共查询到20条相似文献,搜索用时 31 毫秒
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A general formula of interference contrast formed by two arbitrarily polarized elliptical waves propagating along arbitrary directions in three-dimensional (3-D) space is derived. From it a series of inferences for the interference of linear and circular waves including their different combinations are obtained. These formulae are used for polarization optimization in three and four noncoplanar beam interference for the fabrication of 3-D periodic microstructures. The numerical calculations show that the use of circular light can improve the uniform contrast considerably compared with the use of only linear light, and the use of elliptical light may make the contrast even higher. 相似文献
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Vector Approach to Calculating Space-Charge Fields in Crystals withntrast Light Interference Pattern
A new method for calculating space-charge fields in photorefractive crystals with shallow-lying traps illuminated by a light interference pattern of arbitrary contrast and shape is suggested. A space-charge field in a BSO:Cd crystal with shallow-lying traps illuminated by a sine light interference pattern with the high contrast m = 0.99 is calculated. 相似文献
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可获得高衬比干涉条纹的实时全息记录方法 总被引:13,自引:3,他引:10
本文提出了一种可以获得高衬比的实时全息记录方法,它通过分析所记录的第一张实时全息图来获得拍摄最佳衬比实时全息图的拍摄参数,文中指出了拍摄最佳衬比实时全息图需要满足的条件,给出了理论分析和实验验证,实验结果与理论相符甚好,对于透明物体的实时法全息图.条纹衬比可接近最佳值1. 相似文献
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A systematic analysis of interference of three noncoplanar plane waves with identical frequency is provided. This analysis shows that a fiber bundle with spacing of the order of the wavelength, which one may conveniently control by changing the recording geometry, can be formed by this means. The relation between the incident light-wave vectors and the resultant pattern is analyzed. The concept of uniform contrast for an interference pattern is introduced, and the polarization optimization approach for each beam that ensures maximum uniform contrast for each beam is also given. 相似文献
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针对传统方法难以制作结构光三维投影测量设备的灰度正弦光栅元件,并以Ronchi光栅代替从而影响测量准确度,提出了一种制作灰度按正弦分布的光栅模板的新方法.通过对银盐全息干板透过率特性曲线的理论分析,指出在对比度为一的正弦干涉条纹下曝光不能得到线性记录和变换的原因,并提出了采用均匀非相干光预曝光提供偏置点来实现线性记录的新方法.实验表明,采用空间滤波法能够获得对称双光束正弦干涉条纹记录,并准确控制正弦干涉条纹曝光在干板的线性区域,可以达到线性记录并获得尽可能高的反衬度. 相似文献
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Using numerical simulation, an analysis was conducted of the interference structure of a bottomscattered sound field generated by a wideband point source in shallow water under winter and summer conditions. The scattered signals were received from the place where the source was located and were subjected to Fourier transform with a sliding window. The paper demonstrates the possibility of estimating the waveguide invariant for backscattered signals when processing the sound intensity distributions in wide frequency and distance ranges up to the scattering area. A technique is proposed for reconstructing the twodimensional field of internal waves using variations of the interference pattern of reverberation signals. The influence of wind surface waves on the degree of interference band contrast is illustrated. 相似文献
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A grating interferometer composed of two transmission gratings in tandem irradiated incoherently was studied for an atom interferometer. Determination of its interference effect was made with consideration of the optical transfer function. An atom beam had a velocity distribution, which made the influence on the interference phenomenon. The calculated results show that the fringe (grating image) with relatively high contrast is obtained under a certain grating arrangement even if the interferometer is irradiated by a spatially incoherent polychromatic atom beam. 相似文献
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通过结合HF酸洗和微分干涉差显微成像对两组抛光元件的亚表面损伤进行直接观测和分析。结果显示微分干涉差显微成像相比于传统的明场成像具有更好的分辨率,可以更有效检测HF酸洗后暴露的各种浅塑性亚表面损伤。对两组抛光元件的亚表面损伤的对比分析发现熔石英元件在抛光中会产生大量的亚表面损伤,这些亚表面损伤绝大多数是浅塑性的划痕和坑,仅有少量的脆性断裂损伤,较大的抛光颗粒会产生更多更严重的亚表面损伤,并且这些亚表面损伤被表面沉积层所掩盖,表面粗糙度不能反映亚表面损伤的严重程度。 相似文献
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Yuqiang Yang Guiyuan Cao Hong Zhao Yanling Xiong 《Journal of Russian Laser Research》2013,34(4):402-407
Interference contrast is an important parameter for extrinsic Fabry–Perot interferometer (EFPI) based on graded index (GRIN) lenses. It determines the signal-to-noise ratio (SNR) and the measurement accuracy. We discuss the influence of Fabry–Perot (FP) cavity surface errors, which are inevitable in controlling the interference contrast during the manufacturing procedure. Our theoretical analysis and results of numerical simulations demonstrate that the surface errors diminish the interference contrast — the larger the surface error, the smaller the interference contrast. The results obtained contribute to the EFPI application in fiber sensors. 相似文献
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菲涅耳双棱镜干涉在相衬成像和全息显微术中有重要应用。为了促进其应用,本文从信息光学角度研究双棱镜干涉,首先利用光场与脉冲响应函数之间的关系,理论导出了菲涅耳双棱镜干涉条纹强度公式,分析并讨论了狭缝缝宽及狭缝到双棱镜距离对菲涅耳双棱镜干涉条纹的影响,狭缝宽度大于0. 1 mm时,干涉条纹分辨率变差。接着给出了改变狭缝宽度(变化量为0. 08 mm)和改变狭缝到双棱镜的距离(从8 cm变化到12 cm)的实验结果,理论分析和实验结果一致。该结果有助于促进菲涅耳双棱镜干涉在相衬成像等领域的应用。 相似文献
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Yu. N. Markov 《Optics and Spectroscopy》2001,91(4):649-653
A method is developed to design complex-period contrast bandpass interference filters with a band-width continuously varied in a wide range, which cannot be precisely formed by known classes of two-compoent multiple-half-wave passband systems. 相似文献
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We investigate the intensity fluctuations of light backscattered from absorbing random media. A numerical simulation which takes into account the interference among different scattering paths reveals that the contrast of speckle patterns appearing at the surface of the medium decreases with an increase of absorption in weak absorption regime, but increases for strong absorption. It is shown from a simple theoretical model that such a contrast variation is caused by changes in the power of diffusive-scattering waves and in the amplitude distribution of single and low-order scattering waves. 相似文献
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A modified point diffraction interferometer is presented, where interference is made in the first diffracted order of a composite grating. A 180° phase shift between reference and object beam is introduced to obtain a complete image contrast reversal. 相似文献
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实时全息术检测透明物的一种新方法 总被引:2,自引:2,他引:0
介绍了实时全息术检测透明物的一种新方法,它采用物光再现的参考光和参考光通过全息图的直透光所形成的干涉图纹检测透明物体的变化。证明了这组干涉图纹与用参考光再现的物光和物光通过全息图的直透光所形成的干涉图纹分布规律相似,仅在相位上相差π。还讨论了这组干涉图纹的衬比和获得最佳衬比的条件。此方法可消除物光光路上某些因素带来的相位畸变,避开待测物体自发光的干扰,并可在全息图后方任意位置进行记录,这使实时全息术在实践中更具有灵活性,有助于它在更广阔领域内的应用。 相似文献
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A new type of X-ray interferometer is described in which total reflection is established in the process of beam splitting, beam deflection and beam recombination by making essential use of simultaneous Bragg case diffraction from two different sets of net planes.The amplitudes of the interfering beams are calculated along the lines of the dynamical theory of X-ray diffraction. It is found that in the general non-planar three-beam case a complicated interaction of polarization states occurs which results in a destruction of interference contrast. On the other hand, in the planar case the polarization states stay separated and interference contrast can reach 100%.A monolithic interferometer using coplanar (440) and (404) reflections was made from a perfect silicon crystal and operated successfully. The degree of interference contrast was investigated experimentally with NiK radiation of an ordinary X-ray tube and with synchrotron X-rays from DESY.Focusing requirements and source properties influencing the coherence conditions are discussed.Part of doctorate thesis (University of Dortmund, 1976) 相似文献