Dielectric metasurfaces for distance measurements and three-dimensional imaging

TLDR

Ultrathin metasurfaces can control all aspects of light propagation, making them promising replacements for bulky imaging optics with added functionalities. We show that metasurfaces can be used for single‑lens 3‑D imaging by engineering a point‑spread function. We design and fabricate a high‑transmission Huygens metasurface that implements a rotating, double‑helix PSF for depth encoding. Experimental results demonstrate that the double‑helix PSF uniquely encodes object distances over a wide range and enables wide‑field depth retrieval in a 3‑D scene with a single camera and lens.

Abstract

Ultrathin metasurfaces have shown the capability to influence all aspects of light propagation. This has made them promising options for replacing conventional bulky imaging optics while adding advantageous optical properties or functionalities. We demonstrate that such metasurfaces can also be applied for single-lens three-dimensional (3-D) imaging based on a specifically engineered point-spread function (PSF). Using Huygens’ metasurfaces with high transmission, we design and realize a phase mask that implements a rotating PSF for 3-D imaging. We experimentally characterize the properties of the realized double-helix PSF, finding that it can uniquely encode object distances within a wide range. Furthermore, we experimentally demonstrate wide-field depth retrieval within a 3-D scene, showing the suitability of metasurfaces to realize optics for 3-D imaging, using just a single camera and lens system.