Fig. 1. Principle of pulse ToF ranging

Fig. 2. Principle of range ambiguity

Fig. 3. Histogram of photon ToF distribution recorded by TCSPC

Fig. 4. Schematic of typical single-photon LiDAR system

Fig. 5. Schematic of typical coaxial single-photon LiDAR system

Fig. 6. 3D imaging results of LiDAR at 900 m distance with different single pixel acquisition time. (a) Photograph of building; (b)－(f) median filtering results of depth image with different single pixel acquisition time; (g)－(k) TV regularization results of depth image with different single pixel acquisition time

Fig. 7. Simulation and experiment of 2D and 3D imaging reconstruction

Fig. 8. Representative achievements in single-photon LiDAR

Fig. 9. Experiment of 1 km altitude terrain probe

Fig. 10. Experiment of 4.5 km single-photon counting 3D target imaging. (a) System structure; (b)－(d) photographs of experimental scene; (e)－(g) imaging results

Fig. 11. 10 km 3D imaging single-photon LiDAR system. (a) System structure; (b) experiment of 10.5 km hillside target imaging

Fig. 12. Long range single-photon LiDAR 3D imaging results over 45 km

Fig. 13. Long-range target at 21.6 km imaged in daylight and at night

Fig. 14. Ranging results of targets 100 km away from LiDAR based on SNSPD array. (a) Detection result of clouds 106 km away in daylight; (b) detection result of mountains 180 km away at night

Fig. 15. Schematic diagram of LiDAR system with imaging range of 200 km

Fig. 16. Reconstruction imaging result of 126 km mountain target. (a) Photograph; (b) result in literature for comparison；(c) result by Li et al.^[36]

Fig. 17. Transient image segments captured by imaging system