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依据多缝夫琅禾费衍射的基本原理,对一种平面变栅距光栅的光强分布作出了理论分析,导出了光强分布公式。用Matlab软件对变栅距光栅的衍射进行了模拟仿真研究,通过改变栅距变化系数和起始栅距的值,得出了在不同条件下的衍射谱线特征。该计算结果和研究方法在实际的变栅距光栅应用中具有参考价值,为变栅距光栅参数的设计和优化提供了理论依据。 相似文献
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变栅距光栅线位移传感器是一种新型波长编码位移传感器,为进一步提高传感器波长解调的精度和减小光源的体积,提出适用于全工作波段的恒定闪耀角变栅距光栅结构。首先采用经典光学的方法推导出变栅距闪耀光栅衍射强度分布公式,从理论上证明该光栅结构可实现在全工作波段提高变栅距光栅线位移传感器衍射光强。此外,制作出变栅距闪耀光栅样件证实了工艺可行性。在相同的条件下,对一组参数相同的闪耀光栅和矩形槽形光栅进行了衍射光强比对实验,得到变栅距闪耀光栅的衍射光强约为矩形变栅距光栅的衍射光强的1.7倍,并与按此衍射光强分布公式计算的结果一致。 相似文献
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一种亚纳米级变栅距衍射光栅制作方法的研究 总被引:2,自引:1,他引:1
变栅距(VLS)衍射光栅具有自聚焦、像差校正等独特优点。VLS光栅要求的最小栅距变化量为亚纳米数量级,仅靠提高光栅刻划机的分度精度已很难实现,针对这一问题,提出了一种相位扫描方法用于光栅刻划机的变栅距分度控制,即通过对刻划机分度系统的干涉条纹进行微位移扫描来进行相位控制。实验结果表明,相位扫描方法达到了变栅距光栅所要求的亚纳米级的栅距变化精度。 相似文献
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基于现有的相位空间光调制器,提出并实现了计算机制相位彩虹全息近眼显示.指出带限条件下物光在全息面上相位分布的计算及高频闪耀光栅纵向色散的控制是实现相位彩虹全息的关键要素.在计算相位彩虹全息图时,首先利用带限条件下的角谱衍射算法获取全息面上物光的复振幅分布,并利用双向误差扩散算法将复振幅分布编码为相位分布.然后,对参考光对应的高频闪耀光栅的相位进行编码,得到计算机制相位彩虹全息图.最后,设计了包含白色点光源、准直透镜、空间光调制器、4f滤波系统及目镜的全息彩色近眼显示系统,并通过光学再现获得了相位彩虹全息近眼显示效果,证明了所提方法的有效性. 相似文献
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A method for calculating off-axis phase-only holograms of three-dimensional (3D) object using accelerated point-based Fresnel diffraction algorithm (PB-FDA) is proposed. The complex amplitude of the object points on the z-axis in hologram plane is calculated using Fresnel diffraction formula, called principal complex amplitudes (PCAs). The complex amplitudes of those off-axis object points of the same depth can be obtained by 2D shifting of PCAs. In order to improve the calculating speed of the PB-FDA, the convolution operation based on fast Fourier transform (FFT) is used to calculate the holograms rather than using the point-by-point spatial 2D shifting of the PCAs. The shortest recording distance of the PB-FDA is analyzed in order to remove the influence of multiple-order images in reconstructed images. The optimal recording distance of the PB-FDA is also analyzed to improve the quality of reconstructed images. Numerical reconstructions and optical reconstructions with a phase-only spatial light modulator (SLM) show that holographic 3D display is feasible with the proposed algorithm. The proposed PB-FDA can also avoid the influence of the zero-order image introduced by SLM in optical reconstructed images. 相似文献
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在传统的纯相位全息显示系统中, 一般基于快速傅里叶变换(FFT)算法来计算相位全息图, 在FFT的计算中需要遵循Nyquist采样定理, 因此, 重建图像的尺寸往往受限于空间光调制器的固定采样率. 这个限制可以通过卷积算法或者两步菲涅耳衍射算法来解决, 但是需要使用多个FFT的计算, 导致计算量增大. 鉴于此, 提出了一种基于透镜的纯相位全息图计算方法. 在全息图的计算中, 通过透镜的成像原理建立一个采样率可变的虚拟全息面, 通过调节相应的距离参数使得在全息图的计算中可以任意调节原始图像的采样率, 摆脱了传统方法中液晶空间光调制器带宽积对重建图像尺寸的限制, 并且这种算法只需使用一次FFT就能达到变采样率的衍射计算, 大幅提高了全息图的计算速度. 数值模拟及光学实验结果证明了此方法可以在全息显示光学系统中清晰地重建不同尺寸的图像. 同时该系统可以有效地消除由空间光调制器的像素化结构带来的零级衍射. 相似文献
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采用一个极紫外投影光刻掩模衍射简化模型实现了三维接触孔掩模衍射场的快速仿真计算。基于该模型,得到了接触孔掩模衍射场分布的解析表达式,并对光刻成像时的图形位置偏移现象进行了解释和分析。简化模型中,掩模包括吸收层和多层膜两部分结构,吸收层的透射利用薄掩模修正模型进行计算,多层膜的反射近似为镜面反射。以周期44 nm、特征尺寸分别为16 nm和22 nm的方形接触孔为例,入射光方向发生变化时,该简化模型与严格仿真相比,图形特征尺寸误差小于0.4 nm,计算速度提高了近100倍。此外,考虑到多层膜镜面位置对图形位置偏移量的影响,得到了图形位置偏移量的计算公式,其计算结果也与严格仿真相一致。 相似文献
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V. S. Neverov V. V. Voloshinov A. B. Kukushkin A. S. Tarasov 《Physics of Atomic Nuclei》2015,78(10):1112-1119
The influence of molecular clustering on the formerly suggested interpretation of diffraction patterns of hydrocarbon films formed in the vacuum vessel of the tokamak T-10 is analyzed numerically. The simulation of clustering of simple hydrocarbon molecules C(D, H)4, C2(D, H)4, and C6(D, H)6 and molecules composed of curved graphene (fullerenes and toroidal nanotubes) is carried out with the rigid body molecular dynamics method. It is shown that formerly neglected atomic correlations C–C and C–D(H) in the amorphous hydrocarbon component decrease the calculated values of the scattered intensity in the range of scattering vector modulus 5 < q < 20 nm–1 because of homogenization of scatters on the spatial scale of ~1 nm. The allowance for these correlations does not change the diffraction patterns in the range q > 20 nm–1. The results suggest the necessity to introduce to the procedure of determining the structural content of the films, similar to those from the tokamak T-10, the clusters formed by the van der Waals adhesion of hydrocarbon molecules to “graphene” nanoparticles. This simplifies the mathematical optimization to the former level of complexity—but for an extended ensemble of objects—and makes it possible to calculate the diffraction patterns of these objects using the distributed computing resources. A modified algorithm of structural content identification on the basis of joint X-ray and neutron diffractometry is suggested. 相似文献
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本文应用分层模型处理较高浓度的弥散体产生的相关散射。计算各层满足单散射条件时的相函数,求得散射几率函数,利用它再计算前向散射的光能分布;对于较大微粒,按衍射理论计算,建立多重散射模型,应用迭代法计算多重散射的光能量分布;测量了不同浓度的玻璃微珠产生的散射光能量功率谱,将其与模拟计算值作比较,并以上限公布函数作有约束的优化处理,计算了D_(32)。文中用图像分析系统对样品作出二值化图,把统计数据与测量结果作了比较。 相似文献
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《中国科学:物理学 力学 天文学(英文版)》2015,(7)
The plane-wave expansion(PWE) method is employed to calculate the photonic band structures of metal/dielectric(M/D) periodic systems. We consider a one-dimensional(1D) M/D superlattice with a metal layer characterized by a frequency-dependent dielectric function. To calculate the photonic band of such a system, we propose a new method and thus avoid solving the nonlinear eigenvalue equations. We obtained the frequency dispersions and the energy distributions of eigen-modes of 1D superlattices. This general method is applicable to calculate the photonic band of a broad class of physical systems, e.g. 2D and 3D M/D photonic crystals. For comparison, we present a simple introduction of the finite-difference(FD) method to calculate the same system, and the agreement turns out to be good. But the FD method cannot be applied to the TM modes of the M/D superlattice. 相似文献
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