共查询到19条相似文献,搜索用时 218 毫秒
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理论上研究分析了相干高斯光束的符合成像和干涉.导出了相干高斯光束的符合成像公式和符合干涉条纹公式,从这些公式可以看出符合成像和干涉是由于两条光路相应的汇聚投射引起的.符合成像和干涉条纹的质量及能见度可以同时很好.我们的结果表明纠缠光子对和相干高斯光束的符合成像及干涉的物理本质是不同的,相干高斯光束的符合成像和干涉的物理本质是光强的点对点投射,而纠缠光子对的符合成像和干涉的物理本质是双光子的振幅关联. 相似文献
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基于非线性Rosen-Zener隧穿理论, 利用高斯型脉冲研究了双势阱玻色-爱因斯坦凝聚体的非线性Ramsey干涉. 通过数值模拟得到了丰富的非线性Ramsey干涉图样, 分别讨论了粒子间相互作用和高斯型脉冲的周期对干涉图样的影响. 通过哈密顿正则关系得到了干涉条纹的基频表达式, 并借助傅里叶变换对Ramsey干涉条纹的频率进行分析, 得到了干涉条纹的基频随粒子间相互作用及脉冲周期的变化关系. 比较数值和解析结果发现两者符合得很好.
关键词:
玻色-爱因斯坦凝聚
Ramsey干涉
高斯型脉冲 相似文献
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针对强湍流信道下信号衰落的特点,分析了对数正态分布模型与K分布模型的适用范围.基于K分布模型建立大气光通信接收信号模型,并给出了自适应最优门限检测方法.采用四阶和六阶累计量对强湍流信道参量进行估计,采用二阶累计量对其它高斯噪音进行估计,得到K分布参量及高斯噪音统计量的预测值,实现自适应门限更新.基于Monte Calro算法进行仿真,给出了门限更新算法对通信系统误码率的影响,同时分析了信号采样率对估计参量偏差的影响.计算表明,在强湍流情况下,大气光通信系统的误码率性能得到极大的改善,优于基于MLSD检测的接收机. 相似文献
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迈克耳孙干涉仪授课与高科技结合的探索 总被引:1,自引:0,他引:1
从迈克耳孙干涉仪几则科技应用实例讨论干涉、拍频、调制、光电伺服控制、高斯光束特征及噪声控制等问题,以培养学生科学思维能力。 相似文献
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研制了基于菲佐干涉仪的测风激光雷达系统,并使用高斯拟合法和最大似然法反演风速,对两种风速反演方法进行了分析,结果表明:风速较小时,两种方法具有相似的风速反演精度,但高斯拟合法收敛快、受条纹信噪比影响较小;风速较大时,高斯拟合法会由于条纹移出而产生较大误差,而最大似然法在处理风速较大情况时具有优势。实际风速测量时,应根据风速估计值的大小,采用两种方法分别处理大风速和小风速时的情况。最后,使用研制的测风激光雷达系统和风速反演算法,得到了1.5 km以内的大气风速廓线。 相似文献
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Fringe pattern denoising via image decomposition 总被引:1,自引:0,他引:1
Filtering off noise from a fringe pattern is one of the key tasks in optical interferometry. In this Letter, using some suitable function spaces to model different components of a fringe pattern, we propose a new fringe pattern denoising method based on image decomposition. In our method, a fringe image is divided into three parts: low-frequency fringe, high-frequency fringe, and noise, which are processed in different spaces. An adaptive threshold in wavelet shrinkage involved in this algorithm improves its denoising performance. Simulation and experimental results show that our algorithm obtains smooth and clean fringes with different frequencies while preserving fringe features effectively. 相似文献
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We propose a new approach for the direct estimation of the unwrapped phase from a single closed fringe pattern. The fringe analysis is performed along a given row/column at a time by approximating the phase with a weighted linear combination of linearly independent basis functions. Gaussian radial basis functions with equally distributed centers and a fixed variance are considered for the phase approximation. A state space model is defined with the weights of the basis functions as the state vector elements. Extended Kalman filter is effectively utilized for the accurate state estimation. A fringe density estimation based criteria is established to select whether the phase estimation is performed in a row by row or column by column manner. In the seed row/column decided based on this criteria, the optimal basis dimension is computed. The proposed method effectively renders itself in the simultaneous estimation of the phase and the phase derivative. The proposed phase modeling approach also allows us to successfully demodulate the low density fringe patterns. Simulation and experimental results validate the practical applicability of the proposed method. 相似文献
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A two-dimensional multiscale windowed Fourier transform (2D-MWFT), based on two-dimensional Gabor wavelet transform (2D-GWT), for the phase extraction from a spatial fringe pattern in fringe projection profilometry is presented. First, the instantaneous frequencies on x and y direction of the modulated fringe pattern are determined by 2D-GWT, and then the local stationary lengths are obtained. The 2D-MWFT with different two-dimensional Gaussian windows whose width is set according to the local stationary length is preformed for each section of the modulated fringe pattern to achieve multiresolution analysis and phase demodulation. Comparing the result of the phase demodulated by 2D-GWT and two-dimensional windowed Fourier transform (2D-WFT) with that by 2D-MWFT in a numerical simulation, we show that the 2D-MWFT method is superior to these methods, especially for the local non-stationary signal with low frequency. The theory and the results of a simulation and experiment are shown. 相似文献
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A new daughter wavelet definition for reliability-guided phase unwrapping of the optical fringe pattern is introduced. The new daughter wavelet definition is given by normalized mother wavelet with a new factor including a Gaussian function. The modulus of the wavelet transform coefficients, obtained by using daughter wavelet under this new daughter wavelet definition, includes not only modulation information but also local frequency information of the deformed fringe pattern. Therefore, it can be treated as a good parameter which represents the reliability of the reconstructed phase data. Mathematical demonstration of this parameter is given. Both the computer simulation and experiment reveal the validity of the proposed method. 相似文献
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Research on identifying the order of fringe pattern traces using angular scan and zone search method
A method for automatically identifying the order of fringe pattern traces is presented. It uses the simplified Otsu algorithm for obtaining the threshold, the angular scan in the range of 45~ for searching the trace positions, and the zone search technique for identifying different traces. Experimental results show that the proposed method may reliably obtain the order of fringe pattern traces orientating from almost 45° to 90°. 相似文献
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提出了基于混沌粒子群优化的图像Contourlet阈值去噪方法.该方法在Contourlet变换域内利用混沌粒子群算法来确定最优阈值,再通过软阈值函数去噪,且不需要噪音方差等先验信息.实验结果表明:该方法与小波Bayeshrink阈值、基于粒子群的小波阈值、Contourlet自适应阈值等去噪方法相比,能有效地去除高斯白噪音和椒盐噪音的混合噪音,提高峰值信噪比,并较好地保留图像的细节和纹理,从而明显地改善了图像的视觉效果. 相似文献
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在高功率激光系统中,精密微机械修复是减缓磷酸二氢钾(KDP)晶体表面缺陷增长的有效方法,使用精密微铣削机床可以加工出球面型与高斯型修复轮廓。为得到最优的修复结构参数,建立了晶体前表面球面型与高斯型修复轮廓的电磁场有限元模型,通过改变轮廓的宽度、深度等参数,对两种修复轮廓的光强调制能力进行对比研究。仿真结果表明光强调制能力主要是由修复轮廓的衍射效应及入射光在修复界面处的二次入射所引起的干涉作用共同决定;针对初始损伤点,建议采用宽深比大于5的修复轮廓,从而有效提高KDP晶体表面缺陷点的激光损伤阈值,对于宽深比大于10的修复轮廓建议选用高斯型;对宽1000μm,深20μm的两种修复表面的激光损伤实验表明,高斯型修复轮廓具有较高的抗损伤能力,实验与仿真结果相一致。 相似文献
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The point spread function(PSF) is investigated in order to study the centroids algorithm in a reverse Hartmann test(RHT) system. Instead of the diffractive Airy disk in previous researches, the intensity of PSF behaves as a circle of confusion(CoC) and is evaluated in terms of the Lommel function in this paper. The fitting of a single spot with the Gaussian profile to identify its centroid forms the basis of the proposed centroid algorithm. In the implementation process, gray compensation is performed to obtain an intensity distribution in the form of a two-dimensional(2D) Gauss function while the center of the peak is derived as a centroid value. The segmental fringe is also fitted row by row with the one-dimensional(1D) Gauss function and reconstituted by averaged parameter values. The condition used for the proposed method is determined by the strength of linear dependence evaluated by Pearson's correlation coefficient between profiles of Airy disk and CoC. The accuracies of CoC fitting and centroid computation are theoretically and experimentally demonstrated by simulation and RHTs. The simulation results show that when the correlation coefficient value is more than 0.9999, the proposed centroid algorithm reduces the root-mean-square error(RMSE) by nearly one order of magnitude, thus achieving an accuracy of ~ 0.01 pixel or better performance in experiment. In addition, the 2D and 1D Gaussian fittings for the segmental fringe achieve almost the same centroid results, which further confirm the feasibility and advantage of the theory and method. 相似文献