Computer simulation of electrostatic aperture lens systems for electron spectroscopy

The electron optical properties of electrostatic aperture lens systems are studied by means of computer simulations. The influence of the geometric parameters on the focal points, magnification, and aberration coefficients has been discussed. Special cases such as a zoom lens (i.e., a lens which would produce a beam of variable energy and magnification with fixed image distance) are considered. The results have been compared with multi-cylinder lenses. Although the cylinder lenses tend to be slightly superior to the aperture lenses, they are capable of operating over much wider ranges of final-to-initial energy, and due to their greater compactness and simplicity, they can represent a very high quality lens in terms of lens parameters.