共查询到20条相似文献,搜索用时 96 毫秒
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以非线性Rosen-Zener隧穿理论为基础,用两分量Bose-Einstein凝聚体设计了非线性Ramsey干涉计.通过数值模拟实验在时间域上观察到了丰富的Ramsey干涉图样,凝聚体中原子间重要的非线性相互作用导致这些干涉图样明显不同于线性Ramsey干涉时的正弦型条纹.通过进一步对干涉图样作Fourier分析,发现干涉图样的基频能够精确反映系统的非线性和不对称性特征,从而为测量原子的相关性质提供了理论依据.
关键词:
Bose-Einstein凝聚
非线性Ramsey干涉
Rosen-Zener隧穿 相似文献
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提出一种应用机器视觉技术的激光干涉法, 可以研究压电材料的逆压电系数. 在传统干涉测量法中引入机器视觉实现干涉图像灰度最佳估计, 使用数字图像处理技术, 一方面应用降噪算法有效去除激光干涉图样中的噪声, 从而确定激光干涉场的光强分布, 另一方面将干涉图样的明暗变化进一步转化为可量度的灰度变化以提高测量分辨力. 通过合理设计算法, 该方法中对位移的理论测量分辨力可以提高达一个数量级, 为干涉光波长的1/1024, 因此在逆压电系数d31 的实验测量中可以有效提高分辨力.
关键词:
机器视觉
逆压电系数
双光束干涉
数字图像处理 相似文献
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双随机相位加密全息标识防伪技术研究 总被引:22,自引:0,他引:22
在输入面和频谱面上分别放置随机相位加密模板对图像数据进行加密是一种高密级的有效数据加密技术。在研究双随机相位数据加密技术的基础上,结合数字全息技术和印刷技术的特点,提出了一种新的双随机相位加密同轴相位全息标识(简称同轴相位全息标识)印刷防伪方法。理论分析证明了同轴相位全息标识方法能有效地恢复原始图像数据,仿真实验证明了该方法具有强抗随机干扰能力和抗位压缩性能。通过打印和扫描实验验证了同轴相位全息标识可以通过普通的数字印刷技术印制在证件等印刷品中作为防伪标识,印刷品中的同轴相位全息标识可以通过扫描输入计算机,变换生成数字图像,通过解密模板可从中恢复出原始图像数据。 相似文献
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《中国物理 B》2015,(8)
Digital holography can be applied to ultrafast detection when a femtosecond laser pulse is used. In this paper, the interference process of two femtosecond laser pulses is studied and the recording process of the femtosecond laser pulsed digital hologram is simulated. Holograms at different recording angles are generated by integrating the instantaneous interference field. By analyzing the distribution of the reconstructed phase error, the characteristics of femtosecond laser pulsed digital holography are discussed. 相似文献
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We present an original heterodyne holography method for digital holography that relies on two-dimensional heterodyne detection to record the phase and the amplitude of a field. The technique has been tested on objects as much as 13 mm in size. Consistency checks were performed, and high-resolution images were computed. We show the requirement for a spatial filter to select properly sampled near-axis photons. Heterodyne holography is superior to off-axis digital holography for both field of view and resolution. 相似文献
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Image encryption based on extended fractional Fourier transform and digital holography technique 总被引:1,自引:0,他引:1
We present a new optical image encryption algorithm that is based on extended fractional Fourier transform (FRT) and digital holography technique. We can perform the encryption and decryption with more parameters compared with earlier similar methods in FRT domain. In the extended FRT encryption system, the input data to be encrypted is extended fractional Fourier transformed two times and random phase mask is placed at the output plane of the first extended FRT. By use of an interference with a wave from another random phase mask, the encrypted data is stored as a digital hologram. The data retrieval is operated by all-digital means. Computer simulations are presented to verify its validity and efficiency. 相似文献
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Xiao-ou Cai 《Optik》2014
As one of the most important 3-D display technique, reduction of speckle noise in the reconstructed image of digital holography should be grounded on the digital hologram itself. Based on the whole process of the recording and reconstruction of digital holography, the optical distributions of recorded object and reconstructed image of digital holography have been studied. It has been proposed that the root formation cause of speckle noise in its reconstructed image is the speckle noise formed on the recorded object surface when illuminated by coherent light because of its optical roughness. A novel approach has been presented to reduce speckle noise in digital holography by changing the interference structure of hologram itself. First, by reducing the speckle noise in the reconstructed image, the distribution of ideal reconstruction light with reduced speckle noise is acquired. Then in turn, taking the ideal reconstruction light with reduced speckle noise as ideal object light, a new hologram can be rebuilt, which can reconstruct the ideal object light. The experimental results are given to confirm the proposed method. Therefore, it offers a brand-new thought and practical way to reduce the speckle noise in the reconstructed image of digital holography. 相似文献
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光学成像技术极大地拓展了人类的视觉极限,提高了人们观察和理解现实世界的能力。越多地获得目标的光学信息,对其的认识越充分。数字全息术是一种可以将样本的三维信息以二维全息图的形式编码记录下来的一种成像技术。通过获得由携带物体信息的物光波和参考光波叠加产生的干涉图案,可以以数字化的方式实现多种重建模态,例如图像恢复、相位成像和切片成像等。光学扫描全息术是一种独特的数字全息成像技术,通过主动式二维化扫描对三维物体进行成像,其完整的波前信息可以被单像素探测器记录,并基于光外差检测进行信号解调,从而恢复出复数全息图。对光学扫描全息术的最新进展进行介绍。首先,基于双光瞳成像系统,通过特殊的硬件和算法设计,提高光学成像系统的性能,如提高空间分辨率、缩短扫描时间。其次,基于计算成像原理,通过改进和优化全息像重建算法,实现高质量的图像恢复,主要涉及切片成像和三维成像等重建模态。第三,介绍光学扫描全息术的其他研究方向,并讨论该领域未来可能的发展方向。 相似文献
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为实现对相位物体的无损检测和成像,克服数字同轴全息相位物体成像技术在消除零级像和孪生像的干扰时存在的系列问题,提出一种基于Stokes参量的新的数字同轴全息技术。该方法区别于传统的利用干涉光场来记录原始像项的数字全息方法,通过测量物参光合成光束的Stokes参量来分别得到这两束光的振幅和相位差,从而准确、唯一地获得原始像项;再利用数字再现即可重构物光的振幅和相位信息。实验中对弱吸收的相位样品进行了测量,得到样品清晰的振幅和相位分布。结果表明,采用该方法对相位物体进行数字全息再现,可以克服传统同轴全息图中零级像和共轭像对相位物体信息的严重干扰,对于提取相位物体的振幅和相位信息是可行和有效的。 相似文献
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基于棱镜对的单元件干涉可以获得透射物体的相位信息,即数字全息,具有结构紧凑、干涉条纹稳定、测量精度高等优点。采用光线追迹方法,综合考虑了棱镜对的方位角旋转、斜面偏心等参数,建立了光线追迹等效模型,仿真了数字全息干涉条纹,给出了条纹密度变化及倾斜的解析表达式。针对单模和多模光纤等微结构光学元件,获得了干涉数字全息图,并反演出其折射率分布。搭建了显微成像单元件干涉实验装置,获得了实际测量干涉图样,实验与仿真结果一致,证明了本模型的有效性。 相似文献