相干光经过不透明散射介质的聚焦

由于散射介质的散射特性,入射光通过散射介质后相干性受到破坏形成散斑场,使得传统光学成像系统无法聚焦探测内部物体的信息。根据波前整形原理,通过反馈优化算法调控入射光束的相位,在目标位置处将散斑调制为聚焦光斑,光强增强。基于此方法,在实验上搭建实验平台,对空间光调制器(SLM)的每个像素加载系列等间隔相位,一次采集多幅散斑图像,应用局部最大优化算法实现对光束任意点聚焦,并提出了一种得到不同大小区域的均匀的聚焦光斑的新方法,为实现聚焦平面内的目标成像提供了新思路。     

Auto-correlation Properties of Scattering Light in Ultrasound-modulated Random Media

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｅｘｔｒａｃｔｉｎｇｕｓｅｆｕｌｉｎｆｏｒｍａｔｉｏｎａｂｏｕｔｔｈｅｄｙｎａｍｉｃａｌｓｃａｔｔｅｒｅｒｓｆｒｏｍｔｈｅｔｅｍｐｏｒａｌｆｌｕｃｔｕａｔｉｏｎｓｏｆｓｃａｔｔｅｒｉｎｇｌｉｇｈｔｆｉｅｌｄｈａｓｂｅｅｎｓｔｕｄｉｅｄｆｏｒｍａｎｙｙｅａｒｓ.Ｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｄｉｆｆｕｓｉｎｇ ｗａｖｅｓｐｅｃｔｒｏｓｃｏｐｙ[1～ 3 ] (ＤＷＳ)ｈａｓｅｘｔｅｎｄｅｄｔｈｅｔｒａｄｉｔｉｏｎａｌａｐｐｌｉｃａｔｉｏｎｓｉｎｓｉｎｇｌｅ ｓｃａｔｔｅｒｉｎ…     

Auto-correlation Properties of Scattering Light in Ultrasound-modulated Random Media

In this paper, the auto-correlation properties of scattering light in random media modulated by ultrasound were studied. The expression of temporal auto-correlation function of scattering light amplitude in the ultrasound-modulated media was presented. The results show that the auto-correlation function is modulated as the ultrasound is introduced into the media and the modulation amplitude decays with correlation time. The influences of ultrasound amplitude, Brownian diffusion coefficient, scattering and absorption coefficients on auto-correlation function were discussed. The auto-correlation imaging of an object hidden in random media was also studied by the use of Monte Carlo simulations.     

Some Features of the Electrodynamics of Anisotropic Metamaterials

We study the features of propagation of electromagnetic wave fields in anisotropic metamaterials composed of lattices of the so-called split-ring resonators embedded in a dielectric substrate. It is shown that strongly slowed waves can exist in such metamaterials if some components of the tensor of effective magnetic permeability are negative. The presence of such waves explains the experimentally observed effect of wave propagation through cutoff waveguides filled with an artificial medium composed of split-ring resonators.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 2, pp. 152–158, February 2005.     

单色光在损耗介质中激励的受激布里渊散射

研究了单色光在损耗介质中激励的受激布里渊散射，运用分布起伏噪声源模型描述了受激布里渊散射的产生过程，通过傅里叶变换，得到了输出斯托克斯光波的功率谱密度。     

Tomography in Optically Axisymmetric Media

A generalization of the Cormac algorithm for the inversion of the Radon transformation in an optical medium with an axisymmetric index of refraction has been proposed. The distribution of rays is such that only one ray passes through any two points in the circle. A “parallel scanning scheme” of tomography has been considered: a cylindrical object is illuminated by a parallel beam of light, the rays of which are deflected into the cylinder. There is no refraction on the surface of the cylinder. The algorithm assumes the possibility of attenuation on a ray, which also has an axisymmetric character. Such a type of ray deflection occurs in problematic issues of the tomography of GRADANs, light guides, and plasma.

     

Anisotropic Interface Roughness Scattering in a Lateral Superlattice

A novel interface roughness due to the perturbation of the periodic interface structure is studied theoretically for a lateral superlattice realized by an interface corrugated quantum well. It is found by numerical simulation that the correlation function for interface roughness can be well modeled by a sinusoidal function with an exponential decay in the direction of corrugation. Such a feature makes the correlation function far from a Gaussian function which is extensively used as a theoretical approximation of the correlation function for interface roughness. With such a correlation function, the influence of interface roughness scattering on electronic transport in the lateral superlattice is investigated.Consequently, it gives rise to a high anisotropy of electronic transport both in the absence and presence of a magnetic field, by which the relevant experiments can be well explained.     

Anisotropic Scattering in Accordance with Pomraning Phase Function

The emergent intensity I(0,μ) from the equation of transfer in anisotropically scattering medium with Pomraning phase function is derived in n ^th approximation by using Chandrasekhar’s discrete ordinate method. AMS classification: 85A25     

A Quantum Interpretation of Light Scattering near the Boundary between Transparent Media with Kerr Nonlinearity

The transformation of light by a nonlinear beamsplitter is considered. The beamsplitter is formed by a plane interface between two transparent dielectrics, at least one of which has a Kerr nonlinearity; i.e., its refractive index depends on the intensity of the penetrating radiation. It is shown that the interpretation of the result of calculation of quantum fields at the outputs from such a beamsplitter indicates a violation of the principle of causality in the sense that a subsequent event affects the previous one.     

Anisotropic Scattering in BaTiO_3: Ce Single Crystal

InPastdecadesseveralformsoflight-inducedscatteringhavebeenobservedfromBaTiossinglecrystali1luminatedbyalinear,polarizedlaserbeam[1~7j.Ingeneral,thescattteringPatterncanbeisotropicoranisotropicdependingonthepropagationdirectionofthelightbomrelativetothecrystallographicaxesandthebeampolarization,itiscom-monlyacceptedthatthephysicaloriginofthisphenomenonistherandomrecordingofParasiticgratingswrittenbyanincidentbeamanditsscatteredbeamfromcrystalinhomo-geneities[1J.Recently,anewtyPeofnonlinearopt…     

动态光散射中的多普勒效应

动态光散射中的多普勒效应郭凤岐１）刘秋霞２）（武汉工业大学数理系材料学院武汉４３００７０）ＤｏｐｐｌｅｒＥｆｅｃｔｉｎＤｙｎａｍｉｃＬｉｇｈｔＳｃａｔｅｒｉｎｇＧｕｏＦｅｎｇｑｉ，ＬｉｕＱｉｕｘｉａ（Ｄｅｐｔ．ｏｆＭａｔｈ．ａｎｄＰｈｙｓ．，Ｗｕｈａ...     

Superpixel-Based Complex Field Modulation Using a Digital Micromirror Device for Focusing Light through Scattering Media

We present a digital micromirror device(DMD) based superpixel method for focusing light through scattering media by modulating the complex field of incident light. Firstly, we numerically and experimentally investigate focusing light through a scattering sample using the superpixel methods with different target complex fields.Then, single-point and multiple-point focusing experiments are performed using this superpixel-based complex modulation method. In our experiment, up to 71.5% relative enhancement is realized. The use of the DMDbased superpixel method for the control of the complex field of incident light opens an avenue to improve the enhancement of focusing light through scattering media.     

各向异性圆锥体的平面光波散射特性

基于通用的矢量电位和标量电位与介电常数张量无关的原理,由激发的电偶极子与位函数的关系得到了任意各向异性目标散射场的表达式。得到了通用的介电常数张量的变换关系,具体地给出了介电常数张量在球坐标系中的表达式,将目标的内外电场展为级数,得到了各向异性晶体圆锥体一级散射场的解析表达式。理论结果与文献一致,验证了算法的正确性。在光波波长与粒子尺寸相近的情况下,对所得结果进行了仿真,表明各向异性圆锥体的散射具有偶极辐射的特点。所得结果简单、通用,为研究形状更为复杂的各向异性目标、纳米粒子等的光散射研究提供了理论基础。