An electron-optical system for the efficient operation of a constant energy mode π/4 electrostatic parallel plate electron analyzer

Two Einzel lenses are used in conjunction with an intermediately located deceleration grid arrangement to efficiently manipulate the shape and energy of an electron beam prior to the analyzer entrance slit. This system decelerates all electrons to be analyzed to a selectable transmission energy that is held constant for a given spectrum. The Einzel lens parameters are varied dynamically with the deceleration grid potential so that the desired electron energy band is focused and passed to the entrance slit. The cylindrical symmetry of the first lens enhances the intensity. The efficiency of detection is further aided by the planar symmetry of the second lens. The design of this variable band, selectable band width electron filter is discussed. Operational parameters and sample spectra are presented.