空间相机中的偏流角分析

高分辨率星载TDI-CCD相机在成像过程中,偏流角会对相机的成像质量产生影响.因此根据卫星轨道方程给出了偏流角和偏流角角速度随纬度变化的具体形式,基于此分别研究了偏流角在卫星穿航方向和沿航方向引起的像移量和它对相机成像质量的影响.结果表明,偏流角是纬度的函数,由它引起的像移在穿航方向对相机像质的影响较为严重,必须加以校正.并针对极地圆轨道详细计算了像移对像质的影响程度和在MTF偏流角＞0.95的情况下偏流角需要调整的最小时间间隔.     

数字域TDI CMOS相机调偏流方法

为了解决现有的机械式调偏流的像移补偿方法存在的,需要复杂的调偏流机构所带来的问题,提出一种适用于数字域TDI CMOS遥感相机的图像调偏流方法。该方法基于数字图像,通过配准图像像素在数字域对位累加来调整偏流角的失配量。最后为了验证提出算法的有效性开展了成像实验,结果表明在26.56°偏流角情况下直接成像的图像对比度传函为0.132 8,而应用图像法调偏流后提升为0.444 7,证明图像调偏流方法能明显改善成像效果,可行有效。该方法摆脱调偏流机械结构思路的限制,精度高而又简单易行,无需要任何附加硬件开支,有助于改进目前国内现有的像移补偿体系。     

一种斜视画幅遥感相机异速像移计算与补偿实现

以一种斜视胶片步进画幅相机为例,介绍了一种基于该相机的像移补偿策略及具体实现过程。画幅相机由于横向视场较大,使得每幅横向各个视场目标对应物距各异,最终导致目标像相对探测器产生了异速像移。对产生异速像移实质给出了数学推导,对偏流机构存在的必要性进行了分析,提出了一种利用两轴旋转扫描镜,同时结合旋转偏流机构和曝光帘缝的像移补偿方案。最后,在已知相机俯角和视场角等信息情况下,推导出了具体的像移补偿公式。     

偏流角对空间相机影响研究

研究了卫星运行中偏流角对TDICCD相机像质的影响.根据卫星运动状态,推导了偏流角的具体变化形式,以及由其在穿航方向和沿航方向引起的相机像移和由此造成的像质退化调制传递函数(MTF).并针对高度为500km的圆形卫星轨道,定量计算了偏流角导致的像移对相机像质的影响程度.结果表明:偏流角在赤道附近最大,随着纬度的升高,偏流角呈非线性减小.并且,由它引起的像移在穿航方向对相机像质的影响远大于沿航方向.对于给定的轨道参数,偏流角最大值约为3.7°,当积分级数为32时,由其引起的像移调制传递函数接近于零,严重影响了相机的成像质量.为此,提出了使用二维摆镜和调整焦平面方向两种实时补偿偏流角影响的方法.     

基于速度矢量模型的圆轨道空间相机偏流角实时补偿

偏流角是影响线阵CCD 相机推扫成像性能的重要因素。为实现在轨有限计算资源环境下偏流角的快速计算,根据圆轨道卫星飞行与地物随地球自转的速度矢量运动关系,建立了适用于圆轨道正视与前后视成像的偏流角模型,给出卫星飞行过程中星下点相对地物的运动速度矢量作角向振动的数学表达式。根据该模型提出基于旋转CCD 方式的偏流实时补偿方案,并搭建偏流校正成像模拟平台进行了实验验证。仿真和实验表明,速度矢量模型具有更高的计算效率,计算精度和稳定性与坐标变换模型和轨道要素模型一致,能够将偏流导致的图像MTF 下降抑制到5%。该方案适用于 TDICCD 相机与三线阵CCD 立体测绘相机的偏流实时调整机构开发工作。     

基于地球椭球的离轴式双线阵相机像移补偿

离轴反射式双线阵立体测绘相机的视轴和光轴分离,由于地球为椭球体,视轴和光轴对应的地物点的距离随星下点与升交点的地心角而变化。而成像传感器与光轴垂直,对视轴对应的地物点成像,这些因素导致离轴反射式双线阵立体测绘相机的像移速度和偏流角随离轴角等变化。在对离轴反射式空间相机的成像原理进行分析的基础上建立其等效简化模型,推导了基于地球椭球的离轴反射式双线阵立体测绘相机的像移速度和偏流角计算公式。并以某离轴反射式双线阵立体测绘相机为例,对正视相机和后视相机统一调整行周期与偏流角对成像质量的影响进行分析。分析结果表明,以调制传递函数下降不超过5%为约束,当积分级数大于4 时应分别调整正视相机和后视相机的行周期。统一调整偏流角时应以正视相机和后视相机偏流角的均值为准,积分级数应取89 以内。     

影响TDICCD相机成像质量的因素分析

在高分辨率TDICCD相机的成像过程中,偏流角和速高比的变化都会影响相机的成像质量。根据卫星的运动状态,分别推导了偏流角和速高比的表达式,并分析了由其引起的附加像移。结合实际的卫星轨道参数,详细计算了偏流角和速高比随纬度的变换规律以及它们在不同积分级数下引起的像移对相机像质的影响程度,给出了像移调制传递函数大于0.95时允许的最大偏流角和相机侧摆角度。结果表明,随着积分级数的增加,由偏流角和侧摆引起的像移对相机像质的影响越来越大,当积分级数N=32、MTF_(像移)>0.95时,允许的最大偏流角和侧摆角度分别为0.62°和29.5°.     

空间超大视场相机速度失配对成像质量的影响

空间超大视场时间延迟积分电荷耦合器件（TDI-CCD）相机能在提高观测刈幅的同时有效提高相机灵敏度,然而在其遥感过程中,由于存在地球曲率,导致相机边缘视场地面分辨率退化严重。在分析空间超大视场相机成像的基础上,推导出空间超大视场相机在不同视场位置速度失配比和调制传递函数（MTF）的计算公式。并以某空间超大视场相机为例,分析了 TDI-CCD 探测器统一和分片调整行转移周期对成像质量的影响。分析实验结果表明,以 MTF 在空间奈奎斯特频率处下降不超过10%为约束条件,在 TDI-CCD 积分阶数为4阶时,当空间超大视场相机总视场不超过55?时,可以采用统一调整探测器行转移周期的方法进行像移补偿;当空间超大视场相机总视场达到120?时,采用分片调整行转移周期的方法可将满足要求的像元视场从47.8%提高到86.5%。     

面阵CCD航测相机像移补偿技术研究

航空相机在拍照瞬间由于飞机的飞行运动和姿态变化而产生像移,要提高照相分辨率必须通过像移补偿来实现。采用在相机与飞机间增设三轴稳定平台的机械式像移补偿法来补偿姿态像移和前向像移,三轴稳定平台的三轴按照与飞机姿态变化角速率相等、方向相反进行旋转补偿姿态像移,三轴稳定平台的俯仰轴以飞行方向反方向、角速率等于速高比旋转补偿前向像移,并采用坐标变换法计算像移补偿后的残差,通过分析面阵CCD相机像面各点在进行像移补偿后的像移残差均小于1/3像元,符合成像要求。     

TDI-CCD光靶相机动态成像同步误差分析

TDI-CCD相机在对运动目标成像时,由于在光积分时间内成像目标的快速变化,导致目标图像与CCD像元之间存在着相对运动,由此造成不同步采集而产生的像移.针对上述问题.采用像移调制传递函数(MTF)分析了TDI-CCD行扫速率与运动像不同步时对相机成像质量的影响,并利用矩形靶标对TDI-CCD动态成像进行了实验测试.结果表明,在奈奎斯特频率范围内,只要将TDI-CCD推帚成像过程中的同步误差控制在一定的范围内,并使TDI-CCD的驱动时钟处于连续多相的工作方式,就可以明显地减少像移对成像质量的影响.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

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.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

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.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

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.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

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.     

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.