共查询到17条相似文献,搜索用时 125 毫秒
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光束品质因子M2对非同轴激光雷达探测性能的影响 总被引:1,自引:0,他引:1
光束品质因子M2直接影响高斯光束传播特性,光纤口径主要约束激光雷达接收系统的视场角.几何重叠因子是影响激光雷达探测性能的重要参量,其主要受激光束的发射特性、接收系统的结构等影响.通过探讨光束品质因子M2及耦合光纤口径对几何重叠因子的影响,为设计激光雷达发射接收系统,改善激光雷达的探测性能提供了优化方案.数值计算及初步实验表明,光纤的耦合效率与光纤的放置位置及光纤口径有很大的关系;几何重叠因子小于1的探测距离受到M2因子的较大影响且随着M2因子的增大而增大. 相似文献
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基于几何分析,将离轴激光雷达在近距离范围内望远镜视场与发射激光分布的交叠区分为三种形状,并给出了计算离轴激光雷达重叠因子的解析计算公式.基于该公式和发射激光的高斯分布得到了本实验室Mie散射激光雷达重叠因子随高度的变化曲线.利用该曲线对成都地区在不同天气状况下的雷达回波信号进行了校正.在此基础上,利用Klett算法对校正后的回波信号进行了反演,得到了532 nm波长大气消光系数随高度的变化曲线.结果表明,基于文中校正方法得到的大气消光系数能反映实际的天气情况.
关键词:
离轴雷达
重叠因子
高斯模式 相似文献
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由于激光雷达光轴夹角的存在和光束质量分布的非均匀性, 导致理论回波信号与实际回波信号有较大差别, 需要对其进行校正. 基于数学推导和软件仿真, 给出了激光雷达重叠因子的数学表达式, 分析了光轴夹角导致的系统重叠因子在全程探测空间的变化情况; 分析了光束分布为高斯分布和均匀分布时的重叠因子变化情况; 对激光雷达的距离校正信号和Klett算法公式进行了重叠因子修正, 最后在对激光雷达系统参数标定的基础上, 在重叠区域利用修正的Klett公式对其所测得到的回波信号进行了修正, 在探测盲区利用斜率法修正距离校正信号, 进而得到了符合理论与实际情况的激光雷达在全程上校正的消光系数曲线.
关键词:
激光雷达
标定
重叠因子
消光系数 相似文献
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基于CCD成像的侧向散射激光雷达几何标定方法 总被引:1,自引:0,他引:1
通过分析CCD成像特点,设计了侧向散射激光雷达几何标定实验,得到CCD各像元的角宽度,并确定了CCD像元与散射光位置之间的对应关系.对两次实验中采集的回波信号进行标定,并分别与POM02进行相函数比对、与后向散射激光雷达进行探测信号比对,结果表明:相函数廓线和POM02测量结果相吻合;侧向散射激光雷达信号与后向散射雷达的距离修正信号在650m以上的变化趋势一致.侧向散射激光雷达弥补了后向散射激光雷达在近地面段不能探测气溶胶的不足,该标定方法可靠,为进一步利用侧向散射激光雷达研究近地面气溶胶的时空分布奠定了坚实的基础. 相似文献
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基于CCD的侧向散射激光雷达不受几何因子的影响,是探测近地面气溶胶的有力工具。夜晚的探测技术已成熟,由于背景光中夜晚的月光和星光远弱于白天的太阳光,故利用夜晚探测技术得到的白天气溶胶信噪比很低。实验中选用窄带滤光片和小张角镜头,通过校正窄带滤光片透射率、缩短单次曝光时间、多次曝光平均等技术可有效提高白天探测气溶胶的信噪比。白天个例表明,侧向散射激光雷达与后向散射激光雷达反演的气溶胶后向散射系数廓线在0.75~1.50km范围内的变化趋势一致,并对0.75km以下侧向散射激光雷达探测的正确性进行了验证。对合肥地区近地面气溶胶后向散射系数进行了37h的连续昼夜探测,并与同一地点的温度、PM2.5质量浓度联合进行分析。研究表明,改进后的白天侧向散射激光雷达技术是正确、可行的。 相似文献
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The peak position for a lidar return signal is calculated and measured for the horizontal path with variation of the laser beam divergence angle (θ), and the inclination angle (δ) between the telescope and laser axes. This work shows that θ and δ are very important parameters to use in the design or alignment of a lidar system receiving a good lidar signal. This paper describes an experimental determination of geometrical form factors in the lidar equation. We receive the signals and determine the geometrical form factors by slope method in a homogeneous atmosphere. The differential absorption lidar equation is evaluated for the dual-pulse lidar system. A method using a geometrical form factor determined by the experiment is introduced to correct the error in C2H4 measurement. This method shows good correction of measurement error in lidar dual-pulse operation, especially in the short range. 相似文献
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A new method is presented to determine the geometrical form factor in Raman lidar. Mie and Raman backscattering signals are acquired by L625 Raman lidar; then the aerosol backscattering ratio and atmospheric molecular density are derived. By normalizing the molecular density of Raman lidar with radiosonde measurements, the geometrical form factors of lidar are obtained. Experimental results indicate this method is feasible. 相似文献
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Study on the Perturbation Characteristics of Two-Channel Laser Propagation in Atmospheric Turbulence
In order to study the influence factors of acquisition detection target information by lidar and understand the influence degree of each factor, the two-channel phase perturbation model and the two-channel eikonal variance model are derived in detail by using the geometrical optics method in this paper, and each factor is discussed in detail. The results show that the transmission distance is the main factor to affect the two-channel perturbation. With the increase of the transmission distance, the disturbing degree will gradually weaken. With the increase of transverse coordinates, the disturbing of two channels will also be weakened. In order to further weaken the disturbing degree, the feature dimension should be far larger than the wavelength, but far less than the transmission distance. 相似文献
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An ultraviolet (UV) Raman lidar system at 354.7 nm has been developed for accurately measuring the aerosol extinction profiles. A spectroscopic filter combining a high-spectral-resolution grating with two narrowband mirrors is used to separate the vibrational Raman scattering signal of N2 at a central wavelength of 386.7 nm and the elastic scattering signal at 354.7 nm. The aerosol extinction is derived from the Raman scattering of N2 and the elastic scattering by the use of Raman method and Klett method, respectively. The derived results of aerosol extinction are used to compare the difference of two retrieval methods, and the preliminary experiment shows that the Raman lidar system operated in analog detection mode has the capability of measuring aerosol profiles up to a height of 3 km with a laser energy of 250 mJ and an integration time of 8 min. 相似文献
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A ground-based polarization-Mie lidar has been developed to measure backscattering signals from the atmosphere and linear
depolarization ratios at 532 nm. To retrieve depolarization properties of clouds and aerosols, the calibration factor (k) of two polarization channels at 532 nm must be calculated. In this paper three different experimental methods are presented
to determine the calibration factor (k) in this polarization-Mie lidar. Some measured examples are presented and discussed. Experimental and validated results indicate
these methods are feasible. 相似文献
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Ihor Berezhnyy 《Optics and Lasers in Engineering》2009,47(7-8):855-859
We propose a new approach for computation of lidar overlap function, in which light propagation from a lidar to the atmosphere is analyzed with diffraction theory, while the backward propagation is treated with geometrical optics. In this approach, the beam pattern in the atmosphere is represented as a diffraction pattern, and the return beam pattern on the focal plane is built by ray-tracing technique to calculate the overlap function as a ratio of the intensity entering the detector surface to the total intensity on the focal plane. The proposed approach in this paper provides more accurate overlap function of a lidar system. 相似文献
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T. Lindström U. Holst P. Weibring H. Edner 《Applied physics. B, Lasers and optics》2002,74(2):155-165
The lidar technique is an efficient tool for remote monitoring of the distribution of a number of atmospheric species. We
study measurements of sulphur dioxide emitted from the Italian volcano Mt. Etna. This study is focused on the treatment of
data and on the procedure to evaluate range-resolved concentrations. In order to make an in-depth analysis, the lidar system
was prepared to store measurements of individual backscattered laser pulses. Utilizing these repeated measurements a comparison
of three different methods to average the returned signals is made. In the evaluation process we use local polynomial regression
to estimate the range-resolved concentrations. Here we calculate optimal bandwidths based on the empirical-bias bandwidth
selector. We also compare two different variance estimators for the path-integrated curves: local polynomial variance estimation
and variance estimation based on Taylor approximations. Results show that the method performs well. An advantage compared
to previous methods for evaluation of lidar measurements is that an estimate of the mean squared error of the estimated concentration
can be calculated.
Received: 9 July 2001 / Revised version: 15 November 2001 / Published online: 17 January 2002 相似文献