动态散射介质散斑场的电场蒙特卡洛模拟分析
发布时间：2018-12-08 09:33
【摘要】：激光散斑是相干光传输的重要现象之一,其在工业、生命科学领域均有着广泛的应用,如位移测量、激光散斑血流成像等。由于生物组织和悬浮粒子溶液浑浊介质中的散射多为体散射,其中往往包含多次散射,这样的散斑现象较为复杂,难以用波动方程求解,一般只能采用数值方法来进行模拟。然而传统的蒙特卡洛数值模拟往往忽略了介质的运动性质,不能用以模拟研究体散射介质的布朗运动、定向流动等过程中的散斑现象,而这恰恰对研究动态体散射散斑的性质以及实现流速的定量测量十分重要。针对上述问题,本文首先从连续时间序列动态散斑模拟出发,提出了动态散斑模拟的新方法,利用该方法对平移散斑、沸腾散斑的电场自相关函数进行了分析研究,给出在平移、沸腾散斑共同作用下流速与电场自相关函数的关系式(传统的研究方法认为流速与散斑场的去相关时间成反比),并建立了运动浑浊体散射介质模型,利用改进的蒙特卡洛模拟方法对同时包含定向流动、布朗运动散射介质的散斑场进行了模拟与分析,为分析体散射散斑性质以及分析流速测量中的影响因素等提供了工具。本文的具体内容包括： (1)以散斑强度伽马分布模型研究分析散斑现象,提出新的连续时间序列动态散斑模拟方法,对平移散斑、洛伦兹光谱线型动态散斑等进行了模拟,给出像面上电场自相关函数的关系式,并分析了流速与衬比之间的关系。 (2)将电场蒙特卡洛模拟由无限窄光束扩展到有限尺寸大小的光束。针对由此带来的计算量增加问题,我们实现了基于GPU的CUDAEMC,通过并行计算来大幅提升计算速度。使用GTX480显卡运行CUDAEMC时,与i3-2120运行EMC(Electric field Monte Carlo)相比能取得370倍的加速比。 (3)提出了电场蒙特卡洛模拟DMEMC,能对悬浮粒子溶液模型布朗运动以及定向流动进行模拟,然后在此基础上模拟分析运动介质的体散射散斑场。实现了相干光照明下,运动介质体散射散斑场的蒙特卡洛模拟。
[Abstract]:Laser speckle is one of the most important phenomena of coherent light transmission. It has been widely used in industry and life sciences, such as displacement measurement, laser speckle blood flow imaging and so on. Because the scattering in biological tissue and suspended particle solution in turbid medium is mostly bulk scattering, which often contains multiple scattering, such speckle phenomenon is more complicated and difficult to be solved by wave equation. Generally, numerical method can only be used to simulate it. However, the traditional Monte Carlo numerical simulation often ignores the motion properties of the medium and can not be used to simulate the phenomena of speckle in the process of Brownian motion and directional flow. This is very important for the study of the properties of dynamic volume scattering speckle and the quantitative measurement of velocity. In order to solve the above problems, a new method of dynamic speckle simulation based on continuous time series dynamic speckle simulation is proposed in this paper. The electric field autocorrelation function of translational speckle and boiling speckle is studied by using this method. The relationship between velocity and electric field autocorrelation function under the action of translation and boiling speckle is given (the traditional research method holds that the velocity is inversely proportional to the time of speckle field decorrelation), and the scattering medium model of moving turbid body is established. The improved Monte Carlo simulation method is used to simulate and analyze the speckle field in the medium with directional flow and Brownian motion, which provides a tool for analyzing the properties of volume scattering speckle and analyzing the influencing factors in velocity measurement. The main contents of this paper are as follows: (1) A new continuous time series dynamic speckle simulation method is proposed to analyze the speckle phenomena by using the speckle intensity gamma distribution model. The Lorentz spectral linear dynamic speckle was simulated and the relation between the electric field autocorrelation function on the image surface and the contrast ratio was analyzed. (2) the field Monte Carlo simulation is extended from an infinite narrow beam to a finite size beam. In order to solve the problem of increasing computational complexity, we realize that CUDAEMC, based on GPU can greatly improve the computing speed by parallel computing. When using GTX480 graphics card to run CUDAEMC, the speedup is 370 times higher than that of i3-2120 running EMC (Electric field Monte Carlo). (3) it is proposed that the electric field Monte Carlo simulation DMEMC, can simulate the Brownian motion and directional flow of suspended particle solution model, and then simulate and analyze the volume scattering speckle field of moving medium. Monte Carlo simulation of scattering speckle field of moving medium under coherent light illumination is realized.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：R310
本文编号：2368119
[Abstract]:Laser speckle is one of the most important phenomena of coherent light transmission. It has been widely used in industry and life sciences, such as displacement measurement, laser speckle blood flow imaging and so on. Because the scattering in biological tissue and suspended particle solution in turbid medium is mostly bulk scattering, which often contains multiple scattering, such speckle phenomenon is more complicated and difficult to be solved by wave equation. Generally, numerical method can only be used to simulate it. However, the traditional Monte Carlo numerical simulation often ignores the motion properties of the medium and can not be used to simulate the phenomena of speckle in the process of Brownian motion and directional flow. This is very important for the study of the properties of dynamic volume scattering speckle and the quantitative measurement of velocity. In order to solve the above problems, a new method of dynamic speckle simulation based on continuous time series dynamic speckle simulation is proposed in this paper. The electric field autocorrelation function of translational speckle and boiling speckle is studied by using this method. The relationship between velocity and electric field autocorrelation function under the action of translation and boiling speckle is given (the traditional research method holds that the velocity is inversely proportional to the time of speckle field decorrelation), and the scattering medium model of moving turbid body is established. The improved Monte Carlo simulation method is used to simulate and analyze the speckle field in the medium with directional flow and Brownian motion, which provides a tool for analyzing the properties of volume scattering speckle and analyzing the influencing factors in velocity measurement. The main contents of this paper are as follows: (1) A new continuous time series dynamic speckle simulation method is proposed to analyze the speckle phenomena by using the speckle intensity gamma distribution model. The Lorentz spectral linear dynamic speckle was simulated and the relation between the electric field autocorrelation function on the image surface and the contrast ratio was analyzed. (2) the field Monte Carlo simulation is extended from an infinite narrow beam to a finite size beam. In order to solve the problem of increasing computational complexity, we realize that CUDAEMC, based on GPU can greatly improve the computing speed by parallel computing. When using GTX480 graphics card to run CUDAEMC, the speedup is 370 times higher than that of i3-2120 running EMC (Electric field Monte Carlo). (3) it is proposed that the electric field Monte Carlo simulation DMEMC, can simulate the Brownian motion and directional flow of suspended particle solution model, and then simulate and analyze the volume scattering speckle field of moving medium. Monte Carlo simulation of scattering speckle field of moving medium under coherent light illumination is realized.
【学位授予单位】：华中科技大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：R310
【参考文献】
中国期刊全文数据库 前1条
1 段元锋;姜平安;叶贵如;周青松;;应用数字散斑相关法测量结构振动位移和频率[J];公路交通科技;2011年06期
，本文编号：2368119
本文链接：https://www.wllwen.com/yixuelunwen/swyx/2368119.html
