航天TDI CCD相机成像拼接快速配准算法设计与分析

为解决卫星灵活机动多模式成像中多片TDI CCD拼接像元失配的问题,提出了一种实现TDI CCD相机成像搭接与错位像元快速拼接配准的匹配算法。通过分析卫星侧摆成像过程焦平面上像移速度矢量变化导致的多片TDI CCD拼接成像像元失配现象,设计了成像速度矢量光线追迹与齐次坐标变换方法,计算了侧摆成像过程中影响图像失配的偏流角、像移速度矢量和两片TDI CCD拼接纵向错位方向和横向搭接方向的像元数目。利用小卫星姿态控制系统半物理仿真平台和TDI CCD原理样机系统对两片TDI CCD拼接像元匹配算法进行实验验证。结果表明:视场角为10°的TDI CCD相机在卫星侧摆30°成像时,经过1个拼接周期后,两片TDI CCD拼接纵向错位和横向搭接像元数目由初始的148.5和50变为137和49,其中横向搭接像元数目与理论计算结果仅有0.1pixel的偏差,纵向错位像元数目与理论计算结果基本一致。经实验和理论对比分析,所设计的纵向错位与横向搭接像元快速拼接配准算法能够解决TDI CCD图像拼接的准确性,确保图像像元匹配进而获得高质量的图片。     

基于光线追迹逐点匹配的航天时间延迟积分CCD相机机动成像快速几何校正算法

基于线阵时间延迟积分(TDI)电荷耦合器件(CCD)机动成像原理,分析了灵巧卫星在姿态机动过程中动态成像的几何畸变问题。由于地球曲率及姿态机动因素导致像面空间几何映射形状不断改变,通过光线追迹逐点匹配算法推导出了机动成像方式下的空间成像几何关系数学解析表达式。利用小卫星姿态控制系统物理仿真平台对TDI CCD相机机动成像快速几何校正算法进行实验验证,姿态角确定精度与姿态稳定度优于0.05°、0.005°/s。结果表明,在卫星最大扫描角为45°时,所设计的算法能够解决机动成像几何畸变问题,提高成像质量。     

基于联合变换相关的机载航空相机像移测量

为了提高像移测量精度,针对机载航空摆扫相机提出一种坐标变换法和图像相关法相结合的像移测量方法。利用坐标变换法得到初始像移速度,利用图像联合变换相关法对像移速度残差进行补偿。联合图像通过一个面阵CCD获得,该面阵CCD放置在相机焦平面上并与成像线阵TDI CCD平行,其输出的当前图像与参考图像合并构成联合图像进行二维空间联合变换相关运算,得到像移修正矢量。对该矢量分别在相机摆扫方向和载机飞行方向进行分解,从而得到摆扫像移和前向像移的修正量。仿真实验结果表明,在输入图像信噪比为4 dB时,像移测量误差在0.1 pixel以内。     

TDI-CCD全景航空相机的像移速度场计算模型研究

针对扫描反射镜和电荷耦合器件(CCD)时间延迟积分(TDI)无法完全补偿前向像移和摆扫像移的问题,提出了TDI-CCD全景航空相机像移速度场的计算模型。根据相机结构和像移补偿原理,用坐标变换和共线方程建立了成像几何模型,在此基础上利用微分法推导出像移速度场的解析式。数值分析表明,像点位置越接近CCD靶面的后边缘,扫描角和前向补偿角越大,像移速度越大。对于TDI级数为100、CCD像元数为14000的全景航空相机,当扫描角小于-1.5°、前向补偿角小于4.16°时,可满足最大像移补偿残差小于1pixel的要求。实验结果验证了模型的有效性,该模型可作为定量分析TDI-CCD全景航空相机像移补偿误差的理论依据。     

宽覆盖型光学遥感相机侧摆像移速度计算

根据宽覆盖相机的特性,分析了其侧摆成像的几何关系。建立了地面物点到相机像面的空间坐标变换关系,在此基础上,推导了基于圆地球模型的相机侧摆像移速度计算公式,并以像移失配传递函数MTFmismatch作为评价方法分析了相对像移匹配残差对像质的影响。以某宽覆盖型相机为例,计算了不同侧摆角和不同地心角条件下的像面像移速度。计算结果表明：像面各点的侧摆像移速度均不相同,且变化趋势也不相同,远地点处像移速度相对变化量最大。在侧摆角为25°且积分级数为48的条件下,像移失配传递函数的最大值为0.681。外场成像试验结果表明,积分级数控制在16级以内时的相机成像质量良好。     

基于MTF的时间延迟积分CCD成像系统同步误差分析

通过像移调制传递函数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。为验证速度失配对TDI CCD相机成像质量的影响，针对应用环境，利用高对比度靶标对TDI CCD动态成像进行了仿真实验和动态测试，结果表明，在奈奎斯特频率范围内，只要将相机动态成像系统的同步误差控制在±2%的范围内，并使图像时钟处于连续多相的工作方式，就可以基本上消除同步误差对成像质量的影响。     

基于空间相机时间延迟积分传感器拼接区图像的像移测量

为了对由飞船姿态不稳或隔振装置的振动抑制残余量等因素产生的宽频带像移进行测量,提出了基于时间延迟积分(TDI)传感器拼接区所成图像的像移测量方法。定义了偏移系数,用以衡量成像期间像移速度与TDI传感器积分时间之间的失配度,以调制传递函数(MTF)为相机成像质量评价指标,分析了失配度与成像质量之间的关系,确定了满足成像质量的像移测量方法的精度范围;利用两片TDI传感器拼接区所拍图像存在相同内容、拍摄时刻不同的特点,阐述了基于TDI传感器拼接区图像的像移测量原理。实验结果表明测量精度达到0.2377pixel,测量频带达到228Hz,证明该方法能够对宽频带、高精度的像移进行有效测量。     

摆扫式TDI-CCD航空相机传感器MTF分析

TDI-CCD与普通线阵CCD相比具有很多优点,因而广泛应用于航空航天成像领域。在介绍TDI-CCD特点和摆扫式TDI-CCD航空相机扫描成像原理的基础上,分析了扫描像移的大小及行周期,推导出了由几何尺寸、电荷转移损失率、电荷分立运动、速度失配等因素引起图像传感器的调制传递函数退化表达式,给出了传感器线列方向和TDI方向的调制传递函数,提出了提高传感器调制传递函数的几种方法,对TDI-CCD航空相机整机设计提供了参考。     

远距斜视航空相机获取大场景图像技术研究

针对远距航空相机视场角较小的问题,介绍了目前常用的几种像移补偿技术,并对各种补偿方法进行了比较。采用小面阵相机并结合系统光学元件通过在横滚方向的摆扫实现大场景地面成像,对摆扫过程进行了数学分析,得出了摆扫所需的扫描指令。通过仿真实验验证了推导的数学公式的正确性,仿真结果表明,应用该扫描指令即可通过小面阵航空相机实现地面大场景图像的获取。     

TDI线扫相机光学通道建模与仿真

卫星相机建模与仿真研究不论在民用还是军事领域都具有重要的理论研究和实际应用价值。根据TDI线扫相机的工作原理建立了一个TDI线扫相机光学通道的数学模型,该模型包括从景物到TDI CCD离散图像的几何投影关系和能量传递关系两部分,对于确定的成像系统,给定景物参数和光学系统参数,就可以确定对应图像传感器上的离散图像。为了验证模型,对一幅卫星图像进行了计算机仿真。建立的模型可以用来研究当成像条件改变时对图像的影响,进一步还可以用来发展虚拟卫星相机系统。     

白光和红绿蓝光LED可调光源研制

为了提高LED光源色温和亮度的调节精度和准确度,结合色温由低向高变化时光色所呈现的渐变特点,提出了一种低色温白光LED灯珠、高色温白光LED灯珠加红绿蓝光LED灯珠补偿式调光的方法.将色温分成三个部分进行调节,每个部分选用不同的LED灯珠组合来进行调光.实验结果表明:不同组合情况下的LED光源的初始输出色温相对于目标值的偏差范围在1％以内;亮度可以在保证色温不变的情况下独立进行调节,初始输出值与目标值的偏差范围在1％以内;经过微调之后可以达到目标值;达到了色温和亮度独立调节的要求;光源发光稳定,不会因为长时间工作而影响调节精度.     

Visualization and interferometry for cylindrical and spherical sample tomography and profilometry

A technique combining image processing and laser interferometry for visualizing and detecting the deformation of transparent cylindrical and spherical sample is proposed. This deformation includes geometric deformation such as volume transition in profilometry and physical deformation such as refractive index change in tomography. Phase contour lines are used for quantitative analysis and graphical representation of the deformation. This method allows us to visually detect the spatial variation of the deformation field and to evaluate the test quality such as misalignment of optical system. A theoretical analysis using phase contour map to characterize the deformation field is described in detail. A method using phase contour map to qualify the interferometric test is proposed. Analysis of test examples is carried out. Suggestions on using phase contour line method to ameliorate test system design are finally discussed.     

Quantum and Classical Disparity and Accord

Discrepancies and accords between quantum (QM) and classical mechanics (CM) related to expectation values and periods are generally found for both the harmonic oscillator (SHO) and a free particle in a box (FPB), which may apply generally. These indicate non-locality is expected throughout QM. The FPB energy states violate the Correspondence Principle. Previously unexpected accords are found and proven that 〈x ²〉 _CM =〈x ²〉 _QM and τ _CM =τ _QMb (beat period i.e. beats between the phases for adjoining energy states) for the SHO for all quantum numbers, n. However, for the FPB the beat periods differ at small n. It is shown that a particle’s velocity in an infinite square well varies, no matter how wide the box, nor how far the particle is from the walls. The quantum free particle variances share an indirect commonality with the Aharonov-Bohm and Aharonov-Casher effects in that there is a quantum action in the absence of a force. The concept of an “Expectation Value over a Partial Well Width” is introduced. This paper raises the question as to whether these inconsistencies are undetectable, or can be empirically ascertained. These inherent variances may need to be fixed, or nature is manifestly more non-classical than expected.     

黑克、布劳、及伯曼-温采尔代数的诱导及分导系数和量子经典李代数的耦合与重新耦合系数

本文总结了计算黑克、布劳、及伯曼 温采尔代数在各种工数链下诱导及分导系数的线性方程方法(LEM)。特别强调了关于A,B,C,D型李代数及其量子情形与其中心代数之间的舒尔 魏尔 布劳双关性关系。这一关系使我们能够利用相应中心代数的诱导及分导系数计算出经典李代数及其量子情形的耦合与重新耦合系数。讨论了从该方法得到B,C,D型李代数不可约表示克罗内克积分解的应用。基于LEM还得到了处理对应于置换群CG系列问题的黑克代数张量积的方法。     

Rapid and flexible laser marking and engraving of tilted and curved surfaces

We present a novel method for rapid and flexible laser marking and engraving of tilted, curved and freeform work-piece surfaces. The method is based on integrating a three-dimensional (3D) laser measurement system into a 3D laser marking system. We use the same laser source and optics for measurement and processing with a minimum of additional hardware components. A low power CW laser regime is used to measure the 3D shape of a work-piece surface while a high-peak power-pulsed laser regime is used for processing. The acquired 3D surface data are used to determine the 3D trajectory of the processing beam focus. Neither the 3D shape of the work-piece nor its orientation needs to be known in advance as long as the processed surface lies within the working range of the 3D laser processing system. This eliminates the need for exact work-piece positioning before processing and substantially improves processing flexibility (allowing, e.g. variations in work-piece shape or/and orientation from mark to mark). This paper discusses key issues concerning an implementation of the method and presents typical examples of markings and engravings, which demonstrate the advantages of the method with respect to the existing industrial 2D and 3D laser marking and engraving methods. The method can also be applied to flexible laser structuring and microprocessing of curved surfaces.     

Spectroscopy and Photophysics of Iso- and Alloxazines: Experimental and Theoretical Study

We present a systematic study of the effect of methyl substitution on iso- and alloxazines in acetonitrile solutions. Substitution patterns have profound effects on both spectral and photophysical properties, with fluorescence quantum yields varying by more than an order of magnitude. TD-DFT calculation were used for the first time to correlate electronic structure changes with the substitution patterns, with good agreement between calculated and theoretical band positions and oscillator strengths. Both n-pi* and pi-pi* states in these compounds are predicted, with the oscillator strengths indicating that only the pi-pi* states should be observable in the absorption spectra. Substitution patterns are shown to be responsible for energy order inversion between these states.     

Nano and micro-scale fluid and plasma dynamics: present and future applications

In this letter, we illustrate the importance of fluid dynamics research by considering two particular areas of study: nano- and micro-scale fluid and plasma dynamics. We show how improved scientific knowledge of nano- and micro-fluid dynamics can significantly enhance our future. Application is also discussed regarding environmental aspects.     

Geometry and Elasticity of Strips and Flowers

We solve several problems that involve imposing metrics on surfaces. The problem of a strip with a linear metric gradient is formulated in terms of a Lagrangian similar to those used for spin systems. We are able to show that the low energy state of long strips is a twisted helical state like a telephone cord. We then extend the techniques used in this solution to two–dimensional sheets with more general metrics. We find evolution equations and show that when they are not singular, a surface is determined by knowledge of its metric, and the shape of the surface along one line. Finally, we provide numerical evidence by minimizing a suitable energy functional that once these evolution equations become singular, either the surface is not differentiable, or else the metric deviates from the target metric.     

激光跟瞄仿真系统及两种跟瞄方法

基于OpenGL和大气传输光学分析的3维全数字仿真是激光跟瞄系统的重要研究手段。为提高跟踪和瞄准精度,从激光跟瞄仿真系统整体出发,研究了目标成像中的投影变换、成像与跟踪的关系、高精度跟踪现有算法的控制过程仿真等内容,并提出了基于大视口、目标大气传输图像序列的跟瞄仿真技术。说明了仿真系统中跟瞄精度分析的特点。就某仿真场景,设计了"头部顶点"和"两点提取"两种跟瞄方法,在不同大气湍流条件下得到了它们的跟瞄精度,说明应用该激光跟瞄仿真系统,能够预先设计、测试和验证一些跟瞄方法,帮助进行算法分析和改进,从而提高工作效率和节约成本。