Polarization-Multiplexed Binocular Metasurface-Empowered Monolithic Ranging and Dual-Mode Imaging System

Metasurfaces provide a compact platform for multifunctional optical systems. Their applications have expanded to three-dimensional imaging and depth sensing. Passive binocular imaging determines depth from disparity between laterally separated views, and its metasurface-based implementations have been widely explored for compact depth sensing. However, passive binocular ranging remains limited by the finite depth of focus in conventional Gaussian imaging systems. Away from the focal plane, defocus reduces spatial intensity gradients and degrades feature localization accuracy. Here, we report a polarization-multiplexed binocular metasurface system that integrates dual-mode imaging and passive depth sensing within a single architecture. The system employs two identical metalenses separated by a fixed baseline. Each metalens supports polarization-dependent Gaussian and orbital-angular-momentum (OAM) focusing modes to acquire bright-field and phase-contrast images. The complementary information from the two imaging modes enables edge-enhanced images with improved feature visibility even under defocus, supporting feature localization across varying axial positions. Experiments demonstrate passive depth reconstruction with an average relative error of 4.9% over a working distance from 15 mm to 200 mm. This system enables compact integrated imaging and passive depth sensing using a single metasurface.