High-resolution single-photon LiDAR without range ambiguity using hybrid-mode imaging [Invited]

We proposed a hybrid imaging scheme to estimate a high-resolution absolute depth map from low photon counts. It leverages measurements of photon arrival times from a single-photon LiDAR and an intensity image from a conventional high-resolution camera. Using a tailored fusion algorithm, we jointly processed the raw measurements from both sensors and output a high-resolution absolute depth map. We scaled up the resolution by a factor of 10, achieving 1300 × 2611 pixels and extending ~4.7 times the unambiguous range. These results demonstrated the superior capability of long-range high-resolution 3D imaging without range ambiguity.

One pot synthesis of monodispersed L-glutathione stabilized gold nanoparticles for the detection of Pb^2＋ ions

Direct mixture of Au^3＋ with glutathione （GSH）, which act as both reduction agents and stabilizers, in aqueous solution gave rise to production of gold nanoparticles （Au NPs） with uniform sizes of around 21 nm. The GSH stabilizer Au NPs in solution show immediate aggregation after addition of 1 mol/L NaCI aqueous solution containing Pb^2＋ ions. The Pb^2＋-induced aggregation in Au NP solution is monitored by both colorimetric response and UV-vis spectroscopy. A rather broad linear range （from 0.1 to 30 pmol/L） and low detection limit （0.1 pmol/L） are explored for Au NP sensors used for detection of Pb^2＋ ions. Furthermore, the response of GSH-stabilized Au NPs toward Pb^2＋ ions is specific compared with other possible interferants （Hg^2＋, Mg^2＋, Zn^2＋, Ni^2＋, Cu^2＋, Co^2＋, Ca^2＋, Mn^2＋, Cd^2＋, and Ba^2＋）.

Single-photon computational 3D imaging at 45 km

Single-photon light detection and ranging(lidar)offers single-photon sensitivity and picosecond timing resolution,which is desirable for high-precision three-dimensional(3 D)imaging over long distances.Despite important progress,further extending the imaging range presents enormous challenges because only a few echo photons return and are mixed with strong noise.Here,we tackled these challenges by constructing a high-efficiency,low-noise coaxial single-photon lidar system and developing a long-range-tailored computational algorithm that provides high photon efficiency and good noise tolerance.Using this technique,we experimentally demonstrated active single-photon 3 D imaging at a distance of up to 45 km in an urban environment,with a low return-signal level of^1 photon per pixel.Our system is feasible for imaging at a few hundreds of kilometers by refining the setup,and thus represents a step towards low-power and high-resolution lidar over extra-long ranges.