共查询到20条相似文献,搜索用时 31 毫秒
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相移同轴无透镜傅里叶数字全息的分析与实验 总被引:12,自引:4,他引:8
应用菲涅耳衍射和全息理论,详细分析了无透镜傅里叶变换数字全息图的记录、再现方法和再现像的特点,分析了相移数字全息图的记录和再现方法,并进行了相应的实验验证。结果表明:直接对无透镜傅里叶数字全息图进行傅里叶逆变换可同时得到与物体完全相同的再现像及其共轭像;同轴无透镜傅里叶数字全息术能最大程度满足CCD对采样条件的要求,从而可以增大记录物体的尺寸,减小记录距离,明显提高再现像的清晰度和分辨率;相移数字全息术能有效地消除数字再现光场中的零级光场和共轭像,显著提高再现像的信噪比。条件许可时,相移同轴无透镜傅里叶数字全息术是目前解决数字全息术中再现像的分离与满足采样条件之间矛盾的最佳方法。 相似文献
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Pattern recognition by use of polarimetric phase-shifting digital holography is presented. Using holography, the amplitude distribution and phase difference distribution between two orthogonal polarizations of three-dimensional (3D) or two-dimensional phase objects are obtained. This information contains both complex amplitude and polarimetric characteristics of the object, and it can be used for improving the discrimination capability of object recognition. Experimental results are presented to demonstrate the idea. To the best of our knowledge, this is the first report on 3D polarimetric recognition of objects using digital holography. 相似文献
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Quantitative detection and compensation of phase-shifting error in two-step phase-shifting digital holography 总被引:1,自引:0,他引:1
Phase-shifting digital holographic technique is a powerful tool for the measurement of various physical parameters, such as object deformation and liquid or cell’s refractive index change. However, for an accurate measurement, phase-shifting error in the reference wave path is still a major issue. In this paper, three novel and simple algorithms are proposed to quantitatively detect and correct phase-shifting error for a pure phase object in two-step phase-shifting digital holography. Influence of phase-shifting error is illustrated, and the effectiveness of the proposed algorithms is demonstrated by numerical simulation results. 相似文献
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Tatsuki Tahara Yasuhiro Awatsuji Atsushi Kaneko Takamasa Koyama Kenzo Nishio Shogo Ura Toshihiro Kubota Osamu Matoba 《Optical Review》2010,17(3):108-113
We propose an optical implementation of a parallel two-step phase-shifting digital holography that utilizes a polarization
technique. The implementation uses a phase-shifting array device consisting of a retarder array attached to an image sensor,
and does not require the optical system to image the phase-shifting array device onto the image sensor required for the previously
reported optical implementation of the parallel two-step phase-shifting digital holography. Then, the proposed implementation
is essentially simple to align and compose. A preliminary experiment showed that the parallel two-step phase-shifting digital
holography based on the proposed implementation can remove the conjugate image clinging to the image reconstructed by Fresnel
transform alone with DC term suppression. Also, when the reconstruction distance was changed, the qualities of the reconstructed
images were quantitatively evaluated by using normalized root-mean-square error. It was clarified that the proposed implementation
was superior to other parallel phase-shifting digital holographies and Fresnel transform alone. Thus, the validity of the
proposed implementation was confirmed. 相似文献
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We present a digital holography microscopy technique based on a parallel-quadrature phase-shifting method. Two π/2 phase-shifted holograms are recorded simultaneously using polarization phase-shifting principle, slightly off-axis recording geometry, and two identical CCD sensors. The parallel phase-shifting is realized by combining circularly polarized object beam with a 45° degree polarized reference beam through a polarizing beam splitter. DC term is eliminated by subtracting the two holograms from each other and the object information is reconstructed after selecting the frequency spectrum of the real image. Both amplitude and phase object reconstruction results are presented. Simultaneous recording eliminates phase errors caused by mechanical vibrations and air turbulences. The slightly off-axis recording geometry with phase-shifting allows a much larger dimension of the spatial filter for reconstruction of the object information. This leads to better reconstruction capability than traditional off-axis holography. 相似文献
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相移数字全息中的相移准确性决定了重建结果的质量,本文提出了在二步相移数字全息中实现准确相移的方法.该方法使用数字电压源开环控制普通的压电陶瓷微位移器,通过连续以微小的间隔来改变施加在压电陶瓷微位移器上的电压,可以获得一系列对应于不同相移角的全息图像,进而可以利用这些全息图像重建出来物光波在全息面上的强度分布.实验中采用已被CCD直接记录的物光波在全息面上的强度分布作为标准来评价前面重建结果的质量,计算了这些重建结果和评价标准之间的相关系数,结果表明相关系数达到最大时对应的全息图具有准确的相移角π/2.实验中比较了使用所确定准确相移角和理论相移角分别重建出来物光波的质量,计算机模拟和实验的结果证实了该方法的有效性. 相似文献
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In phase measurement or digital holography for phase-shifting interferometry, the key role is the variation of reference light wave and recover algorithm based on interferograms and reference phase, so the calculation result is directly affected by phase-shift accuracy. However, because of the errors of nonlinear and other random factors, it is difficult to control the actual phase-shifting amount accurately. In this paper, we aim to propose an efficient method for phase-shifting interferometry which does not require accurate initial estimation of phase-shift amounts, only a few pixels with several randomly shifted interferograms are sufficient for accurate extraction of phase information. This method has reduced the dependence of reference phase, and can obtain phase-shifting amount directly without using complex revised algorithm for correcting phase-shifting nonlinear errors. 相似文献
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The digital holography with single phase-shifting operation has been studied. Experimental results and computer-simulated work are presented. The phase-shifting error makes the intensity of primary image decrease and the conjugate image appear in reconstruction. The explicit equation for explaining these effects is given. The calculation of the normalized intercorrelation peak between the input and the reconstruction for different algorithms shows that, when the phase-shifting operation is the main error source, the quality of the image reconstructed from the digital holography with single phase-shifting operation is favorable. 相似文献
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Three-dimensional-object recognition by use of single-exposure on-axis digital holography 总被引:6,自引:0,他引:6
On-axis phase-shifting digital holography requires recording of multiple holograms. We describe a novel real-time three-dimensional- (3-D-) object recognition system that uses single-exposure on-axis digital holography. In contrast to 3-D-object recognition by means of a conventional phase-shifting scheme that requires multiple exposures, our proposed method requires only a single digital hologram to be synthesized and used to recognize 3-D objects. A benefit of the proposed 3-D recognition method is enhanced practicality of digital holography for 3-D recognition in terms of its simplicity and greater robustness to external scene parameters such as moving targets and environmental noise factors. We show experimentally the utility of the single-exposure on-axis digital holography-based 3-D-object recognition method. 相似文献
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Peng Xia Tatsuki Tahara Takashi Kakue Yasuhiro Awatsuji Kenzo Nishio Shogo Ura Toshihiro Kubota Osamu Matoba 《Optical Review》2013,20(2):193-197
To improve the quality of reconstructed images, we apply bicubic interpolation and B-spline interpolation to parallel phase-shifting digital holography for the first time. The effectiveness of bilinear interpolation, bicubic interpolation, and B-spline interpolation in parallel phase-shifting digital holography is shown by a numerical simulation. In the simulation result, the application of bicubic interpolation and B-spline interpolation succeeded in decreasing the rootmean- square error of the reconstructed image by 12.6 and 11.9%, respectively. 相似文献
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A lensless, coherent optical microscope is described that uses a version of phase-shifting digital holography (PSDH) in conjunction with a field backpropagation algorithm to form coherent images of transmission-type objects. The PSDH is implemented by use of only two reference waves, in contrast with the usual implementation that requires four quadrature phase-shifting reference waves. Therefore only two digital holograms need to be recorded, and the complexity of the microscopic system is reduced. Experimental results are presented that compare images generated from conventional Gabor digital holography, two-reference-wave PSDH, and conventional white-light microscopy. 相似文献
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一种实现单步相移无透镜傅里叶同轴数字全息的倒频谱技术 总被引:1,自引:1,他引:0
在数字全息技术中无透镜傅里叶同轴数字全息具有高分辨,再现速度快等优点,因此有着广泛的应用前景,但它也存在再现像与直透光场及其共轭像重叠,较难分离的缺点。针对这一问题,在分析了无透镜傅里叶同轴数字全息图记录和再现原理的基础上,提出了单步相移倒频谱技术,并在理论上分析了该技术对分离出清晰再现像的可能性和该技术适用的关键条件。通过仿真实验进行了验证,结果表明:单步相移倒频谱技术能够较好地解决无透镜傅里叶同轴数字全息技术中再现像与直透光场及其共轭像重合这一困难,得到清晰的再现像;同时给出了实际实验中单步相移倒频谱技术能够适用的条件参数,这为后面的进一步实验提供了参考依据。 相似文献
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To simplify the reconstruction calculation of a large-aperture digital hologram we propose a novel Fourier-transformation reconstruction algorithm. When the reconstructed wave is the same as or similar to the reference wave, the higher-order phase term of reconstruction can be compensated for. For example, the variation between the higher-order phase term and the aperture angle with a different field of view in in-line phase-shifting digital holography is analyzed. 相似文献
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This work proposes to obtain surface contouring by phase-shifting real-time holography using photorefractive sillenite crystals which provides the surface contouring from a change in phase of wavefront of the object illumination beam. The real-time holography using the photorefractive Bi12SiO20 crystal and the four-frame phase-shifting technique was used to obtain the phase map, this map was filtered by an anisotropic sin/cos filter and the unwrapping process used was the cellular-automata technique. We obtained experimental results of the surfaces of the large objects with real discontinuities, and these results agree with the dimensions of the object. 相似文献