运动浑浊介质中散射光场特征的电场蒙特卡罗模拟

发布时间：2018-01-04 20:24

本文关键词：运动浑浊介质中散射光场特征的电场蒙特卡罗模拟　出处：《华中科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：激光散斑血流成像是近年来广受关注的活体生物组织二维血流检测技术,在越来越多的生命科学基础研究和疾病诊疗中获得应用。该技术通过激光散斑衬比分析获取浑浊介质中散射子运动造成散射光电场变化的去相关时间,进而测得与该去相关时间有关的散射子运动速度信息。在以往的研究中,多采用布朗运动的散射子运动形式和单次散射模型,通过与此对应的洛伦兹谱型的散射光电场变化自相关函数形式建立激光散斑衬比与散射光电场变化去相关时间的联系。然而,实际生物组织散射特性与血流运动形式均非常复杂,上述简单近似使得激光散斑成像方法仍难以进行血流速度的准确地定量检测。为提高激光散斑成像血流定量检测的准确性,需要充分了解复杂生物组织中散射子做复杂运动时散射光电场变化的自相关函数信息,进而能够从散斑衬比分析更准确地获得散射子运动信息。针对上述需求,本论文结合运动粒子系统和电场蒙特卡罗方法实现了对相干光在散射子呈不同运动形式的浑浊介质中传输时后向散射光电场变化特征的模拟。论文主要内容包括:(1)分析对比了不同运动介质模型中散射光场的电场自相关函数对激光散斑血流成像中速度检测的影响,然后通过实验说明各电场自相关函数应用于激光散斑血流成像时的差异。对散射介质含有静态成份时的电场自相关函数进行分析,给出多曝光散斑衬比分析的拟牛顿-粒子群混合算法的求解方法,并通过模型实验结果验证该方法的有效性。(2)对相干光在动态浑浊介质中传输时后向散射光电场变化特征进行模拟,其中采用了GPU(Graphic Processor Unit,GPU)加速的粒子系统运动控制实现对粒子做布朗运动、定向运动、混合运动和静止情况的模拟,相干光在浑浊介质中传输时后向散射光电场变化也采用了GPU加速的电场蒙特卡罗模拟。(3)利用上述方法,考察了散射子做布朗运动、定向运动,以及布朗运动与定向运动混合,介质含有静态成份等复杂情况下时散射光场的动态变化特征。
[Abstract]:Laser speckle imaging is the living tissue of two-dimensional blood flow detection technology concern in recent years, more and more applied in basic research of life science and technology. The disease diagnosis and treatment by laser speckle contrast analysis for scattering in turbid media movement caused by the scattered light field changes related to time, and then measured get information about the scattering velocity related with the time. In the previous study, the movement form of scattering and single scattering model of the Brown movement, through the corresponding Lorenz spectral type scattering photoelectric field autocorrelation function is established in the form of laser speckle contrast to the relevant time and photoelectric scattering field change. However, the actual biological tissue scattering characteristics and flow movement forms are very complex, the simple approximate speckle imaging method is still difficult to make laser blood flow The accurate quantitative testing. In order to improve the accuracy of laser speckle imaging quantitative detection, it is necessary to fully understand the complex scattering in biological tissue for complex motion when scattering field changes the autocorrelation function of the photoelectric information, and then can get from speckle scatter motion information more accurately than analysis. According to this requirement, the according to the motion of a particle system and electric field simulation of the Monte Carlo method to the scattering field of photoelectric characteristics of coherent light transmission in turbid media in various forms of exercise after scattering. The main contents include: (1) analysis and comparison of the electric field of light scattering from different motion medium model of autocorrelation function of laser speckle influence of speed spot flow imaging detection, and experiments show that the difference of electric field autocorrelation function is applied to laser speckle imaging. The scattering of the medium containing Analysis of the correlation function for static electric field components, gives the multi exposure speckle quasi Newton hybrid particle swarm algorithm for solving method of analysis, and the effectiveness of the method is verified by experimental results. (2) of coherent optical transmission in turbid medium to the dynamic variation characteristics of light scattered field emission by simulation, which uses GPU (Graphic Processor Unit, GPU) the realization of Brown motion, the particle particle system accelerated motion control simulation of mixed directional movement, movement and stillness of coherent light in turbid media transmission when the backscattering optical field changes are simulated by the GPU accelerated Monte Carlo (3 electric field.) using the above method, investigated the scattering of Brown sports, orienteering, and Brown motion and directional motion mixed, complex media containing static components under the dynamic change of light scattering characteristics.

【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R318.51;TN249

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