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We report a time-of-flight photon-counting imaging system in conjunction with a single-photon detector mounted with a fiber optic taper, which equivalently enlarges the active area of the single-photon detector by 100 times. The field of view of the imaging system is extended from ±0.57° to ±7° by using the fiber optic taper to collect the scattered photons. Since only a single avalanche photodiode is used, the noise level of the system is maintained at a low level. We demonstrate the scanning of the targets at a stand-off distance of 28 m with a centimeter depth resolution.

We report a high-speed airborne single-photon counting LiDAR at 1550 nm. By using a quasi-continuous Geiger-mode single-photon detector with sinusoidal gating waves at 1-GHz with a 1-MHz repetition rate pulsed laser as the emitting source, a point cloud rate of 1.4 × 106 points per second was obtained at the average flight height of 620 m, while the receiving aperture of the LiDAR was only 15.3 mm. To preclude the background data in the daylight which was about 30 times higher than the signal data, we proposed a processing algorithm based on the difference of signal and noise in density distribution to distill the three-dimension information of the targets. The clear reconstructed image indicates the airborne LiDAR and its data processing algorithm were qualified for terrain mapping and three-dimensional city modeling.

We report a frequency-multiplexing method for multi-beam photon-counting light detection and ranging (LiDAR), where only one single-pixel single-photon detector is employed to simultaneously detect the multi-beam echoes. In this frequency-multiplexing multi-beam LiDAR, each beam is from an independent laser source with different repetition rates and independent phases. As a result, the photon counts from different beams could be discriminated from each other due to the strong correlation between the laser pulses and their respective echo photons. A 16-beam LiDAR system was demonstrated in three-dimensional laser imaging with 16 pulsed laser diodes at 850 nm and one single-photon detector based on a Si-avalanche photodiode. This frequency-multiplexing method can greatly reduce the number of single-photon detectors in multi-beam LiDAR systems, which may be useful for low-cost and eye-safe LiDAR applications.

We present the results of using a photon-counting full-waveform lidar to obtain detailed target information with high accuracy. The parameters of the waveforms (i.e., vertical structure, peak position, peak amplitude, peak width and backscatter cross section) are derived with a high resolution limit of 31 mm to establish the vertical structure and scattering properties of targets, which contribute to the recognition and classification of various scatterers. The photon-counting full-waveform lidar has higher resolution than linear-mode full-waveform lidar, and it can obtain more specific target information compared to photon-counting discrete-point lidar, which can provide a potential alternative technique for tomographic surveying and mapping.

Large field-of-view (FoV) three-dimensional (3D) photon-counting imaging is demonstrated with a single-pixel single-photon detector based on a Geiger-mode Si-avalanche photodiode. By removing the collecting lens (CL) before the detector, the FoV is expanded to ±10°. Thanks to the high detection efficiency, the signal-to-noise ratio of the imaging system is as high as 7.8 dB even without the CL when the average output laser pulse energy is about 0.45 pJ/pulse for imaging the targets at a distance of 5 m. A 3D image overlaid with the reflectivity data is obtained according to the photon-counting time-of-flight measurement and the return photon intensity.