光栅光调制器阵列交叉效应的理论分析与实验

光栅光调制器是一种基于微机电系统的用于投影显示的器件。为了讨论交叉效应对无源矩阵驱动的光栅光调制器的影响,介绍了光栅光调制器的工作原理,建立了无源矩阵驱动阵列的电学模型。利用基尔霍夫的电流定理和电压定理,对无源矩阵驱动阵列的电学模型进行化简分析,得到交叉效应中半选点像素、非选点像素与全选点像素之间的电压关系。分析表明：交叉效应对半选点像素影响较大,且随着器件阵列的增大,交叉效应更加严重。通过实验得到这三种像素的±1级衍射光强与全选点像素驱动电压的关系。实验结果表明：对于加工的16×16阵列,半选点像素电压约为全选点像素电压的1/2,且远大于非选点像素电压,与交叉效应理论分析相一致。交叉效应会降低阵列的光学对比度。最后,提出抑制交叉效应的两种方法。分析表明：有源矩阵驱动是抑制阵列交叉效应的最佳方法。     

反射面平动式光栅光调制器的实现及机电特性分析

提出了一种新型的光栅光调制器(GLM),它由可动平板阵列和固定光栅构成,通过可动平板的垂直运动,达到调制光束的目的。为验证该结构实现的可能性,得到器件的机电特性,根据微梁的力学理论进行了电力学理论分析,通过Coventor仿真软件进行了有限元仿真。分析表明,该器件所需驱动电压为16V,无明显的迟滞现象,可动平板的有效衍射面积较大,易于实现面阵结构,提高了光学衍射效率。     

光栅光调制器的有源矩阵驱动的设计与优化

通过提出一种光栅光调制器的有源矩阵的驱动方式,分析了有源矩阵光栅光调制器的工作机理和关键指标参数.并且分析指出增大有源矩阵的存储电容值,可以减小由电荷重新分布造成存储电压的降低.有源矩阵的晶体管宽长比和存储电容,影响有源矩阵的保持电压特性和开关速度.结合实际的工艺设计包,利用Cadence软件设计了有源矩阵的版图.设计了有源矩阵与光栅光调制器的单片集成的工艺流程.通过仿真和实验验证了理论分析的正确性,且仿真结果与实验结果基本一致,表明:有源矩阵光栅光调制器可以满足分辨率为1920×1080,帧频30 Hz,256级灰度的显示要求.     

MOEMS阿达玛变换光谱仪的可动光栅光开关阵列

根据微弱光谱信号的快速检测原理,构建了一种适用于阿达玛变换光谱仪的MOEMS(微光机电系统)可动光栅光开关阵列。对一种适用于补偿光栅光调制器件加工误差的阿达玛变换算法进行了分析,设计了以Al膜为主的表面微加工工艺流程,制作出MOEMS可动光栅光开关阵列。实验测试结果表明,可动光栅光开关阵列可以在低至8.1V的电压下进行光调制,开关频率达到140Hz,完全可以满足阿达玛变换光谱仪调制速度快、光谱范围宽、机械磨损小和误差小等要求。     

MOEMS光栅平动式光调制器的吸合电压分析与实验

通过研究提出了一种新颖的利用微光机电系统技术(MOEMS)制造的光栅平动式光调制器GMLM,它可以利用衍射原理对光进行动态调制,其设计适宜形成二维光调制器阵列.针对GMLM,分析并给出了其准静态下的吸合电压计算公式.考虑到MEMS器件的尺寸效应,对电容的边缘场效应影响不能忽略.文巾对GMLM器件的边缘场效应影响因子进行了公式推导,并针对GMLM修正了传统的平行板执行器吸合电压计算公式.实验结果证明,修正后的理论公式可以较好地预测GMLM的吸合电压值,与实际测最值的误差为4.3%.     

光栅平动式光调制器光学特性分析

提出了一种基于微光机电系统的可用于投影显示及相关器件的新型光栅光调制器,介绍了其结构、工作原理和加工流程.对器件进行光学分析,优化和仿真,得出器件结构参数与光学特性之间关系.器件的可动光栅占空比e=0.5,光栅常数d=6 μm,长度L=39 μm,宽度w=36 μm,边距w0=1.5 μm时,理论上±1级衍射效率η=37.0%,对比度V=625;可动光栅与下电极在开态和关态时间距分别为0.65 μm和0.78 μm,器件单像素尺寸为51 μm×51 μm.     

光栅平动式光调制器机械特性分析与仿真

光栅平动式光调制器是基于MOEMS技术的新型光调制器,利用静电力驱动可动光栅对入射光进行调制,因其具有高速开关特性与面阵化等特点使其在显示与打印方面有广阔的应用前景.但是其结构相对复杂,本文通过建立光栅平动式光调制器的机电模型,并依据力学理论及虚功原理对器件的机械特性进行了相应的分析,得出器件的载荷挠度特性.并利用CoventorWare软件进行相应的有限元仿真分析.仿真表明,在工作距离范围内,理论数据与仿真数据具有很好的拟合度,其平均误差在5%左右.     

交叉效应对STN型液晶显示屏图像质量影响的分析及改善

针对动态无源驱动的STN型液晶显示器的交叉效应现象，基于动态无源驱动液晶显示屏的工作原理，综合分析液晶屏的像素点阵单元等效为由线路阻抗及液晶电容构成的RC阻容低通滤波网络对驱动电压波形的影响、液晶透过率-电压特性关系以及V₅₀因素，研究不同驱动电压和反转行数对交叉效应的影响。通过控制变量，保持驱动电压或反转行数一致的情况下改变另一项参数，观察液晶显示器图像显示质量并分析改变参数带来的影响。结果表明：正显状态下，通过适当提高驱动电压能有效减轻交叉效应，调节nLine对交叉效应的改善并不明显；负显状态下，降低驱动电压能减轻交叉效应，通过调试并设置合适的nLine，可进一步降低交叉效应造成的影响，上述方法均可有效提升STN液晶屏的显示质量。     

平行传输阵列光斑器件的研制

本文基于周期物体的自成象效应,研制了二元位相光栅型平行传输阵列光斑器件。16×16,32×32等二维二元π/2及2π/3位相光栅阵列器件,在500mm 的传输距离内,边长为0.3及0.4mm 的方形单元光斑,其光束扩展率<1%。为光数字处理及光计算等系统研制了一种有实用价值的阵列器件。本文由衍射理论及数值分析对该器件的设计原理、技术特点等进行了理论分析,并给出了实验结果。     

全交叉光互连网络的路由选择与控制

为了解决全交叉光互连网络中光信号路由的选择和控制问题,提出和设计了基于矩阵运算的路由算法。首先,根据全交叉网络的链路函数和连接规则,得到光信号变换矩阵,将光互连网络对信号的传输与处理等效为对输入信号阵列的矩阵运算,建立输入/输出信号间的关系;接着,根据输入输出信号阵列确定各级节点的开关状态;最终,完成信号光的路由判断和控制。分析和讨论表明:该算法不仅解决了8×8全交叉网络的路由控制问题,而且对全混洗、榕树网等规则互连网络也具有良好的移植性和兼容性,且稳定性高、操作性强、易扩容,能够满足16×16、32×32、64×64等大端口光互连网络的路由确定和控制。     

发动机电磁气门驱动动态仿真与分析

用有限元法和集总参数法对一试验用电磁气门驱动（EVA）系统进行了动态仿真。在集总参数法中，根据牛顿第二定律和基尔霍夫电压定律分别建立EVA系统的动力学模型和电路模型，而把电磁力随气隙、电流的变化和电流随气隙、磁链的变化分别做成数据表。用集总参数法进行动态仿真，分析了EVA中电磁铁内涡流、励磁线圈电阻和电磁力对EVA动态工作特性的影响。两种仿真都与实验结果吻合较好，但集总参数法计算效率更高，且可仿真EVA的闭环控制过程。     

Semiconductor devices "from inside"

Operation of any semiconductor device can be presented by unique configuration of the electrical field (potential) and charge (doping) distribution within the device. More specifically, the status of operation is described by the quasi-Fermi energy (QFE) profile across the device. Visualization of the dynamic operation of the device and quantitative measurements of the QFE profile is provided by differential voltage contrast (DVC), which is a modification of the secondary electron imaging in a scanning electron microscope (SEM). The DVC consists of storing two images of a tested semiconductor device. Exposed to the electron beam is a cross section, for example, of a field effect transistor (FET). The first image, covering the entire inside of the FET from source to drain, is taken when the device is not biased. The second image of the same area is taken when the transistor is biased. The secondary electron signal is enhanced or retarded by actual distribution of a potential across the tested device. Subtraction pixel by pixel of the two carefully aligned images removes morphologic contrast from the screen, takes away surface features and contamination of the sample, and reveals the contribution of the electrical field to the changes of contrast. The calibration procedure allows measurement of the potential distribution with a precision of 0.05 V. The first derivative of a potential profile provides for distribution of the electrical field and the second derivative gives the doping profile across the tested device. A variety of semiconductor devices such as p-n junctions, Zener diodes, MOSFET's, MESFET's, solar cells and optical detectors, quantum well lasers, etc., were tested. Videotaping of the tested devices allows us to observe the changes in the electrical field and charge distribution as the device operates in a wide range of electrical or optical signals.     

CCD辐射响应函数矩阵的建立与应用

为了能采用物理意义明确的函数式来表述大格式电荷耦合器件(CCD)的性能参数,直观地实现对面阵CCD辐射性能的评价,本文提出利用“辐射响应函数矩阵”概念来表述CCD每个像元的辐射性能参量.首先,分析了该矩阵各元素的物理意义,提出了对CCD每个像元的绝对辐射响应度、响应非线性度、暗噪声、信噪比以及非均匀性的描述方法.其次,对面阵CCD KAI-16000进行辐射性能检测,并利用回归分析计算出各像元的响应系数.最后,以测试结果为例,讨论和描述该矩阵的应用和结果.实验结果表明:该CCD近似成线性响应,通过矩阵函数可以计算出CCD非均匀性为3.1％,暗噪声为3.84.此方法实用,满足对大格式CCD直观表述的要求.     

An extreme learning machine combined with Landweber iteration algorithm for the inverse problem of electrical capacitance tomography

The image reconstruction of the electrical capacitance tomography (ECT) is an ill-posed and sparse problem. In order to increase the accuracy and speed of the image reconstruction, this paper proposes a new reconstruction algorithm which is based on the extreme learning machine (ELM) with the Landweber iteration method. Firstly, a nonlinear mapping model is established between the pixel gray-scale values and the interelectrode capacitances by using the ELM which has a good learning ability and high speed. Secondly, the Landweber iteration method, which has a good performance in convergence and stability, is applied to calculate the output weight matrix of ELM. Finally, a convergence and stable mapping model of ELM with the Landweber iteration algorithm (L-ELM) for ECT image reconstruction is trained on Matlab platform. Both simulation and measurement tests are carried out to evaluate and analyze the proposed method. Experimental results indicate that the proposed algorithm has good generalization ability and high image reconstruction quality which are better than those of conventional ELM algorithm.     

MEMS节点化建模及其在集成微系统设计中的应用

为实现MEMS产品的快速设计和性能验证,在借鉴其结构化设计思想即节点分析法的基础上,提出了一种与常规信号流类比不同,适于集成微机电系统快速仿真的等效电路建模思路和方法。首先,对系统及MEMS器件进行功能及结构分解;然后,分别对各基本单元进行节点化建模,并在一定的机电类比规则下将其转换为等效电网络(元件);最后,根据节点变量约束关系,将这些等效网络(元件)逐层重构为器件级和系统级等效电路。结合一类典型MEMS集成系统——梳齿式静电反馈微加速度计的分析实例,对上述方法进行了具体介绍和验证。利用OrCAD等电路仿真器分析、测试了所建立的体现多能域耦合关系的微系统数字化分析原型,结果显示,相对于VHDL-AMS描述法,该模型具有单一域内的更加直观的模型形式和快捷的仿真速度,表明本文提出的方法在复杂MEMS集成系统的分析设计中具有一定的应用价值。     

微偏振片阵列红外成像非均匀性产生机理及其校正

集成微偏振片阵列红外成像系统的偏振度图像对非均匀性高度敏感,不经非均匀校正的偏振度图像存在较大误差。为了校正微偏振片阵列红外成像的非均匀性,以入射光Stokes矢量形式,建立了光电转换基本过程的偏振像素模型,基于入射激励和辐射响应数据,分析了微偏振阵列与红外焦面联合作用下非均匀性产生机理。提出一种基于多次辐射测量的矩阵形式的非均匀性校正方法,该方法通过构造多组测量方程,求解偏振像元的增益矢量,由相邻四像元增益矢量组成超级像元的增益矩阵,结合Stokes矢量提取矩阵,逆向求解重构点的校正矩阵。实验数据表明:该方法比两点法降低非均匀性约5%~20%,有效改善红外偏振度图像质量。     

飞机地面试验时模拟环境温度的控制

飞机在进行地面试验时，模拟环境用于模拟飞机在空中飞行时的环境温度。由于存在干扰以及其他未知因素，难以精确建立模拟环境温度的数学模型，从而限制了经典估值理论的应用。本文利用逼近原理，给出了模拟环境温度的广义线性模型和与之相应的广义卡尔曼滤波，实现了模拟环境温度的滤波和温度变化趋势的多点预报和模拟环境的温度控制；文章还给出了模拟环境温度控制的决策原则和控制流程；最后通过2个算例，证明了模拟环境温度广义线性模型对于连续系统应用的广泛适用性和鲁棒性。     

A multilayer transducer that contains piezoelectric layers

Formulas for the transfer functions and electric resistance for transducers that consist of an arbitrary number of active (piezoelectric) and passive layers are obtained. Parallel and series electrical connections of layers are considered. Formulas for reducing any active layer to a passive one are obtained. On the basis of the analysis of the obtained expressions and presented calculation results, recommendations for the practical use of the considered transducers are expounded. The obtained data allow the development of transducers with appreciably improved characteristics in comparison to the case where only one active element is used. The proposed new calculation method makes it possible to substantially simplify the determination of formulas for an arbitrary number of layers. The formulas for the main functions of a transducer concern multiple three-sided transducers, on one side of which certain conditions for their electrical connection are imposed. The transfer functions for the reception mode with respect to the voltage at the working surface of the transducer are obtained. The proposed calculation method can be also applied to other types of transducers.     

Investigation of an impact-excitation oscillator of piezoelectric transducers

A model of a shock-excited oscillator was developed. This model takes the voltage across the transducer, which is induced by the flow of a pulse current through an electrical circuit consisting of a piezoelectric transducer (PET) and an electric load, into account. The shapes of the exciting voltage pulses and received echo pulses are calculated as functions of the parameters of the oscillator and a PET with an electrical load. It is shown that changes in the parameters of the PET and its electrical load may have a strong effect on the excitation-pulse shape, thus leading to unpredictable shapes of echo pulses. The factors that cause a strong dependence of the pulse shape on the thickness of the contact layer, when steel serves as the load, were analyzed. The main conclusions of the study were checked experimentally. Recommendations on the use of the investigation results are presented.