We demonstrate a high-speed photon-counting laser ranging system with laser pulses of multiple repetition rates to extend the unambiguous range. In the experiment, the laser pulses of three different repetition rates around 10 MHz were employed to enlarge the maximum unambiguous range from 15 m to 165 km. Moreover, the range of distances was increased as well, enabling the measurement on different targets of large separation distance with high depth resolution. An outdoor photon-counting laser ranging up to 21 km was realized with high repetition rate, which is beneficial for the airborne and satellite-based topographic mapping.

Photon-counting laser ranging has attracted a lot of research interest for its application in the altimeter. In this letter, we report a large scale multi-beam photon-counting laser imaging system by using 100 laser beams in linear array as the light source. Taking advantage of a 100-channel low-noise high-efficiency single-photon detector, the three-dimensional image of remote targets could be constructed rapidly according to the time-of-flight measurement. This system provides a solution for a high-speed, high-resolution, low energy-consumption pushbroom airborne or spaceborne laser altimeter.

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.

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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.