Imaging of human parafoveal area with large field of view in adaptive optics line scanning ophthalmoscope

The parafoveal area,with its high concentration of photoreceptors andfine retinal capillaries,is crucial for central vision and often exhibits early signs of pathological changes.The current adaptive optics scanning laser ophthalmoscope(AOSLO)provides an excellent tool to acquire accurate and detailed information about the parafoveal area with cellular resolution.However,limited by the scanning speed of two-dimensional scanning,thefield of view(FOV)in the AOSLO system was usually less than or equal to 2,and the stitching for the parafoveal area required dozens of images,which was time-consuming and laborious.Unfortunately,almost half of patients are unable to obtain stitched images because of their poorfixation.To solve this problem,we integrate AO technology with the line-scan imaging method to build an adaptive optics line scanning ophthalmoscope(AOLSO)system with a larger FOV.In the AOLSO,afocal spherical mirrors in pairs are nonplanar arranged and the distance and angle between optical elements are optimized to minimize the aberrations,two cylinder lenses are orthogonally placed before the imaging sensor to stretch the point spread function(PSF)for sufficiently digitizing light energy.Captured human retinal images show the whole parafoveal area with 55FOV,60 Hz frame rate and cellular resolutions.Take advantage of the 5FOV of the AOLSO,only 9 frames of the retina are captured with several minutes to stitch a montage image with an FOV of 99,in which photoreceptor counting is performed within approximately 5eccentricity.The AOLSO system not only provides cellular resolution but also has the capability to capture the parafoveal region in a single frame,which offers great potential for noninvasive studying of the parafoveal area.

Improvement of Binocular Reconstruction Algorithm for Measuring 3D Pavement Texture Using a Single Laser Line Scanning Constraint

The dense and accurate measurement of 3D texture is helpful in evaluating the pavement function.To form dense mandatory constraints and improve matching accuracy,the traditional binocular reconstruction technology was improved threefold.First,a single moving laser line was introduced to carry out global scanning constraints on the target,which would well overcome the difficulty of installing and recognizing excessive laser lines.Second,four kinds of improved algorithms,namely,disparity replacement,superposition synthesis,subregion segmentation,and subregion segmentation centroid enhancement,were established based on different constraint mechanism.Last,the improved binocular reconstruction test device was developed to realize the dual functions of 3D texture measurement and precision self-evaluation.Results show that compared with traditional algorithms,the introduction of a single laser line scanning constraint is helpful in improving the measurement’s accuracy.Among various improved algorithms,the improvement effect of the subregion segmentation centroid enhancement method is the best.It has a good effect on both overall measurement and single pointmeasurement,which can be considered to be used in pavement function evaluation.

Temperature Field in Laser Line Scanning Thermography: Analytical Calculation and Experiment

The temperature field in laser line scanning thermography is investigated comprehensively in this work,including analytical calculation and experiment.Firstly,the principle of laser line scanning thermography is analyzed.On this basis,a physical laser line scanning model is proposed.Afterwards,based on Fourier transform(FT)and segregation variablemethod(SVM),the heat conduction differential equation in laser line scanning thermography is derived in detail.The temperature field of the composite-based coatings model with defects is simulated numerically.The results show that the laser line scanning thermography can effectively detect the defects in the model.The correctness of the analytical calculation is verified by comparing the surface temperature distribution obtained by analytical calculation and numerical simulation.Additionally,an experiment is carried out and the changeable surface temperature obtained by analytical calculation is compared with the experimental results.It shows that the error of maximum temperature obtained by analytical calculation and by experiment is 8%with high accuracy,which proves the correctness of analytical calculation and enriches the theoretical foundation of laser line scanning thermography.

Characterization of a nano line width reference material based on metrological scanning electron microscope

The line width(often synonymously used for critical dimension,CD)is a crucial parameter in integrated circuits.To accurately control CD values in manufacturing,a reasonable CD reference material is required to calibrate the corresponding instruments.We develop a new reference material with nominal CDs of 160 nm,80 nm,and 40 nm.The line features are investigated based on the metrological scanning electron microscope which is developed by the National Institute of Metrology(NIM)in China.Also,we propose a new characterization method for the precise measurement of CD values.After filtering and leveling the intensity profiles,the line features are characterized by the combination model of the Gaussian and Lorentz functions.The left and right edges of CD are automatically extracted with the profile decomposition and k-means algorithm.Then the width of the two edges at the half intensity position is regarded as the standard CD value.Finally,the measurement results are evaluated in terms of the sample,instrument,algorithm,and repeatability.The experiments indicate efficiency of the proposed method which can be easily applied in practice to accurately characterize CDs.

Design of operation parameters of a high speed TDI CCD line scan camera

This paper analyzes the operation parameters of the time delay and integration (TDI) line scan CCD camera, such as resolution, line rate, clock frequency, etc. and their mathematical relationship is deduced. By analyzing and calculating these parameters, the working clocks of the TDI CCD line scan camera are designed, which guarantees the synchronization of the line scan rate and the camera movement speed. The IL-E2 TDI CCD of DALSA Co. is used as the sensor of the camera in the paper. The working clock generator used for the TDI CCD sensor is realized by using the programmable logic device (PLD). The experimental results show that the working clock generator circuit satisfies the requirement of high speed TDI CCD line scan camera.

基于PS-based架构的线扫描(Line-scan)影像检测系统

本篇文章主要针对目前线扫描系统之主要组件以及如何取到正确且等比例的线扫描影像作介绍,提供有兴趣或刚开始接触线性扫描系统的使用者作为参考.

New LED light source system with uniform illumination for line-scan CCD imaging systems

A system with uniform light reflection in the inner surface within a horizontal 2/3 cylindrical structure for line-scan CCD of the print testing was designed. The design was based on diffuse reflection uniformity of the integrating sphere and requirement of the strip uniform illumination region. This system was called dome light. White light LED array light sources were used for uniform illumi- nation. The LEDs were filtrated to composite array light source based on coefficient of variation of a single LED. The standard white board and SG color checkers were used in the line-scan CCD imaging experiments under the dome light and ordinary illumination light source. The average color difference （AE） of SG color checkers in CIELAB space was 2. 091 under the dome light and 2. 286 under ordinary illumination light source respectively. Experimental results indicate that the dome light can satisfy illumination uniformity and color rendering consistency for line-scan CCD and provide a standard light source for uniform calibration of different cameras.

Image Correction Method of Color Line-Scan System

As the development of machine vision technology, the color line-scan system is widely applied in the on-line inspection. Due to the non-uniform gray scale and color distortion of the image acquired by the system, the image correction is needed to reduce the problem of image processing and the stability system. Based on reasons mentioned above, a method that using polynomial fitting to correct the image is presented to solve the problem in this paper. The method has been used in the automatic optical inspection of PCB, and has been proved to be effective. So this method will have a potential application to the development of the color line-scan machine vision system.

基于线结构光的大型构件表面尺寸加工质量检测方法

针对大型构件表面尺寸加工质量的高精度三维检测的需求,设计了一套主动式线结构光旋转扫描检测系统.采用相机主动式旋转扫描,适用于不方便移动且跨距大、特征多的大型构件检测.提出了一种新的系统旋转中心快速标定的方法,仅需标靶上一点即可完成标定,适合大型构件检测的现场快速标定.加入编码机构,可根据被测物的特征变化动态调整扫描速度,提高了系统检测效率和通用性.所有元器件均可单独调用,保证了系统的可扩展性.改善了扫描时的串口逻辑,进一步提高了三维点云的密度.实验结果表明,本系统对标准物体的最大偏差为0.0310 mm,标准差最大为0.0150 mm,对大型构件实物的检测误差在0.05 mm以内,满足大型构件表面特征加工质量的高精度三维检测需求.

联合多波束与侧扫声纳的海缆检测方法

为解决海底电缆路由检测中多波束扫测分辨率低、侧扫声纳(SSS)图像位置不准且存在误识别问题,提出了一种联合多波束与侧扫声纳的海底电缆路由自动检测方法,利用多波束图像高精度的位置信息纠正侧扫声纳图像,并顾及侧扫声纳图像海缆成像特点进行线状特征增强与边缘提取,实现海底电缆目标的自动、准确检测。实验结果表明,该方法能实现非掩埋海缆探测的准确探测,为海底电缆检测提供了多源测量信息融合的新思路,丰富了海底电缆检测的技术方法。

基于三维激光扫描技术的智能制造生产线目标检测研究

智能制造生产线目标图像数据采集过程受到噪声、光照变化等问题,导致输入图像的质量不佳,进而影响目标检测的准确性,对此,设计一种基于三维激光扫描技术的智能制造生产线目标检测方法。首先,采用三维激光扫描仪获取待检测目标点云数据,通过点云变换准则计算数据之间的拓扑关联,生成完整三维激光图像。然后,利用杂交小波变换对三维激光目标图像进行去噪处理。最后,使用能量、熵、对比度、相关性4种参数提取图像纹理特征并采取归一化处理,创建最优分类函数,并运用支持向量机算法划分生产线目标样本图像数据,完成智能制造生产线目标检测工作。实验结果表明,所提方法的交并比值最高时达到0.97,F1值最高时达到0.96,平均检测耗时仅为0.53 s,说明所提方法的检测精度高、效率快,鲁棒性强,在实际操作中具备相当的可用性,为智能制造产业提供技术支持。

基于三维点云的轮对踏面轮廓动态测量教学实验设计

通过MV-DP090-02B激光轮廓传感器获取轨道车辆轮对踏面轮廓影像信息,再将物体表面轮廓位置转化为三维点云数据,并对数据进行降噪和特征提取,然后对踏面轮廓进行三维重建。文章结合轮对踏面动态测量实验,对轮对低速转动过程中的踏面轮廓进行了扫描。数据处理结果表明,基于MV-DP090-02B激光轮廓传感器获取的三维扫描点云数据及相关数据处理,可以动态测量轮对转动过程中的踏面轮廓;MV-DP090-02B激光轮廓传感器能够满足实验室的测量需求,操作简便,是“轨道交通车辆机械检修”课程实验中轮对踏面轮廓获取的一种新方法。

不同性型蓖麻花粉的生活力及形态特征研究

研究不同性型蓖麻(Ricinus communis L.)花粉的育性,尤其是雌性系的花粉育性,对于蓖麻杂交育种工作意义重大。本研究首先利用TTC染色法和花粉萌发法分别检测了镶嵌型雌性系、两性系共6种蓖麻种质材料花粉的生活力,随后通过扫描电子显微镜观察了他们的花粉形态,并利用SPSS软件分析了其形态特征值。结果显示:TTC染色和花粉萌发结果基本一致,不同材料间花粉生活力差异显著,蓖麻镶嵌型雌性系HCH3花粉生活力最大(96.97%)、镶嵌型雌性系HCH1花粉生活力次之。两种性型的花粉均呈现为单粒,长球形,赤道面观为长球形,极面观为三裂近圆形,中等大小(花粉极轴长为30.17~42.07μm),属于N_(3)P_(4)C_(3)型花粉。花粉外壁为网状纹饰,脊顶部具有密集的瘤状突起。然而,不同材料间花粉的极轴长、网眼直径、网脊宽度、单位面积网眼数形态值上差异显著。主成分析和聚类分析将6份蓖麻材料按花粉大小分为两类。本研究为蓖麻的花粉可育性和杂交选育提供了新的数据支撑。

原状黄土土-水特征曲线与湿陷性的相关性

为了研究原状黄土土-水特征曲线与黄土湿陷性之间的联系,在陕西西安长安区取地表以下30 m范围内的原状黄土土样,进行基本物理指标试验和湿陷性试验。对不同典型地层的黄土-古土壤试样进行土水特征曲线试验,通过电镜扫描从微观角度分析。研究结果表明:大孔隙的数量与饱和体积含水率呈正相关;中孔隙的数目与过渡区斜率的大小呈正相关,孔隙数目越多土体失水速度越快;微小孔隙的数目和土的塑性指数影响残余含水率的大小。对于不同深度土层,饱和体积含水率和过渡区斜率与土层的湿陷系数呈正相关;塑性指数接近土层的湿陷系数对残余体积含水率的影响不明显;古土壤层的SWCC与湿陷系数之间存在与黄土层相同的正相关性。文章从非饱和土力学的方向去研究黄土的湿陷性,为湿陷性的研究提供一种新的研究角度。

基于2.5D标定扇的线阵相机内参数标定方法

针对工业生产线上或集成设备中线阵相机内参数定期检校困难且成本高的问题,提出一种基于2.5D标定扇的线阵相机内参数标定方法。设计了一款特定的2.5D标定扇,构建包含镜头畸变的线阵相机内参数标定模型,顾及了标靶相对相机的两个姿态角,通过方程线性变换法解算模型参数初值,利用改进的Levenberg-Marquardt(L-M)算法加速优化相机参数的求解过程,给出了详细的解算步骤和数据处理过程,并通过仿真和实测数据验证了方法的可行性。结果表明:该线阵相机标定方法简单灵活,可得到大量分布规律的特征点对,参数标定精度不受相机移动精度和特定移动方向的限制;在扇骨面与靶面间夹角小于10°时,可以获得高精度、高一致性的相机内参数,特征点重投影误差的最大值优于0.28 pixel,平均RMSE为0.11 pixel,标准差仅0.01 pixel。

线扫式拉曼光谱仪的研制与生物医学应用进展

拉曼光谱技术是一种无损、高灵敏的分子成分检测技术,近年来在众多领域得到广泛应用,但由于逐点扫描的观测方式耗时较长,限制了在大面积样品拉曼扫描和成像中的应用。线扫式拉曼光谱通过线形激发光照明、同步采集线形样本区域拉曼信号的方式,相对于点扫式拉曼光谱仪成像速率获得了若干数量级的提升,从而使大面积、大数量样本具有时效性的拉曼光谱观测成为可能。本文对线扫式拉曼光谱仪的原理、搭建方式、系统结构和特点做了简要介绍,综述了其在细胞、组织观测等方面的应用进展,并对线扫式拉曼光谱性能改进及功能拓展技术进行了展望。

一种低驻波宽角波束超宽带双锥线阵列天线研制

设计和制作了一种实现宽角波束扫描的1×3超宽带双锥线极化阵列天线,可以应用于无人机上实现空地宽带通信。由于无人机平台安装尺寸受限,通过用椭球形阵子代替传统锥形阵子,并切割椭球振子外部轮廓使其安装在250 mm×130 mm×90 mm的空间内,实现了低剖面、小型化等特点。仿真结果表明,该阵列天线在0.8~2.4 GHz的频带范围内电压驻波比均小于2.5,在±45°波束扫描范围内的4个波束的最低增益均超过了2 dBi,满足实际的应用需求。

面料性能对A字裙坐姿起皱形态的影响

着装褶皱对服装外观有重要影响,常见的褶皱评价指标及传统的二维图像处理技术无法准确、全面反映三维起褶状态。因此,文章利用三维扫描技术对坐姿下A字裙形成的褶皱从褶皱区域、褶皱类型、褶皱大小和褶皱尖锐度四方面建立了一系列新指标,运用单因素方差分析比较了不同种类面料间的褶皱形态差异,并探究了面料性能与褶皱形态指标之间的相关性。研究结果表明,不同面料成分的A字裙在坐姿下形成的褶皱形态各异,其中棉类与其他面料之间各方面差异最为明显。此外,经密、抗弯刚度、褶皱回复性等面料性能对褶皱形态各指标有着不同程度的影响。研究结果可为面料选择及服装三维仿真提供参考。

顾及杆状物和车道线的城市道路场景轻量化快速点云自动配准

针对激光扫描获取城市场景出现不同时期位置偏差,传统点云配准方法存在效率低和鲁棒性低等局限性,本文提出了顾及杆状物和车道线的点云配准改进方法。首先对滤波后的点云进行体素格网降采样,再利用布料模型滤波对地面点滤波,后使用K均值无监督分类非地面点云,后用先验的随机一致抽样法提取杆状物作为目标特征,并根据点云反射强度提出点云灰度图和空间密度分割法提取车道线。利用改进迭代最近点(ICP)算法和法向量约束,将杆状物作和车道线作为配准基元,几何一致算法剔除错误点对,并使用双向KD-tree快速对应特征点的关系,加快配准速度和提高精度。经实验证明,在低重叠度的城市点云场景耗时不到20 s,且只迭代20次,精度可达1.9877×10^(-5)m,可实现城市道路场景点云的高效准确配准。

激光雷达移动扫描的输电线路实例化分割研究

为实现输电线路的实时实例化分割测距,提出了一种基于激光雷达(LiDAR)移动扫描的输电线路点云分割方法。该方法首先设计滑动空间窗口的卡尔曼滤波策略实现动态点云配准,增强稀疏点云密度;然后构建了面向输电线路目标的三维点云语义分类神经网络模型,通过均匀化下采样和局部特征聚合提高对大尺寸空间目标的整体识别能力;最后应用俯视图投影并设计快速欧氏聚类算法,实现输电线路目标分割和测距。实验结果显示,该方法在LiDAR移动扫描的输电线路三维点云数据集上有94.7%的分类准确率和81.6%的平均交并比,验证了其具备对输电线路目标进行实时实例化分割和测距的能力。