共查询到20条相似文献,搜索用时 453 毫秒
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标量衍射理论形式简洁,有很高实用性,但是在衍射微光学元件分析中显得模型粗糙,准确度下降。严格矢量衍射理论由于计算复杂,非常耗费时间和资源,因此也不是一种很有效的设计工具。 我们在本文中运用了一种简单的近似矢量衍射模型分析了几种典型衍射微光学元件衍射性能,此衍射模型采用了标量衍射理论和近似近场模型的结合。 TE和TM两种偏振模式均运用此近似矢量衍射模型进行了分析,我们发现此衍射模型可以得到比标量衍射理论更准确的结果,而与严格电磁场理论相比,它占用很少的计算时间。 相似文献
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部分偏振部分相干光光栅衍射场的偏振特性和角相关研究 总被引:1,自引:0,他引:1
为了研究部分偏振部分相干光光栅衍射场的衍射特性.利用部分偏振部分相干光的光束相干-偏振(BCP)矩阵,推导出了部分偏振部分相干光通过任意偏振光栅后,衍射场的偏振度及场中衍射级次角相关的一般解析表达式.以部分偏振的高斯-谢尔模型光束(PGSM)为例,数值分析了偏振光栅TE和TM波的复振幅透过率、入射光束的光学参量对衍射场偏振度和场中各衍射级次的角相关的影响.计算结果表明,部分相干光透过偏振光栅后的其衍射光场是一非均匀、周期变化的部分偏振相干光场;场中对称级次的角相干值对应相等,且随衍射级次序数的增大而缓慢递减至零. 相似文献
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A superresolving three-zone plate is applied to a Fresnel diffractive lens. It is shown that for radial incident polarization this combination produces a focal spot approaching superresolution allowed subdiffractive limit of 0.36lambda/NA for focusing. For media responsive to longitudinal field component only, our phase engineering scheme results in a focal spot size of 0.368lambda/NA. When used with a solid immersion lens, the scheme can generate the smallest focal spot available for passive optics. 相似文献
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针对理论上推导轴锥镜的衍射光场分布解析式较为困难,且用菲涅耳衍射理论分析时存在近轴近似及不能适用于近场衍射光场分析的问题,采用了严格遵从标量衍射亥姆霍兹方程的角谱衍射波前重建方法,对轴锥镜在单色和准单色高斯光波照射下的横向和轴向衍射光强分布特性,以及在单色均匀平面光波照射下的轴向衍射光强分布进行了数值计算和分析。结果表明,轴锥镜后单色光衍射光强分布在几何光束重叠的菱形区域内为近似无衍射贝塞尔光强分布,轴上光强沿光轴方向呈振荡变化,轴上光强分布规律与入射光波的垂轴横向光强分布有关;入射光的准单色性使得贝塞尔衍射条纹对比度略下降、轴上光强沿光轴方向振荡程度减小,但分布规律与单色光一致。 相似文献
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Three-dimensional focus shaping with cylindrical vector beams 总被引:1,自引:0,他引:1
A three-dimensional focus shaping technique using the combination of cylindrical polarization with binary diffractive optical element is proposed. The energy density pattern at the vicinity of the focus can be tailored in three dimensions by appropriately adjusting the parameters of the cylindrical vector beam illumination, numerical aperture of the objective lens and the design of the binary diffractive optical element. Focus with extended depth of focus that has both transversal and longitudinal flattop profile is obtained. Optical bubble that has a total dark volume surrounded by high field distributions is also shown. Potential applications of this focus shaping technique are discussed. 相似文献
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大数值孔径衍射透镜的优化设计方法 总被引:4,自引:0,他引:4
本文针对大数值孔径衍射透镜工艺制作难的问题,以菲涅耳衍射透镜为例,研究了相位匹配原理并提出了一种优化设计二元大数值孔径衍射透镜的方法。在菲涅耳衍射透镜原理的基础上,确定了优化设计多相位台阶衍射透镜的结构参数,并给出了一个设计实例,最后对结果元件的衍射效率进行了分析与讨论。 相似文献
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A scheme for a new two-dimensional polarization splitter is proposed based on the transformation optics. When a beam of arbitrary polarization illuminates upon the proposed polarization splitter, the TE (or TM) component is deflected whereas the TM (or TE) component propagates with no deflection. Moreover, the emerging propagation direction of the deflected component can be adjusted by rotating the polarization splitter. The simulation results demonstrated the feasibility and the flexibility of the polarization splitter. Design details and full-wave simulation results are provided. 相似文献
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In the free-space laser communication, there is sometimes a strong need for reduction of the diffraction spot size in the far field. In this paper, instead of the usage of the larger size aperture lens and super-resolution technology in the free-space laser communication system, we introduce photon sieve to compress the center spot in the diffractive far field, which can decrease the weight of the emitting lens. We have designed the photon sieve and calculated its far-field diffractive intensity. We have also calculated the far field Airy diffractive field intensity. Simulation proves that the photon sieve diffractive spot is smaller than the Airy spot with the same transmit aperture. We have set up an experimental system to simulate the far-field diffraction free-space laser communication. Experimental results are in good agreement with the theoretical results. Detailed experiments are presented. 相似文献
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DiffractivelenswithbinaryphaselevelstogeneratetwofocusesLONGPin;LIUJie;SHIWenmin;HSUDahsiung(DepartmenfofAppliedScienceandTec... 相似文献
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EXPERIMENTAL STUDY OF DIFFRACTIVE PROPERTIES OF WAVELENGTH-SIZED SINGLE GROOVE IN Si-Si3N4 SUBSTRATE 下载免费PDF全文
Experimental results are presented for the diffractive properties of wavelength-sized single groove in Si-Si3N4 substrate. The experimental results show that the diffraction of wavelength-sized single grooves in a non-perfectly conducting material is more complex than that of perfectly conducting material. The diffraction intensities change with the change of polarization angle of the incident light. The diffraction intensities for TM polarization light are larger as the groove width is larger. The diffraction intensities of TM polarization light decrease gradually and that of TE polarization light increase gradually when the groove width is close to the wavelength of the incident light. The variations of diffraction intensities are quite different not only for various grooves with different widths but also for different diffraction angles for the same groove. Although the intensity variation of each diffraction order has a very regular sinusoidal dependence on the polarization angles of the incident light, the variation phase of each diffraction order is not all the same. 相似文献
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It has been described that the near-field images of a high-density grating at the half self-imaging distance could be different for TE and TM polarization states. We propose that the phases of the diffraction orders play an important role in such polarization dependence. The view is verified through the coincidence of the numerical result of finite-difference time-domain method and the reconstructed results from the rigorous coupled-wave analysis. Field distributions of TE and TM polarizations are given numerically for a grating with period d = 2.3λ, which are verified through experiments with the scanning near-field optical microscopy technique. The concept of phase interpretation not only explains the polarization dependence at the half self-imaging distance of gratings with a physical view, but also, it could be widely used to describe the near-field diffraction of a variety of periodic diffractive optical elements whose feature size comparable to the wavelength. 相似文献
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The TE/TM polarization conversion characteristics of dielectric grating composed of left-handed materials for the case of
plane wave oblique incidence are carefully investigated by a method which combines the multimode network theory with the rigorous
mode matching method. It is indicated that complete polarization conversion between TE and TM modes can be realized using
left-handed gratings. This can hardly achieve in the conventional right-handed gratings. Comparisons of polarization conversion
properties between right-handed gratings and left-handed gratings are given with physical explanations. This unique merit
of left-handed periodic structure is of important significance for accurate design of new millimeter wave TE/TM polarization
converters. 相似文献
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Based on Wolf's general tensorial theory of coherence, in which the vector nature of electromagnetic fields is considered, the closed-form propagation equation of vector Gaussian-Schell-model (GSM) beams passing through a paraxial optical ABCD system is derived, which shows the general applicable advantage, and is used to study polarization changes of GSM beams in passage through a thin lens. It is found that polarization changes are dependent on the propagation distance, focal length of the lens, beam and coherence parameters and bandwidth of the source spectrum in general. A comparison with the previous results is also made. 相似文献
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Based on Wolf's general tensorial theory of coherence, in which the vector nature of electromagnetic fields is considered, the closed-form propagation equation of vector Gaussian-Schell-model (GSM) beams passing through a paraxial optical ABCD system is derived, which shows the general applicable advantage, and is used to study polarization changes of GSM beams in passage through a thin lens. It is found that polarization changes are dependent on the propagation distance, focal length of the lens, beam and coherence parameters and bandwidth of the source spectrum in general. A comparison with the previous results is also made. 相似文献
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A new method is proposed for polarization modulation of random electromagnetic beams. The changes in the spectral degree and the state of polarization of such after their passage through the gradient-index (GRIN) waveguide lens system are investigated while the parameters of the system are adjusted. It is demonstrated that passage through the GRIN waveguide lens system can lead to more complex changes in the beam’s polarization than its free-space propagation. 相似文献
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利用严格模式理论分析光栅透镜的衍射特性 总被引:4,自引:4,他引:0
光栅透镜因其独特的光学性能而具有广泛的应用.根据光栅透镜的线宽和间距微小渐变的特点,建立了光栅透镜的物理模型,并利用严格模式理论对其衍射特性进行分析.该方法物理概念清晰、公式简洁.对光栅透镜实现谐波分离、聚焦功能时的衍射效率与槽深关系的计算结果表明,其计算速度快、数值计算结果准确可靠.并对加工误差的影响进行了模拟计算,说明了在当前的微细加工的工艺水平条件下,能够制作出满足ICF系统要求的光栅透镜.实验上制作了尺寸为100 mm的大面积光栅透镜,其衍射效率的实验测试结果与理论计算结果一致. 相似文献