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1.
基于Mie散射理论,对大功率发光二极管封装中荧光粉的光激发、吸收、散射等作用进行数值模拟,仿真计算在不同白光色温时前后向散射光的强度比例,研究了荧光粉的颗粒大小对白光发光二极管最大光通量的影响.对保型荧光粉涂覆结构中不同直径荧光粉颗粒和不同色温时的光效进行了分析,还分析了同样色温下不同荧光粉颗粒直径、涂层的厚度对白光发光二极管出光的空间色温分布均匀性的影响.研究中所采用的器件激发光谱和发射光谱都为材料的实测光谱,而并非假设的单一光谱.研究表明:在采用保型荧光粉涂覆结构的前提下,当荧光粉颖粒直径为0.5μm时能使发光二极管光通量达到最大;荧光粉颗粒越小,发光二极管空间色温分布均匀性越好;对给定的封装结构,荧光粉涂层厚度为0.8 mm时空间色温分布均匀性最佳. 相似文献
2.
In detecting particles on a substrate, two-white-spots phenomenon was observed. This gives an illusion that light scattering is caused by two spheres, in fact it is just caused by one sphere. This phenomenon makes particle detection by light scattering much more complicated. Analysis on this phenomenon shows that Mie effect is the reason of formation of two white spots. This experiment demonstrates the images of Mie effect, and provides a strong evidence of theory of Mie effect. 相似文献
3.
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. 相似文献
4.
根据等效颗粒散射模型,运用经典的Mie理论,对生物组织的散射相函数、各向异性因子及散射系数进行了数值计算.计算结果表明:可见光照射生物组织时,各向异性因子、散射系数随等效颗粒直径增大而增大;等效颗粒直径较小时,各向异性因子、散射系数随入射光波长增大而单调减小;随着等效颗粒直径增大,各向异性因子、散射系数随入射光波长变化不再具有单调性.上述计算结果可合理解释公布的实验结果.
关键词:
生物组织
散射
Mie理论
等效颗粒 相似文献
5.
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. 相似文献
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田贵才 《原子与分子物理学报》2002,19(3):334-336
根据Mie散射理论,研究了粒子线度对Mie散射光强的影响,不同性质的粒子,其影响效果不同,在固定入射波长条件下,散射光强随粒子线度呈周期变化,同时发现H2O微粒子散射光强峰峰间距与粒子的线度和波长的关系可简单的表示为Δa=-0.133 3+0.222λ. 相似文献
8.
瑞利散射和米氏散射现象的实验演示 总被引:1,自引:0,他引:1
硫代硫酸钠与稀盐酸反应时,会在溶液中缓慢产生不溶于水的固态硫分子,其直径小于可见光的波长;随着反应的进行,多个硫分子聚结形成较大颗粒,其直径接近并逐渐大于可见光波长.在上述反应过程中,利用白光照射溶液,可以分别观察到瑞利散射和米氏散射现象,并在文中研究和分析瑞利散射时光的偏振特性. 相似文献
9.
We previously demonstrated that Mie scattering of stationary partially coherent light by dielectric spheres generates coherence vortices. In this Letter, we demonstrate that a lattice of coherence vortices can be generated by Mie scattering of partially coherent electromagnetic waves by a system of three coplanar dielectric spheres. Spontaneous coherence-vortex creation and destruction is observed in our computer modeling of this system. 相似文献
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Angle-resolved light scattering spectroscopy of biological cells is investigated in the visible wavelength range. A unified Mie and fractal model is shown to provide an accurate global agreement with light scattering spectra from 1.1 degrees to 165 degrees scattering angles. It is found that light scattering in forward directions (<8 degrees ) is dominated by Mie scattering by the bare cell and nucleus, whereas light scattering at large angles (>20 degrees ) is determined by fractal scattering by subcellular structures. The findings are consistent with the results of experimental investigation of the contributions of different cellular components to light scattering by cells. 相似文献
12.
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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Optical Review - Scattering of visible light by micrometer-scale natural wood fibers is usually treated by assuming fibers to be perfect long cylindrical scatterers. In industrial processes,... 相似文献
15.
R. Ruppin 《Optics Communications》1979,30(3):380-382
The classícal Mie theory for the scattering and absorption of electromagnetic radiation by a sphere is extended to the case of a dieelectric sphere which exhibits spatial dispersion. This is achieved by imposing the usual Maxwell boundary conditions as well as Pekar's additional boundary conditions at the surface of the sphere. 相似文献
16.
The interference nature of resonant Mie scattering, which is described within the Fano model, has been demonstrated. The interference is caused by interaction of an incident electromagnetic wave with reemitted waves that correspond to eigenmodes of a scattering particle. Mie scattering due to the interference can be represented in the form of cascades of resonance lines of different shapes, each of which is described by the classical Fano formula. The effect is observed in resonant light scattering by an arbitrary body of revolution and discussed in detail using the example of scattering by an infinite homogeneous dielectric cylinder. 相似文献
17.
The scattering of a partially coherent electromagnetic beam by a dielectric sphere is described. Two methods are presented: a coherent mode representation and a spherical harmonics expansion. In the case of a distant blackbody source, the coherent modes are plane waves and the scattered intensity is obtained by a convolution of the classical Mie results over the source surface. 相似文献
18.
Gustav Mie and the scattering and absorption of light by particles: Historic developments and basics
Helmuth Horvath 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(11):787-799
Gustav Mie was a professor of physics with a strong background in mathematics. After moving to the University of Greifswald in North-Eastern Germany he became acquainted with colloids, and one of his PhD students investigated the scattering and attenuation of light by gold colloids experimentally. Mie used his previously acquired knowledge of the Maxwell equations and solutions of very similar problems in the literature to concisely treat the theoretical problem of scattering and absorption of light by a small absorbing sphere. He also presented many numerical examples which completely explained all the effects that had been observed until then. Since all calculations were done by hand, Mie had to limit his theoretical results to three terms in infinite expansions, thus he only could treat particles smaller than 200 nm at visible wavelengths. Mie's paper had remained hardly noticed for the next 50 years, most likely because of the lack of computers. It experienced a revival later and up to now it has been referenced more than 4000 times, owing to the widespread use of Mie's approach in sciences such as astronomy, meteorology, fluid dynamics and many others.Gustav Mie did not consider his work on scattering of light by small particles as very important, since he just tried to explain the effects which his students had observed. He concentrated on hot topics in theoretic physics, e.g., the theory of matter. He wrote several textbooks, e.g., on relativity, gravitation theory, and electromagnetism, and all of them had run into several editions. 相似文献
19.
A. Latz M. Letz 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(3):323-343
The theory of light scattering for a system of linear molecules with anisotropic polarizabilities is considered. As a starting
point for our theory, we express the result of a scattering experiment in VV and VH symmetry as dynamic correlation functions
of tensorial densities ρ
lm(q) with l = 0 and l = 2. l, m denote indices of spherical harmonics. To account for all observed hydrodynamic singularities, a generalization of the theory
of Schilling and Scheidsteger [1] for these correlation functions is presented, which is capable to describe the light scattering
experiments from the liquid regime to the glassy state. As a microscopic theory it fulfills all sum rules contrary to previous
phenomenological theories. We emphasize the importance of the helicity index m for the microscopic theory by showing, that only the existence of m = 1 components lead to the well known Rytov dip in liquids and to the appearance of transversal sound waves in VH symmetry
in the deeply supercooled liquid and the glass. Exact expressions for the phenomenological frequency dependent rotation translation
coupling coefficients of previous theories are derived.
Received 3 July 2000 and Received in final form 7 November 2000 相似文献