Illuminating depth: polarimetric time-of-flight sensing with single-photon counting imager

Underwater imaging is crucial for many applications, from marine biology research to industrial inspections, oil and gas exploration, search-and-rescue operations, and defense and security. Yet, underwater imaging poses numerous challenges, including backscatter from suspended particles, light absorption, and distortion caused by the medium's varying optical properties, in which traditional imaging methods often fall short. To address these challenges, we exploit the polarization properties of light by integrating a unique polarization-demultiplexing metasurface with an imager. Both direct imaging using a conventional CCD camera and a time-of-flight single-photon counting camera are used. By correlating the polarization states of emitted and reflected light, our approach enables us to develop means to enhance image contrast and achieve a more accurate estimation of the true target depth.