Cubic‐Encoded Moiré Metasurface Zoom System for Depth‐Invariant Imaging

ABSTRACT

Optical zoom systems with continuously tunable focal length are essential in many imaging platforms but typically rely on mechanically complex lens assemblies. Here, we demonstrate a cubic‐encoded Moiré metasurface zoom system that integrates rotational focal‐length tuning with wavefront‐coded depth‐invariant imaging. The proposed device consists of a metasurface doublet whose relative rotation continuously tunes the effective focal length from 10 to 180 mm without axial motion. By introducing a rotationally invariant cubic phase modulation, the point‐spread function (PSF) becomes significantly less sensitive to axial defocus, extending the depth of focus (DOF) by approximately an order of magnitude compared with the conventional Moiré configuration. Numerical simulations and mid‐infrared experiments at λ = 4.327 µm confirm stable imaging performance across different zoom states. Because the encoded PSF varies only weakly with defocus, captured images can be computationally reconstructed using a single calibration kernel. This approach provides a compact route toward mechanically simplified zoom imaging systems with relaxed alignment requirements.