| LiDAR is an active detection technology that can accurately and quickly obtain the three-dimensional information of targets.As an important research field,single photon LiDAR has been widely used in long-range target recognition and detection in recent years because of its single photon detection sensitivity and picosecond time resolution.The target optical scattering characteristic is an important research content in the field of single photon LiDAR.It directly determines the accuracy of target recognition and detection by LiDAR system.Based on the self-built single photon LiDAR system,the theoretical and experimental researches on the target optical scattering characteristics were carried out in this paper.The main contents and innovations are as follows:1.The detection error and target optical scattering characteristic model of single photon LiDAR were studied theoretically.According to the working principle of single photon LiDAR,the ranging mean error and standard deviation of single photon detection were theoretically analyzed.The simulation results show that the laser pulse width and the detection efficiency of photon detector affect the ranging error of single photon LiDAR.Considering the processes of specular reflection,diffuse reflection and ambient light reflection,based on the single photon LiDAR equation and photon Poisson probability distribution,the Blinn-Phong-BRDF model of laser target optical scattering was modified,and the numerical simulation was carried out.2.The target optical scattering characteristics of single point single photon LiDAR were studied experimentally.A single point single photon LiDAR target scattering test system has been built based on infrared single photon detector and picosecond laser.The single photon scattering characteristics of targets with different shapes,materials and surface roughness were experimentally studied.The experimental results show that the shape characteristics and surface roughness have the great influence on the single photon scattering characteristics of targets.The experimental results agreed with the modified Blinn-Phong-BRDF model.In the range of echo photon number less than3000 Hz,the average fitting error was less than 5%.Compared with the wave scattering characteristics measured by traditional LiDAR,the single photon scattering characteristics of targets are more sensitive to the changes of scattering peak and valley values caused by rotation than the wave scattering characteristics.3.The target optical scattering characteristics of array single photon LiDAR were experimentally studied.Based on the array(64×64)single photon detector,an array single photon LiDAR system has been designed and built,and the target optical scattering characteristics of the array detector were analyzed.The field experiments were carried out to study the single photon scattering characteristics of buildings at 240 m.According to the obtained scattering characteristic parameters,the echo photon number and triggering probability of targets at 1 km were simulated and calculated,so as to provide reference and support for the practical application of single photon LiDAR in the field of long-range target recognition and detection. |
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