单层光学薄膜中薄膜-衬底体系的三光束干涉效应

从高斯光束的传输规律出发,研究了单层光学薄膜中薄膜-衬底体系的反射光干涉问题.给出了聚焦激光束照射单层膜系时反射光干涉的光强分布,分析并讨论了干涉条纹的特点和几个主要因素对干涉条纹的影响.以ZnS薄膜-玻璃单层膜系和未蒸镀薄膜的同性质衬底为样品进行了实验,理论和实验测量结果一致.     

光学编码成像术中光源稳定性研究

针对光学编码成像的光源强度随时间波动对编码成像结果的影响,研究了编码机制对光源光强变化响应的表现,发现了阿达玛变换光学系统对光源强度波动的特异敏感性规律:像元强度改变量与光源光强波动量成比例;一个编码周期内光源光强的多次波动导致像元强度改变量按次累加但并不导致发散;各次源强度波动对像场强度改变量的分布具有循环性.采用数值模拟方法计算了与1×7阵列像场对应的7阶S矩阵编码成像,结果表明光源光强随时间的变化对编码成像质量有严重影响.指出了在编码成像系统中所用的光源的不稳定性应该受到的限制.     

基于彩色伪随机编码单幅图像的三维欧氏重构

文章针对机器视觉中彩色伪随机序列编码与灵活的预标定三维重构技术,研究了基于单幅编码图像的三维欧氏重构系统集成。先对CCD相机采集的编码图像进行必要的预处理,接着对其进行特征点检测与匹配,结合预先标定的LCD投影仪参数,利用层次化的三维欧氏重构理论,即可根据单幅图像恢复该三维场景的三维坐标数据,重构三维场景的三维形貌。     

An elementary quantum network of single atoms in optical cavities

Quantum networks are distributed quantum many-body systems with tailored topology and controlled information exchange. They are the backbone of distributed quantum computing architectures and quantum communication. Here we present a prototype of such a quantum network based on single atoms embedded in optical cavities. We show that atom-cavity systems form universal nodes capable of sending, receiving, storing and releasing photonic quantum information. Quantum connectivity between nodes is achieved in the conceptually most fundamental way-by the coherent exchange of a single photon. We demonstrate the faithful transfer of an atomic quantum state and the creation of entanglement between two identical nodes in separate laboratories. The non-local state that is created is manipulated by local quantum bit (qubit) rotation. This efficient cavity-based approach to quantum networking is particularly promising because it offers a clear perspective for scalability, thus paving the way towards large-scale quantum networks and their applications.     

Massively parallel manipulation of single cells and microparticles using optical images

The ability to manipulate biological cells and micrometre-scale particles plays an important role in many biological and colloidal science applications. However, conventional manipulation techniques--including optical tweezers, electrokinetic forces (electrophoresis, dielectrophoresis, travelling-wave dielectrophoresis), magnetic tweezers, acoustic traps and hydrodynamic flows--cannot achieve high resolution and high throughput at the same time. Optical tweezers offer high resolution for trapping single particles, but have a limited manipulation area owing to tight focusing requirements; on the other hand, electrokinetic forces and other mechanisms provide high throughput, but lack the flexibility or the spatial resolution necessary for controlling individual cells. Here we present an optical image-driven dielectrophoresis technique that permits high-resolution patterning of electric fields on a photoconductive surface for manipulating single particles. It requires 100,000 times less optical intensity than optical tweezers. Using an incoherent light source (a light-emitting diode or a halogen lamp) and a digital micromirror spatial light modulator, we have demonstrated parallel manipulation of 15,000 particle traps on a 1.3 x 1.0 mm2 area. With direct optical imaging control, multiple manipulation functions are combined to achieve complex, multi-step manipulation protocols.     

直流杂散电流干扰缓解方法及其适用性

通过室内模拟试验装置,研究源于强制电流阴极保护系统的直流杂散电流对外部无阴极保护管道干扰的缓解方法,包括跨接电阻法、牺牲阳极法和金属屏蔽线法。文中主要考察跨接电阻、牺牲阳极位置和材质、金属屏蔽线位置和连接方式等对不同干扰类型的缓解效果和规律,讨论不同缓解方法的适用性,并对不同干扰类型提出推荐方法及适用条件,可为实际工程应用提供借鉴。     

Quantum nonlinear optics with single photons enabled by strongly interacting atoms

The realization of strong nonlinear interactions between individual light quanta (photons) is a long-standing goal in optical science and engineering, being of both fundamental and technological significance. In conventional optical materials, the nonlinearity at light powers corresponding to single photons is negligibly weak. Here we demonstrate a medium that is nonlinear at the level of individual quanta, exhibiting strong absorption of photon pairs while remaining transparent to single photons. The quantum nonlinearity is obtained by coherently coupling slowly propagating photons to strongly interacting atomic Rydberg states in a cold, dense atomic gas. Our approach paves the way for quantum-by-quantum control of light fields, including single-photon switching, all-optical deterministic quantum logic and the realization of strongly correlated many-body states of light.     

Sub-poissonian loading of single atoms in a microscopic dipole trap.

The ability to manipulate individual atoms, ions or photons allows controlled engineering of the quantum state of small sets of trapped particles; this is necessary to encode and process information at the quantum level. Recent achievements in this direction have used either trapped ions or trapped photons in cavity quantum-electrodynamical systems. A third possibility that has been studied theoretically is to use trapped neutral atoms. Such schemes would benefit greatly from the ability to trap and address individual atoms with high spatial resolution. Here we demonstrate a method for loading and detecting individual atoms in an optical dipole trap of submicrometre size. Because of the extremely small trapping volume, only one atom can be loaded at a time, so that the statistics of the number of atoms in the trap, N, are strongly sub-poissonian (DeltaN2 approximately 0.5N). We present a simple model for describing the observed behaviour, and we discuss the possibilities for trapping and addressing several atoms in separate traps, for applications in quantum information processing.     

一种用于DSSS中抗单频干扰的判决反馈算法

为了降低噪声对判决算法的影响,将变步长LMS算法、动量算法与判决反馈算法相结合,提出了一种新的变步长动量判决反馈算法(Variab le step-size DFIS).变步长、动量算法特性保证了这种算法具有较快的收敛速度,同时由于降低了背景噪声对判决的影响,使得这种算法在抗单频干扰方面具有优势.理论分析和仿真结果表明该算法优于其他判决反馈抗干扰算法.     

Macaque monkeys categorize images by their ordinal number

The recall of a list of items in a serial order is a basic cognitive skill. However, it is unknown whether a list of arbitrary items is remembered by associations between sequential items or by associations between each item and its ordinal position. Here, to study the nonverbal strategies used for such memory tasks, we trained three macaque monkeys on a delayed sequence recall task. Thirty abstract images, divided into ten triplets, were presented repeatedly in fixed temporal order. On each trial the monkeys viewed three sequentially presented sample stimuli, followed by a test stimulus consisting of the same three images and a distractor image (chosen randomly from the remaining 27). The task was to touch the three images in their original order without touching the distractor. The most common error was touching the distractor when it had the same ordinal number (in its own triplet) as the correct image. Thus, the monkeys' natural tendency was to categorize images by their ordinal number. Additional, secondary strategies were used eventually to avoid the distractor images. These included memory of the sample images (working memory) and associations between sequence triplet members. Thus, monkeys use multiple mnemonic strategies according to their innate tendencies and the requirements of the task.     

基于单幅图片的唐代服饰三维重建

针对传统建模方法的局限性和对唐代服饰进行建模自身的特点,提出了一种将数字建模和物理建模相结合的基于单幅图片的唐代服饰的三维重建的方法。由于唐代历史悠久,遗留的下来的服装文物基本为二维水彩画,陶俑等,能从中提取的信息及其有限,因此利用Open CV的自动扫描技术和根据服装横截面近似椭圆的特性计算得出服装大致的数字模型,而数字模型只有服装的大致轮廓,无法呈现逼真的三维服饰,则再将数字模型的数据数据输入三维建模软件Maya中进行细节修改,并对其添加动力学特性,纹理贴图渲染。仿真结果显示三维重建出的唐代服饰模型,不仅逼真,而且效率高。     

影像的空间信息变化探测

为了解决影像空间信息变化探测中自动化程度和正确率均较低的问题,采用实验的方法探讨了基于属性、基于区域和基于像元的探测方法的原理,并结合专业软件ArcGIS对上述方法进行实验,取得了较好的实验结果.实验结果表明在自动发现的基础上辅以GIS、影像处理技术以及交互的方式进行信息的探测可以取得较高的探测精度和较快的探测方法.     

人脸图像年龄估计

为了解决人脸识别中识别率随年龄变化急剧下降的问题,提出了一种自动的年龄估计方法。通过年龄函数建立人脸特征和年龄之间的对应关系,人脸特征由形状特征和纹理特征组成。首先,通过改进的活动形状模型自动定位人脸形状特征点,再通过形状拉伸获得单纯的纹理图像,然后用主分量分析分别得到形状特征向量和纹理特征向量,合成作为人脸特征,最后,按照最优化的准则得到年龄函数,结合人脸变老方式的分类,自动估计年龄。实验结果表明,这种方法对年龄估计十分有效,平均200人的多年龄人脸数据库上的估计误差为1.1a。     

人脸图像年龄估计

为了解决人脸识别中识别率随年龄变化急剧下降的问题,提出一种自动的年龄估计方法。通过年龄函数建立人脸特征与年龄之间的对应关系,人脸特征由形状特征和纹理特征组成。首先,通过改进的活动形状模型自动定位人脸形状特征点,再通过形状拉伸获得单纯的纹理图像;然后用主分量分析分别得到形状特征向量和纹理特征向量,合成作为人脸特征;最后,按照最优化的准则得到年龄函数,结合人脸变老方式的分类,自动估计年龄。实验结果表明,这种方法对年龄估计十分有效,平均200人的多年龄人脸数据库上的估计误差为1.1 a。     

环F2+uF2循环码及其二元象

进一步研究了环F2 uF2上循环码的结构;通过定义该环上的Nechaev-Gray映射而得到了一类二元循环码;最后研究了该环上循环码与其剩余码以及挠码的关系。     

基于单模光纤偏芯结构的光纤干涉型高温传感器

利用单模光纤的偏芯结构,提出了一种光纤干涉型高温传感器.光在通过传感区域时存在纤芯模与包层模的干涉.当温度变化时,根据干涉谷对温度的敏感性,即可实现温度测量.此传感器可用于高温测量,当温度从400℃上升到750℃时,干涉谷波长变化了32.2 nm,温度灵敏度为0.092 nm/℃.     

基于图像的机器人运动序列生成

提出一种基于图像的运动序列生成技术 ,此项技术不需要已知目标物体及所在背景的 CAD模型 ,也不需要对摄像机进行标定。在样本图集的基础上 ,通过 Karhunen- L o-eve(K- L)变换得到图像的特征表示。建立了机器人关节角与图像特征之间的非线性关系。在机器人关节空间进行轨迹规划 ,最后生成关于机器人虚拟运动的图像序列。以 UP6机器人为目标物体 ,进行虚拟运动实验 ,得到 UP6机器人的虚拟运动 ,结果表明该技术方便有效     

纽结及其镜面像

给出了一种纽结的构造,它具有如下性质:对于该纽结的某一个图,当改变其中的一个交叉点时即可得其镜面像。使用纽结多项式及一些特殊构造,证明了这样的素纽结有无穷多个。