Whitepaper #355 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: basic research. Additional topics: ground-based missions/projects; solar physics.
Novel constraints on coronal magnetism are available through visible and infrared spectropolarimetry. We advocate for investments in the highest resolution spectropolarimetric methods at large-aperture coronagraphic facilities. We identify necessary instrumentation development and the need for off-limb solar adaptive optics supported by technologies similar to the proposed ORCAS mission.