Development of Multi-Layer Achromatic Metasurface Risley Prisms for a Scanning Coronal and Heliospheric Imager

High-resolution white light observations of the solar corona over a large field of view (FOV) are crucial for understanding the structure and evolution of large coronal structures, including coronal mass ejections. With current telescopes for imaging the corona and inner heliosphere, there is a tradeoff between spatial resolution and the FOV; coronagraphs typically provide high-resolution (<1 arcminute) imaging over a relatively small region while heliospheric imagers are designed with a wide FOV, sacrificing spatial resolution for coverage. Incorporating a scanning system enables the conservation of high spatial resolution while adding the ability to map over a large field of regard; however, with conventional optical designs, this would require large/complex gimbaled systems, which are risky for space-based instrumentation. The Coronal and Heliospheric imaging with Achromatic Metasurfaces Pathfinder (CHAMP) aims to address this need, consisting of a visible light telescope which uses novel achromatic metasurface Risley prisms (MRPs) to create high-resolution, wide-FOV maps of the solar corona in a small form factor. With this design, optical beam steering is achieved by rotating two MRPs relative to each other using rotational stages, eliminating the need for gimbaled systems. Here we describe the CHAMP instrument concept and efforts to develop multi-layer achromatic MRPs which perform across a wide bandpass (similar to 100 nm) in the visible light regime.