方形环孔和圆环孔形成的散斑场及相位奇异特性的理论分析和实验验证

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.     

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.     

弱散射屏的像面散斑自相关函数特性的实验研究

在对随机弱散射屏进行表面参数的原子力显微镜测量和建立了门积分取样平均的随机光强自相关函数测量系统的基础上,对弱散射屏在严格像面和离焦像面上产生的散斑自相关函数进行了测量。发现在严格像面上,散斑平均颗粒的大小随表面粗糙度增加而减小,且光强自相关函数次极大的相关间隔宽度随粗糙度增加而减小;而次极大的超伏随粗糙度的增大而增大;在离焦像面上,离焦量的增加使光强的自相关函数下降变得平滑,并使极小值点和次极大点变得不明显或者消失。     

Correlation and fractal properties of speckles in the extremely deep Fresnel diffraction region

Based on the Kirchhoff approximation and the theoretical analysis of the random light fields,the speckle intensity distributions in the extremely deep Fresnel diffraction region are simulated.The fractal property of the speckles as well as the relation between the speckle intensity distribution and the corresponding random surface is investigated.We design a microscope system to detect experimentally the speckles in the extremely deep Fresnel diffraction region,and the experimental results prove the conclusions drawn from our simulations.     

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.     

小孔衍射和近场散射数值计算的格林函数方法

从简谐光波满足的亥姆霍兹方程出发,将由格林定理得到的介质分界面上的积分方程转化为以表面上的光波及其导数为未知量的线性方程组,并对其进行数值求解,实现了光场的数值计算。然后将这一方法应用于亚波长尺度的小孔衍射的光波以及自仿射分形表面产生的随机光场及其在近场区域范围内的传播的计算。在随机表面产生的光场计算中．提出了类比推导夫琅禾费面上散斑场自相关函数的方法产生随机表面,以及计算其导数的傅里叶变换方法。对光场的计算结果表明,在近场范围内,光场随离开表面的距离的增加而迅速变化,其传播特性完全不同于光场在远场范围内的传播特性。     

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.     

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.