The aberration correction due to misalignment in electrstatic lenses. +CD

A computational investigation has been carried out in the field of charged-particle optics. The work
is concerned with the design of electrostatic lenses with and without misalignment effect operated under different magnification conditions.The potential field distributions of einzel and immersion electrostatic lenses have been represented by analytic functions. The paraxial ray equation has been solved for the proposed fields to determine the trajectory of the charged particles traversing each lens. From the axial potential distribution and its first and second derivatives, the optical properties such as the focal length and spherical and chromatic aberrations have been compute. The electrode shape of each electrostatic lens has been determined in the two-and three-dimensions. The aberration of the electrostatic lens is highly dependent on the alignment of the electrodes and it has been found to be an important parameter affecting the geometry of the electrostatic lens system.The results of this investigation not only prove in theory the possibility of designing electrostatic lens systems with low aberration but also show the possibility of constructing such lenses in practice.