基于耦合技术的单色光谱吸收法检测甲烷气体浓度

针对电子检测装置在甲烷气体浓度检测时存在易燃易爆等安全隐患,本文提出了一种基于光纤耦合技术的单色光谱吸收法检测甲烷气体浓度的方案。给出了单色光源的选择依据,设计了基于光纤耦合技术的单色光谱吸收法检测装置,提出了应用Matlab对甲烷气体浓度与输出电压两组数据进行线性拟合。通过输出电压预测出甲烷气体浓度,并检测了预测值与真实值的误差。实验结果表明,将光纤耦合技术应用于单色光谱吸收法检测甲烷气体浓度,可以在无电力介入的情况下对甲烷气体浓度进行实时检测,误差不超过2%。     

红外光谱技术在气体检测中的应用

根据气体在红外光谱区的吸收,可以采用红外光谱来检测气体的浓度.本文介绍了红外光谱技术在气体浓度检测方面的应用情况以及国外的研究进展.以甲烷和一氧化碳气体为例,描述了用红外半导体激光器或发光二极管结合红外光谱技术实现的气体探测系统.最后介绍了几种气体传感系统的实例.     

光纤瓦斯多点传感系统的设计

差分吸收法是基于近红外光谱吸收、远距离监测气体浓度的重要方法.采用双波长差分检测法,选取1 653.7 nm作为甲烷气体的吸收峰,1 652 nm作为参考波长,设计了一种新型远距离多点测量的光纤瓦斯传感系统,可以对甲烷气体浓度进行实时检测.通过对光路链路损耗的预算及吸收系数的计算,综合考虑气室结构和数字信号处理电路等影响系统性能的重要因素,从理论上论证了该方案的可行性.系统的稳定性及测试灵敏度需通过实验验证,仍有较大的提高空间,同时也可用于实现其他气体浓度的监测和远程监控.     

光纤甲烷气体浓度传感器及测试系统研究

本文介绍的光纤甲烷气体浓度传感系统以甲烷分子的吸收谱带1.331μm为吸收工作波长,以邻近无吸收区的1.27μm 为参考波长,采用双波长差分吸收法原理,通过 A/D 转换,利用微机实现了对甲烷气体浓度的实时检测。目前实测的最低浓度为2%。     

光纤光栅式甲烷浓度差分检测系统研究

基于甲烷气体的近红外光谱吸收特性,研究了一种全光纤差分吸收式甲烷检测系统.分析了差分吸收检测的基本原理,建立了甲烷检测的数学模型.系统选用发光二极管(LED)作光源,用光纤布拉格光栅进行滤波实现差分吸收检测,并结合光源强度调制技术和锁相放大技术,消除了光路干扰和光源强度波动的影响,提高了测试灵敏度.最后给出了该甲烷气体浓度检测系统的实验结果.     

吸收光谱学测量甲烷激光器的研究

基于气体在其特征吸收波长下的光的吸收随其浓度变化的机理,通过对甲烷气体吸收光谱的分析,研究了光谱吸收式甲烷气体浓度检测方法.通过波长调制实现气体浓度的谐波检测,利用二次谐波与一次谐波的比值来消除由光源的不稳定和变化所引起的检测误差,并建立了谐波检测的模型,给出了甲烷气体谐波检测方案.     

基于F-P滤波器实现宽谱光源的甲烷差分检测

构建了一种利用F-P滤波器实现甲烷气体差分检测的系统。该系统采用宽谱LED作光源，选用甲烷气体在6060．6cm^-1附近的梳状吸收谱作为探测对象，通过F-P滤波器选择与待测甲烷吸收谱匹配的探测光，对F-P的精细度和腔长进行选择，推导得出了甲烷气体浓度的计算方法，实现了系统的差分吸收检测。该系统进一步提高了气体测量的灵敏度和稳定性。     

锯齿波调制半波扫描技术对甲烷检测系统的性能改进

为了能够在复杂的环境下实现甲烷气体浓度的高精度和高稳定性检测,在基于光谱吸收原理的光纤甲烷检测系统的基础上,提出了利用锯齿波调制的半波扫描技术,较大程度改进了系统的性能指标。采用锯齿波调制光源的方式,同时对光信号进行波长调制和强度调制,实现对甲烷气体的洛伦兹吸收线型扫描。锯齿波调制的方式能够解决信号链路噪声、环境噪声等随机信号对光强造成的干扰,消除光源波长漂移对检测带来的影响,且实现了积分处理,进一步提高检测精度;但由于甲烷吸收光谱的对称性,采用通用的全波扫描方式,气体吸收光强后进行微分处理会出现正弦型曲线,无法准确确定吸收的光强所对应的数字量;而采用半波扫描方式,气体吸收光强后进行微分处理只出现凹型曲线,可以准确确定吸收的光强所对应的数字量。实验结果表明:采用锯齿波调制的半波扫描方式,可以准确测得甲烷气体浓度;测量范围为0%~10%,精度由100 ppm提升到10 ppm（1 ppm=10-6）,稳定性由0.3%提升到0.01%。该系统经过改进后在复杂环境下受温度影响小,精度高,稳定性好,抗干扰能力强。     

光纤甲烷气体传感器的研究

基于甲烷气体近红外吸收的机理,研究了一种高灵敏度易于实现的光纤甲烷气体传感器。分析了半导体激光器的调制特性和谐波检测的基本原理,建立了传感器的数学模型。系统采用分布反馈式半导体激光器做光源,气室采用小型渐变折射率透镜构成的气室,加入参考光路和参考气室,使光源输出的中心波长锁定在气体的吸收峰上,通过光源调制实现气体浓度的谐波检测,给出了甲烷气体测量的实验结果。     

采用Tm光纤光源的甲烷气体相关光谱检测

报道了以半导体激光器泵浦掺Ｔｍ３＋光纤为光源的甲烷气体相关光谱检测系统，研究了７８８ｎｍ波长泵浦下掺Ｔｍ光纤光源的一些光谱特性，并在实验上用这种光源及系统对甲烷气体作了测量。在５．７ｃｍ长的测量腔下，系统噪声幅度对应的最小气体检测浓度为０．４７％，远低于甲烷气体的爆炸低限（５％），证明了这种光纤光源用于甲烷气体浓度测量的可行性。     

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.     

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.     

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.     

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.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

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.