Narrow ion-beam figuring: a new tool to address extreme slopes on small surfaces located near telescope pupils

Advanced shapes can now be produced for the corrective optics placed near a reimaged pupil, or even a deformable mirror surface. These surfaces can be improved and even apodization added to improve contrast. In this paper, we describe a special form of Narrow Ion Beam Figuring (NIBF) developed at L-3 Tinsley. In contrast to existing Ion Beam Figuring (IBF) machining schemes, the FWHM beam width is controlled in a much narrower band while still providing high beam currents.