共查询到20条相似文献,搜索用时 15 毫秒
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Multilayer volume holographic optical memory 总被引:3,自引:0,他引:3
We demonstrate a scheme for volume holographic storage based on the features of shift selectivity of a speckle reference-wave hologram. The proposed recording method permits more-efficient use of the recording medium and yields greater storage density than spherical or plane-wave reference beams. Experimental results of multiple hologram storage and replay in a photorefractive crystal of iron-doped lithium niobate are presented. The mechanisms of lateral and longitudinal shift selectivity are described theoretically and shown to agree with experimental measurements. 相似文献
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We propose a method of reconstructing an image from a volume hologram at a wavelength different from the recording one. Spectrally broad but spatially coherent light was used as a probe beam. Each angular spectral component of the recorded hologram could be Bragg matched at one particular wavelength within the broadband spectrum. We experimentally demonstrated that a whole image could be reconstructed by using polychromatic light, whereas only a partial image was obtained by using single-mode laser light. We discuss the required bandwidth of the probe beam and the deformation of the reconstructed image. 相似文献
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A method of reconstructing positive and negative images from Fourier holograms recorded without the dc components is demonstrated by use of a coaxial holographic storage system. Reconstructed images are obtained by adding a phase-modulated dc component of the signal beam on reading. Contrast reversal of the reconstructed images can be achieved by reversing the readout reference pattern. This method can realize not only optical noise reduction but also less consumption of the dynamic range of the recording medium, potentially contributing to increasing the number of multiplexed holograms. 相似文献
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Romuald Pawluczyk 《Optics Communications》1973,7(4):366-370
Some experimental results relating to the coherent noise elimination in a holographic microscope are presented. The method proposed is also useful in the field of holographic microinterferometry. 相似文献
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The anisotropic Bragg diffraction of the volume holographic gratings in photorefractive crystals are investigated based on the model of anisotropic coupled-wave theory. The effect of the initial intensity ratio and the recording angles of the two recording waves on the anisotropic Bragg diffraction properties is discussed. It is shown that both the ratio of the initial intensity and the incident angles of the recording waves are selective action for the anisotropic Bragg diffraction efficiency of the volume holographic gratings, while these two recording conditions are not selective action for the isotropic Bragg diffraction. Furthermore, the Bragg phase matching condition of anisotropic diffraction is analyzed when the recording angles change. 相似文献
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《Physics letters. A》2001,278(6):325-330
The problem of memory of past is discussed for a Langevin particle subject to Gaussian noise of a general type. The most probable trajectories of a particle are found and a generalisation of the Girsanov formula is proposed. 相似文献
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The imaging capability of spatially distinct and independent sub-channels in holography has been experimentally investigated. It is shown that images synthesized from sub-channel images may, under certain conditions, be comparable to full channel images, and that, when it is not so, the synthesized images may still be useful. 相似文献
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反射式全息滤光片背景噪声的抑制 总被引:1,自引:0,他引:1
与传统的干涉滤光片相比,背景噪声高是全息滤光片的主要缺点.本文介绍了用倾斜条纹抑制全息滤光片背景噪声的方法,可以收到较好的效果. 相似文献
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Yasuda S Ogasawara Y Minabe J Kawano K Furuki M Hayashi K Haga K Yoshizawa H 《Optics letters》2006,31(11):1639-1641
A technique for reconstructing positive and negative images from an identical intensity-modulated hologram is demonstrated theoretically and experimentally by use of a coaxial holographic storage system. Negative images are obtained by adding a phase-modulated dc component of signal beam on reading. By comparing positive and negative images, the bit error rate (BER) is improved by two orders of magnitude. This technique can reduce optical noise of reconstructed images to attain low BERs. 相似文献
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We consider stochastic differential equations of the Langevin type in which the noise enters nonlinearly. In particular we study quadratic gaussian noise and we derive equations for the probability density under different approximations. In the limit of small intensity and small correlation time of the noise we obtain a Fokker-Planck equation which accounts for the main effects of the nonlinear noise. We present some examples and we discuss the consequences of our results in the analysis of an electrohydrodynamic instability in liquid crystals in the presence of external noise. 相似文献
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Yukako Takizawa Yoichi Kitagawa Tetsuya Matsumoto Akio Mizuno Takaharu Sato Osamu Matoba 《Optical Review》2011,18(1):187-190
Volume holographic optical element (VHOE) for imaging under white light illumination is integrated with imaging elements and
background noise reduction filter. An integrated VHOE and the band pass filter which is optimized to the VHOE can develop
the optical setup for a wearable eye-gaze detection system. An integrated VHOE is fabricated in photopolymer and then the
effects of noise reduction filters as a function of the direction of the incident plane wave into an image sensor are evaluated.
Experimental results show that the background noise reduction filter should be designed to reduce the incident light with
wide direction of the transmitted light. 相似文献
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On small scales spacetime can be understood as some kind of spacetime foam of fluctuating bubbles or loops which are expected
to be an outcome of a theory of quantum gravity. One recently discussed model for this kind of spacetime fluctuations is the
holographic principle which allows to deduce the structure of these fluctuations. We review and discuss two scenarios which
rely on the holographic principle leading to holographic noise. One scenario leads to fluctuations of the spacetime metric
affecting the dynamics of quantum systems: (i) an apparent violation of the equivalence principle, (ii) a modification of
the spreading of wave packets, and (iii) a loss of quantum coherence. All these effects can be tested with cold atoms. 相似文献
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Effect of excess noise on continuous variable entanglement sudden death and Gaussian quantum discord 下载免费PDF全文
A symmetric two-mode Gaussian entangled state is used to investigate the effect of excess noise on entanglement sudden death and Gaussian quantum discord with continuous variables. The results show that the excess noise in the channel can lead to entanglement sudden death of a symmetric two-mode Gaussian entangled state, while Gaussian quantum discord never vanishes. As a practical application, the security of a quantum key distribution (QKD) scheme based on a symmetric two-mode Gaussian entangled state against collective Gaussian attacks is analyzed. The calculation results show that the secret key cannot be distilled when entanglement vanishes and only quantum discord exists in such a QKD scheme. 相似文献
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Yeh-Wei Yu 《Optics Communications》2010,283(20):3895-3900
A paraxial equation for calculating pixel-based 2-D shifting selectivity of collinear holographic storage system is proposed. The equation shows that the broader reference pattern makes high shifting selectivity. In addition, both amplitude and phase modulation make no obvious change in shifting selectivity so shifting selectivity is not affected through advanced design of reference pattern. Besides, a simplified formula based on a point signal is proposed, which shows a clear physical insight that the shifting selectivity is the square of Fourier transform of the intensity distribution of reference pattern and does not depend on thickness of the disc when a point signal is applied. 相似文献