Outline of a variable-axis lens with arbitrary shift of the axis in one direction

A sophisticated electrostatic “variable-axis lens” is proposed which allows an arbitrary shift of the axis in one direction. For this purpose we employ a periodic arrangement of the electrodes in a direction perpendicular to the initial axis. The excitations of the electrodes are chosen in such a way that stigmatic imaging is conserved when the axis is shifted. The purely electric field components guarantee a fast dynamic shift of both the axis and the focusing field. Owing to the translational symmetry of the arrangement, the system enables much larger displacements of the axis than the conventional “variable-axis lens.” Moreover, this concept allows the simultaneous shift of many spatially separated lenses. Since the multiple beam system avoids a common crossover of the individual beams, large total currents can be employed.