Recent advancements in full-shell X-ray optics at MSFC

At NASA’s Marshall Space Flight Center (MSFC), we maintain an active research program to develop thin (~1 mm or less), high-resolution full-shell X-ray optics that will meet the requirements of future flagship X-ray astronomy missions such as Lynx. For over two decades, we have been making electroformed nickel replicated shell optics from super-polished mandrels and assembling them into optical modules for both flight and ground-based applications. Recent developments in our mandrel fabrication and mirror electroforming processes have systematically improved the angular resolution of the optics. Improvements in the deterministic super polishing of the mandrels have greatly improved the low- and mid- spatial frequency figure errors of the optics. We have optimized the electroforming bath configuration to enhance the uniformity of the electric field which reduced the mid-frequency spatial errors and the edge deformations of the optics. One of the major sources of figure errors in electroformed full-shell X-ray optics is deformation due to built-in stress in the optics. These figure errors contribute towards the circularity of the shell and affect at the order of a few arcseconds of distortion. Internal stress fields from the electroforming process are reduced by modifying the mandrel configuration in the electroforming tank. Combining the contributions from the deterministic super polishing and improved electroforming, angular resolution has improved from a few tens of arc seconds to sub 5 arcseconds half-power diameter.