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Intensity Distribution and Phase Vortices of Speckle Fields Generated by Multi-Aperture Random Scattering Screens
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The intensity distribution and phase vortices of the speckle fields generated by multi-aperture random scattering screens are simulated, and it is found that the vortices exhibit layer-like structures and the dislocation phenomena occur in the local phase patterns produced by the two-pinhole aperture, whose phase distributions appear as striped structures. For three- or four-pinhole aperture, there are many circular bright spots appearing in the speckle grains, and there is one vortex between the neighboring circular bright spots. The positive and negative phase vortex lattices appear in the phase distributions, and the regions circled by the isothetic phase lines form irregular quadrilaterals or hexagons. Moreover, the relative positions of the vortices or bright spots can be adjusted by changing those of the pinhole apertures. 相似文献
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通过对二维高斯相关随机表面在远场平面上产生的散斑场及其相位的计算模拟, 发现在某一平面上除了实部零值线与虚部零值线有传统相交之外, 还有相切和重合的情况.切点和重合线也可以形成相位奇异, 并且其周围相位分布与传统的实部零值线与虚部零值线相交形成的奇点周围相位的螺旋变化不同, 呈现出对称性和不连续性的特征. 随着光波的传播, 在不同的观察面上散斑场复振幅的实部零值线和虚部零值线的相对位置经历了由相切到重合再到相交的演变过程, 相位奇异现象也随之发生变化.
关键词:
相位奇异
相位跃变
散斑场 相似文献
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通过对方形环孔和圆环孔形成的散斑场及其相位奇异性的研究,发现在某一平面上实部和虚部零值线的位置关系出现了复杂相切相交的情况,复杂相切相交点也形成相位奇异,并且其周围相位分布与传统的实部零值线与虚部零值线相交形成的奇异点周围相位的螺旋变化不同,呈现出对称性和不连续性的特征.方形环孔和圆环孔形成的散斑场的散斑颗粒分布与传统方孔不同,受散射孔径的调制分别排成水平或竖直的条纹状轮廓和类似于圆形的轮廓,在散斑场的局部光强图中出现了很多类似于圆形的黑暗区域,称其为"光强暗核",其中心对应着一个相位分布较均匀的涡旋. 相似文献
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由散斑场和参考光的干涉图样提取散斑场复振幅、相位和强度的数值分布,并对其统计特性进行实验研究,消除了散斑场强度统计函数特别是概率密度函数的传统测量方法中噪声引起的偏差,并实现了散斑场复振幅和相位统计特性的实验研究.通过对不同散射角处散斑场的研究发现随着散射角度的增大散斑颗粒逐渐呈现出横向展宽的现象,且其平均宽度表现为各向异性,但是其概率密度函数并没有发生变化,与小角度情况一样属于圆形高斯散斑场.
关键词:
散斑
概率密度
干涉 相似文献
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Extraction of Parameters of Random Self-Affine Fractal Surfaces from Light Scattered Intensity by Levenberg-Marquardt Algorithm
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A method for simultaneously extracting the parameters of self-affine fractal surfaces from a single experimental profile of scattered intensity data is proposed. The Levenberg-Marquardt algorithm is introduced to fit the theoretical equation for the scattering intensity profile to the experimental data. A precision system is designed for acquisition of scattering intensity data using the Boxcar integration technique. The surface parameters extracted (root-mean-square roughness w, lateral correlation length ζ, and roughness exponent α) are compared to those obtained using atomic force microscopy. 相似文献
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