Single Cubic Metalens for Compact 3D Microscopic Imaging with Extended Depth of Field

Simultaneous depth sensing and extended-depth-of-field imaging are essential for a wide range of three-dimensional (3D) microscopic imaging applications, including observation of thick biological tissues and noncontact defect inspection of miniature devices. However, existing solutions often rely on bulky optical relays and time-multiplexed acquisition or suffer from a limited depth of field, thereby increasing system complexity or restricting imaging speed. Here, we demonstrate a compact 3D microscopic imaging approach enabled by a polarization-multiplexed cubic metalens. This metalens generates a pair of laterally shifted, conjugate Airy-beam-based point spread functions, introducing a built-in disparity between two polarization-resolved images that supplies parallax cues for depth estimation. Through the computational reconstruction of the captured image pair, both the in-plane intensity image and an accurate depth map are simultaneously retrieved over an extended defocus range. The proposed method eliminates the need for bulky optics and time-multiplexing and enables reliable snapshot 3D reconstruction with an extended depth of field in a compact and easily integrable platform, which shows promising applications in biological microscopy and industrial 3D metrology.