共查询到18条相似文献,搜索用时 382 毫秒
1.
基于Mie散射理论,给出了金属粒子的散射、吸收和消光截面以及散射场强度的计算公式,并计算了三种金属粒子在不同折射率基质中的光学截面和散射强度。结果表明,金属粒子的散射行为随基质折射率的变化规律相同,折射率越大散射特性越明显。 相似文献
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基质折射率对金属粒子散射特性的影响 总被引:2,自引:0,他引:2
基于Mie散射理论,给出了金属粒子的散射、吸收和消光截面以及散射场强度的计算公式,并计算了三种金属(金、银、铜)粒子在不同折射率基质中的光学截面和散射强度.结果表明,在近红外区,这三种金属粒子的散射行为随基质折射率的变化规律相同,折射率越大散射特性越明显. 相似文献
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根据Mie散射理论,给出了金属粒子的散射、消光和吸收截面以及散射场强度的计算公式,并数值计算了在λ=r=1μm时,金属Au粒子在五种不同的基质中的散射截面和散射光强,结果表明基质折射率越大散射特性越强。 相似文献
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介绍了一种综合利用能见度仪、微脉冲激光雷达和光学粒子计数器测量大气气溶胶折射率的新方法。首先使用能见度仪和激光雷达测量出大气气溶胶的消光系数和消光后向散射比,然后使用粒子计数器测量出粒子谱分布,结合气溶胶粒子折射率,根据球形粒子的米(Mie)散射理论,可以得到气溶胶消光系数和消光后向散射比。通过分析消光系数、消光后向散射比、粒子谱分布和折射率之间的关系,结合已知的消光系数和消光后向散射比,反演出大气气溶胶粒子的折射率。 相似文献
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以黑碳和水两种成分组成的内混合单分散气溶胶粒子为例,根据其各消光效率因子、吸收效率因子和散射相函数,分析了用等效折射率来描述含有不同成分的内混合气溶胶系统的适用性。结果表明:在瑞利散射区和几何光学区内,内核(碳粒)体积比为0.01,0.1,0.5,0.9时,消光效率在大多数尺度参数下等效性都很好,但在米散射区内相对较差;当体积比大于0.3时,其吸收效率、消光效率等效性较好;除瑞利散射区外,散射相函数在各体积比下的等效性都很差。当考虑内混合气溶胶粒子系统的散射和吸收特性时,一般不难找到等效折射率,但在光散射技术中,应用相函数反演等效折射率的可靠性还有待商榷。 相似文献
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一种内混合气溶胶粒子模型光散射的等效性 总被引:1,自引:0,他引:1
以包含灰尘、黑碳和水三种成分的单分散内混合初次气溶胶为例,利用消光、吸收、散射效率因子和不对称因子,探讨了以等效折射率描述具有不同成分的内混合气溶胶粒子系统的适用性。结果表明,在尺度参数为0.1~25时不同半径比下,消光、吸收和散射效率因子的等效性较好,相对误差分别在3%、3%和4%以内;不对称因子的等效性相对稍差,相对误差在13%以内。当半径比a/b小于1/5,即内混合体中所含灰尘和黑碳较少时,等效折射率实部和虚部值基本可以确定,而不必考虑尺度参数的影响。用除散射相函数之外的其他光学量来等效时,较为容易找到等效的气溶胶粒子。 相似文献
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基于Fournier Forand体积散射函数,建立了一种水中激光脉冲后向散射仿真模型.运用该模型可用Monte Carlo方法模拟光子在水中的传播过程,并得到光波后向散射的冲击响应.将初始激光脉冲与冲击响应进行卷积并求其傅里叶谱,即可得到激光脉冲后向散射信号的时域和频域特征.利用该模型分析了入射为高斯型激光脉冲时,水中散射体的尺度分布、散射体与纯水的相对折射率以及水体衰减系数对激光脉冲后向散射特性的影响.结果表明:随着小尺度散射体相对数量的增多、散射体与纯水相对折射率的增加、水体衰减系数的增大,激光脉冲后向散射信号能量增强,宽度增加,低频分量显著增大. 相似文献
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提出一些折射率比锗还高的中红外材料(第一类)以及中红外反常色散材料(第二类)可以用于无序介质的光子定域化研究.基于Mie散射理论的研究发现,即使在低浓度散射体近似下,也容易在第一类无序介质中实现光子定域化;同时可在第二类无序介质中实现一定意义下(含一定的吸收)的光子定域化,且频率位于各自的剩余射线带内.研究还发现,基质的折射率效应在这两类无序介质中的作用完全不同.还提出了散射体平均等效散射截面饱和的假设,讨论了因此而导致的问题
关键词:
光子定域化
无序介质
中红外
反常色散 相似文献
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A polydisperse sphere model with the complex refractive index is employed to describe the propagation of light in biological tissue. The scattering coefficient, absorption coefficient and scattering phase function are calculated. At the same time, the inverse problem on retrieving the particles size distribution, imaginary part of the refractive index and number density of scatterers is investigated. The result shows that the retrieval scheme together with the Chahine algorithm is effective in dealing with such an inverse problem. It is also clarified that a group of parameters including the scattering coefficient, absorption coefficient and phase function are associated with another group including the refractive index, particle size distribution and number density of scatterers, which is a problem described in two different ways and the anisotropy factor is not an independent variable, but is determined by the phase function. 相似文献
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Jiayu Yi Liling YangKe Yao Chao YangYingsong Song Shouhuan Zhou 《Optics Communications》2012,285(24):5276-5282
We report a systematic study based on the random laser behaviors of comparable systems in which the refractive indices are varied. Threshold and spectra features have been obtained. The experimental results indicate that the threshold (Eth) of the random laser depends on the refractive index of the scatterers and surrounding solvents. The larger the refractive index of scatters or smaller the refractive index of solvents is, the smaller the Eth will be. The theoretical explanation based on Mie scattering theory for this phenomenon is made. We introduce refractive index contrast-ratio w. The thresholds variation is attributed to the alteration of w which influences the scattering strength and the transport mean free path. As for the spectra, typical emission evolution spectra have been observed. The peak positions vary with the change of scatterers and solvents, the reason of the variation is the absorption of the samples. 相似文献
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R. Spurr J. Wang J. Zeng M.I. Mishchenko 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(6):425-439
We present a new linearization of T-Matrix and Mie computations for light scattering by non-spherical and spherical particles, respectively. In addition to the usual extinction and scattering cross-sections and the scattering matrix outputs, the linearized models will generate analytical derivatives of these optical properties with respect to the real and imaginary parts of the particle refractive index, and (for non-spherical scatterers) with respect to the “shape” parameter (the spheroid aspect ratio, cylinder diameter/height ratio, Chebyshev particle deformation factor). These derivatives are based on the essential linearity of Maxwell's theory. Analytical derivatives are also available for polydisperse particle size distribution parameters such as the mode radius. The T-matrix formulation is based on the NASA Goddard Institute for Space Studies FORTRAN 77 code developed in the 1990s. The linearized scattering codes presented here are in FORTRAN 90 and will be made publicly available. 相似文献
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Small angle X-ray scattering of Fe1–x
P
x
, 0.05<x<0.25 suggests the existence of some volume percent of small domains with an electron density different from that of the matrix. The experimental diagrams can be described assuming three kinds of scatterers with different diameters not only in amorphous but also in microcrystalline material or in material including both phases. The diameters of the scatterers of one class are independent of composition and the microstructural state. The effect of annealing on a suitably defined inhomogeneity parameter indicates a different nature of the three classes of scattering centers. More information in this respect results from additional measurements of other physical properties. 相似文献
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To solve the problem of light scattering by multilayer scatterers of an arbitrary axisymmetric shape, a separation of variables
method that involves special scalar potentials and their expansions in spherical functions is developed. The approach is shown
to yield highly exact results even for particles that have 100 layers or more. A graphic library that illustrates the optical
properties of layered and homogeneous (with an effective refractive index) spheroids, spheres, and Chebyshev particles of
various shapes and sizes (about 650 figures) is created and is put on the Internet. It is noted that the linear polarization
of radiation transmitted forward through a polydisperse medium containing partially oriented nonspherical porous particles
strongly depends on the structure of scatterers. It is shown that the difference between the degrees of polarization of layered
and corresponding homogeneous scatterers can exceed 200–300%. 相似文献
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To improve light extraction from organic electroluminescent (EL) devices, we introduced a diffusive substrate with 25 μm thickness
consisting of high refractive index resin and scattering particles. It is expected that the diffusive substrate with high
refractive index matrix converts the waveguided emission into external emission from both glass substrate and indium-tin-oxide/organic
layer. We used the ray tracing method to optimize the scattering effect and to verify the coupling out effect of the diffusive
high refractive index substrate. With the use of the ray tracing calculation, an increase in the external emission up to a
factor of 2.7 was expected compared to use of a common glass substrate. Experimentally, the coupling out effect of the diffusive
high refractive index substrate strongly depended on the thickness of electron transporting layer (ETL) due to the well-known
interference effect. The current efficiency increased by a factor of 1.3 for an organic EL device with a 60-nm-thick ETL and
by a factor of 6.8 for one with a 120-nm-thick ETL. 相似文献