监测甲烷浓度的红外光吸收法光纤传感器

研制了一种用于监测甲烷气体的红外光纤传感检测系统。该系统采用双波长差分吸收测量法,将低损耗的光纤作为传光回路,用1/4周期的自聚焦棒作为准直透镜,能实现3km的远距离遥测。     

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.     

多种气体一体化测量的光纤传感技术研究

基于气体在吸收峰波长下对光的吸收随浓度变化的原理,研制一种光纤式气体监测仪,根据被测气体的吸收峰对应的波长选择分布反馈式半导体激光器作为光源,采用不同频率的光源驱动电路实现对多种气体浓度的同时检测。对甲烷和乙炔气体浓度的检测实验表明,该系统具有一定的检测灵敏度和精度。     

差分吸收式光纤甲烷气体传感器的研究

根据甲烷气体的吸收光谱 ,研究了用 L ED作光源的差分吸收式光纤甲烷气体传感器。选择两个同型号 L ED光源作为差分吸收信号 ,光源驱动器自动实行交替斩波。建立了气体浓度差分吸收的数学模型 ,给出了甲烷气体浓度的测量结果。实验表明该仪器的测量灵敏度达到 2× 10 - 4。     

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.     

基于谐波检测原理的双气室气体传感器研究

基于气体的近红外吸收机理,研究了一种双气室光纤气体传感系统。通过光纤光栅和压电陶瓷对宽带光源LED进行波长调制,获得与气体吸收峰对应的窄带反射出射光。利用谐波检测原理,检测测量气室和参考气室的二次谐波信号,以它们的比值作为系统输出,消除了吸收系数随环境的变化、光源光功率的波动和光路干扰对测量精度的影响。利用波分复用技术实现了多种气体的高精度测量,甲烷气体测量的实验结果表明该系统的测量灵敏度可以达到1×10-5。     

吸收式气敏传感空芯光纤的设计和制备

研发了红外波段吸收式气敏传感空芯光纤.空芯光纤的内面镀有银膜和介质膜,在目标波长提高反射率从而降低损耗.银膜和介质膜分别采用化学银镜反应法和液相镀膜法成膜.优化介质膜的材料和膜厚.光纤在可见光到中红外波段实现了低损耗特性.空芯光纤不仅可以用作气体传感的光吸收气室,而且也可用作红外光的传输媒介.初步实验结果显示这种空芯光纤可以替代普通的气体吸收气室,实现传感系统小型化.     

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%。     

本刊对来稿中统计学符号书写要求

利用甲烷气体在倍频2ν3带较强吸收线R(4)支的波长为1 650.96 nm,基于气体红外特征光谱吸收原理,设计了一套多点实时监测甲烷气体浓度的光纤传感器网络,并建立了谐波检测的数学模型.该系统以1 650 nm波段的分布反馈式半导体激光器(DFB LD)作为光源,采用锁定放大器SR830对微弱电信号进行处理.实验表明,系统中单个传感器的分辨率可达200×10-6,长时间的精确度和稳定性均可满足实际要求,单个传感器的响应时间小于2 s.通过理论分析得出系统中各传感器可放置于离地面20 km以上的矿井中,且系统可在多场合进行多点的实时监测.     

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.     

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.     

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.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks