参考光干涉提取复振幅的散斑统计函数的实验研究

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     

Manipulation of Surface Plasmon Polaritons by Phase Modulation of Source Field with Inverse Problem Algorithm

The predetermined field distributions can be achieved the propagation of surface plasmon polaritons （SPPs） by phase modulation of the source field to manipulate The modulations of the radius of the circular slit are according to the phase distributions on the slit, which are calculated by using the Gerchberg Saxton algorithm with the known field. We design the surface geometric shape of the radius-varied circular slit for exciting the SPP field with the linear, triangular, square and circular distribution characteristics, respectively. The slit structure designed for the circular field distribution is a plasmonic vortex lens that can be used to generate the vortex with the specified size of the primary ring, which shows that this heuristic method has the potential to devise plasmonic devices.     

FLAKE STRUCTURE IN THE SPECKLE FIELD PRODUCED BY A FEW SCATTERERS

This paper reports a new phenomenon, namely, flake structure in the speckle field produced by a few scatterers. This structure appears in the off-axis region and its size is much larger than that of the normal speckles. The one-dimensional simulations show that as the roughness of the random surface sample increases or its lateral correlation length decreases, the flakes go farther away from the axis, their relative intensities increase, their sizes become bigger and the fluctuations in them decrease. A sub-scatterer model that we call isoclinic element is proposed to explain the formation and properties of flakes. Experimental evidence shows the existence of the flake structure.     

Extraction of Parameters of Random Self-Affine Fractal Surfaces from Light Scattered Intensity by Levenberg-Marquardt Algorithm

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.     

Experimental method for the extraction of intensity profiles by imaging the scattered pattern with a charge-coupled devic

A practicable experimental method for measuring scattering on rough surfaces is reported.The scattered patterns are captured on a screen composed of two pieces of ground glass and then imaged using a chargecoupled device.The scattered intensity profiles are extracted by converting the patterns in real space into the wave vector space.Isotropic and anisotropic samples of the rough backsides of silicon wafer are investigated respectively,and their intensity profiles are measured.The profiles of the anisotropic sample are obtained by reading the pixels on the specific orientation curves.The parameters of the samples are extracted using angle-resolved light-scattering schemes and theories.The results well agree with measurements obtained using an atomic force microscope.     

变孔径像面散斑平均光强标定随机表面的理论与实验

采用随机表面的高斯相关模型和统计光学原理,推导出弱散射体在4f系统中的像面上光强的表达式.在此基础上提出了均方偏差粗糙度和横向相关长度的标定方法,该方法用理论结果对实验测量的像面散斑平均光强随滤波孔半径的关系曲线进行拟合,同时测量出被测样品表面的两个统计量.实验上制作了高斯相关随机表面样品,对其表面参数进行了测量,与AFM所测结果符合得较好,这表明该方法具有较高的精度. 关键词： 弱散射体 像面散斑 平均光强     

Properties of Movement and Boiling of Speckles Produced by Moving Objects Illuminated with Partially COherent Light

Properties of movement and the boiling of dynamic partially coherent speckles are investigated.Theoretical analysis of the correlation functions shows that in front of and behind the Fraunhofer plane,the directions of the movement of the dynamics partially coherent speckles are the samp and opposite to that of the object,respectively,The boiling occurs according to a parabolic factor with respect to time separation τ.These properties are observed experimentally by using an elaborately chosen extended source to meet the requirement of intensity and coherence.The boiling of the speckles is measured with the photon counting system,which is refitted for the automatic data acquistition,and the experimental results are confirmed by the theory.     

气/液界面上双萘菁夹心化合物有序超分子结构的组装

研究了气/液界面上双(八-十二烷硫基)萘菁铒{Er[Nc(SC₁₂H₂₅)₈]₂}形成的Langmuir单层膜中的超分子结构. 表面压-面积(π -A)等温线表明该化合物形成了稳定的单层膜. 将其沉积在云母片上, 用原子力显微镜(AFM)进行观察, 表明分子形成了取向高度有序的结构, 聚集体特征长度在100 nm左右(有的长达300 nm), 宽为20~30 nm.用紫外-可见光谱、偏振紫外-可见光谱、小角X射线衍射等对 LB膜进行了研究, 发现分子大环平面与基片平面夹角为54°, 每层厚度为3.53 nm. 研究表明形成的超分子结构由4~6列以面对面堆积形成的柱状体构成.     

Experimental study of regional fractal speckle produced in large angle scattering

Using the interference of speckle and the spherical reference wave,we extract the real and the imaginary parts of the complex amplitudes of the speckle in large angle scattering.By calculating the spatial correlation functions of intensity,we find that the speckle has a property of regional fractality,i.e.the fractal exponent equals 1 in a small spatial region and it becomes less than 1 in a bigger region.The empirical analytic expression of the intensity correlation function is gained.The probability density distributions of the intensities and the complex amplitudes show that the regional fractal speckle still obeys zero-mean circular complex Gaussian statistics.     

表面粗糙度的变波矢光散射测量方法的研究

提出了表面粗糙度变波矢光散射测量方法，通过散射光强中心亮点光能量的参数ｌｎ，Ｅ随变化的线性关系来确定粗糙度ｗ，对６块粗糙度不同的硅片背面样品进行了实验测量。