Near-infrared 3D imaging with upconversion detection

We demonstrate a photon-sensitive, three-dimensional (3D) camera by active near-infrared illumination and fast time-of-flight gating. It uses picosecond pump pulses to selectively upconvert the backscattered photons according their spatiotemporal modes via sum-frequency generation in χ 2 nonlinear crystal, which are then detected an electron-multiplying CCD with photon sensitive detection. As such, it achieves sub-millimeter depth resolution, exceptional noise suppression, high detection sensitivity. Our results show that can accurately reconstruct surface profiles of occluded targets placed behind highly scattering lossy obscurants 14 optical (round trip), using only milliwatt power. This technique may find applications biomedical imaging, environmental monitoring, wide-field light ranging.