Edgeways electrostatic deflectors with reduced aberrations

Electrostatic deflection systems in which the deflector plates are edgeways to the beam – i.e. the plates are flat sheets that lie in a plane perpendicular to the beam – are investigated. A deflection system that can deflect in both transverse directions is considered and the geometry is optimized to minimize the aberrations, which are found to be from 4 to 30 times smaller than the aberrations of conventional deflection systems.