Design of Large‐Aperture Hybrid Refractive Metalens System

ABSTRACT 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.