Applications of Ion-Beam Milling and Deposition Techniques to HEL (High Energy Laser) Optics.

This effort was a feasibility investigation to examine applications of ion beam techniques to optical substrates and dielectric coating material, to remove or add material to the surface of an optic in a controlled manner during fabrication. Removing material by ion beam milling is accomplished at the expense of increased surface roughness. Measurements of optical surface roughness were made versus milling depth for various ion beam conditions and geometry arrangements. A Twyman-Green interferometer was constructed such that the optical surface could be observed in the vacuum chamber during coating or ion milling.