基于穆勒矩阵的目标光学反射特性研究
发布时间：2018-07-28 17:15
【摘要】：目标光学反射的偏振特性研究在民用和军事上显示出了极大的应用价值和发展潜力。传统偏振特性研究,根据目标自身穆勒矩阵的表达形式,将其分解为起偏、退偏和衰减等模块,是一种目标特性的数学表征,缺乏物理意义,具有一定的局限性;而本文将麦克斯韦方程与穆勒矩阵相结合,推导出利用穆勒矩阵计算目标折射率,消光系数,退偏振系数等的方法,这些系数具备明确的物理意义,可以作为新的偏振特征,从而为目标光学反射特性研究提供更有价值的信息。本文首先对最基础的麦克斯韦方程组微分形式进行求解,得到关于电磁场强度矢量的波动方程,根据目标表面有无电导率,结合折射率定义,得出了光学常数的存在。其次根据菲涅尔反射公式中,p波s波的反射系数,定义了两者的振幅比以及相位差。然后根据测量所得穆勒矩阵,将其转换为穆勒琼斯矩阵,穆勒琼斯矩阵是一个可以由菲涅尔反射系数表示的矩阵,对其进行求解,即可得到振幅比以及相位差。最后再结合菲涅尔反射公式以及折射定律,得出光学常数关于入射角的表达式。其次,本文推导出一种路径积分矩阵,它与穆勒矩阵存在转换关系。将路径积分矩阵分解,得到参量退偏振系数,它可以用来反映被测量目标对偏振特性的改变程度。由于路径积分矩阵是每束光传播路径的琼斯矩阵的概率混合,这一特性使得路径积分矩阵成为混合材料以及粗糙表面物理建模的好方法。并且由于多次散射容易造成退偏振,造成多次散射的原因是物体表面曲率较大甚至不光滑时,因此退偏振系数与物体表面粗糙度存在一定的关系,可以用于粗糙表面的实验仿真,并将其作为一个重要参数对目标进行分辨。为了获得目标自身穆勒矩阵,本文设计出一种多旋转式测量装置,通过偏振片和波片的不同组合来获得不同偏振态的出射光。由于穆勒矩阵包含16个元素,为了能够精确得到穆勒矩阵中的每一个参数信息,首先构建一个多角度的测量系统,使用七种不同的入射角(30°,37.5°,45°,52.5°,60°,67.5°,75°)对目标反射光进行测量,即入射光和反射光与法线的夹角可以变化。控制起偏系统得到6组不同的入射光斯托克斯矢量照射到目标表面,同时针对每组入射光控制检偏系统测量6组反射光斯托克斯矢量。为了能够精确地控制经过起偏系统后出射光的偏振态,在扩束透镜组与起偏系统之间加入了一组圆偏振态发生器,使通过起偏系统后产生的多组入射光光强值保持一致。最后,根据测量得到的目标穆勒矩阵,计算出反映目标光学特性的偏振参量,对路径积分矩阵进行分解得到的退偏振系数也用于偏振特性分析。利用所设计的系统对自然界中典型的目标以及复杂自然背景下的人造目标和伪装目标进行大量实验测量。结果表明,本文推导的偏振指标可以对不同种类的目标进行区分,并且可以对目标所表现出的偏振特性差异进行分析,论证了通过理论推导所得的目标光学常数以及退偏振系数对于区分目标的可行性与实用性。
[Abstract]:The study of the polarization characteristics of the target optical reflection has shown great application and development potential in civil and military. The study of the traditional polarization characteristics, based on the expression of the Muller matrix of the target itself, decomposes it into a module of bias, depolarization and attenuation. It is a mathematical representation of the specificity of the target, lacking physical meaning and has a certain degree. In this paper, the Maxwell equation and the Muller matrix are combined to derive the method of using the Muller matrix to calculate the target refractive index, the extinction coefficient, the depolarization coefficient and so on. These coefficients have clear physical meaning and can be used as new polarization characteristics, thus providing more valuable information for the study of the target optical reflection characteristics. First, the differential equation of the most basic Maxwell equation group is solved, and the wave equation about the intensity vector of the electromagnetic field is obtained. According to the conductivity of the target surface and the definition of the refractive index, the existence of the optical constant is obtained. Secondly, the amplitude ratio of the P wave S wave is defined according to the reflection coefficient of the Finel reflection formula, and the amplitude ratio of the two is defined. The phase difference is then converted to a Muller Jones matrix according to the Muller matrix measured. The Muller Jones matrix is a matrix which can be expressed by the Finel reflection coefficient. The amplitude ratio and the phase difference can be obtained by solving it. Finally, the equation of Finel reflection and the law of refraction are combined to obtain the angle of the optical constant about the incident angle. Secondly, this paper derives a path integral matrix, which has the transformation relationship with the Muller matrix. The path integral matrix is decomposed and the parameter depolarization coefficient is obtained. It can be used to reflect the degree of change of the polarization characteristic of the measured target. Because the path integral matrix is the probability mixing of the Jones matrix of each beam propagation path, This characteristic makes the path integral matrix a good method for the physical modeling of the mixed material and the rough surface. And because the multiple scattering is easy to cause depolarization, the cause of multiple scattering is that the surface curvature of the object is larger or not smooth, so the depolarization coefficient has a certain relation with the surface roughness of the object, and it can be used in the rough surface. In order to obtain the Muller matrix of the target itself, a multi rotation measuring device is designed to obtain different polarization states of the emitted light by different combinations of polarizers and wave plates. The Muller matrix contains 16 elements, in order to be accurately obtained. Each parameter information in the Muller matrix is first constructed with a multi angle measurement system, using seven different incident angles (30, 37.5, 45, 52.5, 60, 67.5, 75) to measure the reflected light of the target, that is, the angle between the incident light and the reflected light and the normal line can be changed. The control deviation system gets 6 different incident light of the incident light. The vector is irradiated to the target surface, and 6 groups of reflected light Stokes vectors are measured for each group of incident light control detection. In order to accurately control the polarization state of the ejection light after the polarizing system, a set of circular polarization generator is added between the beam enlargement system and the offset system to make the multiple groups of input generated by the polarizing system. The intensity of light intensity is consistent. Finally, according to the measured target Muller matrix, the polarization parameters that reflect the optical properties of the target are calculated. The depolarization coefficient of the decomposition of the path integral matrix is also used for the analysis of polarization properties. The target and the camouflage target are measured in a large number of experiments. The results show that the polarization indexes derived in this paper can be distinguished from different kinds of targets, and the polarization characteristics of the target can be analyzed. The feasibility of the target optical constant and the depolarization coefficient to distinguish the target can be demonstrated by the theoretical deduction. Sex and practicality.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O436.3
[Abstract]:The study of the polarization characteristics of the target optical reflection has shown great application and development potential in civil and military. The study of the traditional polarization characteristics, based on the expression of the Muller matrix of the target itself, decomposes it into a module of bias, depolarization and attenuation. It is a mathematical representation of the specificity of the target, lacking physical meaning and has a certain degree. In this paper, the Maxwell equation and the Muller matrix are combined to derive the method of using the Muller matrix to calculate the target refractive index, the extinction coefficient, the depolarization coefficient and so on. These coefficients have clear physical meaning and can be used as new polarization characteristics, thus providing more valuable information for the study of the target optical reflection characteristics. First, the differential equation of the most basic Maxwell equation group is solved, and the wave equation about the intensity vector of the electromagnetic field is obtained. According to the conductivity of the target surface and the definition of the refractive index, the existence of the optical constant is obtained. Secondly, the amplitude ratio of the P wave S wave is defined according to the reflection coefficient of the Finel reflection formula, and the amplitude ratio of the two is defined. The phase difference is then converted to a Muller Jones matrix according to the Muller matrix measured. The Muller Jones matrix is a matrix which can be expressed by the Finel reflection coefficient. The amplitude ratio and the phase difference can be obtained by solving it. Finally, the equation of Finel reflection and the law of refraction are combined to obtain the angle of the optical constant about the incident angle. Secondly, this paper derives a path integral matrix, which has the transformation relationship with the Muller matrix. The path integral matrix is decomposed and the parameter depolarization coefficient is obtained. It can be used to reflect the degree of change of the polarization characteristic of the measured target. Because the path integral matrix is the probability mixing of the Jones matrix of each beam propagation path, This characteristic makes the path integral matrix a good method for the physical modeling of the mixed material and the rough surface. And because the multiple scattering is easy to cause depolarization, the cause of multiple scattering is that the surface curvature of the object is larger or not smooth, so the depolarization coefficient has a certain relation with the surface roughness of the object, and it can be used in the rough surface. In order to obtain the Muller matrix of the target itself, a multi rotation measuring device is designed to obtain different polarization states of the emitted light by different combinations of polarizers and wave plates. The Muller matrix contains 16 elements, in order to be accurately obtained. Each parameter information in the Muller matrix is first constructed with a multi angle measurement system, using seven different incident angles (30, 37.5, 45, 52.5, 60, 67.5, 75) to measure the reflected light of the target, that is, the angle between the incident light and the reflected light and the normal line can be changed. The control deviation system gets 6 different incident light of the incident light. The vector is irradiated to the target surface, and 6 groups of reflected light Stokes vectors are measured for each group of incident light control detection. In order to accurately control the polarization state of the ejection light after the polarizing system, a set of circular polarization generator is added between the beam enlargement system and the offset system to make the multiple groups of input generated by the polarizing system. The intensity of light intensity is consistent. Finally, according to the measured target Muller matrix, the polarization parameters that reflect the optical properties of the target are calculated. The depolarization coefficient of the decomposition of the path integral matrix is also used for the analysis of polarization properties. The target and the camouflage target are measured in a large number of experiments. The results show that the polarization indexes derived in this paper can be distinguished from different kinds of targets, and the polarization characteristics of the target can be analyzed. The feasibility of the target optical constant and the depolarization coefficient to distinguish the target can be demonstrated by the theoretical deduction. Sex and practicality.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O436.3
【参考文献】
相关期刊论文 前10条
1 杨蔚;顾国华;陈钱;周骁俊;徐富元;;穆勒矩阵图像的获取及处理[J];红外与激光工程;2015年12期
2 唐s顂，
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