共查询到18条相似文献,搜索用时 156 毫秒
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Talbot效应是一种近场自成像效应,通常只有周期光栅可以产生Talbot效应,而环形光栅无法产生.本文通过引入保角变换,发现可以在环形光栅外部设计适当的折射率渐变层介质,使得其中也能够产生严格的Talbot效应,并计算了对应的自成像半径表达式.本文利用FDTD软件分别将一个环形光栅放置在真空中以及人工设计的折射率渐变层中进行了模拟,并对二者的结果进行了比较分析,发现这种折射率渐变层介质确实对点光源入射的环形光栅的自成像情况有着很好的改善.希望这一工作能够推广Talbot效应的应用范围. 相似文献
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光学系统中的光栅衍射自成像现象:广义的Talbot效应 总被引:17,自引:4,他引:13
本文基于菲涅耳-克希霍夫(Fresnel-Kirchhoff)积分推导了在菲涅耳(Fresnel)近似下,光栅在光学系统中的衍射自成像现象:广义的Talbot效应。并把几何成像归结为Talbot成像的一个特殊情况。依据广义Talbot公式,讨论了在平行光、球面波照明时,光栅的衍射自成像特点。最后,用干涉观点解释了光学系统中的衍射自成像现象。 相似文献
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本文首次用矩阵光学理论结合光栅衍射相干条件,推出双光栅成象的几何光学表示式,用象位移叠加的观点解释了双光栅成象系统Talbot自成象以及双光栅成象现象,首次将双光栅成象现象分为1)基于光栅和透镜组成系统对第一块光栅进行成象的双光栅成象和2)基于编码光源成象原理的双光栅成象,指出这是两种截然不同的双光栅成象,扩展了双光栅成象的物理意义。最后给出了实验结果。 相似文献
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用部分相干光衍射理论研究光栅成像系统 总被引:6,自引:3,他引:3
对可用于研究X射线源光谱特性的光栅成像系统进行了研究,运用部分相干光成理论对系统的成像性质和传递函数进行分析,指出像面上的光强分布正比于光栅复振幅透过率函数的自相关函数的傅里叶变换和光源在接收面上的几何投影像之间的卷积,并进一步救是光栅成像系统的传递函数正比于光栅率的自相关函数。 相似文献
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一、引言近年来,各种光电技术的广泛应用是光学测量技术发展的热点.其中以CCD的使用最为常见.利用CCD对图象进行记录和测量在各种光学度量方面都进行了许多尝试.尤其是光束小角度偏转的检测,在光学检验的各个方面都有意义.使用Talbot效应对小角度光束进行测量,是一个十分有效的光学检测手段,近年来已十分成熟地应用于光束的各种物理量的测量,其基本原理简述如下:当平行光垂直照射一个周期性物体时,将在空间某处形成准确的自成像,称之为Talbot像.设周期性物体是光栅常量为d的郎奇光栅,则在Talbot距离z。处产生自成像.若在… 相似文献
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The Fresnel theory of the Talbot effect of the grating is reviewed in this paper, and the general formula of the Fresnel diffraction of the grating with finite aperture size is presented. The aperture effect of the grating on the Talbot image is discussed and a number of numerical calculations are performed. The variation rule of the diffraction intensity distribution at the Talbot distance with the aperture size of the grating and the case at different Talbot distances are obtained through the calculations, and the corresponding explanations of these phenomena are given in this paper. We think that these discussions provide the theoretic basis for the practical application of the Talbot effect of the actual grating. 相似文献
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用反向调制照明法分析光栅成像效应 总被引:2,自引:1,他引:1
提出了用反向调制照法明分析光栅成像效应的观点,研究了光栅系统的反向衍射干涉效应,成功地揭示了泰伯效应与劳效应的内在联系,并在白光双光栅衍射干涉的“消色效应”的基础上获得了白光扩展光源照明下白光光栅成像效应和具有实用意义的四光栅干涉系统。 相似文献
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Francisco Javier Salgado-Remacha Francisco Jose Torcal-MillaLuis Miguel Sanchez-Brea Eusebio Bernabeu 《Optics and Lasers in Engineering》2011,49(3):356-360
Steel tape is used in optical applications due to its mechanical properties. However, roughness of steel surfaces affects to wave propagation. The effect can be observed using diffraction gratings with low periods. In such a case, self-images of the grating appear at certain periodic distances from the grating (Talbot planes). When standard steel is used, the contrast of Talbot self-images strongly decreases with the distance from the grating. In this work, we prove that controlling the surface quality of steel, it is possible to improve its optical behavior and, as a consequence, high quality surface steel represents a good choice for diffractive optics when the use of chrome-on-glass masks is not indicated. As an example, we have manufactured a diffraction grating over a high quality steel surface by means of an ablation process with a nanosecond pulsed laser. The contrast of the self-images for these gratings decreases very slowly with the distance, in comparison with the self-images obtained with standard steel tape gratings. 相似文献
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利用杨氏双缝干涉讨论Talbot效应 总被引:5,自引:3,他引:2
利用杨氏双缝干涉原理讨论了平行光垂直照射下光栅的Tablot及分数Tablot现象.在成像平面上所观察到的光栅衍射条纹实质上是光栅中一定缝距的许多双缝对的杨氏干涉条纹的可除相干叠加条纹,其条纹间距和明暗中心位置都未变化;但是像相对于光栅即条纹分布相对于光栅刻线可能有半个周期的偏移,这可由双缝对参数α的奇偶决定,如果α为偶数则没有偏移,如果α为奇数则有偏移. 相似文献
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Muqaddar Abbas Liu Wenzhang Yong-Chang Zhang Nan Cong Pei Zhang 《Annalen der Physik》2024,536(3):2300329
2D Raman generated classical and quantum Talbot imaging is proposed in a three-level gain assisted system. First, a 2D Raman induced grating (RIG) will be constructed by modulating transmission function in the weak probe channel using a strong control standing wave field. Furthermore, RIG will diffract a probe field, by shining a probing light beam on an optically generated lattice within a rubidium vapor cell. This study uses gain assisted Raman medium [Nature 406 , 277 (2000)] to examine classical and quantum Talbot imaging. In the case of Raman-induced classical imaging, the diffraction pattern repeats itself at planes with integer multiple Talbot lengths. Additionally, by taking into account entangled photon pairs, the scenario of Raman-induced quantum imaging is investigated. This study also looks at the RIG's amplitude and phase information with adjustable image size variation. As a result of the gain feature and zero absorption, this system is anticipated to be more suitable from the perspective of application. This analysis may pave the way for further research into the Talbot effect's nonlinear and quantum dynamical properties. Also, it provide a non-destructive, lensless method for imaging very cold atoms or molecules. 相似文献
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Liang Fang Na Yao Mingbo Pu Changtao Wang Xiangang Luo 《Applied Physics A: Materials Science & Processing》2015,118(4):1543-1549
We numerically demonstrated the sub-diffraction-limited magnified Talbot imaging in a metamaterial composed of cylindrical stacked metal/dielectric multilayer. It was found that the magnified Talbot imaging could occur without the requirement of the metal/dielectric permittivity matching condition as satisfied in the hyperlens. Specifically, in this work, a practical realization of the magnified Talbot imaging was performed by Ag/Al2O3 multilayer stack at the wavelength of 337 nm. Unlike the traditional Talbot effect, the Talbot length in this case is not a constant but a variable and the variable Talbot length can be predicted roughly by ray optics approach. The contrast of the magnified Talbot imaging is decided by both the imaginary part and the real part in permittivity of the metamaterial. In order to obtain a deep sub-wavelength magnified Talbot image at the outer surface of the cylindrical metamaterial, the outer cylindrical radius should be optimized and the imaginary part in the permittivity should be small enough. 相似文献
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随着高性能第三代同步辐射光源的建成开放,基于X射线相干特性的实验方法得到了快速发展和广泛应用.作为一个典型的例子,X射线相位衬度成像已经成为常规的X射线实验方法并向用户开放.相干散射、相干衍射成像、光子关联谱等X射线实验方法正日益受到重视,在高空间分辨、时间分辨等研究领域已显示出其独特的优越性.因此,研究和测量第三代同步辐射的空间相干特性对进一步发展这些新的实验方法具有重要意义.基于Talbot自成像原理成功测量了上海光源X射线成像线站发射的X射线的空间相干长度,并进而测得了相应光源的空间尺度.光子能量为33.2 keV时,测得的X射线光束垂直方向空间相干长度为8.84μm,对应的光源尺寸为23μm,测量结果与理论分析相符. 相似文献