低能激光武器的防护技术

随着激光技术的发展，低能激光武器装备不断增多，如何防护低能激光武器对人眼、光电探测器和光学系统等的破坏显得越来越重要。本文对低能激光武器的防护技术进行了介绍。     

新概念高能激光武器与强激光光学计量检测技术

新概念高能激光武器的研究与发展已有四十多年的历史。第一代高能激光武器主要采用连续波化学激光器，其输出功率可达百万瓦。第二代高能激光武器主要采用了波长更短的节能固体激光器件，其输出功率为100kW。与第一代高能化学激光武器采用超高能量直接烧毁杀伤目标不同，第二代高能固体激光武器寻求节能型杀伤方式，即以最小程度的破坏来实现致命杀伤的效果。随着高能激光武器的发展和实战部署，作为高能激光武器核心的高能激光系统总体性能参数(能量/功率、激光波形、光束质量、近场和远场的强度分布、光束指向稳定性、光谱和偏振特性等)的计量和测试显得尤为重要。文中围绕新概念高能激光武器的历史、研究现状和未来发展展开论述。高能激光武器系统的研制对强激光光学计量检测技术提出的新要求和挑战有助于推进强激光光学计量检测技术的发展。     

车载高精度激光警戒装置

激光警戒装置已经被广泛使用，用于迅速发现激光威胁，使受攻击平台迅速采取对抗措施。激光警戒装置的方位测量精度可以很宽，低的为90。，中等的一般为3。，高的可达0.06。。方位测量精度要求取决于用途，当然也取决于买主手中的钱。坦克等装甲战斗车辆在利用火炮、激光武器对     

激光在现代海军中的应用

激光技术应用于海军，不仅可以提高海军现有常规武器的命中率，而且可为海军提供新型战术武器，从而大大增强海军在现代海战中的作战能力。激光在国外海军最成功的应用是激光测距、目标指示以及武器制导等；激光探雷、激光测深仪等已处于试验、试用阶段；而舰载激光武器、激光对潜通讯和激光陀螺等还处在论证、试验阶段。     

车载激光武器

战术激光武器发射高功率激光束，可以损伤光电传感器，致盲人服或者使光电传感器饱和，使人眼发生闪光盲，在光电对抗中可以作为主动对抗器材，发挥重要的作用。在海湾战争期间，美国陆军部署了马T·玛丽埃塔公司研制的AN／VLQ－7“鱼工鱼”激光武器和洛克希德·桑德斯公司研制     

激光武器反卫星技术研究

针对激光武器反卫星的机理进行分析和研究,得出两个结论:激光武器摧毁空间目标具有速度快、攻击空域广的特点,利用激光的光效应和高能热效应,直接照射卫星可以破坏其光电探测器,从而破坏敌方的卫星装置;建立了卫星探测器的一维热模型,在对探测器材料的破坏阈值进行理论计算的基础上,利用CW COIL辐照PV型InSb探测器对破坏阈值进行实验研究,二者数据吻合较好。     

大气对激光武器系统的影响分析

强激光的大气传输效应是影响激光武器系统性能的重要因素。通过理论分析和数值计算表明,光功率衰减主要跟能见度有关,而光束辐照面积的增加主要是由湍流和热晕的强度决定的。激光武器系统仅适用于中低强度湍流和热晕,除此之外,在其它条件下,激光武器系统的作用距离将大大受限。     

星载激光告警技术

随着激光武器技术的迅速发展，美、俄两国多次进行激光反卫星试验，卫星面临的激光威胁已日趋严重，进行星载激光告警技术研究势在必行。本文针对这项技术进行分析。     

两类强激光定向能：概念与应用

把足够的激光能量沿给定的方向输送到远处确定的目标上去的技术称为“强激光定向能技术”。定向能技术可以有各种不同的和平应用与军事应用，涉及到多学科前沿的科学、技术与工程问题，是当前国际上引人注目的研究领域。西方首先介绍激光定向能的概念，然后按物理与技术特征的不同，将其分为两类：远距离、小光斑型的为A类，其典型应用有激光清除空间垃圾、激光武器；较近距离、大光斑型的为B类，其典型应用有激光清除海面石油污染等。对两类激光定向能科学技术特征的差异进行了分析。正确理解强激光定向能的物理概念和技术特性，对实际应用系统的合理设计，具有重要意义。     

激光应用 激光军事应用

TJ95 2005021069 空间对抗中的激光武器=Laser weapon in counter-space [刊,中]／任国光(北京应用物理与计算数学所．北京 (100088)),黄裕年//激光与红外.-2004,34(5).-323-328 作为威慑战略的一部分,美国正在发展摧毁卫星的能 力,而开发激光反卫武器是实现空间控制的重要研发计划 之一。初步分析了卫星对激光武器的易损性,然后评述和 讨论了地基激光、机载激光和可伸缩的空天全球激光交战 反卫武器的系统概念,关键技术和部件的重大进展,以及     

Stable isotopic and geochemical variability within shallow groundwater beneath a hardwood hammock and surface water in an adjoining slough (Everglades National Park,Florida, USA)

Data from a 10-month monitoring study during 2007 in the Everglades ecosystem provide insight into the variation of δ¹⁸O, δD, and ion chemistry in surface water and shallow groundwater. Surface waters are sensitive to dilution from rainfall and input from external sources. Shallow groundwater, on the other hand, remains geochemically stable during the year. Surface water input from canals derived from draining agricultural areas to the north and east of the Everglades is evident in the ion data. δ¹⁸O and δD values in shallow groundwater remain near the mean of?2.4 and?12 ‰, respectively. ¹⁸O and D values are enriched in surface water compared with shallow groundwater and fluctuate in sync with those measured in rainfall. The local meteoric water line (LMWL) for precipitation is in close agreement with the global meteoric water line; however, the local evaporation line (LEL) for surface water and shallow groundwater is δ D=5.6 δ¹⁸O+1.5, a sign that these waters have experienced evaporation. The intercept of the LMWL and LEL indicates that the primary recharge to the Everglades is tropical cyclones or fronts. δ deuterium to δ¹⁸O excess (D_ex values) generally reveal two moisture sources for precipitation, a maritime source during the fall and winter (D _ex>10 ‰) and a continental-influenced source (D _ex<10 ‰) in the spring and summer.     

The effect of scratch technique on the thermal-product value of temperature sensors

The effect of different scratch techniques, mainly abrasive papers and scalpel blades used to form the junctions of temperature sensors, on the thermal-product value of these sensors, was examined. A dynamic calibration procedure of scratched sensors in a shock tube facility which allows easy evaluation of their thermal-product value is outlined. The thermal product of a particular sensor was found to be dependent on the flow Mach number, junction scratch technique, junction location, and also on the enthalpy conditions. It was shown that using different scratch techniques normally results in different thermal-product values of sensors. The experimental procedure used in the present study has yielded practical data on characteristics of scratched temperature sensors; these data can be used in accurate measurement of transient heat transfer under hypersonic flow conditions.     

Novel calibration method for non-overlapping multiple vision sensors based on 1D target

The global calibration of multiple vision sensors (MVS) with non-overlapping views has been widely studied. In this paper, a novel calibration method for MVS with non-overlapping fields of view based on 1D target is presented. First, two neighboring vision sensors are selected. The rotation matrix between the two vision sensors is computed using the co-linearity property of the feature points on 1D target. Then the translation vector is computed according to the known distances between feature points on 1D target. The global calibration of all vision sensors is realized by repeating the above pair-wise calibration on different pairs of vision sensors. Due to the small volume and mobility of 1D target, the proposed global calibration method can be applied to vision sensors distributed in a large area or narrow space. Experiment results show that the RMS error of global calibration is within 0.060 mm.     

Stable water isotope patterns in a climate change hotspot: the isotope hydrology framework of Corsica (western Mediterranean)

The Mediterranean is regarded as a region of intense climate change. To better understand future climate change, this area has been the target of several palaeoclimate studies which also studied stable isotope proxies that are directly linked to the stable isotope composition of water, such as tree rings, tooth enamel or speleothems. For such work, it is also essential to establish an isotope hydrology framework of the region of interest. Surface waters from streams and lakes as well as groundwater from springs on the island of Corsica were sampled between 2003 and 2009 for their oxygen and hydrogen isotope compositions. Isotope values from lake waters were enriched in heavier isotopes and define a local evaporation line (LEL). On the other hand, stream and spring waters reflect the isotope composition of local precipitation in the catchment. The intersection of the LEL and the linear fit of the spring and stream waters reflect the mean isotope composition of the annual precipitation (δ_P) with values of?8.6(±0.2) ‰ for δ¹⁸O and?58(±2) ‰ for δ²H. This value is also a good indicator of the average isotope composition of the local groundwater in the island. Surface water samples reflect the altitude isotope effect with a value of?0.17(±0.02) ‰ per 100 m elevation for oxygen isotopes. At Vizzavona Pass in central Corsica, water samples from two catchments within a lateral distance of only a few hundred metres showed unexpected but systematic differences in their stable isotope composition. At this specific location, the direction of exposure seems to be an important factor. The differences were likely caused by isotopic enrichment during recharge in warm weather conditions in south-exposed valley flanks compared to the opposite, north-exposed valley flanks.     

Optical pressure sensors for high-pressure–high-temperature studies in a diamond anvil cell

We review the various optical pressure sensors that are suitable for high-pressure and high-temperature studies in a diamond anvil cell. Two different kinds of sensors are considered: those based on the pressure shift of a fluorescence line (ruby, SrB₄O₇:Sm²⁺) and those based on the pressure shift of a Raman line (c-BN, diamond). The calibration of those sensors are presented in detail, and discussion is made on their useful pressure and temperature ranges.     

Integrated SU-8 photonic gas sensors based on PANI polymer devices: Comparison between metrological parameters

In this work, we have designed and developed three families of integrated photonic sensors for ammonia detection. These photonic sensors are integrated onto single-mode TE₀–TM₀ SU-8 polymer planar waveguides and based on a polyaniline (PANI) sensitive polymer material. The first family relies on the deposit of a PANI–polymethyl methacrylate (PMMA) composite sensitive layer on a given SU-8 waveguide. The second family relies on a PMMA passive layer deposited on the SU-8 waveguide before applying the PANI sensitive layer on the PMMA passive layer. The third family takes advantage of a PANI layer deposited by plasma technique directly onto the SU-8 waveguide. The working principle of such sensors is based on the optical intensity modulation induced within the single-mode waveguide owing to the interaction between the evanescent field and the sensitive layer. The sensing proprieties of these integrated photonic sensors to ammonia gas at room temperature were characterized and the comparison between these different families of photonic sensors is presented. Experimental results show that the sensor based on new plasma–PANI as sensitive layer has the better metrological parameters.     

Progress in pressure measurements with luminescence sensors

Abstract

Various luminescence sensors for pressure measurements are compared with the generally used ruby sensor. Typical advantages and disadvantages of different luminescence sensors based on lanthanide ions in various hosts are discussed. Emphasis is given to the sensor based on Sm^2?: MFCl (M =Sr, Ba) with respect to its sensitivity, temperature dependence and range of applicability.     

Tuning the electronic and magnetic properties of germanene by surface adsorption of small nitrogen-based molecules

The structural, energetic and electronic properties of germanene adsorbed with small nitrogen-based molecules, including N₂, NH₃, NO₂ and NO, have been investigated by using first-principles calculations. The results show that all nitrogen-based molecules considered bind much stronger to germanene than to graphene due to the hybridized sp²-sp³ bonding of Ge atoms. The N₂, NO and NO₂ molecules all act as an acceptor, while the NH₃ molecule donates electrons to germanene. We also found sizable band gaps (2–158 meV) are opened at the Dirac point of germanene through N₂, NH₃, and NO₂ adsorptions, but with only slightly destroying its Dirac cone shape. The NO₂ molecule also shows a heavy p-type doping character and makes germanene to be metallic. Moreover, when adsorbed by NO molecule, the germanene can change to be a ferromagnetic half-metal with 100% spin-polarization at the Fermi level. Overall, the different adsorption behaviors of small nitrogen-based gas molecules on germanene provide a feasible way to exploit chemically modified germanene for a wide range of practical applications, such as field-effect transistors, gas sensors and spintronic devices.     

Fiber-optic sensor based on evanescent wave absorbance around 2.7 μm for determining water content in polar organic solvents

The feasibility of sapphire fiber-optic sensors based on evanescent wave absorption spectroscopy in the infrared range for quantitative determination of water content in polar organic solvents has been investigated. Evanescent wave absorption spectra of sapphire fiber-optic sensors in glycerol, ethanol, and glycol with different water concentrations obtained and analyzed, respectively. Evanescent absorbance of the sensors in those organic solvents has been utilized to implement for in situ monitoring water concentration in organic solvents. The evanescent absorbance of sensors in glycerol and glycol has been found to vary linearly with water content in the range 0–30 % and in ethanol in the range 0–10 %, respectively. The fiber-optic sensors based on evanescent absorbance for monitoring water concentrations in those organic solvents are acceptably accurate, cost-effective, and reliable. Some methods to improve the accuracy of predicated water content in those organic solvents are also suggested. Overall, the results demonstrate that the sapphire fiber-optic sensor based on evanescent absorption spectroscopy is a promising candidate for prediction of water content in polar organic solvents in on-line and remote situation.     

Robust baseline correction algorithm for signal dense NMR spectra

This paper outlines a fully automated algorithm for baseline correction. Based on our experience with NMR spectra of complex mixtures, this algorithm is designed to automatically differentiate signal points from baseline points. The algorithm's strength is its ability to accurately determine baseline points in very dense spectra, without destroying the line shapes of prominent peaks. The algorithm described is implemented in Chenomx NMR Suite 4.6. It is demonstrated here using two separate spectra acquired on two different NMR spectrometers.