Patent ID: 6891168

Claim:
A method for operating a particle-optical apparatus to manipulate at least one beam of charged particles, the apparatus comprising at least one row of field source members extending in a row direction, the field source members being disposed periodically in the row direction and at a distance from each other such that there exists at least one set of symmetry planes such that the field source members of the row are disposed symmetrically with respect to each of the symmetry planes, the method comprising: setting source strengths of the field source members to generate a field for manipulating the beam such that a field intensity distribution of the field in a region of the field comprises a first intensity component and a second intensity component, wherein the first intensity component is displaceable in the row direction and the second intensity component is substantially independent of a displacement of the first intensity component, wherein the source strengths of the field source members are substantially representable according to a formula U i =F m ( x i −x 0 )+ F 2 ( x i ) (1) wherein U i is the source strength of an i th field source member, x i represents a position of the i th field source member in the row direction, x 0 represents the displacement of the first intensity component, F m (x) is a function representing the first intensity component, and F 2 (x) is a function representing the second intensity component, and wherein the source strengths of the field source members are further representable by at least one correction term applied to the formula (1), said correction term having an amount which increases in an interval of |x 0 −x s | as |x 0 −x s | increases from zero, wherein x s represents a position in the row direction of that symmetry plane of the at least one set of symmetry planes which is closest to the position x 0 .