Design of Large-Aperture Hybrid Refractive Metalens System

Metalenses flexibly control wavefronts in compact systems, but large-aperture broadband imaging remains challenging because phase compensation increases rapidly and full-wave simulations are computationally prohibitive. We propose a wavefront-constrained joint optimization framework for large-aperture hybrid refractive metalens imaging systems. The method couples ray tracing of the refractive lens, angular spectrum propagation of the metalens-modulated field, and manufacturable meta-atom phase mapping, enabling system-level optimization of the hybrid optical path without full-aperture full-wave modeling. The refractive lens provides the primary focusing power; the metalens introduces an optimized continuous phase profile to compensate residual aberrations and reduce broadband image-plane wavefront errors. Here, we design and fabricate a 40-mm-aperture, F/2 hybrid refractive metalens system operating over the 7.7-9.5 μm long-wave infrared (LWIR) band. Compared with the single refractive lens baseline, the optimized hybrid design reduces the root-mean-square (RMS) wavefront error and peak-to-valley (PV) value by 44% and 37%. The fabricated system achieves modulation transfer function (MTF) values higher than 0.2 at the detector Nyquist frequency. A frequency-aware neural reconstruction module suppresses residual blur and noise. These results demonstrate that the method provides a practical route to scaling refractive-metalens optics toward large-aperture, compact, and broadband infrared imaging systems.