Advanced Manufacturing and Smoothing of X-Ray Mirrors, Phase II

C53-07a-271318The advancement of grazing incidence X-ray optic technologies brings promise of new discoveries and novel applications for synchrotron applications, space exploration, and more. However, these goals are limited by the current state of the art of domestic manufacture and metrology of diffraction-limited x-ray mirrors, specifically those for synchrotron applications. This proposal outlines a set of novel manufacturing processes based on a robotic platform that aim to eliminate the pseudo-periodic signature of existing sub-aperture manufacturing techniques. This signature is detrimental to the performance of x- ray mirrors. Through novel pad, path, and optimization techniques, the proposed technique eliminates the signature and readies the surface for final finishing with ion beam figuring. The Phase I effort demonstrated feasibility of the robotic smoothing techniques to remove manufacturing signatures of single-point diamond turning. Several different smoothing pad and slurry compound combinations were tested. A three-step process was formulated, first removing mid-spatial frequency errors, followed by two steps to reduce the surface roughness. Reduction in mid-spatial frequency errors was demonstrated, and sub-0.3 nm surface roughness achieved. In the end, the diamond turning process was not deemed adequately scalable. Therefore, a separate “grolish” process (using the same robotic platform but with different tooling) was devised to address initial grinding signature while also performing some correction of form error. Initial tests show feasibility of the approach. The Phase II effort will build upon the results of the Phase I effort. The work plan addresses the size and ultimate precision required for synchrotron x-ray optics, thereby advancing the state of the art and creating a domestic source for ultra-precision x-ray mirrors. Commercial applications of the proposed technology extend beyond high-precision synchrotron mirrors. Mirrors with improved precision are needed for upcoming space missions, some of which require hundreds, if not thousands, of individual mirrors. Improved silicon polishing and smoothing techniques are also required for directed energy mirrors and any technology improvements developed under this effort will be directly applied to this market.