electrostatic corrector, comprising:a rectilinear optical axis for eliminating chromatic aberration of particle lenses having a first corrective part and a second corrective part, said first corrective part being arranged behind said second corrective part along said rectilinear optical axis with said first corrective part and said second corrective part each having electrical quadrupole fields and superimposed circular lens fields; an astigmatic intermediate image of a first cross-section created by an axis point lying in a first part of said electrostatic corrector and an astigmatic intermediate image of a second cross-section lying in a second part of said electrostatic corrector, said second cross-section being perpendicular to said first cross-section; a first corrector unit having said first corrective part formed from at least three quadrupoles, said first corrector unit having an input side and an output side at which two additional electrostatic quadrupoles are arranged at each of said input side and said output side of said first corrector unit, and with axial paths being telescopically represented with a 1:1 representation; and, a second corrector unit having said second corrective part formed from at least three quadrupoles, said second corrector unit having an input side and an output side at which two additional electrostatic quadrupoles are arranged at each of said input side and said output side of said second corrector unit, and with axial paths being telescopically represented with a 1:1 representation, said first corrector unit and said second corrector unit being of substantially similar construction with said first corrector unit arranged behind said second corrector unit along said rectilinear optical axis, with said first corrector unit and said second corrector unit rotated through 90Â° about said rectilinear optical axis.