激光主动层析探测成像时空特性仿真分析

发布时间：2018-11-09 08:45

【摘要】：激光探测技术目前广泛应用于水下探测,气象监测等各个领域,发展飞速。而激光主动层析探测技术则是通过电子门的开关对激光沿程传输和成像过程进行切片分离,把整个沿程成像的过程分解为不同距离范围内的多幅切片像。使用这样的成像方式极大的降低了激光沿程传输过程中大气介质的光散射、闪烁等噪声对成像的影响,使成像的信噪比有了很大的提升。并且不同的时序切片像包含着探测中的距离信息,对不同时序切片像的处理分析有助于后期对探测目标的三维重建工作。综上,本文将对激光主动层析探测的整个过程进行仿真研究。着重考虑激光传输链路的时空特性,本文建立了激光层析探测中与时域和空间回波能量有关的算法数学模型,并使用简单三维目标的成像结果与蒙特卡洛法(MCM)进行了对比验证;本文使用仿真程序对两种简单三维探测目标在不同激光脉冲宽度和门控宽度条件下的回波能量空间分布情况和最终层析成像结果进行了分析研究,并使用质心法初步对多幅仿真切片像进行了图像的三维重建工作;为了分析主动探测过程中激光在空间中的能量传输特性,本文首先使用电磁学软件对不同气溶胶粒子的光学特性进行了计算分析,并最终建立了不同粒子光学特性数据库和在仿真程序中的调用模型。对不同粒子光学特性数据库的调用完善了激光传输与能量衰减等算法模型,为激光能量传输过程的计算提供了数据基础;为了建立完整的层析成像仿真平台,针对复杂三维探测模型的成像、大气介质的衰减与回波探测和目标的三维重建等问题,本文建立了学校附近大楼三维模型来进行不同参数下的仿真成像工作,并对不同参数下得到的切片像序列进行了三维重建并评价了重建结果的优劣和其影响因素,为激光主动层析探测实验的参数选择和系统设计提供了仿真数据基础。
[Abstract]:Laser detection technology has been widely used in underwater detection, meteorological monitoring and other fields. On the other hand, the laser active tomography is used to separate the laser from the imaging process through the switch of the electron gate, and the whole process of the laser along the path is decomposed into multiple slice images in the range of different distances. By using this imaging method, the light scattering and scintillation of atmospheric media in the process of laser propagation are greatly reduced, and the signal-to-noise ratio (SNR) of the imaging is greatly improved. And different sequential slice images contain the range information in detection. Processing and analysis of different sequential slice images is helpful to the 3D reconstruction of target detection in the later stage. In summary, the whole process of laser active tomography detection is simulated. Considering the space-time characteristic of laser transmission link, a mathematical model related to time domain and space echo energy in laser tomography detection is established in this paper. The imaging results of simple 3D target are compared with Monte Carlo method (MCM). In this paper, the spatial distribution of echo energy and the final tomography results of two simple 3D targets under different laser pulse widths and gated widths are analyzed and studied by using the simulation program. Using the centroid method, the 3D reconstruction of a number of simulated slice images is carried out. In order to analyze the energy transmission characteristics of laser in space during active detection, the optical properties of different aerosol particles are calculated and analyzed by electromagnetic software. Finally, the database of optical properties of different particles and the call model in the simulation program are established. The algorithm models of laser transmission and energy attenuation are improved by calling the database of optical properties of different particles, which provides a data basis for the calculation of laser energy transmission process. In order to establish a complete tomography simulation platform, aiming at the problems of imaging of complex 3D detection model, attenuation of atmospheric medium and echo detection and 3D reconstruction of target, etc. In this paper, a three-dimensional model of the building near the school is established to simulate the imaging under different parameters, and the sequence of slice images obtained under different parameters is reconstructed, and the merits and demerits of the reconstruction results and the influencing factors are evaluated. It provides the simulation data basis for the parameter selection and system design of laser active tomography detection experiment.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN249

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