Space telescopes need ultra-flat mirrors to make sure they provide undistorted images. The problem is that polishing can remove too much surface material from the mirror.
Two US inventors, Jacques Kools of California and Adrian Devasahayam of New York, have a solution (US 2003/0224620). An inert gas, such as argon, is ionised and fired as a low-energy beam towards the surface of a copper mirror in a vacuum. By carefully controlling the beam’s energy and making sure it hits the surface head on, the pair have found they can physically “hammer” the surface atoms flat without etching away the coating.…
