测量单泡声致发光中气泡R(t)曲线的前向Mie散射技术

光干涉原理和Mie理论计算结果表明,单泡声致发光中气泡前向Mie散射的振荡信号,主要是由于气泡的透射光束和表面反射光束之间光干涉产生的. 这些干涉波峰形成了测量气泡半径的空间标尺,标尺的单位长度δR由散射角θ,检测光波波长和流体光折射率确定,而每个波峰就是标尺的刻线,它们与该时刻的气泡半径大小一一对应. 在30°—50°散射角范围内,利用前向Mie散射实验测定了单泡声致发光中气泡的最大半径,R(t)曲线及平衡半径,表明前向Mie散射是一种便捷的测定气泡运动特性的有效方法. 关键词： 单泡声致发光 前向Mie散射 光干涉     

Mie光散射理论的数值计算方法

Mie散射级数的计算速度和精度对颗粒测量结果有着重要的影响。针对不同颗粒直径和相对折射率，一般采用前向递推，后向递推，连分式法等计算Mie散射级数。在这3种方法的基础上提出一种改进算法，即首先通过连分式法计算Mie散射级数的初始值，然后后向递推其余各值。该算法在Matlab中实现时，数据以数组的数据类型存储和调用，程序采用递归算法。通过比较计算结果发现，该算法耗时短且结果不易溢出，具有快速、稳定、不受颗粒直径和折射率范围影响等优点。     

测量单泡声致发光中气泡R(t)曲线的前向Mie散射技术

光干涉原理和Mie理论计算结果表明,单泡声致发光中气泡前向Mie散射的振荡信号,主要是由于气泡的透射光束和表面反射光束之间光干涉产生的.这些干涉波峰形成了测量气泡半径的空间标尺,标尺的单位长度δR由散射角θ,检测光波波长和流体光折射率确定,而每个波峰就是标尺的刻线,它们与该时刻的气泡半径大小一一对应.在30°-50°散射角范围内,利用前向Mie散射实验测定了单泡声致发光中气泡的最大半径,R(t)曲线及平衡半径,表明前向Mie散射是一种便捷的测定气泡运动特性的有效方法.     

声致发光

对当前非线性声学界和物理学界的一个热门课题———单泡声致发光现象的研究，进行了系统的评述，并介绍了有关最新的进展和应用前景     

稀土盐水溶液单泡声致发光中的特征光谱

在溶有稀有气体的稀土盐氯化铽水溶液中进行了单泡声致发光光谱的研究. 在固定驱动超声频率、不同驱动声压下, 观察到了一系列OH自由基从第一激发态A²∑⁺到基态X²Π 各振动能级跃迁所产生的谱线, 包括波长307 nm处的(0, 0)跃迁谱线, 335 nm处的(0, 1)跃迁谱线以及276 nm处的(1, 0) 跃迁谱线等. 实验结果表明较高的驱动声压有利于 276 nm处谱线的产生, 而较低的驱动声压则有利于 307 与 335 nm 处谱线的产生. 通过定义线状光谱与连续谱的光强比, 定量地表征了线状光谱在总光谱中的相对强度, 并给出了驱动声压对各跃迁谱线光强比的影响. 关键词： 单泡声致发光 驱动声压 线状光谱 光强比     

单泡声致发光过程的等离子体描述

对单泡声致发光过程采用等离子体描述,考虑了各种等离子体输运过程,假设了声致发光的轫致辐射机制,数值模拟的结果与实验很好地吻合,有力地支持了声致发光的热转向的解释,预言了声致发光中可能出现的极端电现象,对各物理量时空剖面的分析表明,强电场的出现中能产生的Ｒａｙｌｅｉｇｈ－Ｔａｙｌｏｒ不稳定性有制约作用,这可能是声致发光约１０＾１２能量汇集的原因之一。     

单分散系微粒的Mie散射计算

Mie散射是公认的一种极具发展前途的微粒测试技术,应用于工厂、企业排放烟尘中微粒粒度和浓度的测试,具有非接触、精度高、重复性好和可实时在线测量的优点,是研究检测污染排放的主要技术手段,也是微粒粒度和浓度分析的理论基础.本文对Mie散射理论的多个参量进行计算并给出其数学表达式.     

Mie散射物理量的数值计算

介绍Ｍｉｅ散射物理量，如振幅函数，强度函数，偏振度，散射系数，消光系数和吸收系数等的数值计算法，给出这一算法的计算公式和运行时间，并与其它Ｍｉｅ散射物理量计算算法进行比较。     

简易Mie散射数值计算方法的研究

在回顾光散射理论发展史的基础上,分析了常规Mie散射计算实现过程中的问题,并论述一种改进的简易Mie散射数值计算方法。参照科学记数法定义了一种“EDecimal”类型的数据结构及其基本数学运算和三角函数运算。采用动态链表技术实现了高效的C++ Mie散射计算程序。该程序不仅可以用来处理极端条件下的Mie散射计算,而且显著降低了算法的时间复杂度,提高了执行效率。与相同精度要求下采用Wiscombe编写的MIEV0程序的计算结果进行了比较,并指出此程序精确可靠。     

A bubble detection technique based on light intensity and Mie scattering theory for spinning solution

A novel bubble detection technique based on light intensity and Mie scattering theory for spinning solution is presented theoretically and experimentally. With the light intensity in every direction, the particle or bubble size distribution can be calculated with the Mie scattering theory. The light intensity distribution in every direction, corresponding to the light intensity received by every assumed annulus of the detector has been calculated theoretically. According to the light intensity distribution, the size distribution of bubbles can be deduced. A series of standardized polystyrene micro-sphere (with 7 μm diameter) solution has been used not only as sample for experiments and calibration, but also as the bubbles in the glycerin. Theoretical and experimental results show that the technique can be used for bubble detection, in order to improve the traditional bubble detection scheme, and to lower production costs.     

球形粒子Mie散射特性分析

越来越多的与微粒相关的技术问题在许多领域出现,这些问题都与Mie散射理论有关。利用Matlab改进算法,对球形微粒子Mie散射特性做了较为全面和深入的分析,有助于Mie散射理论的研究和应用。     

金属类散射体的Mie散射特性研究

基于Mie散射理论研究发现,各种金属在中红外区的的散射行为极为相似,是一种反照率极高但散射效率极低的散射体,数值研究揭示了这类散射体系的光学截面以及散射强度的分布的内在联系.     

Direct recursion of the ratio of Bessel functions with applications to Mie scattering calculations

The primary goal of this paper is to describe a method to directly calculate the ratios between the Bessel functions of the first and second kind. This new method is introduced and discussed under the context of Mie scattering calculations. Past work on Mie calculations has mostly relied on calculating the Bessel functions separately, then taking the ratio. This technique fails when the order of the functions becomes appreciably larger than the argument. To solve this problem, we developed a stable method to directly calculate the ratio. When applied to Mie scattering calculations, the new method improves the control of the desired accuracy and enables calculations with higher precision. Since many other wave propagation problems also involve the ratios of Bessel functions and our method provides reliable and accurate calculations over a wide range of conditions, we expect it to find applications beyond Mie calculations.     

Two-particle characterization by pulse induced and time resolved Mie scattering

With this numerical investigation we demonstrate the determining of particle size and particle distance for a two-particle system by time resolved Mie scattering. The optical interaction of the fs-laser pulse with the particle configuration produces a sequence of scattered light signals on the femtosecond time scale. The temporal differences between these signals represent typical dimensions of the particle system. The different ray tracks of the specific scattering orders, which are the reason of the temporal behaviour, have been verified by models of geometric optics. We have simulated the Mie scattered light by an algorithm for multi-particle scattering. For all examples the detector was positioned in the back scattering region at a scattering angle of θ=150°.     

Mie散射向前递推连分式算法及其数值模拟

提出了一种新的Mie散射算法。针对Mie散射系数计算中直接递推所存在的数据溢出问题,对散射系数的递推公式进行改进,以连分式形式进行计算,将两个关键函数分别向前递推,避免了直接计算时贝塞尔函数值超出计算机最大数据限而造成的数据溢出问题。利用Matlab编程,分别计算了不同粒径参数和不同折射率情况下的散射光强分布,并对两种算法的模拟结果进行了分析比较。结果表明,在两种算法都有效的范围内这两种算法的计算结果完全相符,而改进的向前递推连分式算法用一个变量循环叠代就能完成连分式的计算,展宽了使用范围,不仅能够计算超大粒径参数散射,而且算法对折射率虚部没有任何限制。     

Improving the accuracy of laser particle sizer with Mie scattering theory

Using the classical Mie scattering theory and Fraunhofer diffraction theory,adetailed analysis of the differences of the light energy distribution falling on the multi-elementconcentric photo-detector of a diffraction based laser particle sizer is given.Numerical calcula-tions and computer simulation are carried out. Experimental studies are also made with latexspheres as Standard Reference Material.Our research shows that when the classical Mie scat-tering theory is used,the accuracy of the particle sizer can be essentially improved not only inthe small size range,but also for large paticles.At the same time the time needed for data re-duction in both cases is almost the same.