【作者】 姜燕冰；

【导师】 严惠民；

【作者基本信息】 浙江大学 ， 光学工程， 2009， 博士

【摘要】 人类对于信息捕获技术的探索是无止境的,面阵成像三维激光雷达技术作为一种能够快捷、准确地获取大信息量三维信息的重要技术,在军事领域、国民经济建设领域、农林生态领域等都可以得到广泛应用。而目前面阵成像三维激光雷达还处于发展之中,其理论模型还没有建立完善,其性能尚未完全满足各方面的应用需要。本论文围绕着提高性能为主题,在面阵成像三维激光雷达系统的噪声理论模型、高效率光学系统、三维分辨率的相互影响等方面进行深入的研究。本文的主要研究内容和创新点如下:以典型的面阵成像激光雷达结构为基础,通过对各个工作过程中引入噪声的分析,建立以ICCD为核心探测器的面阵成像激光雷达的完整噪声模型,在此模型的基础上,分析了噪声模型对测距精度的影响,提出了面阵成像激光雷达的体分辨率概念,得到了描述面阵成像激光雷达性能的能量观点,并指出提高雷达性能的途径和研究方向。提高光学系统的效率是提高面阵成像激光雷达的性能最有效途径之一,因而着重进行这方面的研究。率先采用总相对精度作为评价函数,分析照明的光强分布对雷达性能的影响,发现在出射总能量一定时,均匀化照明能使时达到最好的总相对精度,将比整形前厄米高斯型能量分布的照明效果降低25%的总相对误差。对半导体激光器堆叠的高效率均匀化照明方法进行深入研究。提出基于倾斜多高斯模型光束的均匀化照明方案,对倾斜多高斯光束的理论进行分析,给出其平均光强解析表达式,发现这种光束在远场传播过程中可以保持平顶特性,非常适合用于远场的均匀化照明。采用时域和傅里叶频域相结合的分析方法,阐明影响该模型光束照明均匀性的参数和影响规律。提出半导体激光器光束整形成倾斜多高斯光束的光学设计方案,并在光学模拟计算中得以实现,结果显示:在现有的半导体激光器堆叠的误差失配下,该方案仍然可以达到80%的均匀性和75%以上的整形效率。提出基于混光筒的均匀化整形方案,经过光学软件的验证,其均匀性和效率分别为80%和73%。提出基于复眼透镜的均匀化照明方案,经过光学软件的验证,其均匀性和效率分别为85%和75%。研究接收光学系统对于雷达性能的影响因素,给出高效成像光学透镜和中继透镜的结构和关键参数。研制用于光纤标定用途的低成本、高可靠性的光纤耦合系统。在搭建新型面阵成像激光雷达的基础上,研究光学传递函数对于系统性能的影响。首先利用特征目标图像的刀口像法,测定系统的光学传递函数,利用测定的光学传递函数,从理论上分析点扩散函数对测距分辨率的退化作用,分析结果与实验获得的测距分辨率的实际退化相一致。通过分析,发现在现有器件的光学传递函数水平下,对城市和常见目标,进行适当的多像素binning可以有效提高测距分辨率且不降低目标在距离图像中的空间分辨率。利用多重复特征目标法,进行户外实验测定新型面阵成像激光雷达的测距分辨率在600m到1000m的选通距离内为1.6m到13.5m。发现基于强度的面阵成像激光雷达因受限于量子散粒噪声,其测距分辨率与目标距离、目标本身特性等的有关,其关系符合本文提出的面阵成像激光雷达的噪声模型。更多还原

【Abstract】 Information capture technology is an endless exploration. The Array Imaging Three-Dimensional Ladar (AI3DL) technique, as one of most attractive information capture technology, has a capability to provide precision and rapid capture of vast 3D information. AI3DL technique is highly sought in a wide variety of applications in military, national economic construction, agricultural ecology, etc. However, there are still many problems desiderate to be solved to meet the strict requirements of application. In the view of theoretical research and practical application, the noise model and the ways to improve 3D resolution performance are studied thoroughly in this dissertation.The main researched contents and their achievement are as follows:On basis of the prototypical AI3DL, the noises factors and system error factors from each detection process are analyzed to establish noise model of AI3DL. The noise model is used to analyze the range resolution of AI3DL. It is found that the energy received by the detectors limits the resolution. The research results indicate ways to improve the performance of AI3DL.One of the solutions is to enhance the efficiency of the optics system. Evaluation function of the illumination effect to range resolution is proposed. It is found that uniform illumination can reduce the total relative error by 25% compare to Gaussian irradiance distribution of the same transmit energy. Beam shaping method of uniform illumination for laser diodes stack is studied. A beam shaping method by superposition of tilted fundamental mode Gaussian beams to form a nearly uniform illumination is proposed. The analytical formula for average intensity of the multi-tilted Gaussian beams (MTGB) propagating is derived and used to study the uniform properties of the beam profile by the Fourier analysis method. It is found that the MTGB maintain the flat-topped shape as it propagates. And the uniform properties of the MTGB are closely related to the parameters of fundamental beams and superposition. Both analytical formula derivation and the numerical examples are illustrated. The optical design is proposed in detail. The results show uniformity better than 80% and a shaping efficiency about 75% on the condition of presently LD stack rigging error. The uniform illumination method for LD stack based on light pipe is proposed, simulation results showed 80% uniformity and 73% shaping efficiency. Another uniform illumination method for LD stack based on fly’s eyes is proposed and proved in ASAP software. The influence of the receiver optics including imaging lens and relay lens to resolution is analyzed. The structure and parameters of high efficiency imaging lens and relays lens are presented. A low cost optical fiber coupling system used for fiber accuracy calibration is developed.A novel pulse shape free AI3DL is proposed and its experiment system is introduced.The effect of optical transfer function to range resolution and spatial resolution in range images are studied. The edge response is used to caculated Modulation Transfer Function (MTF) of the AI3DL system in outdoor test. The range resolution degradation by MTF influence is proved by the experiment. It is find that the present system MTF is about 251p/mm and these make proper pixels binning an acceptable approach to improve the range solution without reduce the spatical resolution in range image.The range resolution is evaluated by measuring the several repeatable objects. The experiment shows that the range resolution is affected by the object charactircs and object range. At a gated range of 600m to 1000m, the range solution is 1.6m to 13.5m. It is another proof to the noise model of AI3DL.更多还原