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金属/介质多层薄膜结构光极化调控特性 总被引:1,自引:0,他引:1
基于等效介质理论, 描述了金属/介质多层薄膜周期结构的各向异性, 提出了分析这种结构光传输特性的理论方法, 研究了不同取向薄膜结构的光学性能。通过理论分析和基于有限元方法的全波电磁仿真后发现, 在不考虑损耗的情况下, 通过调整金属/介质多层薄膜周期结构中的材料参数、薄膜结构取向, 能使得垂直入射的TE波和TM波的透射效果有很大差异, 说明该结构具有光极化调控特性。根据这一光极化调控特性, 设计了由碳化硅和二氧化硅薄膜的组合结构, 成功构造了10.6 μm红外波段的光极化分离器。金属/介质多层薄膜结构光极化调控特性对于光学器件中极化分离和极化变换的实现提供了一条新的途径。 相似文献
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旋转不变的三维物体识别 总被引:4,自引:0,他引:4
提出一种具有旋转不变性的三维物体识别的新方法。该方法通过结构照明的方法,使物体的高度分布以变形条纹的形式编码于二维强度像中。由于条纹图像包含有物体的高度分布信息,因而对条纹图的相关识别具有本征三维识别的特点。旋转不变性是通过使用多通道滤波器实现的,此滤波器可以由不同方向三维物体对应的变形条纹图像经计算机处理得到。相关识别方法可以用光学匹配空间滤波器实现。计算机模拟实验证明了这种方法的有效性,它不仅可以实现旋转不变的三维物体识别,还可以给出物体旋转角度的估计值。 相似文献
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提出一种在光学扫描全息系统中采用环形光瞳滤波器来实现选择性边缘提取的方法,基于双光瞳外差扫描技术使用单个二维光学扫描来获取三维物体的全息信息。首先,采用小孔滤波器和环形光瞳滤波器作为两个光瞳来形成复合光场对物体进行扫描,以提取物体的边缘信息;其次,通过移动并破坏环形光瞳滤波器的对称性,并选择两个完全相同的环形光瞳滤波器来实现对物体各向异性的选择性提取。计算机仿真实验的结果表明,通过在光学扫描全息系统中使用环形光瞳滤波器,可以很好地实现各向同性与各向异性的选择性边缘提取。 相似文献
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对称光学结构的双光信道旋连接装置 总被引:8,自引:0,他引:8
本文介绍了双光信道旋转连接器的实现方法,提出了实现双信道互连的对称光学系统结构和基于这种光学结构的双光信道旋转连接器。详细分析了这种光学结构的设计原理,并对光路进行了计算和分析,指出了它在中间环节需要旋转耦合连接的仪器设备中的应用前景。 相似文献
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为了实现3维物体旋转不变实时识别,应用微透镜阵列的多视角成像特点,利用透射像阵列的高关联性,实现3维物体信息与2维透射像阵列信息之间的转换,从而可以利用光学2维图像识别技术实现3维物体的识别。对转换和识别过程进行了理论分析,用匹配滤波的方法进行了实验验证,实现了3维物体旋转不变实时识别。得到了良好的识别效果,并实现了旋转方向的准确定位和旋转角度大小的比较判别。结果表明,应用微透镜阵列可以实现旋转3维物体旋转不变实时识别。 相似文献
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Faraday rotators using permanently magnetized ferrite materials are used to make quasi-optical isolators and circulators at millimeter wave and sub-millimeter wave frequencies that have far higher performance than their waveguide equivalents. This paper demonstrates state-of-the-art performance for four-port quasi-optical circulators with 60-dB isolation, 0.2-dB insertion loss, and better than 80-dB return loss for devices centered at 94 GHz. A method is presented for the accurate characterization of the complex permeability and permittivity of permanently magnetized ferrites via a series of frequency and polarization dependent transmission and reflection measurements. The dielectric and magnetic parameters for the sample are determined by fitting theoretical curves to the measured data. These fitted parameters are then used in a model for a complete quasi-optical Faraday rotator, including matching layers, allowing the accurate design and fabrication of these devices for any specific operational frequency band in the millimeter wave and sub-millimeter wave regime. Examples are given showing typical results and demonstrating how temperature cycling can significantly improve the temperature stability of these devices, while allowing fine tuning of the center frequency. We also indicate the performance possible at higher frequencies to above 1 THz and outline performance of truly planar isolators where lossy polarizer material is built into the Faraday rotator matching structure 相似文献
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一种基于虚拟三角形的图像自动配准方法 总被引:1,自引:0,他引:1
图像配准是图像处理和分析的关键技术之一.本文提出了一种基于虚拟三角形的图像自动配准方法来处理具有全局刚体变换的图像配准问题.该方法主要分三步:首先采用改进的Harris算子从参考图像和待配准图像中分别提取角点特征,将每三个角点顺次连接起来构成一个虚拟三角形;然后运用刚体变换模型下匹配虚拟三角形对全等的准则找到全等性最好的一对虚拟三角形,利用它们的对应顶点求解刚体变换模型参数的初始值;最后根据刚体变换模型参数的初始值和一个预设的门限得到所有的匹配角点特征,通过它们求得最终的刚体变换模型参数.实际图像实验结果表明:本文提出的图像自动配准方法是正确和有效的,并具有较高的配准精度. 相似文献
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Lui W.W. Xu C.-L. Hirono T. Yokoyama K. Wei-Ping Huang 《Lightwave Technology, Journal of》1998,16(5):910-914
Device characteristics of optical polarization rotators are founded upon the vector properties of the Maxwell equations. Recently, a bending waveguide based polarization rotator has been proposed and demonstrated. To provide a rigorous basis for the analysis and design of this polarization rotator, the full-vectorial wave equations for both E&oarr; and H&oarr;-field in bending waveguides are derived. It is found from these wave equations that under a broad range of circumstances, a bending waveguide can be analyzed using the equivalent straight waveguide approximation. Details of the model for optical polarization rotators, which is based on the coupled-mode theory, will be described in a companion paper 相似文献
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阻抗三角形、电压三角形、功率三角形是电工基础理论中的三个重要知识点。以RLC串联电路为例,在分析三个三角形各边的矢量关系和数量关系的基础上,得出它们之间图形的相似性及关系式,最后通过例析说明相关应用。 相似文献
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三星时差定位的最佳星座布局 总被引:1,自引:0,他引:1
从三星时差定位的原理出发,构建定位方程组,推导理论定位精度公式,详细分析各种星座布局对定位的影响。根据定位误差的几何稀释,得出面积相同的三角形,等腰三角形定位效果最优;在两边长固定的等腰三角形中,等腰直角三角形是最佳星座布局的结论。 相似文献
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《Electron Devices, IEEE Transactions on》1986,33(5):590-594
In the context of applications requiring high gain and minimal noise at microwave and millimeter-wave frequencies, the optimization of a number of interrelated structural and electrical parameters is necessary. This paper discusses the relative importance of these parameters in the design of TEGFET devices and their influence on the considerations necessary far wideband LNA design. The discussion is illustrated with recent microwave data obtained with millimeter-wave TEGFET devices. 相似文献
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Bonache J. Gil M. Gil I. Garcia-Garcia J. Martin F. 《Microwave and Wireless Components Letters, IEEE》2006,16(10):543-545
In this letter, a method to obtain the electrical characteristics of complementary split ring resonators (CSRRs) coupled to planar transmission lines is presented. CSRRs have been recently proposed by some of the authors as new constitutive elements for the synthesis of metamaterials with negative effective permittivity, and they have been applied to the fabrication of metamaterial-based circuits in planar technology. The method provides the electrical characteristics of CSRRs (including the intrinsic resonant frequency and the unloaded Q-factor), as well as the coupling capacitance between line and CSRRs, and the parameters of the host line. Parameter extraction from the proposed method is applied to two different structures corresponding to the basic cells of left handed (LH) and negative permittivity lines. The method is of actual interest for the design of microwave circuits and metamaterials based on these complementary resonant particles. 相似文献