New techniques for high-resolution imaging and high-precision wavefront sensing via masked-aperture interferometry
Achieving high-angular-resolution imaging on subarcsecond scales is fundamentally limited by wavefront aberrations imparted by the propagation medium and by optical elements along the light path. Accurate recovery of source structure at these fine angular scales therefore relies on precise, real-time sensing and correction of wavefront aberrations. Drawing inspiration from radio interferometry, we have developed different approaches using masked apertures that directly measure both the amplitude and phase of the distortions to the electromagnetic wavefront while simultaneously reconstructing the underlying source structure. First is radio interferometry style self-calibration which can recover the complex electric field aberrations across the aperture with subarcsecond phase accuracy, equivalent to nanometer-level precision in optical pathlength, and simultaneously reconstruct the source structure with milliarcsecond (sub-micron) accuracy. Second is closure invariant-based source reconstruction which allows to bypass self-calibration and errors therein entirely while achieving comparable fidelity in the recovered source structure. These methods have been validated on the ALBA synchrotron beamline. Together, these methods provide a reliable framework for nanometre-scale high-precision wavefront sensing and subarcsecond-scale high angular resolution imaging, enabling new possibilities for masked-aperture interferometry. Potential applications span laboratory and synchrotron facilities to astronomy, including beam diagnostics in the Large Hadron Collider and masked-aperture interferometry on space telescopes such as the James Webb Space Telescope.