Pseudo-random modulation continuous-wave lidar for the measurements of mesopause region sodium density
Pseudo-random modulation continuous-wave lidar for the measurements of mesopause region sodium density
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DOI：
10.1364/oe.410852
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发表时间：
2021-01-18
期刊：
影响因子：
3.8
通讯作者：
Dou, Xiankang
中科院分区：
文献类型：
--
作者：
Li, Feng;Li, Tao;Dou, Xiankang
钠荧光激光雷达利用589 nm窄带脉冲激光系统测量中层顶区域原子钠密度、大气温度和风。然而，这个系统是复杂和不稳定的。连续波钠激光系统具有超窄带宽、全固态、体积小等优点，在移动的、航空航天等领域具有重要的应用价值。在本研究中，我们使用一个输出功率约为1.2W的电光调制窄带589nm连续激光器，研制了第一台伪随机调制连续波（PMCW）钠激光雷达。采用长度为127的伪随机M序列码对激光进行调制，然后对光子信号进行解码，从而获得高度信息。同时，设计了一种收发光轴间距为9 m的双轴结构，以抑制强近地面信号，这对提高PMCW激光雷达系统的信噪比至关重要。2019年12月2日至4日的夜间测量显示，钠层峰值处的信噪比大于10，对应于钠密度的统计不确定性小于10%，时间和空间分辨率分别为5分钟和1.05公里。比较PMCW激光雷达和同位脉冲激光雷达同时观测到的钠离子浓度垂直廓线，结果显示出很好的一致性。(C)根据OSA开放获取出版协议的条款，2021年美国光学学会
The sodium fluorescence lidar utilizes a 589 nm narrowband pulse laser system to measure mesopause region atomic sodium density, atmospheric temperature, and wind. However, this system is complicated and unstable. The continuous-wave (CW) sodium laser system can achieve ultra-narrow bandwidth, all-solid-state, and small compact size, as such it is extremely valuable for mobile, aircraft, and space-borne applications. In this study, we developed the first pseudo-random modulated CW (PMCW) sodium lidar by using an electro-optic modulated narrowband 589 nm CW laser with an output power of similar to 1.2W. A pseudorandom M-sequencecode with a length of 127 is used to achieve altitude information by modulating laser and then decoding photon signals. Also, a biaxial structure with 9 m separation between the optical axes of the transmitter and receiver is designed to suppress the strong near-ground signals, which are crucial for improving the signal-to-noise ratio (SNR) of the PMCW lidar system. Nighttime measurements on December 2-4, 2019 show that the SNR at sodium layer peak is more than 10, corresponding to a statistical uncertainty of less than 10% in sodium density with temporal and spatial resolutions of 5 min and 1.05 km respectively. The comparison of vertical profiles of sodium density simultaneously observed by PMCW lidar and collocated pulse lidar shows good agreement. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement