用四象限光电探测器获得光斑参数

对四象限光电探测器的信号处理方法进行了研究.分析了用四象限光电探测器获得光斑参数的方法,研究了其各项指标及误差来源,提出了一种新的采用微动法的四象限光电探测器光斑参数的计算方法,并与传统方法进行了比较.采用微动法获取四象限光电探测器的光斑参数,不仅能够得到光斑的光心坐标,还能够计算出传统方法得不到的光斑的半径,增加了信息量.与传统的方法相比,该方法具有误差与光斑中心位置、光斑半径无关的优点.理论分析、仿真和实验都证明,采用四象限光电探测器获得光斑参数的方法具有相当多的优点.获得的参数由两个增加到三个,采用Φ30 mm的GaAs-PIN四象限探测器时,最大误差由18%减小到1.2%以下,将其应用于车辆问大气激光通信光电精定位系统中证明,响应时间可减少30.75%.     

掺铂环楔阵列光电探测器

一、引言环楔阵列光电探测器是光学计算机混合型功率谱分析系统的关键器件。它的作用是对傅里叶功率谱采样,然后输入计算机进行处理。环楔阵列探测器由64个探测单元组成,它们的形状和分布是根据傅里叶变换的特点设计的。一般图像的空间函数为实函数,其傅里叶功率谱是中心对称的,所以在半个谱面上就包含了输入图像的全部信息。因此在圆形硅片的半圆内设置了32个同心的半圆环形探测单元,用以检测径向分布的功率谱;而在另外半圆内设置了32个楔形探测单元,用以检测角向分布的功率谱。为了定中心,在探测器的中心部分设置了四象限探测单元。图1示出该探测器的     

碲镉汞光导探测器在中红外激光测量中的热问题

为了准确测量中红外高能激光系统的远场功率密度时空分布等参数,分析了室温光导型碲镉汞(HgCdTe)探测器在环境温度变化和光热效应情况下存在的探测器光敏元温升等热问题,并分别给出了应对措施。从HgCdTe的电学参数经验公式和光导型探测器工作原理出发,分析了暗电阻和响应率与光敏元工作温度的相关性。建立了计入接触热阻和自然对流效应的光导型HgCdTe探测器热分析模型,并对模型进行了实验验证。分析了光敏元与环境温度间的热平衡时间特性,提出了连续激光测量中的环境温度校正模型。讨论了激光辐照下探测器的动态响应特性,给出了激光加热探测器光敏元导致的附加光热信号的修正方法,该方法在典型应用条件下可将测量系统的单通道测量不确定度降低2%以上。目前,所述方法均已成功应用于多套远场激光光斑定量测量系统。     

微动法获得四象限光电探测器光斑参数的研究

摘要：对四象限光电探测器的信号处理方法进行了研究,分析了目前采用的四象限光电探测器获得光斑参数的方法,研究了 其各项指标及误差的来源,提出了一种新的采用微动法的四象限光电探测器光斑参数的计算方法,并与传统的方法进行了比 较。采用微动法获取四象限光电探测器的光斑参数,不仅能够得到光斑的光心坐标,还能够计算出传统方法得不到的光斑的 半径,增加了信息量。该方法与传统的方法相比,还具有误差与光斑中心位置、光斑半径无关的优点。理论分析、仿真和实 验都证明,采用的四象限光电探测器获得光斑参数的方法具有相当多的优点。获得的参数由两个增加到三个,采用Φ30mm 的GaAs-PIN四象限探测器时,最大误差由18%减小到1.2%以下。本方法在车辆间大气激光通信的光电精定位系统中实际应 用证明,该方法速度快,精度高,收敛性好。     

近红外光谱仪

由Stellar Net公司生产的NIRX-SR系列近红外光谱仪采用512元的InGaAs光电二极管阵列和高速USB2．0接口,其工作波长范围为0．9～2．2μm。这种坚固防震的光谱仪配置两级热电致冷器和具有高光谱分辨力的光学元件。当用于特殊的光谱研究时,该仪器可选用1024元的探测器列阵,从而可将其光谱分辨力从16nm提高到8nm。     

新型PIN阵列探测器

采用将数个PIN探测器叠放在一起形成阵列的方法,研制Φ80mm×800μmPIN新型阵列探测器,该阵列探测器灵敏度比一般PIN探测器灵敏度高一个量级以上,可以近距离直接测量注量率小于1014S-1cm-2的γ辐射,有效解决了光电探测器和以前国产硅PIN探测器在该注量率范围内的测量困难.     

四种用于跟踪的探测器比较与分析

对于激光跟踪系统,常采用两种探测器件,QAPD、面阵CCD作为跟踪探测器.它们的共同特点是信标光成像光斑同时能被四个独立的敏感单元探测,通过测量他们的输出电压来判断光斑的中心,进而提高控制精度.但是,这两种探测器的探测机理有些不同,此外,CMOS图像传感器也属于固体图像传感器,但CMOS图像传感器的制造工艺、工作原理、性能特点与CCD有明显的不同.它将图像传感部分和控制电路高度集成在同一芯片里,其体积不仅明显减小,功耗也大大降低.低廉的价格使其在通讯及其它应用领域具有巨大的潜力,从而使CMOS图像传感器成为研究和开发的热点.PSD也可用于跟踪探测器.文中针对这四种探测器进行具体分析,并对各方面性能进行了比较.     

基于刀口法的激光横向变形检测与标定方法

为测量材料的横向形变,提出了一种基于刀口法的激光横向变形检测与标定方法。通过控制遮挡板的精密机械运动来模拟刀口切割射向光电探测器的矩形光束,从而改变光电探测器接收的光照强度以检测光斑能量分布情况并建立光照强度与刀口运动位移的对应关系,最终根据位移与光强度的线性关系检测矩形光斑能量匀化状态并对移动的位移进行反向精确标定。试验得出:曲线交点坐标相对误差不高于1.63%,且遮挡板不同运动模式以及多点位实验中,矩形光斑中间1mm区域线性决定系数均为0.998,表明该方法可以借助精密控制的遮挡板的机械运动模拟材料的横向形变,为材料横向形变测量提供便利的检测模拟手段和方法。     

激光跟踪仪的光电瞄准与定位系统

考虑激光跟踪仪的光电瞄准与定位直接影响仪器的整体测量精度和使用性能,讨论了激光跟踪仪的光电瞄准和跟踪定位控制技术并提出了光电探测瞄准、信号调理采集、数字处理及智能跟踪伺服的系统整体技术方案。对系统关键部件进行选型,利用角锥棱镜和位敏探测器(PSD)作为光电探测核心,设计了探测光路和信号处理电路。研制了系统样机,搭建了目标位移量标准测试平台,对样机光电瞄准系统探测信号进行了测试。测试结果显示:采用该设计方案设计的激光跟踪仪样机的静态定位测量精度达到6μm,随机动态跟踪测量速度大于1m/s。结果表明:提出的方法可解决激光跟踪仪定位精度低、动态跟踪效果差等常见问题,可为研制高精度、大范围、大尺寸测量仪器提供技术参考。     

纳秒激光等离子体光源的光谱测量技术

提出了一种新的探测和测量激光等离子体软X射线源光谱强度的方法。此方法使用通道电子倍增器和定标过的硅光电二极管为探测器,前者是非标准探测器,后者为标准探测器。应用电荷灵敏前置放大器和峰值探测器测量探测器产生的电量,并以高分辨率的光谱仪为分光元件,在已知光栅效率、通道电子倍增器增益、硅光电二极管能量响应的条件下,给出了计算激光等离子体软X射线源在某一波长光谱强度的公式。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.