A study of miniaturized electrostatic octupole deflectors

In this paper the computer simulation and the computational results of miniaturized electrostatic octupole deflectors have been presented. It has been shown that both axial and azimuthal fringing effects must be taken into account for such deflectors with small length-to-radius ratio. The axial fringing effects make deflection sensitivity higher, have no effects on deflection coma and chromatism coefficients, and change the behaviors of deflection field curvature, astigmatism, and distortion coefficients for the round-lens-type aberrations. The azimuthal fringing effects decrease deflection sensitivity but hardly affect any round-lens-type deflection aberration coefficients. For miniaturized electrostatic octupole deflectors the computational results also show that four-fold deflection coma, astigmatism, and distortion are all extremly small and can be completely neglected.