Method and apparatus for ion etching and deposition

Abstract

The disclosure relates to a method and apparatus using ion etching and ion assisted deposition to reform a surface of an object, such as a large lens, from its existing topography to a predetermined topography. The method comprises comparing the existing topography of the surface of the object to the predetermined topography. In one embodiment, the comparison can be used to distinguish objects having surfaces which are readily or economically reformable to the predetermined topography from those which are not suitable for such reforming. The method novelly utilizes an algorithm comprising image restoration. The ion etching structure of the apparatus comprises an ion source grid which can be used to provide an ion beam of a preselected spatial distribution. The grid is constructed of a nonconducting, vacuum compatible material, such as a ceramic sheet coated with a conductive layer on each side. Apertures are drilled through the grid in a selected pattern. The ion beam produced from a plasma source when a suitable voltage is applied across the coatings has a spatial distribution in accordance with the aperture pattern. In one embodiment the coatings comprise discrete corresponding areas on each surface and different voltages are appliable to each area to further control beam spatial distribution. Ion assisted deposition may be simultaneously performed under the algorithm to add material to the surface in accordance with the desired predetermined topography.