Polarised full-waveform warning LIDAR with dust backscattering suppression

LIDAR, when used under adverse weather conditions such as fog and dust, suffers from attenuation and backscattering. In particular, backscattering creates spurious echo peaks in the received waveforms at incorrected ranges and leads to false alarms. As a solution, this paper proposes polarised full-waveform warning LIDAR for dust backscattering echo suppression, intended for applications under dusty environments. To this end, first, a theoretical model of the polarised LIDAR is developed based on the LIDAR equation and depolarisation characteristics of dust backscattering and target reflection. Thereafter, the depolarisation characteristics are experimentally evaluated under an artificially generated dusty environment; the results reveal that the target reflection features a strong depolarisation characteristic, whereas dust backscattering has a weak one. When the LIDAR emits linearly polarised light, a significant orthogonal-polarised component exists owing to the target reflection, and dust backscattering induces a mainly parallel-polarised component. On interposing an orthogonal-polarisation analyser in the receiving optical path, the parallel-polarised component from the dust backscattering and target reflection is blocked, whereas the orthogonal-polarised component is allowed to pass; this helps improve the contrast of the target reflection to dust backscattering. Finally, based on the theoretical model of the polarised LIDAR and experimental results, an orthogonal-polarised LIDAR prototype is designed and fabricated. Using this prototype, target detection experiments in a dusty environment are performed; the corresponding experimental results indicate that the orthogonal-polarised LIDAR effectively suppresses dust backscattering echoes and that the contrast of the target reflection to dust backscattering is improved by 4.78–7.12 dB. Utilization of the polarised full-waveform warning LIDAR can significantly reduce the false alarm rate and improves the LIDAR system performance when used under dusty environment conditions, in applications such as smart mining and autonomous driving.