共查询到16条相似文献,搜索用时 109 毫秒
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介绍了衍射孔的菲涅耳衍射和分数傅里叶变换的对应关系,使得可以用分数傅里叶变换来描述光由原始光场经过菲涅耳衍射区一直到无穷远处夫琅禾费衍射区的自由空间标量衍射传播全过程。 相似文献
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讨论了分数傅里叶变换与菲涅尔衍射的关系,提出球面衍射过程就是一种具有尺度因子的分数傅里叶变换,并应用分数傅里叶变换进行衍射光学元件的设计。 相似文献
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计算机模拟任意形状衍射屏的衍射 总被引:6,自引:3,他引:3
把菲涅耳衍射积分化为含快速傅里叶变换的积分,对任意形状衍射屏的衍射进行模拟,其特点是直接用含快速傅里叶变换的积分求解出不同传播距离观察屏上的光场分布,得出菲涅耳衍射和夫琅禾费衍射的衍射花样.通过计算机对常见的缝孔的衍射的模拟,有助于理解衍射光在传播方向上近场衍射和远场衍射的不同和衍射花样的分布特征. 相似文献
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黄德权魏继峰高学燕周文超 《强激光与粒子束》2013,(B05):9-12
对激光发射系统内的衍射效应进行了模拟计算,利用菲涅耳衍射积分公式的二维傅里叶变换形式,并采用快速傅里叶变换计算方法,讨论了使用快速傅里叶变换计算时二次相位因子满足采样定理的条件,提出了适用于不同传输距离的计算方法,重点对初始光束强度调制对激光传输的影响进行了详细分析。 相似文献
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根据菲涅耳衍射公式,导出了含介质的单透镜与双透镜系统输出面的光场复振幅分布,并与分数傅里叶变换定义式比较,得到了实现分数傅里叶变换的系统结构参量.运用矩阵光学方法,导出上述系统的ABCD矩阵,并与分数傅里叶变换矩阵比较,研究发现两种方法所得结果一致. 相似文献
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Relations between chirp transform and Fresnel diffraction, Wigner distribution function and a fast algorithm for chirp transform 下载免费PDF全文
Two physical interpretations of chirp transform related to Fresnel diffraction and Wigner distribution function are given.The chirp transform can be regarded as a Fresnel diffraction observed on a spherical tangent to the diffraction plane,or a rotation and stretching transformation of the Wigner distribution function space.A general fast algorithm for the numerical calculation of chirp transform is developed by employing two fast Fourier transform algorithms.The algorithm,by which a good evaluation can be achieved,unifies the calculations of Fresnel diffraction,arbitrary fractionalorder Fourier transforms and other scalar diffraction systems.The algorithm is used to calculate the Fourier transform of a Gaussian function and the Fourier transform,the Fresnel transform,the Fractional-order Fourier transforms of a rectangle function to evaluate the performance of this algorithm.The calculated results are in good agreement with the analytical results,both in the amplitude and phase. 相似文献
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Qinfeng Xu 《Optik》2011,122(2):114-117
Compared with the symmetrical lens system, the structure which contains double cylindrical lenses is also the basic units of a complex system and implement practical asymmetrical fractional Fourier transforms. Based on the theory of scalar diffraction and on the Fourier optics, we implement several kinds of asymmetrical fractional Fourier transforms and make the different mathematical manipulation at the corresponding coordinates, while the symmetrical system cannot. Meanwhile, the simulation experiment shows that such system not only makes the two perpendicular coordinates to be independently operated, but also increases the flexibility of the optical setup. All these characteristics make it flexible to application domain in optics. 相似文献
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Fractional Fourier transformation of an object can be approximated by the object's free-space Fresnel diffraction pattern under some restricted conditions and plane wave illumination according to Hua's method. A better approximation is achieved under least-squared conditions developed in this paper. Simulation results verify that our theoretical development works for any fractional order a compared with the previous approach. 相似文献
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D. Le Bolloc’h J. F. Sadoc 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,81(4):481-487
Diffraction of coherent X-ray beams is treated through the fractional Fourier transform. The transformation allow us to deal
with coherent diffraction experiments from the Fresnel to the Fraunhofer regime. The analogy with the Huygens-Fresnel theory
is first discussed, a generalized uncertainty principle is introduced and the successive diffraction of two objects is interpreted
through the fractional Fourier transform. 相似文献
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基于多重菲涅耳衍射变换和相位密码板,设计了一种新的图像加密计算方法.待加密的明文图像在多重离散菲涅耳衍射变换和相位密码板的共同作用下,变换为一个具有随机码特征的密文矩阵;衍射距离和相位密码板是主要的密钥.只有当所有密钥都正确时,才能成功地解密密文.结果表明,该加密算法能抵抗JPEG有损压缩、图像剪切、重度噪音污染和重采样等攻击,因此该法具有较强的鲁棒性;由于很难破解多重密钥,所以该算法具有极高的安全性. 相似文献
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We propose a new concept for wavefront curvature sensing, which is based on diffraction grating and fractional Fourier transforms systems. An explicit formula is derived expressing the wavefront curvature, and the wavefront shape can also be retrieved rapidly. The experimental setup is presented and numerical simulations show the validity of the proposed method. 相似文献