Coherent wave propagation in viscoelastic media with mode conversions and pair-correlated scatterers

The influence of correlation between scatterers on coherent waves propagation is studied in the case of a viscoelastic medium hosting a random configuration of either spherical or cylindrical scatterers. A distinction is made between the hole correction and the additional disturbances to the pair correlation function beyond the excluded volume via a radial and concentration dependent Ursell function. The effect of the Ursell function on the effective wavenumber is shown to be of order 3 in concentration and order 2 in scattering, and the corresponding formulas generalize those of Caleap et al. (2012) for an ideal fluid host medium. The whole order 3 in concentration is calculated; its other part is of order 3 in scattering. Both parts of the order 3 in concentration are the sum of two terms, one related to mode conversions, the other not. The numerical study is performed mostly for aluminum spheres in epoxy, which is a rather illustrative situation of the different phenomena that participate to the coherent propagation. The Ursell function effect is enhanced at low frequency, while counteracted partly at higher frequency, by the other term of order 3 in concentration. The most visible effects of both terms are on the attenuation. The Ursell term related to mode conversions is larger than the one with no mode conversions included in the low frequency regime.     

用于校准能见度仪的标准散射体定标系统的校准方法

为了实现对用于校准能见度仪的标准散射体的快速准确定标,通过测量标准散射体不同散射角的散射系数,实现对标准散射体不同散射角所模拟的大气能见度进行准确定标并对定标系统进行校准.根据定标系统的组成与工作原理,确定定标系统的校准方法并建立相应的校准链,并设计校准链的各组成部分的校准方法.通过对已知散射系数的标准散射体进行定标,验证校准后定标系统定标结果的准确性,进而验证了定标系统校准方法的正确性.实验结果证明:定标系统对标准散射体的散射系数定标结果的误差为7.93%;经由定标系统定标的标准散射体所模拟的大气能见度的最大误差为8.61%,满足用于校准能见度仪的标准散射体的使用要求.     

侧面遮拦式日晕光度计的杂散光理论分析

提出了一种侧面遮拦结构的日晕光度计,在镜筒内通过设置多层挡板结构逐层抑制处于内视场的挡板边缘衍射光,同时采用倾斜布置的上挡板结构抑制处于外视场的入射窗口边缘衍射光和侧壁散射光.建立数学模型对这些杂散光抑制挡板进行了仿真计算,结果表明,优化各挡板的几何参数后,日晕光度计的设计视场可达3.5～10个太阳半径,视场内的杂散光水平均可低于10-8平均太阳亮度.相对于高山天文台的日晕光度计在4～8个太阳半径的视场内总杂散光达到10-2平均太阳亮度,该日晕光度计扩展了可观测视场,并使杂散光抑制提高了一个量级.     

用于校准能见度仪的标准散射体定标系统中光学系统的设计

为了实现校准能见度仪中标准散射体的快速准确定标,建立了用于校准能见度仪的标准散射体的定标系统.研究了定标系统中全景成像折反光学系统的设计方法.根据抛物面反射镜的光学特性推导出抛物面面型的计算方法.根据定标系统对光学系统的要求,完成全景成像色度计光学系统的设计.对全景成像折反光学系统进行建模仿真并设计实验验证光学系统的设计与仿真结果的正确性.实验结果表明:全景成像折反光学系统的空间检测俯仰角范围为0°~90°,方位角范围为0°~360°,且最小角分辨率为1°,与仿真结果基本一致,满足用于校准能见度仪的标准散射体定标系统中光学系统的设计要求.     

流动注射光散射法测定微量镍

用丁二酮肟流动注射光散射法测定微量镍,将经典的丁二酮肟-镍沉淀法改为光散射法并采用流动注射技术克服这类沉淀光散射法的稳定性问题。建立测定微量镍（Ⅱ）的丁二酮肟（DMG）-流动注射光散射法。将DMG-NaOH溶液与含镍（Ⅱ）水样流混合,在430nm处对反应形成的Ni（DMG）2沉淀微粒进行光散射检测,线性范围为5—20μg/mL,检出限为0.171μg/mL,测定频率为34次/h。本法的测定灵敏度较高、选择性较好、分析速度快,应用本法测定废水中镍含量,结果满意。     

Comparative study of rare gas-H<Subscript>2</Subscript> triatomic complexes

This paper presents a comparative analysis of complexes made of one rare gas (Rg) atom and molecular hydrogen, for five different Rg atoms. In particular, the vibrational band origins have been calculated, as well as the structural properties of the associated wavefunctions. The study is extended to ultra-cold Rg–H₂ collisions, object of a recent experiment aimed at producing ultra-cold H₂ [1]. The molecular systems are studied variationally using a simple, yet effective, isotropic trial wavefunction. A large number of potential energy surfaces available from the literature is considered. A comparative analysis shows that differences of up to two orders of magnitude exist for the zero-energy elastic cross sections of the five complexes. Corrections to the isotropic model have also been considered, showing no significant effect.     

基于成像法的气溶胶粒形和散射分析仪

粒形是影响气溶胶粒子光散射特性的基本参量,其定量信息的研究受到越来越多的关注。气溶胶粒形的常规测量手段为散射法和显微成像法。将散射法与显微成像法有机结合,提出了基于成像法设计气溶胶粒形和散射分析仪的新方案,实现了仪器测量的自身完善。利用自编的无限长圆柱理论的仿真程序,分析了线偏振光入射下,已知形状的单个棉絮纤维粒子的散射强度和偏振。实验数据和程序运算结果的比较表明,用该方法设计的分析仪的检测是可靠的。     

Wide tuning characteristics of double-ring coupled lasers

The wide tuning characteristics of double-ring coupled lasers with/without an extended waveguide are analyzed and optimized using the scattering matrix formalism. To obtain the optimum design schemes of the tunable laser diodes, the cross coupling ratios of two rings, the tuning enhancement factor, the propagation loss of passive waveguides, the optical gain of an active region, and the back and front-facet reflectivity of the waveguide are taken into account. When the coupling ratio of the ring and input/output waveguides is fixed, the extinction ratio and the linewidth are decreased as the tuning enhancement factor is increased, while the tuning range is increased.     

J-matrix method of scattering in one dimension: The nonrelativistic theory

We formulate a theory of nonrelativistic scattering in one dimension based on the J-matrix method. The scattering potential is assumed to have a finite range such that it is well represented by its matrix elements in a finite subset of a basis that supports a tridiagonal matrix representation for the reference wave operator. Contrary to our expectation, the 1D formulation reveals a rich and highly nontrivial structure compared to the 3D formulation. Examples are given to demonstrate the utility and accuracy of the method. It is hoped that this formulation constitutes a viable alternative to the classical treatment of 1D scattering problem and that it will help unveil new and interesting applications.     

脉冲激光辐照光学薄膜的缺陷损伤模型

建立了缺陷吸收升温致薄膜激光损伤模型,该模型从热传导方程出发,考虑了缺陷内部的温度分布以及向薄膜的传导过程,通过引入散射系数简化了Mie散射理论得出的吸收截面.对电子束蒸发沉积的ZrO₂:Y₂O₃单层膜进行了激光破坏实验,薄膜样品的损伤是缺陷引起的,通过辉光放电质谱法对薄膜制备材料的纯度分析发现材料中的主要杂质元素为铂,其含量为0.9％.利用缺陷损伤模型对损伤过程进行了模拟,理论模型和实验结果取得了较好的一致性.