采用正交参考光束的全光学联想存储器

本文采用LiNbO_3晶体作为动态全息存储元件和相位共轭反射镜,实现了全光学联想存储器。提出了正交参考光束法存储图像,用于以上结构时,可使联想存储器的存储容量提高一倍。     

高速高精度体全息光学相关器

体全息光学相关器基于体光栅的布拉格选择性,在记录介质的共同体积中利用角度复用存储多幅图像。相关计算时,输入一幅图像可以并行输出所有的相关点,每个相关点的强度代表输入图像与对应库图像之间的内积值。分析了提高体全息光学相关器运算精度和速度的关键技术。总结了近年来采用散斑调制技术降低相关通道串扰,采用二维随机交错方法消除图案依赖行为,采用多样本并行估计方法提高并行运算精度,采用读写分离结构实观系统小型化集成等体全息光学相关器技术方面的研究进展。目前体全息光学相关器已经实现超过7500通道的并行运算能力,运算速度达到138GHz。系统在遥感图像匹配、指纹识别等领域的成功应用证明了其高速高精度运算能力。     

存储器、锁存器

Y2000-62079-331 0021069光存储:Optical storage[会,英]//1999 IEEE Confer-ence on Lasers and Electro-Optics.—331-335(F)本部分收录7篇论文摘要。题目是:双倍掺杂铌酸锂晶体中多路永久全息图象,铌酸锂晶体中用于光互联的热修复体相位全息.全息数据存储用新材料的分子机理和当前的困难,利用体全息的高密度、高性能数据存储,用于全息体存储器的倍频可调 Yb:YAG 微片激光器,用于全息记录和光数据存储的 Mn:YalO_3     

消息及其他

消息及其他光折变全息数据存储系统斯坦福研究组报导了据说是首例全数字多页全息数据存储器系统，可用以存储数字彩色图象和视频信息。用掺铁ＬｉＮｂＯ３晶体作存储介质，已把计算机硬盘上的数字图象和视频数据复制到全息系统上燃后再把文件从全息系统转回硬盘，并检验了...     

基于化学计量比Mg:Fe:LiNbO_3的全息存储系统

以K_2O为助熔剂,采用顶部籽晶熔融法成功地生长出近化学计量比Mg:Fe:LiNbO_3(Mg:Fe:SLN)晶体.测量了晶体的紫外吸收光谱及响应时间,且和同成分Fe:LiNbO_3(Fe:CLN)晶体作了比较.结果表明,Mg:Fe:SLN晶体更适于作为全息存储器来应用.针对全息存储中固有的高原生误码率问题,采用快速响应矩阵码(QR)编码技术对原始数据进行编码,缓解了对系统设计和部件质量等方面的压力.以Mg:Fe:SLN晶体作为存储介质,构建了体全息存储系统,将QR码编、译码技术用于包含音频和视频的多媒体数据的全息存储,重构数据能成功回放.     

光折变晶体体全息子波相关图象识别系统

基于光折变晶体体全息存储和子波相关理论 ,本文提出并构建了一个新型的多通道体全息子波相关识别系统。文中深入分析了引入子波变换对体全息相关器所产生的作用 ,给出了系统一次并行输出相关通道数目的估算方法及提高系统并行性能的主要途径。在人脸识别中的初步应用研究验证了系统的合理性和有效性。     

基于小波变换的体全息相关识别系统

在体全息相关识别系统中,如何改善相关峰质量是提高识别率的关键问题.该文选用的化学计量比Mg:Fe:LiNbO3晶体因其良好的光学均匀性,使系统的散射噪声大量减少.同时提出了一种小波多尺度变换法,对输入图像做边缘提取,保留不同图像间最具差异的平面波分量,滤除公共的0级平面波来改善相关峰的质量.以ORL标准人脸库中的图像作原始图像,建立了包含400幅全息图的相关识别系统,实验表明,该方法的相关峰锐利,旁瓣少,具有很强的抗噪能力,取得了良好的识别结果.     

光学多通道体全息快速目标识别技术

体全息存储技术是一种超越现有串行存储方式的并行存储技术,同时又兼备内容寻址的功能.能实现高密度、大容量、高传输率的数据存储及并行多通道光计算.利用体全息相关器作为基准图像库和粗处理微处理器,与传统光电系统相结合,可并行地进行实时图像与基准图像的相关匹配,快速进行复杂景象的搜索与识别,进行快速飞行目标的锁定和跟踪.由于匹配算法的并行性,可大大减小由于处理延迟而产生的跟踪误差.在高分辨率精准导航定位或侦察监视系统中,由于目标图像及图像库数据容量大,采用体全息存储相关技术结合DSP处理技术,对大幅面数据页在大规模图像库中进行进行快速搜索截获,可以将处理速度大为提高.文中简要介绍了体全息存储及相关识别的原理;多通道体全息存储快速目标识别的系统结构;提高体全息相关器通道密度的方法;提高识别精度的方法;基于体全息相关识别的图像预处理算法;基于体全息存储技术的地形匹配技术与目标跟踪技术;最后展望了光学多通道体全息快速目标识别技术在以大数据量,高速,精准为特征的导航定位或侦察监视等武器平台中的应用前景.     

高密度盘式全息存储及其热固定的实验研究

利用空间-角度复用方式与球面参考波相结合的全息复用存储技术，在盘状LiNbO3：Fe晶体单一扇形区域内成功存储10000幅高分辨率图像，存储面密度达33．7bits／μm^2。在此基础上，将分批热固定的方法应用于盘式体全息存储，分4批次存储了5000幅高分辨率图像，从而将存储面密度进一步提高到50bits／μm^2。会聚的球面参考波及优化的光路配置减小了参考光的反射光斑尺寸，同时也减少了有害的杂散光从晶体表面反射进入成像光路，保证存储图像能得到良好的再现。     

光折变晶体中的盘式三维全息存储

利用空间-角度复用和球面参考波技术在盘式光折变铌酸锂晶体中存储了2000 幅高分辨率图像,并获得满意的再现。给出了选取盘面旋转角度等主要参数的基本依据和存储器达到的主要性能指标。研究表明,实验结果与理论分析符合得很好,证实了全息光盘在大容量信息存储方面的可行性。     

Recognition and storage of metal heart marker position from biplane X-ray images at video rates

We have developed a semiautomatic microcomputer-based instrument for recording the three-dimensional positions of metal heart markers from biplane X-ray images at 60 frames/s. This instrument eliminates the need for film processing and tedious digitizing by human operators. Markers are recognized electronically on each video line using criteria of density changes (edge detection), size, and location. Only the X-Y or Z-Y location of each marker is stored. This transformation of the gray scale image into a list of coordinates achieves a data compression of 250 fold. A small fast memory and a second large one provide an effective slowing of the high peak rates of the marker location data. This buffering allows the marker coordinates to be permanently stored on a floppy disk for later analysis. Four s of data can be stored in one burst when 20 markers are used. The instrument was designed to measure the pumping action of the heart through the calculation of instantaneous local strain, wall thickness, and chamber volume. This paper compares alternate recognition strategies and storage methods.     

光伏电场对大容量体全息存储的影响与抑制

Fe∶LiNbO3 晶体有很强的光伏效应。通过理论分析和实验验证 ,在全息存储过程中 ,光伏效应会在晶体表面产生非均匀的光伏直流电场 ,它不仅降低了材料的动态范围 ,并且引起了Bragg失配 ,使得再现图像失真。消除光伏直流电场的方法是使用电解质溶液短路晶体表面电荷。采用这种方法 ,在晶体一个公共区域内 ,可存储 1 0 0 0幅能够清晰再现的全息图像     

液晶运动图像投影仪

由产生图像的液晶显示元件，投影图像的光学机构和显示屏即构成液晶运动图像投影仪。液晶材料可将图像信息暂时储存，称为储存效应。连续图像投影方法是，在液晶材料中产生图像并暂时储存起来，将投影光源对准液晶材料，然后作为液晶透射或散射光函数的图像投影到投影屏上，可连续地产生投影图像。     

Low Power Techniques for Gray Shades in Liquid Crystal Displays

The largest transition in the select waveform of successive approximation technique is eliminated to reduce power dissipation in liquid crystal displays. Power dissipation in the driver circuit is analyzed for gray scale images by considering three select sequences. They are compared and a new select sequence is proposed to achieve low power dissipation. An additional pulse is introduced in the select waveform to reduce peak amplitude of select and data waveforms to achieve a low supply voltage for the driver circuit.     

Ce∶Ho∶LiNbO_3晶体的全息存储特性的研究

报道了Ｃｅ：ＨＯ：ＬｉＮｂＯ３晶体的生长，研究了晶体的衍射效率、存储时间、图像质量等全息存储性能。用Ｃｅ：ＨＯ：ＬｉＮｂＯ３晶体作记录介质，实现了实时关联存储。     

Bistable and Reconfigurable Photonic Crystals—Electroactive Shape Memory Polymer Nanocomposite for Ink‐Free Rewritable Paper

Paper has remained the world's most‐widely accessible information medium even as sustainable and reusable paper replacements have attracted increasing attention. Here, an ink‐free rewritable paper concept is developed that combines recent developments in photonic crystals, shape memory polymers, and electroactive polymers in a nanocomposite that matches the benefits of paper as a zero‐energy, long‐term data storage medium, but provides the additional advantage of rewritability. The rewritable paper consists of a ferroferric oxide‐carbon (Fe₃O₄@C) core–shell nanoparticle (NP)‐based photonic crystal embedded in a bistable electroactive polymer (BSEP). Electrical actuation induces large deformation in the z‐axis of the nanocomposite, creating distinct color change in the actuated area. This nanocomposite stores high fidelity color images without inks, the images remain stable after more than a year of storage in ambient conditions, and the stored images can then be rewritten over 500 times without degrading. A seven‐segment numerical display is also demonstrated.     

A 0.5-GHz CMOS digital RF memory chip

In the application of digital RF memory (DRFM) chips for radar jamming, an RF signal is sampled, stored in random access memory (RAM) and later recreated from the stored data. A CMOS (l/SUB eff/=1 /spl mu/m) DRFM chip is described that integrates static RAM, control circuitry, and two channels of shift registers on a single chip. The sample rate achieved was 0.5 GHz. VLSI density was made possible by the low-power dissipation of quiescent CMOS circuits. An 8K RAM prototype chip has been built and tested.     

Convergence in neural memories

One of the simplest optimization problems solved by Ising spin models of neural memory is associative memory retrieval. The authors study deterministic convergence properties of the Hopfield synchronous retrieval algorithm for such models. In this case a memory, stored in the network by an appropriate choice of connections, is retrieved by setting the neural outputs to the binary pattern of the recall key (probe) and allowing the network to converge to a stable state. Precise conditions are developed that ensure that all stored memories are fixed points of the retrieval algorithm. An orthogonality-nearness criterion is then obtained for a memory probe itself to be a stationary point and thus outside the error-correcting capability of the memory. A local stability result quantifies the spatial relationship required for fast convergence