共查询到20条相似文献,搜索用时 75 毫秒
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基于凹面光栅的几何理论,推导了子午、弧矢聚焦曲线的数学表达式和全息平像场凹面光栅制作参数的计算关系式.提出了一种新的在整个使用波长范围内同时消除子午和弧矢像差的最佳优化设计方法.这种方法不同于以光线追迹技术为基础的标准光学设计软件如CODEV或ZEMAX的优化设计方法,而是从数学表达式出发,采用光栅优化因子,对凹面光栅的子午聚焦曲线和弧矢聚焦曲线进行拟合,从理论上找到最佳的能够使子午和弧矢像差同时趋于零的像平面,然后再根据拟合参数设计制作光栅.用Matlab软件解决了子午聚焦曲线超越方程无法解的困难;讨论了不同光栅常数和入射角度时对两聚焦曲线拟合程度的影响.提出了在宽光谱使用条件下,可以通过减小入射角度和光栅刻线数来提高光谱像质. 相似文献
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根据在一般坐标系下均匀布拉格光纤光栅的传输矩阵,得到了取样布拉格光纤光栅的传输矩阵。利用傅里叶变换得到了取样布拉格光纤光栅的谐振方程。结果表明,在不考虑平均折射率变化的情况下,谐振峰的位置是由光栅的周期和取样周期共同确定的,与取样时的占空比、光栅长度和耦合系数没有关系。类似于物理光栅,取样布拉格光纤光栅也存在缺级现象,给出了出现缺级的条件。 相似文献
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针对全息波导显示系统中输入光栅、转折光栅和输出光栅的光栅参量不一致,导致系统设计和光栅制作难度增大的问题.对比正常配置和锥形配置下的光栅方程,可得全息波导显示系统中全息光栅具有相同周期需要满足转向光栅60°锥形配置.由此提出波导侧面装有反射镜的三光栅单波导板显示构型,其中三个光栅周期完全相同,输入光栅和转向光栅条纹走向一致.使用光学设计软件CODE V对该构型进行仿真,验证了该构型的可行性.与传统全息波导显示构型相比,侧面反射镜的光路折叠作用使得该构型系统无效显示面积和耦合效率损失减小;三个光栅周期相同且输入光栅和转向光栅条纹走向一致,可以降低系统设计和全息光栅制作难度.该构型可以用于虚拟现实显示或者头戴式显示. 相似文献
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正弦锥光纤光栅的数值计算分析 总被引:1,自引:0,他引:1
本文利用耦合模方程对正弦锥光纤光栅的反射谱进行了较为详细的计算和分析,发现,这种光纤光栅的反射谱与普通均匀周期光栅的反射谱有着很大的不同,通过控制光栅锥的形状,可得到类似于梳状滤波器的功能,对这种新型光栅在光纤激光器等方面的应用有指导意义。 相似文献
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本文指出全息干版薄膜在曝光后处理过程中的收缩性和折射率变化对制备全息光栅的周期、倾斜度、布喇格入射角及衍射角的影响问题,并根据实验数据对光栅设计进行修正,再结合Kogelnik衍射方程及折射率调制度和曝光量的线性关系,在实验中基本上能准确设计出指定周期、倾斜度和衍射效率的全息光栅。 相似文献
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天文导航中星体高精度细分定位方法研究 总被引:2,自引:0,他引:2
介绍了一种从星体图像中高精度提取恒星位置的方法.这种方法把星光成像看成是高斯点扩散函数模型,利用线性内插和最小二乘法拟合得到高斯曲面参数,从高斯曲面模型中得到亚像素级的恒星位置.由于直接进行高斯曲面拟合计算非常复杂,将二维曲面拟合转化为两个方向上的一维曲线拟合,分别得到不同的曲面系数.仿真结果表明当信噪比小于0.05时,定位精度能达到1/20像素,与质心法比较,高斯曲面拟合法精度高,抗噪声能力强. 相似文献
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S.T. CHOI 《Journal of sound and vibration》2003,259(3):525-539
Free-vibration characteristics of cantilever non-circular curved panels are analyzed by using the differential quadrature method (DQM) in this paper. The equations of motion of a curved panel are based on the Love's hypothesis and are expressed in an orthogonal curvilinear co-ordinate system. By applying the differential quadrature formulation and the proposed modified relationships for specified boundary conditions, the free-vibration equations of motion of the curved panel are transformed to a set of algebraic equations. Natural frequencies of a cantilever flat plate and a circular curved panel are obtained for verifying the applicability of the present approach. Good convergent trend and accuracy are observed. Effects of shallowness, thickness and aspect ratios on the natural frequencies of a cantilever curved panel are also investigated. Furthermore, natural frequencies of parabolic curved panels are obtained. In all cases studied, the efficiency and convenience of the DQM are illustrated. 相似文献
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T. Dobrowolski 《Physics letters. A》2009,373(42):3867-3871
In the framework of the two-dimensional field model the influence of the curvature on kink width is discussed. Breading of the kink width in a curved region of the manifold is observed. Examples of kinks on curved manifolds are studied analytically and numerically as well. The deformation of the kink front in the form of the travelling waves propagating along the curved surfaces are found. Enlarging of the travelling wave speed in a curved regions of the manifold is predicted. 相似文献
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《Physics letters. A》2020,384(25):126604
For a free particle that moves non-relativistically on a curved surface, there are curvature-induced quantum potentials that significantly influence the surface quantum states. However, the experimental results in topological insulators, whether curved or not, indicate no evidence of such a potential for the relativistic particles constrained on the curved surface. Within the framework of Dirac quantization scheme, we demonstrate a general result that for a Dirac fermion on a two-dimensional curved surface of revolution, no curvature-induced quantum potential is permissible. 相似文献
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For spatial free vibration of non-symmetric thin-walled circular curved beams, an accurate displacement field is introduced by defining all displacement parameters at the centroidal axis and three total potential energy functionals are consistently derived by degenerating the potential energy for the elastic continuum to that for thin-walled curved beams. The closed-form solutions are newly obtained for in-plane and out-of-plane free vibration analysis of monosymmetric curved beams respectively. Also, two thin-walled curved beam elements are developed using the third and fifth order Hermitian polynomials. In order to illustrate the accuracy and the practical usefulness of the present method, analytical and numerical solutions by this study are presented and compared with previously published results or solutions by ABAQUS' the shell element. Particularly, effects of the thickness curvature as well as the inextensional condition are investigated on free vibration of curved beams with monosymmetric and non-symmetric cross-sections. 相似文献
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L.H. Liu 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,102(2):293-303
In graded index media, the ray goes along a curved path determined by Fermat principle. Generally, the curved ray trajectory in graded index media is a complex implicit function, and the curved ray tracing is very difficult and complex. Only for some special refractive index distributions, the curved ray trajectory can be expressed as a simple explicit function. Two important examples are the layered and the radial graded index distributions. In this paper, the radiative heat transfer problems in two-dimensional square semitransparent with layered and radial graded index distributions are analyzed. After deduction of the ray trajectory, the radiative heat transfer problems are solved by using the Monte Carlo curved ray-tracing method. Some numerical solutions of dimensionless net radiative heat flux and medium temperature are tabulated as the benchmark solutions for the future development of approximation techniques for multi-dimensional radiative heat transfer in graded index media. 相似文献
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M. B. Belonenko N. N. Yanyushkina N. G. Lebedev A. V. Zhukov 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(12):1576-1578
The density of states and the electronic spectrum of long-wave electrons in a curved graphene nanoribbon is calculated on
the basis of the Dirac equation in curved space-time. Using this density of states, we obtain the current-voltage characteristics
of tunnel junctions of nanoribbons with metal and quantum dots. The dependence of the curved nanoribbon on the geometric parameters
is found. 相似文献