摆镜式激光通信终端光束指向与粗跟踪特性

基于两正交旋转轴的单平面镜（摆镜式）激光通信终端的粗跟踪问题,提出了一种求解光束指向的法矢量求解算法,给出了该类型通信终端的粗跟踪算法。采用矢量反射定律和矩阵旋转变换规律,理论推导了摆镜的光束指向模型和跟踪模型,对比分析了不同安装方式对光束指向和畸变的影响,并对模型分别进行了建模仿真和实验研究。结果表明:光束传输模型和粗跟踪模型的精度优于3 μrad,所研制的摆镜式激光终端粗跟踪精度,最大误差优于15.5 μrad (3σ),均方根误差优于10.5 μrad,满足激光通信终端对高精度粗跟踪的技术要求。该研究工作对摆镜式扫描系统的光束指向分析和激光终端粗跟踪具有借鉴意义。     

船-岸无线激光通信实验

针对船载平台的特性设计了激光光束跟踪控制策略,并根据船-岸激光通信的特点,设计了155Mbit/s岸上通信终端和船载通信终端完成船-岸激光通信跟踪实验。其中船载终端x轴跟踪残差为3.5μrad(σ),y轴为6.7μrad(σ);平均接收光功率为-29.76dbm,标准差0.35dbm。岸上终端x轴跟踪残差为1.7μrad(σ),y轴为3.9μrad(σ);平均接收光功率为-28.18dbm,标准差0.26dbm。实验验证了该跟踪控制策略适用于船载激光通信。     

空间激光通信单探测器复合跟踪控制技术研究

空间激光通信终端伺服系统是一种高精度的跟踪机构,在扰动条件下,通信系统对跟踪系统的稳定性及精度提出了较高的要求。本文主要介绍了激光通信伺服系统的复合跟踪技术,详细论述了单探测器复合跟踪方式的选择以及激光通信伺服系统的控制流程。最后,在振动平台上进行了粗精复合的激光跟踪实验。实验结果显示,当通信终端系统跟踪最大振动加速度为0.22°/s2的振动平台时,跟踪目标平稳性较好,单独采用粗跟踪时误差为60 μrad,采用粗精复合跟踪时位置误差可以达到2 μrad。实验结果表明,空间激光通信系统中单探测器复合跟踪技术的设计满足了系统跟踪精度的要求,为激光通信控制系统的设计提供了一定的参考。     

基于迭代学习控制的潜望式激光通信终端系统的动态跟踪设计

为提高潜望式激光通信终端伺服系统的动态跟踪性能,针对基于永磁同步电机的二维伺服转台的控制系统进行了设计。通过采取空间矢量控制方法实现电机的解耦控制,建立控制模型并完成了各控制回路的设计。针对动目标跟踪设计了迭代学习控制方法以提高通信终端的动态跟踪性能,并对控制系统的速度阶跃响应进行测试,分析通信终端系统的低速平稳性。最后,搭建了4.62 km激光通信的动态跟踪实验,利用六自由度转台模拟平台抖动,为动态跟踪验证实验创造外部平台扰动条件。实验结果表明:通信终端系统速度阶跃响应的稳态误差为±0.02 (°)/s,表明伺服系统速度回路具有较快的动态响应特性和较高的稳态精度,在最大加速度为0.219 (°)/s2的正弦波扰动条件,二维伺服转台的动态粗跟踪精度可以达到62 μrad,粗精复合跟踪精度优于2 μrad,验证了通信终端伺服系统的有效性及其动态跟踪性能,为进一步提高终端系统的跟踪精度奠定基础。     

基于二维振镜与位置灵敏探测器的高精度激光跟踪系统

提出了一种基于二维振镜与位置灵敏探测器的高精度激光跟踪系统;基于光线追迹方法建立跟踪系统的几何光学模型,并对跟踪系统进行误差分析,通过仿真对激光跟踪系统的指向精度以及跟踪性能进行分析。仿真结果表明:在跟踪距离100 m处,跟踪系统的位置指向精度可达0.35 mm,角度指向精度为0.72″,跟踪范围为-10°～10°,最大跟踪速度可达3.6 rad/s,能够实现对远距离快速运动目标的高精度实时主动跟踪。     

使用自适应阈值的图像篡改检测与定位算法

为了实现对机载移动目标的快速捕获和粗跟踪瞄准,设计了粗跟踪演示系统,完成了外 场飞行实验的 初步验证。本文系统利用GPS数据完成对目标的捕获,通过对姿态数据的校正,方位误差降 到0.60°(1σ),俯 仰误差降到0.40°(1σ),有效缩小了不确定区域;系统还对跟踪算 法进行了优化改进,利用分段式函数等效 非线性调整函数,有效解决动态目标跟踪时快速调整和超调之间的矛盾。飞行实验表明, 本文的粗跟踪演示 系统的捕获时间优于10s,粗跟踪精度优于480μrad,为精跟踪子系统实现最终的目标精确跟踪瞄准提供了 有利条件,实验结果验证了该系统用于激光通信链路快速建立的可行性。     

空间激光通信中复合跟踪技术研究

空间激光通信前提是信标光束的精确对准,因此复合轴的跟踪技术是关键,粗精复合的耦合性问题成为研究重点。设计了一套基于单探测器复合轴的跟踪系统,对其原理及关键技术进行阐述,采用粗跟踪配合补偿精跟踪偏转量的方法,解决了耦合性问题,并完成伺服控制系统设计。搭建实验系统对跟踪性能及指标进行验证,实验结果表明,在±0.25°@0.1Hz扰动下系统跟踪误差控制在1个像素之内,跟踪误差均方根为0.13,结合实际条件知,系统像元角分辨率22μrad,故系统整体跟踪精度优于3μrad,可实现对信标光的精确跟踪,满足空间激光通信的应用需求。     

激光通信系统中快速反射镜控制技术研究

为满足激光通信系统跟踪精度的要求,采用快速反射镜系统作为精跟踪控制核心.选用大行程、高分辨率、高带宽的音圈电机驱动快速反射镜,对音圈电机控制方法进行了研究.首先,定性分析了快速反射镜系统的组成及工作原理.然后,根据音圈电机的等效电路模型进行建模分析,得到快速反射镜的传递函数模型.最后,介绍了模拟控制器的设计原理,给出了比例-积分-微分(Proportional-Integral-Derivati ve,PID)电路、位置检测电路以及功率放大电路的具体设计.实验结果表明,设计的快速反射镜的角分辨率为1 μrad,重复定位精度为3 μrad,闭环带宽(-3 dB)为300 Hz@1 mrad,满足激光通信系统稳定可靠、精度高、抗干扰能力强等要求.     

空间激光通信捕获、对准、跟踪系统动态演示实验

捕获、对准、跟踪(APT)系统是空间激光通信重要组成部分,是通信正常进行的前提与保障。对APT系统组成原理、工作原理、关键技术、系统设计、工程实现等内容进行了详细的研究,在此基础上开展室内模拟实验及野外演示验证实验。室内模拟实验跟踪精度达到2~3μrad,表明本系统可应用在星间激光通信中。野外双端动态演示实验在飞艇-船舶间进行,结果表明系统捕获概率优于95%,捕获时间小于60s,系统跟踪精度由于受到大气湍流影响而降低,多次实验测试表明在湍流中跟踪精度达到5~25μrad。APT系统的成功研制为空间激光通信顺利进行奠定了基础。     

改进的内模控制在机载激光通信系统的应用

为了减少机载激光通信光电跟踪稳定平台的脱靶量误差，提出一种基于观测器的二自由度内模控制方法。以经过电流环化简后的速度环为被控对象，采用二自由度内模控制对系统进行校正，将干扰观测器的控制律引入到二自由度内模控制中以降低模型误差和外部扰动对系统性能的影响。通过仿真和实验验证了所提方法的高性能。实验结果显示，改进的内模控制在抗干扰能力、鲁棒性和跟踪性能上都优于传统内模控制；将改进的内模控制算法用于实际系统中也有较好的跟踪性能，其跟踪精度约为143μrad，与传统内模控制相比提高了约24%。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.