Ultra-precision Surface Finishing by Ion Beam Techniques

Ion beam etching based ultra precision surface finishing is a versatile technology with a high degree of predictability due to the high stability of state of the art ion sources and the acquired knowledge of the physics of beam surface interaction. The independent control of the ion energy and the ion current density over wide ranges and the possible additional use of chemical reactive species in combination with physical sputter removal allow solving tasks in a wide variety of applications. The paper summarizes the present status of more than 20 years of development of ion beam finishing technology in IOM. It gives an overview on the equipment and the components developed for production purposes and on the ion beam technologies developed to achieve nanometer and sub-nanometer depth accuracies over the entire spectrum of spatial surface wavelength from the full aperture size down to the microroughness level of only micrometer lateral feature size. Results of the finishing of high-end optical surfaces shown demonstrate the outstanding performances of the techniques with topography and roughness control on the atomic scale.