共查询到20条相似文献,搜索用时 15 毫秒
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彩色全息图的计算机产生和数字再现 总被引:3,自引:0,他引:3
提出了一种基于色彩合成以及菲涅尔衍射原理,用计算机产生全息图并用数字方法再现彩色全息图的方法。该方法的第一步是将物体的彩色RGB图像分离为三基色强度图,再利用博奇编码的方法制成修正离轴参考光分色计算机全息图;第二步是分别对分色全息图在频域进行调制以实现用原参考光真实再现原始物光波。通过滤波消除零级衍射及共轭像的影响,获得了所需要的实像并提高了像质。提供的实验是选用一幅RGB图像作为原始物体,给出了用博奇编码法制成的全息图以及最后经色彩合成获得的再现像。结果表明,该方法能使各分色全息图的再现像准确重合,解决了在色彩合成时容易出现的色串扰问题。 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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Sergio De Nicola Pietro Ferraro Andrea Finizio Giovanni Pierattini 《Optics and Lasers in Engineering》2002,37(4)
Off-axis holograms recorded with a CCD camera are numerically reconstructed in amplitude by calculating through the Fresnel–Kirchhoff integral. A phase-shifting Mach–Zehnder interferometer is used for recording four-quadrature phase-shifted off-axis holograms. The basic principle of this technique and its experimental verification are described. We show that the application of this algorithm allows for the suppression of the zero order of diffraction and of the twin image and that the contrast of the reconstructed images can be further enhanced by digital compensation of the aberrations introduced by the holographic recording system 相似文献
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K. Nagashima 《Optics & Laser Technology》1993,25(5)
Two-level quantized phase holograms produced by using a combination of an iterative method and an error diffusion method are presented. By using a previously proposed iterative method, images reconstructed from two-level quantized phase holograms are rapidly improved with small amounts of iterative operations but further improvement of the image quality is difficult even if the iterations are greatly increased. Therefore, in order to exceed the improvement limitation of the image quality, the combination of the iterative method and an error diffusion method was used for the hologram-making process. Experimental results using the combination method showed better images than those obtained by the iterative method alone, when referred to results from synthesized holograms. 相似文献
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A new method for making distortion-free multiplex holograms is proposed. The original images of them are processed by a computer to cancel the distortion of the final image. Examples of the reconstructed images are also presented. 相似文献
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A comparative analysis of the experimental data on recording and multiplexing holograms, including speckle holograms, by an axial scheme is presented. The contrast and signal-to-noise ratio in the images reconstructed are compared. It is demonstrated that the thickness of the photosensitive material has an effect on the image quality during the recording of filamentary holograms. 相似文献
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Two original methods are proposed here for digital in-line hologram processing. Firstly, we propose an entropy-based method to retrieve the focus plane which is very useful for digital hologram reconstruction. Secondly, we introduce a new approach to remove the so-called twin images reconstructed by holograms. This is achieved owing to the Blind Source Separation (BSS) technique. The proposed method is made up of two steps: an Adaptive Quincunx Lifting Scheme (AQLS) and a statistical unmixing algorithm. The AQLS tool is based on wavelet packet transform, whose role is to maximize the sparseness of the input holograms. The unmixing algorithm uses the Independent Component Analysis (ICA) tool. Experimental results confirm the ability of convolutive blind source separation to discard the unwanted twin image from in-line digital holograms. 相似文献
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Akshay Sharma Gyanendra Sheoran Z.A. Jaffery Moinuddin 《Optics and Lasers in Engineering》2008,46(1):42-47
The basic problem in optical and digital holography is the presence of speckle noise in the reconstruction process, which reduces the signal-to-noise ratio (SNR). The presence of speckle noise is serious drawback in optical and digital holography since it substantially reduces the SNR in the reconstructed image. In this paper, we present wavelet filtering to improve SNR in the reconstructed images from digital holograms. Experimental results are presented. 相似文献
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We propose and experimentally demonstrate a new (to our knowledge) digital holographic method to reconstruct section images of objects with wavelength-dependent reflectivity. A number of holograms of an object are taken as the illumination angle of the laser beam with a specific wavelength is changed in regular intervals. The complex object fields reconstructed from the holograms are numerically superposed to show the image of a sliced section of the object, whose position and thickness can be chosen arbitrarily. By changing the wavelength of the illumination beam, wavelength-dependent section images can be obtained with our method. 相似文献
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《Ultrasonics》1986,24(2):59-65
For a thorough study of bubble dynamics in cavitation bubble fields one has to resort to holography to circumvent the problems caused by bubbles moving out of focus during their three-dimensional motion. The development and application of high speed holography and holocinematography in cavitation physics is reviewed in this paper. The state of the art is that several thousand holograms with frame size a few square millimetres can be taken at rates up to 300 000 per second. Digital image processing, a valuable tool which is used to cope with the huge information content of series of holograms, is discussed. Results on bubble dynamics obtained via holography are presented, in particular on shock wave emission and bubble oscillation, splitting and interaction in a sound field. Global field dynamics and streamer stability are also discussed. 相似文献
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Hongyan Li 《Optics Communications》2011,284(9):2268-23630
In on-axis lensless Fourier phase-shifting synthetic aperture digital holography, to compose all of the phase-shifting sub-holograms to a large synthetic aperture digital hologram effectively, firstly, the cross-correlation algorithm of the object waves is presented to correct the joint misplacement of the sub-holograms. Secondly, to make the phase-shifting synchronization matching of different sequence phase-shifting holograms, the cross-correlation algorithm of the phase-shifting holograms is employed. Compared with the traditional cross-correlation algorithm of the sub-holograms, the proposed approach makes the joint precision of the sub-holograms reach sub-pixel accuracy, and the resolution of the reconstructed image is improved significantly. In general, the proposed approach is effective in restraining the quality degradation of the synthetic reconstructed image that comes from the joint misplacement of the sub-holograms and the phase-shifting non-synchronization of the phase-shifting holograms. 相似文献
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P. W. Wachulak M. C. Marconi R. A. Bartels C. S. Menoni J. J. Rocca 《Opto-Electronics Review》2010,18(1):80-90
Holographic 2D/3D imaging with nanometer resolution using short wavelength extreme ultraviolet (EUV) light is presented in
this paper. Gabor’s holograms were recorded with a highly coherent table top EUV laser with different numerical apertures
demonstrating ultimately a spatial resolution of 46+/−2 nm, comparable with the illumination wavelength, in 2D holographic
imaging. Three dimensional images were obtained from a single high numerical aperture hologram recorded in a high resolution
photoresist and numerically reconstructed at different image planes, allowing numerical optical sectioning with a lateral
resolution ∼170 nm and depth resolution of 2.4 μm. The holograms were recorded in a high resolution photoresist and digitized
with an atomic force microscope. To assess the spatial resolution of the numerical reconstructions of the holograms a correlation
method was used. The algorithm allows for simultaneous estimation of the resolution and the feature size of the image under
analysis. 相似文献
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Binary computer-generated holograms for security applications from a synthetic double-exposure method by electron-beam lithography 总被引:3,自引:0,他引:3
We have developed a new multiplexing method for producing binary computer-generated holograms (CGH's) for security applications. This method is based on double recording of two types of coding method upon binary CGH's. The CGH synthesized by the proposed method can have multiple image planes from the region close to the hologram (image region) to infinity (Fraunhofer region) without severe degradation of reconstructed images in the image region. A CGH containing simultaneous image- and Fourier-type holograms is fabricated by electron-beam lithography. Some experimental results are presented. 相似文献
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Takashi Kakue Mitsuo Kuwamura Yuki Shimozato Tatsuki Tahara Yasuhiro Awatsuji Kenzo Nishio Shogo Ura Toshihiro Kubota Osamu Matoba 《Optical Review》2011,18(1):180-183
We propose an in-line color digital holography that can suppress a 0th-order diffraction image and a conjugate image. This
technique reconstructs the image of an object from two holograms that are formed at two different distances from the object
for each primary color. We numerically simulated the proposed technique and confirmed that it enabled the reconstruction of
higher-quality images of an object than the Fresnel transform alone, which is the simplest reconstruction algorithm in digital
holography. The effectiveness of the proposed technique was also quantitatively shown by evaluating the reconstructed images
using root-mean-square errors. Thus, it was confirmed that the proposed technique was capable of recording and reconstructing
both three-dimensional information and color information of an object. 相似文献
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The first holograms of bubble tracks in a bubble chamber have been recorded. Three-dimensional images have been reconstructed with a resolution of few microns. The technique provides new improvements to the visualization of short-lived particles. 相似文献
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The reconstruction of an in-line Fraunhofer (far-field) hologram is re-examined, and an analytical solution of the intensity distribution throughout the entire reconstructed image is presented. The solution bridges the gap between previously documented solutions which are limited to the plane-of-focus image and distant out-of-focus images. The analysis is motivated by a particle velocity measurement technique which attempts to distinguish the focussed image by photographic thresholding. The general methodology is presented for objects of one- and two-dimensional cross-section. Specific results are presented for the single exposure holograms of a long wire and a small particle of circular cross-section. The one-dimensional solution is verified experimentally. The results show precisely how the Fresnel diffraction term creates peaks in the intensity distribution, both upstream and downstream of the focussed image. This characteristic limits the resolution of methods which use thresholding as a means of distinguishing focussed images from their out-of-focus neighbors. 相似文献
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从线全息图分析彩虹全息 总被引:5,自引:3,他引:2
本文从彩虹全息固有的线全息图出发,不采用传统狭缝像的概念来分析彩虹全息的成像机理.论述了线全息图的宽度与再现像最小分辨距离及体视极限的关系;讨论了几种典型彩虹全息术中线全息图的特征及其对再现象的影响,提出并实现了不通过狭缝实像来观察再现像的新方法. 相似文献