共查询到18条相似文献,搜索用时 125 毫秒
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地空链路无线光通信链路上,云层是影响激光传输散射特性的主要因素之一,主要是由水滴、冰水或者具有其他混合的核壳结构冰晶粒子等组成。建立了考虑晶核以及中间混合层结构的2、8和39个球形核壳结构团聚冰晶粒子模型,分析了晶核尺寸对于理想团聚形核壳结构冰晶粒子消光、吸收和散射系数的影响;且通过对均匀混合层折射率的计算,对比了纯冰晶、理想核壳和考虑中间混合层的核壳三种多球团聚形冰晶粒子散射强度随散射角度的变化情况。数值结果表明:理想核壳结构和中间混合层的核壳结构对冰晶粒子的散射特性影响较大;相同条件下,三种不同团聚形核壳结构冰晶粒子消光、吸收和散射系数存在显著差异。该研究结果对冰晶粒子的散射特性研究结果更为精确,为开展无线光信号在随机分布冰云中的传输分析奠定理论基础。 相似文献
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为了研究太赫兹波在沙尘大气中的衰减特性,根据Mie散射理论计算了单次散射情况下沙尘粒子不同尺寸参数下的散射效率因子和不同散射角下的散射相函数值。并得到了具有一定尺寸分布的沙尘粒子的单位距离衰减和能见度的关系曲线。还利用Monte Carlo方法对太赫兹波在沙尘中的多次散射特性进行了模拟计算,分析了不同能见度和不同沙尘类型对太赫兹波传输过程中能量损耗的影响。结果表明:单次散射条件下沙尘粒子的散射主要受尺寸参数影响;沙尘能见度较低时必须要考虑多次散射的影响。研究结果对太赫兹技术在大气环境监测和烟尘和风沙的探测等方面的应用具有参考价值。 相似文献
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激光在沙尘暴中的衰减特性研究 总被引:16,自引:4,他引:16
复杂环境中激光传输和散射特性是目标与环境光散射特性研究的基础。主要讨论了激光信号在沙尘中的传输衰减特性。根据Mie理论研究了具有一定粒径分布沙尘粒子对于激光信号的单次散射衰减特性,给出了不同分层沙尘粒子的平均散射截面、粒子平均反照率、平均不对称因子和平均相函数。利用四通量法和蒙特卡罗法研究了激光在分层沙尘大气中的多重散射和斜程传输衰减特性,并给出它们与能见度及高度的变化关系。最后,在考虑多重散射时,分别用以上两种方法数值计算了1.06μm激光在斜程沙尘大气中的衰减率,并与单次散射结果进行了比较。结果表明,能见度较低时,不考虑多重散射效应会带来较大的误差;在斜程沙尘大气激光传输时,随分层数增加,数值结果就越精确。 相似文献
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针对云层介质对激光传输有较强的吸收和散射作用,严重影响了激光对潜通信系统的应用范围这一问题,采用Monte Carlo法来模拟激光在云层中传输的过程。得出云层光脉冲的时间扩展特性和部分参数的模拟结果,为通信系统进行后期的分析和设计提供了一定的理论和实用价值。 相似文献
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为了给激光测距、激光对大气的探测等实际工程应用提供理论依据,采用逐线积分方法计算大气分子吸收,结合离散纵标法,并耦合卷云的单次散射特性,对由实心六棱柱状冰晶粒子组成的卷云在波长为1.064μm时的散射特性和辐射特性进行了理论分析,得到了该波长上激光在卷云中传输时的反射率随入射光源的位置、观测器的位置以及卷云参量(云光学厚度、粒子尺度等)的关系。结果表明,卷云在1.064μm附近对激光的主要影响是散射,吸收在消光中占了很小的部分;其次,卷云的散射明显改变了光辐射的空间分布,散射的方向变化主要由卷云的散射相函数以及光线入射角度和观测角度决定。这一结果对实际工程应用(比如激光测距、激光对大气的探测等)是有帮助的。 相似文献
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Temperature‐Induced Stacking to Create Cu2O Concave Sphere for Light Trapping Capable of Ultrasensitive Single‐Particle Surface‐Enhanced Raman Scattering 下载免费PDF全文
Xiaoxia Li Yang Shang Jie Lin Anran Li Xiaotian Wang Bin Li Lin Guo 《Advanced functional materials》2018,28(33)
The fabrication of bowl or concave particles with “asymmetric centers” has drawn considerable attentions, in which multiple scattering occurs inside the particles and the ability of light scattering is distinctly enhanced. However, the limited variety of templates, the uncontrollable dimensions such as the size of concavity and the complex growth process have posed serious limitations to the reproducible construction of concave particles with desired geometries and their light‐trapping properties. Herein, a “temperature‐induced stacking” strategy is proposed to create controllable concavity Cu2O spheres for the first time. Different sizes of F68 micelles can be formed through aggregation under different reaction temperatures, which can serve as soft template to tailor concave geometries of Cu2O spheres. The as‐prepared Cu2O concave sphere (CS) can serve as single‐particle (SP) surface‐enhanced Raman scattering (SERS) substrate for highly repeatable and consistent Raman spectra. The unique cavity of Cu2O CS entraps light effectively, which also enhances the scattering length owing to multiple light scattering. Combined with slightly increased surface area and charge‐transfer process, Cu2O CS exhibits remarkable single‐particle SERS performance, with an ultralow low detection limit (2 × 10?8 mol L?1) and metal comparable enhancement factor (2.8 × 105). 相似文献
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1.315 μm波长冰晶粒子辐射特性的模拟研究 总被引:2,自引:2,他引:0
利用逐线积分法(LBL)计算得到了大气分子红外吸收信息,结合不同形状冰晶粒子的单次散射特性,通过离散纵标法(DISORT),模拟计算了由实心六棱柱状冰晶粒子组成的卷云在波长为1.315μm时的散射特性和辐射特性,定性分析了激光在卷云中传输时的衰减和散射规律与入射光的位置、卷云光学厚度、冰晶粒子有效尺度等参数的关系。与晴天大气相比较,卷云的散射明显改变了光辐射的空间分布,被其他传感器探测到的可能性增大,其结果对于激光测距、激光探测等有关工程设计方面有非常重要的参考价值。 相似文献
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流式细胞仪利用微球光散射特性对测试细胞进行分析,细胞病变将改变细胞的光学特性,而粒径和折射率是改变细胞散射光光强分布的两大因素,针对激光散射流式细胞仪前向散射光采用单个光敏元件进行一维探测,只针对细胞粒径进行分析的缺点,提出一种前向散射光线阵式探测的方法。首先,根据微粒的Mie氏散射特性建立了模型。然后根据散射模型仿真结果,对不同散射光曲线的特征权值进行了分析。最后基于K-modes聚类算法,对试验数据进行聚类分析。实验结果证明,该方法不仅能替代传统方法对不同粒径大小的颗粒进行分群,同时可以对相同粒径,不同折射率的微球进行分群,误差小于4.51%。 相似文献
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Volger P. Zhaoyan Liu Sugimoto N. 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(3):550-559
Spaceborne lidar observations have a great potential to improve our knowledge of the atmosphere. However, contrary to ground-based or airborne lidar measurements in observations from space multiple scattering (MS) has to be accounted for under all atmospheric conditions. A simple way to achieve this is to introduce the approximative MS factor F in the single scattering lidar equation. We determined F for measurements of aerosols, ice and water clouds as they were planned with the Japanese space lidar ELISE. We found that F is almost constant in cirrus clouds and in water clouds which are penetrable by lidar. In aerosol layers F depends on penetration depth, extinction coefficient and aerosol type. In comparison to LITE the MS factor is smaller (for aerosols and water clouds) or almost equal (cirrus) 相似文献
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Neil P. Dasgupta Shicheng Xu Hee Joon Jung Andrei Iancu Rainer Fasching Robert Sinclair Fritz B. Prinz 《Advanced functional materials》2012,22(17):3650-3657
Conductive nanowires (NWs) provide several advantages as a template and electrode material for solar cells due to their favorable light scattering properties. While the majority of NW solar cell architectures studied are based on semiconductor materials, metallic NWs could provide equivalent anti‐reflection properties, while acting as a low‐resistance back contact for charge transport, and facilitate light scattering in thin layers of semiconductors coated on the surface. However, fabrication of single‐crystalline highly anti‐reflective NWs on low‐cost, flexible substrates remains a challenge to drive down the cost of NW solar cells. In this study, metallic NixSi NW arrays are fabricated by a simple, bottom‐up, and low‐cost method based on the thermal decomposition of silane on the surface of flexible Ni foil substrates without the need for lithography, etching or catalysts. The optical properties of these NW arrays demonstrate broadband suppression of reflection to levels below 1% from 350 nm to 1100 nm, which is among the highest values reported for NWs. A simple route to control the diameter and density of the NWs is introduced based on variations in a carrier gas flow rate. A high‐resolution TEM, XRD and TEM‐EDS study of the NWs reveals that they are single crystalline, with the phase and composition varying between Ni2Si and NiSi. The nanowire resistivity is measured to be 10?4 Ω‐cm, suggesting their use as an efficient back electrode material for nanostructured solar cells with favorable light scattering properties. 相似文献