TOF相机实时高精度深度误差补偿方法

TOF（Time-Of-Flight）相机获取的深度值存在着边角畸变和精度偏移，目前主要是通过误差查找表或曲线拟合等技术进行误差补偿，计算量大且补偿速度慢。通过对TOF相机在不同距离的深度误差分布规律的分析，提出了一种实时、高精度的误差补偿方法。该方法利用TOF深度图像的旋转对称性以及误差分布的特性，简化了误差补偿模型、降低参数数量级，有效提升了补偿的精度和速度。将算法应用于基于TOF原理的Kinect v2深度传感器进行深度补偿，使得有效距离内平面度误差下降到0.63 mm内，平均误差下降到0.704 0 mm内，单帧数据补偿时间在90 ms内。由于该算法仅基于光径差进行补偿，因此适用于所有TOF原理的相机。实验结果表明，该算法能够快速有效减少TOF相机的深度误差，适用于实时、高精度的大视场三维重建。     

基于优化点激光的平面度测量研究

为了提高平面度测量的精度,提出优化点激光方法。首先将点激光测量坐标系进行转换;然后用激光束进行平面标定,同时通过滑动滤波对激光采集混有的噪声点进行降噪,以免影响测试,建立测量数据的非线性误差和激光位移传感器输出模型进行输出误差补偿;最后通过最小二乘算法获得最佳拟合平面。实例验证结果显示,优化点激光的平面度误差测量平均值为5.189μm,相比直接法、平面扫描仪法、横截线扫描法、点激光测量法、光谱共焦法测量平面度误差,分别减少了18.77%、16.78%、12.45%、9.17%、6.54%,测量精度较高。     

一种新的深度传感器内部参数标定方法研究

针对双镜头深度传感器(以Kinect为例)出厂标 定参数精度不高的问题,提出一种新的标定方法。 对于Kinect 2.0深度镜头,利用空间线定长约束,通过间接平差方法求解待求参数;根据求 解参数,将深度图 像坐标转转换值Kinect坐标并将其与对应的彩色影像坐标点进行关联,基于中心投影方程标 定彩色镜头。实 验结果表明,本方法将深度影像点转换到Kinect坐标时精度优于2.5 mm,深度影像坐标转换至彩色影像坐标 时精度优于1pixel,高于Kinect微软开发包内置参数的计算精度,对一些需要较高参 数精度的应用,本文算法解算的参数更优。     

透镜畸变模型下的亚像素对应点匹配方法

对应点搜索的精度是保证基于条纹投影的三维测量系统性能的关键因素之一,它直接影响到后期深度测量数据的匹配及融合的精度。目前基于相位相关技术的亚像素查找技术能够保证精度,但前期双方向条纹采集时间过长;而基于单方向条纹相位插值算法的对应点搜索未考虑镜头畸变,模型简单化造成精度下降。在透镜畸变模型下提出以绝对相位和极线参数作为两方向坐标,并结合相位线性插值算法的亚像素对应点搜索方法。理论分析和实验结果证明了所提出方法的有效性。     

基于惯性传感器和Kinect摄像机的OFCM图像匹配算法

提出了一种基于图像三维信息及摄像机运动参数的图像匹配算法,用于解决智能监控系统中图像匹配实时性差、鲁棒性低等问题。该算法分别利用惯性传感器和Kinect摄像机估计出摄像机的运动外参矩阵和图像的深度信息,再根据射影几何原理,结合当前帧图像的像素坐标计算出该像素点在下帧图像的像素坐标,从而完成图像匹配。利用该算法对实际采集的图像序列进行了分析与处理,并从配准精度、鲁棒性和实时性方面与经典匹配算法KLT进行对比。实验结果表明:该算法极大地降低了计算量和计算时间,不仅能满足智能监控系统对图像匹配精度和稳定性的要求,更能满足系统实时性的要求。     

基于GPS和改进MapDrift的机载UWB SAR运动补偿

传统的基于载机运动传感器的SAR运动补偿对传感器测量精度提出了很高的要求,而基于回波数据的Map- Drift(MD)自聚焦效果对成像场景存在一定的依赖性。本文针对UWB SAR系统的特点,提出了一种结合GPS(Global Position System)粗补偿和改进重叠MD精补偿的机载SAR运动补偿方法。利用GPS的三维位置信息补偿回波时移误差,利用三维速度信息补偿回波相位误差,然后再利用改进重叠MD补偿剩余误差。本文提出的UWB SAR运动补偿方法没有使用高精度的惯导系统,节约了系统成本,降低了补偿系统的实现难度,并减小了MD算法对成像场景的依赖性,有效提升了SAR图像质量。实际UWB SAR数据的处理验证了本文方法的有效性。     

三次样条插值在称重仪表误差补偿中的应用

介绍了采用三次样条曲线插值方法对称重仪表的非线性误差进行修正的方法,该修正方法对于线性误差较大的传感器有很好的补偿效果,在某些测量精度较高的场合采用三次样条曲线插值可以获得比流行的多段折线线性补偿方法更高的精度。通过对一款5位半仪表采用三种误差处理方法比较,验证了三次样条曲线插值误差补偿方法对传感器误差的补偿效果。该方法对于其他的数据采集系统精度提升有一定的借鉴意义。     

基于结构光扫描的彩色三维信息测量技术

提出了一种基于线结构光扫描的彩色三维信息测量方法，建立了扫描测量的数学模型，利用一种圆孔阵列平面靶标完成了系统光平面参数的标定。利用所研制的系统对一标准棱块进行测量，空间测量精度优于0．1mm。提出了通过计算测量点对应彩色图像中像素坐标获取颜色信息、对整个扫描数据进行颜色渲染的方案，并对小花盆进行了三维测量和颜色渲染，获得了完整准确的彩色三维数据。系统具有测量精度高、颜色渲染快速和准确的特点。     

基于量块的线结构光视觉传感器直接标定方法

线结构光视觉传感器的标定精度直接关系到测量结果的精度。传统的有模型标定方法为了提高标定精度,相应的模型也会越复杂,计算量也很大。为了实现高精度、高效率、低成本地标定线结构光视觉传感器,提出一种基于标准量块的线结构光视觉传感器直接标定方法,设计了标定靶标,不需要标定模型,直接建立查找索引表,在查找索引表中搜索直接得到或者采用最小二乘法拟合算法得到待标定点的空间三维坐标。实验结果表明该标定方法具有较高的标定精度,y方向平均绝对测量误差为0.0279mm,z方向平均绝对测量误差为0.0237mm,能够满足高精度测量需要,且计算简单、易于实现。     

多光通道结构光三维测量系统误差补偿研究

本文通过对多光通道结构光三维测量系统误差分 析发现,相机采集光强受通道间串扰以及投影、采 集图像器件非线性响应等误差影响。在分析串扰和非线性误差影响投影和采集光强的基础上 ,提出了针对 相机采集光强进行系统误差补偿的数学模型。投影0－255灰度图像到 白色平板并由相机采集,计算得到系 统内各光通道的非线性响应参数,以及投影纯色彩色条纹到白色平板计算得到各通道间串扰 系数,通过构 建的误差模型,同时补偿了非线性和串扰误差。实验结果表 明,经过误差模型修正后,展开 相位差从1.044 rad 降到0.121 rad,测量误差从0.707 mm减少到0.058 mm。本文提出的补偿模型从系统误差分析出发,可对串 扰和非线性误差同时测量与补偿,有效提高了多光通道结构光三维测量系统的测量精度。     

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.