Super Polishing of Aluminum 6061-T6 Mirrors

An innovative 2D super-polishing process for Aluminum 6061-T6 planar mirrors which removes diamond point turning (DPT) grooves and attains rms surface finishes below 10 Angstroms has been developed. Present techniques for post-polishing of DPT grooves fail to completely remove the periodic structure resulting in a loss of specular energy into undesired diffracted orders. The long-term objectives of this project are to transfer the 2D process onto a 3D polishing platform, and to develop robust, automated production processes for both 2D and 3D Aluminum optics. Once achieved, this will be the most significant advance in the polishing field in many decades. Super-polished surface finishes below 10 Angstroms will allow scientific instruments utilizing mirrors to achieve results at or near their theoretical limits. Robust, automated production processes for Aluminum optics will result in significant improvements in the technical performance and cost-effectiveness of optics in many scientific and commercial markets. The general methodology for achieving these goals is to collaborate with Zeeko Technologies and use well-chosen designed experiments that will efficiently screen the tool parameter response space and identify the best operating window to achieve super-polished surface finishes on the Zeeko IRP200 platform. The technology for producing super-polished Aluminum optics will assist NASA in surpassing optical specifications required in upcoming missions such as Terrestrial Planet Finder (TPF), Single Aperture Far Infrared Observatory (SAFIR), International X-ray Observatory (IXO), and Space Interferometry Mission (SIM Lite). Aluminum 6061-T6 has been used extensively in past optical designs and it will continue to play a critical role in these and future NASA missions.