Abstract
Ion beam etching is effectively used for the fabrication of high-precision optics. The main application of ion beam etching is to figure large optical surfaces to correct their shape errors remained on polished surfaces. To figure small or medium sized optical surfaces, the generation of ion beam with smaller diameter and higher ion current is required. In this study, we designed a magnetic lens with quadrupole magnets using permanent magnets to obtain ion beam with small diameter. The magnetic lens is installed between the outlet of an ion gun and a chamber, which enables the changing of the trajectory of ion beam in the chamber. Thus, the trajectories of ion beam were simulated when a doublet or a triplet magnetic lens was used. Moreover, ion beam distributions on a workpiece surface were simulated for both magnetic lenses. As a result, the simulations showed that the ion beams can be focused on a workpiece surface when a doublet or a triplet magnet lens is used: the distribution of ion beam on a workpiece surface was simulated to be shrunk from approximately 30 mm to 2.2-5 mm by the triplet magnet lens.
