全固态钠层风温探测激光雷达关键技术研究

发布时间：2018-06-26 20:22

本文选题：激光雷达 + 钠层探测　；参考：《中国科学院大学(中国科学院武汉物理与数学研究所)》2017年博士论文

【摘要】：中高层大气温度和风场的高分辨探测是当今大气探测和空间物理领域的研究热点之一。窄线宽钠多普勒激光雷达可实现中层顶大气温度和风场的同时探测,是大气科学研究、空间环境监测预报等的重要观测手段,为开展大气波动传播、能量和动量循环过程、高中低大气相互耦合作用等前沿科学问题的研究提供关键数据来源。本文主要开展了可实现中层顶温度和风场探测的全固态钠激光雷达系统关键技术的研究,大幅提升了窄线宽钠多普勒激光雷达系统工作的可靠性和稳定性,为钠激光雷达的进一步推广和应用提供了关键技术手段,为系统的自动化操作、远程或极端环境条件下的部署奠定了重要基础。论文对钠层风温探测原理、全固态激光雷达系统设计和研制、数据处理和风温反演方法及钠层风场和温度的初步探测结果等进行了详细介绍。主要研究内容如下:(1)成功研制出具有国际先进水平的全固态钠层风温探测激光雷达,基于固体激光和频技术,利用两个工作波长分别为1064nm和1319nm的连续光种子激光器输出单模窄线宽激光,分别注入到两个Nd:YAG激光器并进行脉冲和频,获得了能高效激发钠层的高功率589 nm脉冲激光发射源,提高了钠激光雷达发射激光系统工作的稳定性和可靠性;设计了全光纤耦合的种子注入激光单元,种子光稳频和移频等关键技术均采用光纤传输的模块化设计,大大减少了注入种子单元的光学调整;通过种子激光和频获得了窄线宽589 nm连续激光,并利用钠原子饱和吸收光谱和数字智能反馈程序控制1064 nm和1319nm种子激光器,实现了将和频生成的589 nm连续激光频率长期锁定到钠D2a共振跃迁线上;利用光纤耦合的声光移频技术,结合光纤开关的时序控制设计,实现了发射激光在三个工作频率上自动循环切换工作,并通过计算1064 nmNd:YAG激光腔的纵模间隔,对移频工作频率的选择进行了优化,有效提高了三频率种子注入的可靠性;系统采用三方向分光发射和同步接收采集,设计了发射光束二维调节远程控制软件平台,提高了三方向探测的视场匹配调节的精度和系统的自动化水平;开发了数据采集和系统控制软件,实现了多通道的回波信号同步采集、自动存储、实时显示和整机时序控制等。(2)开展了钠层风温数据处理和反演方法的研究,原始回波信号的预处理包括异常数据剔除、时间积分、背景扣除、功率归一化、高度平滑等,利用三频比率技术给出了温度和风速比值的计算方法,详细阐述了利用二分法由温度和风速比值结合理论的二维校准曲线反演获得温度和视线风速的基本过程,给出了视线风速校正和水平风速合成的方法,分析了温度和风场探测的误差来源,包括汉勒效应、光泵效应、饱和效应、激光频率偏差等带来的系统误差以及光子噪声导致的随机误差,并给出了风温探测精度的计算方法。(3)利用研制的全固态钠激光雷达系统开展了中层顶温度和风场的初步观测。以2016年9月19日和9月20日两晚温度观测结果为例,对相邻两天钠层夜间温度进行了比较分析,表明中高层顶温度结构具有较为明显的日变化特征。将激光雷达测量得到的温度与测量时间和地理位置相近的卫星温度数据进行了对比,结果显示两者随高度变化趋势基本一致,并观测到了明显的温度波动结构。将激光雷达测量的水平风速结果与地理位置相近的流星雷达风场数据进行了对比,两者探测结果随高度和时间变化趋势基本符合。与流星雷达相比,激光雷达的风速测量对小尺度的重力波扰动更为敏感,因此激光雷达的风廓线结果中表现出更多的波动结构,而流星雷达的观测结果随高度变化更平缓。两种仪器探测的水平风随时间演化结果中,均表现出相位向下传播的潮汐波动结构,潮汐波的水平波长尺度大于两种仪器探测的大气空间尺度,因此两种仪器均可探测到潮汐的波动变化。通过温度和水平风探测结果的对比分析,初步验证了该全固态钠激光雷达系统温度和风场探测的稳定性和可靠性。
[Abstract]:The high resolution detection of atmospheric temperature and wind field in middle and upper atmosphere is one of the hotspots in the field of Atmospheric Exploration and space physics. Narrow linewidth sodium Doppler lidar can detect the atmospheric temperature and wind field at the middle layer at the same time. It is an important observation means for atmospheric scientific research and space environment monitoring and prediction to carry out atmospheric wave propagation, The research on the energy and momentum cycle, the mutual coupling of high school and low atmosphere, and other frontier scientific problems provide the key data sources. This paper mainly carried out the research on the key technology of the all solid state sodium laser radar system which can realize the middle layer temperature and the wind field detection, and greatly improved the work of the narrow linewidth sodium Doppler lidar system. It provides the key technical means for the further popularization and application of sodium laser radar, which lays an important foundation for the automatic operation of the system and the deployment of the remote or extreme environmental conditions. The principle of the sounding of the sodium layer wind temperature, the design and development of the all solid state laser radar system, the data processing and the method of wind temperature inversion and sodium are also used in this paper. The preliminary investigation results of the layer wind field and the temperature are described in detail. The main contents are as follows: (1) the all solid state sodium layer wind temperature detection laser radar with the international advanced level is successfully developed. Based on the solid laser and frequency technology, the single mode narrow line of the continuous light seed laser with two working wavelengths is 1064nm and 1319nm respectively. Wide laser pulse and frequency are injected into two Nd:YAG lasers respectively. The high power 589 nm pulse laser emitting source which can efficiently stimulate the sodium layer is obtained. The stability and reliability of the laser system of the sodium laser radar are improved, and the key techniques of the whole fiber coupled seed injection laser unit, the frequency of the seed light and the frequency shift are designed. The optical fiber transmission is designed to reduce the optical adjustment of the injection seed unit, and the narrow linewidth 589 nm continuous laser is obtained through the seed laser and frequency, and the 1064 nm and 1319nm seed opper are controlled by the sodium atom saturation absorption spectrum and the digital intelligent feedback program. The 589 nm continuous laser generated by the sum frequency is realized. The frequency is locked to the sodium D2a resonance transition line for a long time. By using optical fiber coupled acousto-optic frequency shift technology and the timing control design of optical fiber switch, the automatic cycle switching of the emitting laser at three working frequencies is realized, and the selection of frequency shift frequency is optimized by calculating the longitudinal mode interval of the 1064 nmNd:YAG laser cavity. The reliability of the three frequency seed injection is improved. The system adopts the three directional light emitting and synchronous receiving collection, and designs a two-dimensional remote control software platform for the transmitting beam. It improves the accuracy of the field matching and the automation level of the three direction detection, and develops the data acquisition and system control software, and realizes the multipass. The echo signal of the channel is synchronous acquisition, automatic storage, real-time display and the timing control of the whole machine. (2) the research on the data processing and inversion method of the sodium layer wind temperature is carried out. The pre processing of the original echo signal includes the elimination of abnormal data, the time integration, the background deduction, the power normalization, the high smoothness and so on. The temperature and the temperature are given by the three frequency ratio technique. The method of calculating the ratio of wind speed is described in detail. The basic process of retrieving temperature and line of sight wind by the two-dimensional calibration curve of the theory of the ratio of temperature to the wind speed is described in detail. The method of line of sight wind correction and horizontal wind speed synthesis is given. The error sources of temperature and wind field detection are analyzed, including the Han Le effect and the optical pump effect. The system error caused by saturation effect, the laser frequency deviation and the random error caused by the photon noise, and the calculation method of the wind temperature detection precision are given. (3) the preliminary observation of the temperature and wind field of the middle layer is carried out by the developed all solid state sodium laser radar system. The results of the temperature observation of the two nights in September 19, 2016 and September 20th are the results of the observation. A comparative analysis of the night temperature of the sodium layer for two adjacent days shows that the temperature structure of the top top roof has a more obvious diurnal variation. The temperature measured by the laser radar is compared with the satellite temperature data similar to the measuring time and the geographical location. The results show that the two temperatures are basically consistent with the height variation. The result of the horizontal wind velocity measured by laser radar is compared with the wind field data of the meteor radar, which is similar to the geographical position. The detection results are basically consistent with the changing trend of height and time. Compared with the meteor radar, the wind velocity measurement of the lidar is more sensitive to the small scale gravity wave disturbance. The results of the wind profile of the optical radar show more wave structures, and the observation results of the meteor radar are more gentle with the height variation. In the evolution of time, the horizontal winds of the two instruments show the tidal wave structure that propagates downward in phase, and the horizontal wavelength scale of the tidal waves is larger than the space scale of the two instruments. Therefore, the fluctuation of the tides can be detected by the two instruments. The stability and reliability of the temperature and wind field detection of the SSR system are preliminarily verified by the comparison and analysis of the results of temperature and horizontal wind detection.
【学位授予单位】：中国科学院大学(中国科学院武汉物理与数学研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TN958.98

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