共查询到20条相似文献,搜索用时 31 毫秒
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We are building a long-range FM/cw nonscanning imaging lidar breadboard. This lidar system achieves ranging based on a frequency
modulation/continuous wave (FM/cw) technique, implemented by an amplitude modulated mid-IR diode laser transmitter with a
linear frequency modulation (LFM) of the subcarrier. Firstly, various schemes of light beam modulation are analyzed. Secondly,
we put forward a laser modulation scheme whose core was formed by a 1.55 μm electro-absorption modulated laser diode (EML) and an erbium-doped optical fiber amplifier (EDFA), then a corresponding
experimental system architecture and components for light beam modulation and detection are established. Finally, a corresponding
experiment of laser beam modulation is completed for the first time. In our experiment, the EML amplitude is modulated by
a 200 MHz to 800 MHz LFM signal, whose amplitude value is 2.05 V. The average output power of the modulated laser obtained
in the experiment is 10 W, peak power is 16.4 W, and the average modulation depth is 78%. The results of tests predict that
this laser modulation scheme is likely to improve the imaging range of the FM/cw lidar. 相似文献
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研制了一套接收硬目标回波的差分吸收激光雷达系统以用于全天候监测大气CO2浓度变化.系统采用10和12 kHz正弦波分别对处在CO2吸收峰内和吸收峰外的波长进行强度调制,利用单频检测技术提取回波信号.提出了一种利用激光扫频推算系统精度的方法,从而弥补了长期以来只能在理论上计算差分吸收激光雷达系统精度的不足,给实际系统自定标问题提供了一种解决方案.该系统采用全光纤结构,结构可靠,便于移动.利用此系统获得了上海市多天CO2浓度变化曲线,在450 m的积分路径长度上,1 s的积分时间取得了优于3.39×10-6的测量精度. 相似文献
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非同轴激光雷达由于存在发射激光与接收望远镜之间的不完全重叠区, 造成近场回波信号与真实大气信号不一致. 对于多波长激光雷达, 这种不一致更为突出和复杂. 然而, 近场大气是人类活动最集中的区域, 因此对多波长激光雷达近场信号进行校正, 对于了解和探究边界层大气具有十分重要的意义. 提出了一种利用粒子谱仪测量近地层气溶胶尺度谱分布并运用Mie 散射理论和低层大气指数衰减规律, 进而直接校正多波长激光雷达消光系数廓线近场信号的新方法. 通过对晴天、多云天气和雾天多波长气溶胶消光系数廓线近场信号的校正, 证明了该方法的可行性和实用性. 该方法着重考虑了多波长激光雷达比的波长依赖性和气溶胶粒子谱分布的天气相关性, 将该方法用于近地层大气消光系数廓线校正, 减少了由于不考虑这两个因素带来的消光系数廓线反演和校正的不确定性. 该方法对于研究不同天气情况下边界层内的大气气溶胶物理、光学特性具有一定的实用价值和借鉴意义. 相似文献
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基于风场探测的需求,采用1 550 nm波长连续激光种子源搭建了一套全光纤结构多普勒相干测风雷达系统。从雷达方程出发,对连续激光相干雷达载噪比方程和不同雷达收发望远镜聚焦位置下风速合成权重进行了分析。针对测风雷达要求设计了5~200 m的变焦激光收发望远镜模块。扩束系统采用伽利略折射式结构,发射光束准直下扩束比为23,光学质量接近衍射极限。标定测试通过对旋转电机圆盘转速测量完成。转盘转速范围为-3 000 r/min到+3 000 r/min,转盘直径为26 cm。在视向速度多普勒频移分别为正向和负向时,雷达系统速度测量结果与通过圆盘转速计算值的相关系数为0.998与0.993,标准差为0.151 m/s和0.229 m/s。使用该测风激光雷达开展室外大气风速探测实验,取得了良好效果。 相似文献
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提出了利用Fabry-Perot干涉仪的反射场实现高光谱分辨率激光雷达精细探测大气光学参量的新方法和思路.设计了高光谱分辨率的分光系统,并分析了干涉仪反射场的光谱透过特征曲线.结合高光谱激光雷达探测信号特征,讨论分析了谱分离比和瑞利信号透过率随反射率和腔长的变化曲线,同时结合误差传递公式,建立了仿真分析模型,讨论了回波光束发散角和入射角变化对激光雷达探测结果的影响.结果表明,所提出的Fabry-Perot干涉仪反射场可以实现高光谱分辨率激光雷达探测系统的精细分光,同时探测结果误差随回波光束发散角变化不敏感,控制发散角在10 mrad以内,入射角在1.5 mrad以内时,可以实现气溶胶光学参数廓线的高精度探测. 相似文献
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相干多普勒激光测风雷达系统研究 总被引:3,自引:0,他引:3
大气中风速和风场分布的精确测量具有重要的军用和民用价值。近20年来,相干激光雷达对风场的遥测被经常用于大气边界层风场的精确测量。首先介绍了相干激光测风雷达的工作原理;然后对其相关的指标体系进行了详细的分析和论证,主要包括工作波长、探测灵敏度、测速精度以及作用距离与发射功率的关系等技术指标;最后给出了目前较优的相干激光测风雷达系统的技术方案和技术途径。在此基础上,采用1.5μm窄线宽激光光源设计了一套全固态、小型化激光相干测风实验装置,并进行了相关实验。 相似文献
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Wahyu Widada Hideki Kinjo Hiroaki Kuze Nobuo Takeuchi Makoto Sasaki 《Optical Review》2001,8(5):382-387
This paper describes the lidar inversion of the tropospheric aerosol extinction profiles under the influence of multiple-scattering effects for various elevation angles of lidar detection. A single-scattering lidar equation is employed to analyze lidar signals with multiple-scattering contributions that are calculated by the Monte Carlo method for given atmospheric conditions. We calculate errors in the optical thickness from the results with and without multiple-scattering effects. It is found that the errors vary in a range of 2#x2013;18#x0025; according to the optical thickness variation of 0.19#x2013;3.8. The dependence of the error on the field-of-view angle of the lidar observation is also discussed. 相似文献
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Swati Raman B.K. Yadav N.S. Bisht M. Husain H.C. Kandpal 《Optics and Lasers in Engineering》2009,47(11):1282-1285
An experimental study is carried out to investigate a special kind of three-dimensional intensity distribution of a partially coherent optical beam known as optical bottle beam produced by using an annular aperture and lens combination (Lens Aperture System). In this paper, we are demonstrating the experimental results of our observations. The investigation also includes the effects of coherence modulation and central obstruction of the annular aperture (used in Lens Aperture System) on the resultant partially coherent optical bottle beam. The method discussed in this paper is simple and cost effective. 相似文献
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Geary K. Schwemmer Richard D. Rallison Thomas D. Wilkerson David V. Guerra 《Optics and Lasers in Engineering》2006,44(9):881
We have developed and investigated the use of holographic optical elements (HOEs) and holographic transmission gratings for scanning lidar telescopes. Rotating a flat HOE in its own plane with the focal spot on the rotation axis makes a very simple and compact conical scanning telescope. We developed transmission and reflection HOEs for use at the first three harmonic wavelengths of Nd:YAG lasers. The diffraction efficiency, diffraction angle, focal length, focal spot size and optical losses were measured for several HOEs and holographic gratings, and found to be suitable for use as lidar receiver telescopes, and in many cases could also serve as the final collimating and beam steering optic for the laser transmitter. Two lidar systems based on this technology have been designed, built, and successfully tested in atmospheric science applications. This technology will enable future spaceborne lidar missions by significantly lowering the size, weight, power requirement and cost of a large aperture, narrow field of view scanning telescope. 相似文献
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WavefrontmatchsimulationonreceiversurfacesincoherentlidarZHAOYuanSUNDongsongQIAOLijieNANJingda(DepartmentofAppliedPhysics,Ha... 相似文献
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对舰船尾流激光散射机理及探测过程的数值模拟是研究舰船尾流激光探测与制导的重要基础.首先分析了Monte Carlo方法引入到尾流激光雷达数值模拟领域研究的可行性.结合自行研制的尾流激光雷达实际参数,建立了尾流激光探测的Monte Carlo数值仿真模型.通过对仿真结果进行统计,深入剖析了仿真结果方差大及光子利用率低等问题的成因.为解决该问题,基于有偏采样理论和分裂-轮盘赌基本原理提出了接收光学视场内光子强行碰撞方法和以光子自由程总长度为准则的光子分裂方法,并进行了两方法的融合.仿真与实验结果的对比分析表明,提出的模型仿真结果与实验数据符合较好,验证了模型的正确性;提出的接收光学视场内光子强行碰撞方法和光子分裂方法能有效减小方差并提高光子利用率;解决了Monte Carlo方法引入到尾流激光雷达模拟过程中的适用性问题. 相似文献
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Linearity Requirement for a Linear Frequency Modulation Lidar 总被引:1,自引:0,他引:1
The nonlinear of the frequency modulation in linear frequency modulation (LFM) lidar seriously affects the accuracy of range and velocity. We describe the influence of nonlinear of the frequency modulation on the accuracy. The frequency-domain analysis of heterodyne signal is used to deduce the linearity requirement for LFM lidar. 相似文献