瑞利测风激光雷达的高时空分辨率外场试验技术研究

Global wind field measurement would address one of the key unmet observational requirements for understanding and predicting the future state of the earth-atmosphere system. High accuracy and real-time wind data will lead to improved long-range weather forecasting, more accurate prediction of severe weathers, such as improved hurricane tracking, improved climate models, further atmospheric dynamic process research, more safety guarantee for various aircraft. Comparing with the other wind remote sensors, the direct-detect Doppler wind lidar is so far the only tool that is able to directly measure three-dimensional wind field with high accuracy, high temporal and spatial resolution in the global region..For stratospheric wind detection, a mobile Rayleigh wind Lidar is developed by researchers in the University of Science and Technology of China. Naturally, there are some unexpected obstacles to overcome during the development and operation phases of the Lidar, specifically in condition of field experiment. .First of all, the system stabilization is a great challenge. The long-term optical frequency drift may arise from the continuous wave seeder, while short-term frequency jitter may arise from the Nd:YAG oscillator. Thus a system-level optical frequency control method is proposed in this project. Another problem is the optical contamination of the telescope, which weaken the intensity of the Rayleigh backscattering from stratosphere, resulting in a low signal-to-noise ratio. To solve this problem, we are planning to develop a optics protection system incorporating electrostatic ion generator. Steady dry and clean ion beams are used to neutralize the surface coating of the telescope. In this process, ozone is produced, which protects the telescope against insects well. Finally the effect of thermal blooming on the Doppler wind lidar will be studied. A mode scrambler is proposed to eliminate this effect..With such three updates, the time resolution will be improved to 2 minutes, which allows the Rayleigh wind lidar to detect fast dynamic process in troposphere. The stability and measurement accuracy will also be improved.

全球范围内的大气风场数据是深入研究大气动力学、全球大气活动和空间环境预警的最主要参数之一。..为了观测对流层、平流层的风场，研制了车载瑞利测风激光雷达。在设备研制和调试的各个阶段，遇到了一些技术难题，严重抑制了系统的总体实用性。特别是外场试验时，恶劣的自然环境对系统的稳定性、探测可靠性带来挑战。项目聚焦以下三个问题：首先，提出一种系统级光学频率控制技术，消除多普勒频移测量时的快速光学频率抖动，直接提高测量精度和稳定性。其次，研究大气热晕现象对瑞利测风激光雷达的影响，并使用光学扰模的方法，消除这种影响。最后，望远镜的污染直接导致光学接收效率降低，降低探测信噪比。提出一种基于等离子风的保护技术，除了除尘防霜作用外，产生的臭氧可驱赶野外昆虫。.通过技术改进，瑞利测风激光雷达的时间分辨率将提高到2分钟，适合对流层、平流层快速动力学过程（如重力波）的观测。同时，系统的运行稳定性和探测精度得到提高。

对基于双边缘技术的车载瑞利多普勒激光雷达进行了升级。1064nm连续光分作三部分：一部分用来锁定FPI标准具；一部分用作种子注入Nd:YAG主振激光器；最后一部分和脉冲激光器输出的1064nm脉冲光相干拍频。脉冲激光器中，通过倍频晶体和三倍频晶体，出射光包括3个频率：355nm、532nm、1064nm。其中，355nm波长作为工作波长。脉冲激光器的532nm波长经过碘吸收池，探测出射激光绝对频率，形成伺服信号，锁定种子激光器1064nm出射连续光的频率。完成亚洲首次零风层、高空激流探测。. 为了消除大气温度对测风激光雷达的影响，发明了分子高光谱分辨测温雷达。将其集合传统瑞利积分测温方法，实现了平流层温度和风场同时探测。. 世界首次实现了采用量子上转换技术的多功能、眼安全、小型化的直接探测多普勒激光雷达。采用光学集成器件，制造了全光纤耦合周期极化铌酸锂波导和法-皮标准具。采用时分复用技术，基于单通道、单探测器实现了双边缘探测。