高性能机载云粒子成像仪研制及应用

机载云粒子成像仪是目前直接观测云中粒子谱分布和形状特征的关键设备，在云物理结构探测、遥感反演验证、数值模式云物理过程改进和人工影响天气等领域具有十分重要的作用。因此，针对现有进口仪器性能和应用方面的不足，开发更高性能的云粒子探测仪器十分必要。通过2011年启动的国家重大科学仪器设备开发专项—机载云粒子谱仪与成像仪研制项目，研制出国产高性能机载云粒子测量系统。经过多年的研制和反复测试，解决和显著改进了激光光束均匀化、弱信号探测、多路并行处理及微粒消衍射等关键技术，从而提高了探测器像元的光功率均匀性和一致性，使光斑区域内平均光功率密度提高约3倍，从而改进了粒子成像能力。采用更高分辨率国产光电线阵探测器，测量响应时间明显缩短，对小云粒子的探测能力明显提高。研制的仪器通过一系列基础参数测试、系统优化、环境适应性实验和累计60多架次的飞行测试。对2018年11月5日进行的两架次对比探测结果的初步分析表明，新研制的云粒子成像仪对小粒子浓度的测量精度较进口仪器提高一个量级左右，测量数据起伏更小，稳定性更高，并且可正确获得更清晰可靠的云粒子形态特征。 

Development and application of the high-performance airborne cloud particle imager

The airborne imager of cloud particles is a key scientific instrument that can directly obtain the properties of size distributions and images in clouds. It plays an important role in probing cloud microphysical structures, verifying remote sensing data, improving cloud microphysical processes in numerical weather models and operating weather modification. Therefore, it is important to continuously improve and develop the instrument of higher probing ability. This study introduces the principles of measurement, the main performance indexes, the calibration method and the application results of observational experiments using the airborne cloud imager that was newly developed in 2011. By repeated trials for several years, some key technologies such as beam homogenization, weak signal detection, multiplex parallel processing algorithm and particle diffraction elimination have been either solved or greatly improved. The homogenization and consistence of optical power have been greatly increased. The mean optical power density in light spot is increased by about three times, and thus the imaging ability has been greatly improved. The higher resolution of linear photo diode array is used with high response speed, which apparently increases the detection ability for small-size cloud particles. A series of basic tests of parameters, system optimization and environmental adaptation, and over 60 in-situ flights have been conducted during the period of study and development of the instrument. Compared with observations of an imported instrument in two flights on 5 November 2018, the preliminary experiment results using the newly development instrument indicate that the accuracy of number concentrations for small-size particles can increase up to one order of magnitude. Meantime, the instrument has higher stability and reliability during the flight, and can correctly obtain clearer cloud habits.