Average-stitching wavefront control method for solar dual-conjugate adaptive optics

In solar observation, multi-conjugate adaptive optics (MCAO) enable ground-based large-aperture telescopes to achieve near-diffraction-limited imaging across a broad field of view by overcoming the effects of three-dimensional atmospheric turbulence with two to three wavefront correctors conjugated to different altitudes. The main wavefront control method for solar MCAO is wavefront tomography based on least squares optimization, which is facing an ill-posed problem. For a dual-deformable-mirror MCAO system, also known as dual-conjugate adaptive optics systems, this paper proposes what we believe to be a novel wavefront control method based on the average-stitching algorithm. The method decomposes the three-dimensional atmospheric aberration into two components: the averaged wavefront aberration, corrected by the ground-layer deformable mirror, and the residual wavefront, which is stitched into the meta pupil according to the guide star regions' geometric arrangement, corrected by the high-altitude deformable mirror. The simulation results demonstrate that, compared to wavefront tomography, the proposed method achieves smaller remaining errors and noise-related errors, as well as lower closed-loop residuals, and offers greater flexibility in selecting the reconstruction order. Experiments on the testbed demonstrate the superior imaging correction capability of the proposed method. Following closed-loop correction, the mean Strehl ratio over the field of view with the proposed method is 0.54, outperforming the 0.43 achieved by tomography.