Long-range active imaging has a variety of applications in remote sensing and target recognition. Single-photon LiDAR (light detection and ranging) offers single-photon sensitivity and picosecond timing resolution, which is desirable for high-precision three-dimensional (3D) imaging over long distances. Despite important progress, further extending the imaging range presents enormous challenges because only weak echo photons return and are mixed with strong noise. Herein, we tackled these challenges by constructing a high-efficiency, low-noise confocal single-photon LiDAR system, and developing a long-range-tailored computational algorithm that provides high photon efficiency and super-resolution in the transverse domain. Using this technique, we experimentally demonstrated active single-photon 3D-imaging at a distance of up to 45 km in an urban environment, with a low return-signal level of $\sim$1 photon per pixel. Our system is feasible for imaging at a few hundreds of kilometers by refining the setup, and thus represents a significant milestone towards rapid, low-power, and high-resolution LiDAR over extra-long ranges.

中文翻译：

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45 公里处的单光子计算 3D 成像

远程主动成像在遥感和目标识别方面有着广泛的应用。单光子 LiDAR（光探测和测距）提供单光子灵敏度和皮秒时间分辨率，这是长距离高精度三维 (3D) 成像所需要的。尽管取得了重要进展，但进一步扩大成像范围仍面临巨大挑战，因为只有微弱的回波光子返回并混有强噪声。在此，我们通过构建高效、低噪声的共焦单光子 LiDAR 系统，并开发可在横向域提供高光子效率和超分辨率的远程定制计算算法来应对这些挑战。使用这种技术，我们通过实验证明了在城市环境中最远 45 公里的主动单光子 3D 成像，每像素 1 光子的低返回信号水平。通过改进设置，我们的系统可以在数百公里处进行成像，因此是实现超长距离快速、低功耗和高分辨率 LiDAR 的重要里程碑。