Efficient non-line-of-sight imaging with computational single-photon imaging

Single-photon detectors time-stamp incident photon events with picosecond accuracy. When combined with pulsed light sources, these emerging detectors record transient measurements of a scene containing the time of flight information of the direct light reflecting off of visible objects, and also the indirectly scattered light from objects outside the line of sight. The latter information has recently been demonstrated to enable non-line-of-sight (NLOS) imaging, where advanced inverse methods process time-resolved indirect light transport of a scene to estimate the 3D shape of objects hidden around corners. In this article, we review computationally efficient NLOS approaches that build on confocally scanned data, where the light pulses used to probe a scene are optically aligned with the detection path. This specific scanning procedure has given rise to computationally efficient inverse methods that enable real-time NLOS image reconstruction.