Fringing field optimization of hemispherical deflector analyzers using BEM and FDM

In this paper we present numerical modeling results for fringing field optimization of hemispherical deflector analyzers (HDAs), simulated using boundary-element and finite-difference numerical methods. Optimization of the fringing field aberrations of HDAs is performed by using a biased optical axis and an optimized entry position offset (paracentric) from the center position used in conventional HDAs. The described optimization achieves first-order focusing thus also further improving the energy resolution of HDAs.