共查询到18条相似文献,搜索用时 151 毫秒
1.
偏振BRDF模型的计算往往非常复杂,为了简准确地获取伪装目标和背景的反射光偏振度差值,采用特殊值法和理想化方法对Maxwell-Beard BRDF模型中的微面元分布函数和遮蔽函数进行简化,使微面元分布函数较Torrance-Sparrow模型准确,较Maxwell-Beard模型更简单.然后利用Fresnel反射中物体对光线平行分量和竖直分量反射率不同的性质,采用物理理论分析的方法计算得到表示反射过程的Muller矩阵,并建立了其矢量BRDF模型.针对面内反射,利用Matlab对模型进行模拟,仿真结果证明:模型可以描述粗糙表面反射偏振特性.研究结果对研究粗糙表面反射偏振特性的影响因素及伪装目标偏振探测有一定的理论和实践意义. 相似文献
2.
为了表征典型卫星表面材料的近红外偏振特性,基于微面元模型并综合考虑镜面散射及漫散射来描述目标表面的反射特性,引入镜面系数及漫反射率来明确两种反射对偏振度的影响,并考虑实际粗糙材料表面存在的遮蔽效应,建立一种更完善的多参量偏振双向反射分布函数模型,进而推导出适用于粗糙材料表面的光学反射偏振度表达式.对典型卫星表面材料进行近红外偏振实验,采用遗传算法从实验数据中反演卫星表面材料的多参量数值,进而得到偏振信息仿真曲线.结果 表明,该多参量偏振双向反射分布函数的仿真值与实验测试值能够较好的吻合,不同卫星表面材料的近红外偏振特性有较大分布差异. 相似文献
3.
太阳能电池片是光伏发电系统的核心部件,其光学反射特性对光伏组件的发电效率和缺陷检测的研究有着重要的理论意义,但实际应用中难以对其直接观察与测量。本文依据菲涅尔定律与多层介质模型研究了光伏组件的光学传输过程。首先基于微面元理论建立太阳能电池片表面的双向反射传输模型;然后借助多层介质模型推导了太阳能电池板偏振双向反射分布函数(bidirectional reflectance distribution function,BRDF) ,通过偏振相机搭建光伏组件光学偏振特性观测平台并开展偏振实验。在此基础上,利用遗传算法从实验测量数据中反演模型的参量数值,并得出偏振度信息随观测角变化的仿真曲线。通过实验表明,本文提出的光学传输模型仿真值与实验观测数据能够较好的吻合。该模型为太阳能电池板表面缺陷检测提供新的理论参考。 相似文献
4.
通过基于微面元理论的偏振双向反射分布函数模型,推导分析了物体表面红外辐射偏振传输方程的Stokes表达式,得出物体表面红外线偏振度与表面反射率(发射率)、波长、探测角度以及波长、目标与背景辐射差异等参数的数学关系;针对环境因素对红外偏振度的影响,开展了不同材质以及标准黑体的中、长波红外偏振成像及红外高光谱偏振成像实验,结果表明:黑体表面的红外偏振度与波长不相关,进而提出以标准黑体红外偏振特性作为溯源基准进行红外偏振定量处理的方法. 相似文献
5.
基于混合遗传算法的偏振双向反射分布函数优化建模 总被引:1,自引:0,他引:1
为了表征复杂涂层表面的光学散射特性,在微面元理论的基础上,建立了典型涂层样片的偏振双向反射分布函数模型.由于实验数据与模型参数之间存在复杂的非线性关系,采用了遗传算法对模型参数进行反演.针对遗传算法收敛速度慢及易限于局部极小的特点,在传统遗传算法参数反演的基础上,在适应度计算中引入了模拟退火算法对偏振双向反射分布函数模型进行优化建模.实验结果表明:模型的计算结果与实验结果吻合较好.从误差收敛曲线来看,这种混合遗传算法优化方法不仅可以有效避免目标函数陷入局部极小,而且可以有效缩短目标函数的收敛时间.这可以为后续的目标特征提取与识别工作提供参考. 相似文献
6.
为了有效检测光学基底和镀膜后的光学元件质量,根据微面元电磁散射理论建立了一阶极化光散射模型,推导求解出其极化双向反射分布函数,获得了极化双向反射分布函数PP项与散射角和方位角的三维关系。数值模拟分析了入射角、基底粗糙度及不同涂层厚度对极化双向反射分布函数的影响。数值结果表明:极化双向反射分布函数与入射角、相关长度、均方根高度及涂层厚度均成反比。P极化入射产生的P极化双向反射分布函数强烈依赖于入射角、散射角和方位角。布鲁斯特角的位置随着入射角的增加逐渐向散射方位角小的方向移动。 相似文献
7.
自然光照下目标的光学特征仿真 总被引:8,自引:2,他引:6
分析了双向反射分布函数,试验数据经验拟合公式,OpenGL中的Phong公式等几种目标表面材料面元的光学反射持征模型之间的差异。应用面元的双向反射分布函数推导出在阳光,天地背景光照下材料表面的反射光强分布函数的简化公式,讨论了OpenGL简化模型对光学特征仿真的影响。基于OpenGL,提出了3D模型建立途径和材料光学参数的选取方法,对复杂形体光学特征仿真中阴影和天地背景光目标照明的实现提出了相应的OpenGL算法,并给出仿真结果。 相似文献
8.
提出了一种空间目标红外动态辐射特性的建模方法。目标红外辐射包括自身发射辐射和对背景的反射辐射。根据目标与背景特征建立了空间目标辐射特性的物理模型。基于表面材料属性对目标表面进行区域与面元划分,根据能量守恒定律,利用目标在宇宙空间的热平衡方程建立了空间目标自身红外辐射特性的数学模型。同时,引入双向反射分布函数模型描述目标表面面元的反射特性,将目标所有面元反射分量叠加建立了目标红外反射特性的数学模型。最后,构建目标本体坐标系,通过坐标变换确定目标、背景辐射源与探测器的相对位置关系。根据给定的轨道参数、目标几何尺寸和表面物性参数仿真获得空间目标在轨红外特性。计算结果验证了模型的有效性,为空间目标的红外探测与识别提供参考数据。 相似文献
9.
10.
11.
A model-based approach that improves the spatial resolution of a buried inhomogeneous object using an active microwave imaging system is discussed. Algorithms are developed for quasi-real-time processing using a microwave camera specifically constructed for civil engineering applications using reflection mode imaging. The model is generated by numerically solving an integral equation representing the ideal scattered field of the object. The model is used to develop an optimal spatial filter to process the measured field. Finally, the inverse problem is solved using an imaging algorithm based on diffraction tomography and Fourier transforms. Experimental results indicate a reasonable performance of the approach 相似文献
12.
13.
V. I. Ushanov V. V. Chaldyshev V. V. Preobrazhenskiy M. A. Putyato B. R. Semyagin 《Semiconductors》2018,52(4):468-472
The optical reflection in periodic structures based on a semiconductor AlGaAs matrix containing two-dimensional arrays of plasmonic AsSb nanoinclusions was studied. The number of periods was 12 or 24. The spatial period was near 110 nm in both cases. In the experimental optical reflection spectra at normal incidence we observed resonant Bragg diffraction with the main peaks at wavelengths of 757 or 775 nm, depending on the spatial period of the nanostructure. The magnitudes of the resonance peaks reached 19 and 31% for the systems of 12 and 24 AsSb–AlGaAs layers, while the volume fraction of the nanoinclusions was much less than 1%. In the case of light incident at inclined angles, the Bragg-diffraction pattern shifted according to Wulff-Bragg’s law. Numerical calculations of the optical reflection spectra were performed using the transfer-matrix method by taking into account the spatial geometry of the structures and the resonance characteristics of the plasmonic AsSb layers. 相似文献
14.
在运动目标检测技术中,使用传统的高斯混合背景模型所得到的检测结果并不能完美地获取运动目标的轮廓信息,而图像中像素的梯度信息,刚好就是反映了各物体的轮廓和边界,并且相对于颜色信息而言,梯度信息对于噪声并不敏感。为此,该文对传统的高斯混合背景模型进行了改进,提出基于梯度时空信息的高斯混合背景模型,证明了改进的算法确实能够取... 相似文献
15.
V. I. Ushanov V. V. Chaldyshev V. V. Preobrazhenskii M. A. Putyato B. R. Semyagin 《Semiconductors》2016,50(12):1595-1599
The optical reflection from periodic structures based on a semiconductor AlGaAs matrix containing 2D arrays of plasmonic AsSb nanoinclusions is studied. The number of nanoinclusion layers is 12 or 24, and the nominal spatial periods are 100 or 110 nm, respectively. In the experimental spectra of the optical reflection coefficient at normal incidence, we observe resonant Bragg diffraction with the main peaks at wavelengths of 757 or 775 nm (1.64 or 1.60 eV), depending on the spatial period of the nanostructure. The magnitudes of the resonance peaks reach 22 and 31% for the systems of 12 and 24 AsSb–AlGaAs layers, while the volume fraction of the nanoinclusions is much less than 1%. In the case of light incident at inclined angles, the Bragg-diffraction pattern shifts according to Wulff–Bragg’s law. Numerical simulation of the optical reflection spectra is performed using the transfer-matrix method by taking into account the spatial geometry of the structures and the resonance characteristics of the plasmonic AsSb layers. 相似文献
16.
17.
An external cavity traveling-wave semiconductor ring laser with narrow linewidth is used as a light source for research in frequency domain reflectometry. The optical frequency of the laser is linearly chirped by an intra-cavity phase modulator. The time-delayed reflection signal is mixed with a reference signal to produce a microwave frequency that indicates the position of the reflection. For optical fiber measurement, a spatial resolution of 30 m and a one-way dynamic range of 28 dB for Rayleigh backscattered light have been achieved 相似文献
18.
We use spatial chirp of the built-in grating to improve optical bistability on reflection from distributed feedback semiconductor laser amplifiers. We show that improvements in the on-off switching ratio occur because spatial chirp greatly affects the saturation behavior of the reflectivity resonances, allowing access to states of low reflection during bistable switching. We also show that spatial chirp modifies the spectral range of the variety of hysteresis shapes that occur on reflection. In doing so, we discover a new type of hysteresis loop that reveals a qualitative difference between the loop-shaped hystereses occurring near the two edges of the stop band. With spatial chirp, the new hysteresis loop can exhibit an on-off switching ratio in excess of 100000 相似文献