共查询到17条相似文献,搜索用时 78 毫秒
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将分数傅里叶变换用于全息图制作,针对各种记录方式,全面研究了分数傅里叶变换全息图无透镜再现像的共轭关系和放大率关系,确切完整地给出了分数傅里叶全息术傍轴几何光学理论的数学表达和物理解释.计算机模拟实验证明了结论的可靠与可行. 相似文献
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无透镜傅里叶变换全息图数值再现中的图像处理 总被引:2,自引:4,他引:2
针对无透镜傅里叶变换全息图数值再现过程的特点,提出了一套不同于以往的削弱或消除全息图0级衍射和孪生像的数字图像处理算法。该算法分为三步。首先,对所拍摄的数字全息图通过高通滤波实现衬比度增强预处理,以提高全息图的衍射效率并消除再现图像的0级衍射斑;其次,对再现图像进行带通及Ⅴ型滤波,以降低背景噪声并使再现视场均匀;最后,对所得到的再现像进行平滑处理,通过小波滤噪和中值滤波进一步提高再现像的信噪比。实验结果表明,该方法只需记录一幅数字全息图,通过简单的数字图像处理,便可明显改善图像质量,尤其适用于无透镜傅里叶变换全息图的数值再现,并且更加实用化。 相似文献
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阐述了用小型全息设备做傅里叶变换全息图存储资料实验所采用的光路、详细的操作步骤和实验中的关键问题. 相似文献
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Real color fractional Fourier transform holography is proposed based on fractional Fourier transform holography. The method of fabrication, the principle of reconstruction and the design of system parameters are discussed in detail. The experiments prove real color fractional Fourier transform holograms possess the better function of anti-counterfeit than common fractional Fourier transform holograms. 相似文献
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Kenji Nagashima 《Optics & Laser Technology》2001,33(5)
Improvement of images reconstructed from 3D computer-generated holograms using 1D Fourier transform operations is presented. Required computing time for making 3D holograms is decreased when 1D Fourier transform method is used instead of 2D Fourier transform method, but reconstructed images from the holograms created by the 1D Fourier transform method are somewhat inferior in quality to the images by 2D Fourier transform method. In this paper, we propose a method that the disadvantageous properties of the holograms made by 1D Fourier transform are improved. We have performed two step improvements in this experiment. From the numerical experiments, the images that are reconstructed from the holograms created from 1D Fourier transform method show marked improvement. 相似文献
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液晶光阀用于光学傅里叶变换 总被引:2,自引:1,他引:1
结合我校开设的液晶光阀实验,介绍了几个典型的静态傅里叶变换实验内容,以液晶光阀在计算全息扫描器中的应用为例,对其在动态傅里叶变换中的应用进行了讨论。 相似文献
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A simplified approach is presented, to obtain two-channel computer-generated holograms of detour type. The method allows effectively to handle up to two flat objects (two digitized images), in x and ydirections. The experimental results demonstrate the effectiveness of the suggested procedure. 相似文献
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Image encryption and decryption using fractional Fourier transform and radial Hilbert transform 总被引:1,自引:0,他引:1
A technique for image encryption using fractional Fourier transform (FRT) and radial Hilbert transform (RHT) is proposed. The spatial frequency spectrum of the image to be encrypted is first segregated into two parts/channels using RHT, and image subtraction technique. Each of these channels is encrypted independently using double random phase encoding in the FRT domain. The different fractional orders and random phase masks used during the process of encryption and decryption are the keys to enhance the security of the proposed system. The algorithms to implement the proposed encryption and decryption scheme are discussed, and results of digital simulation are presented. 相似文献