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利用偏振-米散射激光雷达探测对流层大气气溶胶的光学特性及其时空分布.介绍了该雷达的结构、技术参数和探测原理.获得了气溶胶的消光系数垂直廓线和光学厚度,并对这些结果进行了分析和讨论.结果表明,该雷达能较好地探测对流层大气气溶胶的光学特性及其时空分布. 相似文献
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初步反演结果表明,Fernald前向积分法(FFIM)能够用于机载大气探测激光雷达气溶胶后向散射系数的反演,但相应的理论解释没见国内外相关文献报道.根据合肥地基大气探测激光雷达2008年2月27日的探测数据模拟得到的机载激光雷达数据,对FFIE用于机载大气探测激光雷达气溶胶后向散射系数的反演结果进行了定量分析,分析表明:当反演标定点的高度选在10 km左右时,FFIM能够用于机载大气探测激光雷达气溶胶后向散射系数反演的主要原因有3个:1)Fernald前向积分方程(FFIE)分母中两项的差值一般远大于零,
关键词:
大气光学
Fernald前向积分法
机载大气探测激光雷达
气溶胶后向散射系数 相似文献
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利用中国气象局南京综合观测基地的微脉冲激光雷达对南京北郊的气溶胶特性进行了常规的观测,并计算了气溶胶的退偏振比,反演了气溶胶的消光系数,分别得到气溶胶退偏振比及消光系数廓线。分析了不同天气情况下退偏振比和消光系数变化趋势的关系,发现退偏振比和消光系数有一定的相关性,即粒子非球形的程度对其消光的大小有一定的影响。初步探测结果发现:在同一个时刻,晴天和雾霾天时二者变化趋势相同,探测到水云时二者变化趋势相反,探测到冰相云时二者变化趋势相同,研究表明:当探测到气溶胶和冰相云时,粒子的非球形特性越明显其消光系数越大;当探测到水云时,粒子越近似球形其消光系数越大。 相似文献
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介绍了自行研制的用来探测对流层大气气溶胶消光特性的双视场米散射激光雷达.该激光雷达采用两个具有独立接收视场的探测通道分别接收高低层532 nm的大气回波信号,可以兼顾低层大视场角低探测盲区和高层小视场角高探测高度的要求.叙述了该雷达系统的总体结构和技术参量以及数据处理方法,给出了合肥地区(东经117.16°,北纬31.90°)大气气溶胶消光系数廓线和对流层光学厚度的探测结果.测量结果表明,该雷达具备昼夜连续观测对流层大气气溶胶的能力,可以很好地反映气溶胶粒子的时间和空间分布特征. 相似文献
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《光学学报》2015,(10)
为了评估激光诱导荧光雷达对生物气溶胶粒子的有效探测距离及随生物气溶胶浓度变化的敏感性,在阐述生物气溶胶探测原理的基础上,设计了一台激光诱导荧光雷达。该雷达选用波长为355 nm的二极管抽运的Nd:YAG固体激光器作为激励光源,基于脉冲能量、脉冲数量、滤光片带宽、望远镜口径、接收视场角以及生物气溶胶粒子荧光非弹性散射截面积等主要参数,对生物气溶胶荧光回波信号的信噪比进行数值仿真。仿真结果表明,生物气溶胶粒子的质量分数为10-12时,在探测误差小于10%的情况下,系统在白天和夜晚的有效探测距离分别可达1.0 km和7.8 km;而在探测距离定义为0.5 km时,系统对生物气溶胶质量分数的最小分辨能力,白天和夜间分别为1.8×10-13和1.0×10-14。仿真结果有利于了解激光诱导荧光雷达系统的最优参数设定和最佳的实验环境,进而实现对生物气溶胶的有效探测。 相似文献
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利用MODTRAN模型在水平低仰角探测模式下,对生物气溶胶探测的问题进行了分析讨论.用傅里叶变换红外(FTIR)光谱技术对生物气溶胶进行探测研究.首先介绍了MODTRAN模型的大气模式和廓线,根据FTIR光谱技术对生物气溶胶的被动探测要求,利用辐射传输理论和最简单的三层模型,仿真计算得到大气背景和目标生物气溶胶之间的辐射亮度差?L,然后对?L进一步差值得到信号?2Lt,同时再结合光谱仪自身的噪声等效辐射亮度值,得到实际情况下的信号值?2Lt;最后根据探测条件和MODTRAN提供的大气模式,使用被动遥测红外光谱方法预测每种大气模式下生物气溶胶的探测限浓度.每种大气模式下探测限浓度的不同,是因为边界层温度、透过率和背景辐射亮度的不同所导致,同时还与生物气溶胶的吸收系数有关.研究表明,FTIR光谱被动遥测技术能够探测到生物气溶胶的存在,进一步说明探测生物气溶胶的可行性,也为生物气溶胶实际探测提供了一种方法. 相似文献
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Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide 总被引:1,自引:0,他引:1
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs. 相似文献
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A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users. 相似文献
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S. G. Nedel’ko M. A. Krysyuk A. L. Apanasenko L. N. Lymarenko Z. T. Moroz 《Journal of Applied Spectroscopy》1997,64(1):55-61
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped
with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly
described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation
(5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum
cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics
of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure
crystals is analyzed (preliminarily).
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997. 相似文献
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A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output. 相似文献
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The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper. 相似文献
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We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed. 相似文献
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Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell. 相似文献
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A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques. 相似文献
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Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing. 相似文献