Electrostatic device for correcting chromatic aberration in a particle-optical apparatus

A corrector for correcting the chromatic aberration of a charred particle beam system comprising:

• correction elements, each of which is provided with electrodes for producing electric quadrupole fields, said electrodes being arranged in successive layers along the optical axis, the quadrupole fields produced by the electrodes in the layers being rotated through an angle of substantially 90° about the optical axis relative to the quadrupole field produced by the electrodes in an adjacent layer, the correction elements including at least five layers of quadrupole electrodes.

A method of operating a corrector for correcting the chromatic aberration of a focusing lens of a particle optical apparatus comprising:

• providing a corrector includes correction elements, each of which is provided with electrodes for producing electric quadrupole fields, said electrodes being arranged in successive layers along with optical axis, the quadrupole fields produced by the electrodes in the layers being rotated through an angle of substantially 90° about the optical axis of the apparatus relative to the quadrupole field produced by the electrodes in an adjacent layer;
• and
• producing the quadrupole fields in such a manner that a point of a first correction element of the corrector with a chromatic magnification error equal to zero is coincident with a corresponding point of a second correction element of the corrector.