共查询到20条相似文献,搜索用时 15 毫秒
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实验研究了基因改性菌紫质BR_D96N薄膜在不同偏振光记录下的全息存储特性,比较了不同 偏振态记录光和读出光对衍射像光强及信噪比的影响. 实验结果表明,与其他偏振全息记录 相比,正交圆偏振光记录可实现衍射光偏振状态与散射噪声偏振状态的分离,得到高信噪比 的衍射像,同时还具有高的衍射效率. 以 He_Ne 激光器(633nm,3mW)为记录和读出光源 ,用空间光调制器作为数据输入元件,CCD作为数据读出器件,采用傅里叶变换全息记录的 方法,在 BR_D96N 薄膜样品60μm×42μm的面积上进行了正交圆偏振全息数据存储,达到 了2×108bit/cm2的存储面密度,并实现了编码数据的无误读出与 还原.
关键词:
菌紫质
偏振全息
光致变色
光致各向异性
高密度光存储 相似文献
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Capacities for angular and wavelength multiplexed holographic data storage systems are considered. Limitations due to the spatial resolution of the recording and reconstructing fields and to the holographic recording process are derived. 相似文献
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We present a technique that enables true associative data search in phase-encoded volume holographic storage systems. The
technique overcomes crucial shortcomings related to the only two methods proposed for associative searches in phase-encoded
systems so far. An additional interferometric readout during content addressing is utilized to ascertain the cross-correlations
between an input information and all data pages that are recorded by superposition in one location of the storage media. We
present experimental investigations and thoroughly discuss the reliability of the technique. Under realistic conditions the
inevitable normalization procedure, used to determine absolute correlation values, as well as the probability of small correlation
values crucially affect the capabilities of associative search in phase-encoded holographic storage systems.
PACS 42.30.-d; 42.40.Pa; 42.79.Hp 相似文献
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To read out correct data from shift-multiplexed holographic data storage, we propose a novel method of pixel matching by use of a tiny plane-parallel refraction plate placed in the path of converging readout beams. Tilting the refraction plate produces a shift in the lateral position of the readout beam incident upon the holographic storage disk, leading to compensation for pixel-mismatch errors by an improvement in bit-error rate of 3 orders of magnitude. 相似文献
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We describe what we believe to be a novel postprocessing algorithm for compensating for misregistrations between a detector array and the coherent image of a pixelated two-dimensional data page. A lookup table of baseline local offsets is combined with the dynamically measured global offset of the received data page, producing an estimate of the total lateral shift of each small block of pixels. A serial algorithm then reallocates the appropriate portion of the signal detected by each pixel to its neighbors, accounting for both the linear and the quadratic contributions introduced by coherent illumination of square-law detectors. This procedure can relax the tight constraints on page registration, optical distortion, and material shrinkage that currently hamper page-oriented holographic storage systems. Experimental results from a pixel-matched 1-Mpixel volume holographic system are presented, showing an increase in position tolerance (for a raw bit-error rate <10(-3)) from +/-16% to +/-40% of the pixel pitch. 相似文献
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The degradation of SNR caused by the higher uniaxial crystalline anisotropy field (Hk) of medium and small write fields of narrower write width is one of the problems for achieving higher areal density. The SNR dependence on Hk of a medium with different write fields of head using the discrete track medium (DTM) is investigated by using micromagnetics simulation. As a result, the curves of SNR as a function of Hk have peak values. In DTM, the peak values of SNR are almost constant at any Hk of the medium and different write fields. Higher SNR is realized even at low Hk and small write field in DTM. 相似文献
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Holographic data storage system is a candidate for the information recording due to its large storage capacity and high transfer rate. We propose an unequally spaced four levels phase encoding in the holographic data storage system here. Compared with two levels or three levels phase encoding, four levels phase encoding effectively improves the code rate. While more phase levels can further improve code rate, it also puts higher demand for the camera to differentiate the resulting smaller grayscale difference. Unequally spaced quaternary level phases eliminates the ambiguity of pixels with same phase difference relative to reference light compared to equally spaced quaternary levels. Corresponding encoding pattern design with phase pairs as the data element and decoding method were developed. Our encoding improves the code rate up to 0.875, which is 1.75 times of the conventional amplitude method with an error rate of 0.13 % according to our simulation results. 相似文献
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Phenanthrenequinone-doped poly(methyl methacrylate) photopolymer bulk for volume holographic data storage 总被引:1,自引:0,他引:1
We present the design and fabrication of a phenanthrenequinone-doped poly(methyl methacrylate) photopolymer material. Large blocks of samples were made, and the material showed negligible shrinkage after optical exposures. We recorded and reconstructed 250 holograms at a single spot, using a 1-cm(3) block. 相似文献
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Distortions in pixel-matched holographic data storage due to lateral dimensional change of photopolymer storage media 总被引:2,自引:0,他引:2
Dimensional changes in polymerizable storage materials during exposure are a source of pixel misregistration in digital holographic storage. Lateral shrinkage or expansion of photopolymer recording materials can be deduced from quantitative measurement of the shift and the magnification errors of reconstructed holograms. 相似文献
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We demonstrate shift-multiplexed holographic storage of 180 digital data pages with low symbol-error rates in a thick (250 μm) SiO2 nanoparticle-polymer composite film using step-growth thiol-ene photopolymerization. A two-dimensional 2:4 modulation code was employed for formatting digital data pages in order to reduce the average intensity of code block without decreasing the coding efficiency. This study clearly shows the feasibility of the thiol-ene based nanoparticle-polymer composite system as a holographic data storage medium. 相似文献
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To compensate misalignments between a detector array and a spatial light modulator (SLM) in page-oriented holographic data storage, a method based on a three-pixel model is proposed. Three neighboring pixels in one-dimensional direction on the SLM that make contributions to the center pixel on the detector are considered in the three-pixel model. Recursive solutions are carried out to recover the true values of the SLM pixels. Both simulation and experimental results show that the signal-to-noise ratio (SNR) can be doubled approximately by use of the compensation method based on the three-pixel model. The proposed method is appropriate for relatively small apertures, and has the similar effects with the equalization method, which effectively improves the SNR. 相似文献
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Holographic data storage is being widely studied for the purpose of developing next-generation large optical memories. A prospective
use of this type of memory is in building image archives in large-scale data centers. In particular, demand for energy conservation
at data centers, and therefore for holographic data storage, is growing. In holographic data storage, interference between
bits occurs owing to wave aberration in the optical system, shrinkage of the medium, and crosstalk noise from neighboring
holograms during multiplex recording; as a result of the interference, the reproduced image deteriorates and the bit error
rate (BER) increases. In this study, to reduce the BER in both off-axis-type recording and coaxial-type recording, a two-dimensional
finite impulse response (FIR) filter is applied to a reproduced image that has been recorded by angle multiplex recording
and shift multiplex recording. First, for the optimization of the FIR filter coefficients, the linear minimum mean square
error (LMMSE) method is applied; this method optimizes the coefficients by reducing the BER. Furthermore, for evaluating the
optimization performance of the LMMSE method, the optimization performance is compared with that of the real-coded genetic
algorithm (RCGA), which has the capability to search a wide range of coefficients. The optimization by the LMMSE method has
been found to be excellent for off-axis-type recording but not for coaxial-type recording. It is speculated that this is because
of the brightness irregularity in the reproduced image, resulting from crosstalk. On the other hand, a marked reduction in
the BER is observed using the RCGA, despite the brightness irregularity. In this study, the effectiveness of the LMMSE method
for signals recorded by coaxial-type recording, in which large brightness irregularity is expected, is examined using automatic
gain control (AGC). It is found that the application of AGC reduces the BER even in the case of coaxial-type recording. 相似文献
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Yuta Goto Atsushi Okamoto Masanori Takabayashi Kazuhisa Ogawa Akihisa Tomita 《Optical Review》2018,25(5):549-554
We experimentally implemented and proved the concept of multiplexing and demultiplexing in digital images using virtual phase conjugation, which was proposed in our previous study. In the experiment, we concluded that two digital images multiplexed in a single signal beam are recorded in a holographic medium, and these images are independently and successfully reproduced. In this method, the digital images are multiplexed by superimposing them on a complex amplitude, and not using volume hologram’s multiplexing. Thus, the exposure amount in the holographic medium is constant regardless of the number of multiplexing of digital images, and the method has great potential for achieving high recording density. 相似文献
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Katano Yutaro Nobukawa Teruyoshi Muroi Tetsuhiko Kinoshita Nobuhiro Ishii Norihiko 《Optical Review》2021,28(6):662-672
Optical Review - We developed a modulation code using a complex amplitude and established a method to demodulate the code based on a convolutional neural network (CNN) for holographic data storage.... 相似文献
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Emerging networks and applications require enormous data storage. Holographic techniques promise high-capacity storage, given resolution of a few remaining technical issues. In this paper, we propose a technique to overcome one such issue: mitigation of large magnitude peaks in the stored image that cause material saturation resulting in readout errors. We consider the use of ternary data symbols, with modulation in amplitude and phase, and use a phase mask during the encoding stage to reduce the probability of large peaks arising in the stored Fourier domain image. An appropriate mask is selected from a predefined set of pseudo-random masks by computing the Fourier transform of the raw data array as well as the data array multiplied by each mask. The data array or masked array with the lowest Fourier domain peak values is recorded. On readout, the recorded array is multiplied by the mask used during recording to recover the original data array. Simulations are presented that demonstrate the benefit of this approach, and provide insight into the appropriate number of phase masks to use in high capacity holographic data storage systems. 相似文献
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利用耦合波理论对体全息存储角度复用方式的基本原理进行了讨论,分析了对称写入、非对称写入及邻面写入等不同光路几何配置对角度复用度的影响。考虑存储介质临界角的限制,推导出最大角度复用度的计算公式。理论分析及数值模拟表明:非对称入射光路比对称入射光路更有利于提高系统的角度复用度;邻面入射光路的角度复用度最高且与参考光入射角改变量成正比,邻面入射光路是最佳的角度复用存储光路。 相似文献