压电陶瓷驱动机抖激光陀螺抖动特性仿真分析

二频机抖激光陀螺由于静态锁区和动态锁区的客观存在,要求光学谐振腔体不仅要绕敏感轴作正弦抖动,还要按一定的随机规律改变抖动幅度.二频机抖激光陀螺捷联惯导系统机械结构较复杂,很难通过解析法求解其振动特性,采用有限元法对二频机抖激光陀螺抖动特性的仿真方法进行研究.对激光陀螺的关键点进行激光测振实验,对激光陀螺的输出信号进行了高频采样;并对所得采样数据进行功率谱分析,证明了仿真方法的正确性.采用该方法对激光陀螺工作状态进行动力学仿真,可获得工作状态下任意位置的动力学参数,对分析激光陀螺及捷联系统因抖动而产生的误差有重要意义.     

内含热薄透镜四镜环形腔的光束特性

二平二凹四镜8字型环形腔是色心激光、激光陀螺等研究经常采用的谐振腔。本文采用热薄透镜模型,运用等效腔方法,分析了四镜环形腔的光束特性。详细讨论了热效应对谐振腔基本特性的影响,给出了四镜环形腔的热不灵敏条件。这些结果对谐振腔的设计和应用具有一定的指导作用。     

提高机械抖动激光陀螺抗振性能

通过提升谐振腔抗光路变形能力,可以有效提高机械抖动激光陀螺的抗振动性能。对机械抖动激光陀螺振动中光路扭偏的产生机理进行了理论计算与仿真分析,分析结果表明,抖动切向惯性力和振动冲击惯性力是引起振动中光路扭偏的主要原因。通过振动中光路扭偏对振动性能影响的理论分析指出,减小振动附加上去的朗缪尔零偏,提高陀螺抗振性能的两大有效措施是减小工作电流和提高光路抗失谐能力。通过物理试验验证了振动中光路扭偏机理仿真分析的正确性。不同工作电流的振动对比试验表明,降低工作电流可显著提高陀螺的振动性能,这对于机抖激光陀螺振动特性的提升具有重要指导意义和工程实用价值。     

大功率CO2激光器输出窗口热性能分析

为了研究大功率CO2激光发射过程中输出窗口吸收激光能量产生热性能变化的问题,建立了输出窗口传热学和结构力学耦合非稳态模型,通过对模型进行有限元分析得到表征输出窗口变化的温度、热变形和热应力等参数分布。首先,针对大功率CO2激光特点,讨论了输出窗口材料GaAs和ZnSe的物理特性。然后,基于10 kW级大功率CO2激光器光学谐振腔结构和输出窗口材料物理特性,建立了输出窗口传热学和结构力学的有限元模型。最后,利用COMSOL软件对该模型进行求解,得到以GaAs和ZnSe为材料的输出窗口的温度、热变形和热应力等参数分布,并对比分析不同窗口材料对参数的影响。研究表明:在10 kW级激光作用下,ZnSe窗口温升小于GaAs窗口;两种输出窗口产生m量级热变形;由于GaAs材料的热导率高,GaAs窗口的热变形和热应力分布更为均匀。     

反射镜热形变对激光器谐振腔参数的影响

本文讨论了反射镜热形变对激光谐振腔参数的影响.在具体设计高功率激光器,特别是折迭式CO_2激光器谐振腔时,应尽可能预先考虑这种影响.     

集成光学陀螺最佳调制频率确定的研究

以无源环形光学谐振腔为核心敏感器件的谐振式光学陀螺结构,被广泛应用于集成光学陀螺设计中.该结构通过对光信号进行外差式调频处理,提高系统灵敏度,调制频率的选择对最终实现的灵敏度有重要影响.根据调频光谱测量原理,从微分吸收谱测量出发,毋须复杂的数学处理,可以推导出理论上实现陀螺极限灵敏度的最佳调制频率,证明其与谐振腔谐振特性的半高全宽有确定的数量关系.因此,对任何结构的谐振式光学陀螺,谐振腔结构参数确定后,最佳调制频率亦随之唯一地确定.     

高功率CO2激光器高反膜红外耦合窗热形变的半解析方法的研究

为了有效地解决高功率CO2 激光器高反膜红外耦合窗吸收谐振腔内激光能量产生热效应问题 ,通过对红外耦合窗镀膜参数和工作特性分析 ,建立了红外耦合窗热模型。基于热传导方程和边界条件 ,利用半解析热分析方法得出当CO2 激光器具有理想的TEMoo模式输出时红外耦合窗的温度场和热形变的计算表达式 ,同时对影响红外耦合窗温度场分布的各种因素进行了讨论。研究结果与以往将谐振腔内振荡激光做均匀光强处理作了对比 ,不仅热模型更符合激光器系统 ,而且计算出温度场分布也更加准确。研究方法和结论还可以应用到其它具有轴对称性激光束模式产生的温度场、热形变分析工作中     

机械抖动激光陀螺的随机噪声注入效率问题的研究

向抖动中注入一定强度的随机噪声,以消除机械抖动激光陀螺的动态闭锁误差。研究了噪声注入效率问题,通过理论推导得到了噪声注入效率与抖动系统品质因素的关系。     

全数字化激光陀螺控制系统设计

提出全数字化激光陀螺控制方案,并实现了全数字控制的激光陀螺——数字陀螺。对比分析了正在使用的模拟控制激光陀螺和数字激光陀螺原理及结构,介绍了数字陀螺的优点和关键技术,给出了抖动驱动为脉宽调制方式实现的波形图和数字陀螺图形化测试数据。实验结果表明,数字陀螺符合激光陀螺发展方向,提高了调试和生产效率,简化了对导航系统的设计和调试要求。     

一种优化的激光陀螺自适应抖动剥除算法

去除激光陀螺输出信号中的抖动信号是机械抖动偏频激光陀螺(MDRLG)信号处理电路的主要工作之一。文章对LMS算法中误差因子响应特性对LMS自适应抖动剥除效果的影响进行了研究。为改善抖动剥除效果,在自适应抖动剥除算法中引入了带通滤波器,并采用基于FPGA的激光陀螺自适应抖动剥除系统对误差因子采用带通滤波时的静态性能和动态响应特性进行了测试。试验结果表明,误差因子采用带通滤波时,LMS自适应抖动剥除的收敛速度和收敛精度都要优于差分运算,并且二者具有相同的动态频率响应曲线。     

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.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

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.     

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.     

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.     

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.     

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.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.