Research On The Range Walk Error And Back Scattering Of Underwater Photon Counting Lidar

Compared with linear system lidar,photon counting lidar has extremely high sensitivity due to its different design concept and detection system.It can respond to the energy of a single photon,and can solve the contradiction between the increasing detection performance and the limited system resources.Introducing photon counting lidar underwater detection,which is helpful to solve the problems of the traditional underwater detection system such as huge size,high system complexity and shallow detection range.And it can help to improve the current traditional sonar detection in complex area,and it is conducive to improving our country's understanding of the ocean,and it is of strategic significance in terms of economic construction,national defense consolidation and national sovereignty maintenance.The thesis focuses on the photon counting lidar prototype and its underwater detection.The research status of photon counting lidar is introduced,the detection principle and detection model of photon counting lidar and single photon detector are analyzed,the working mode of statistical histogram of Time-Correlated Single Photon Counting is expounded.For photon counting range walk error problem in laser radar,the basic principle of range walk error are analyzed.Based on the mathematical derivation of range walk error and starting from detector timing jitter,a model between range walk error and detector timing jitter is established.After the software simulation,experiments were carried out with our prototype,and the results verified the accuracy of the model.Aiming at the backscattering problem of photon counting lidar in underwater detection,its scattering characteristics are calculated and simulated based on the Mie scattering model,which shows the influence of backscattering on the underwater detection of photon-counting lidar.Then the polarization-sensitive method is proposed to suppress the backscattering.Then the theoretical principle of the polarization-sensitive method is analyzed by means of the Mie scattering theory and Monte Carlo method.Finally,a self-designed polarization modulation system was added to the experimental prototype and a detection experiment of photon counting lidar about two meters underwater was carried out.Through the analysis of the data obtained from the experiment,the inhibition effect of water backscattering reached 6d B,which verifies the rationality and engineering feasibility of the method used,and provides a beneficial reference for the development and application of photon counting lidar underwater detection in the future.