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为满足氦(He)激光雷达系统的探测指标,实现200~1000km大气中He原子密度的测量,对He密度探测激光雷达系统的参数和性能进行设计(主要包括激光发射部分、光学接收部分、数据采集和控制部分),对比在不同亚稳态He密度、不同积分时间、不同距离分辨条件下系统接收光子数与距离的关系,其中亚稳态He的密度对信号强度的影响最大。用较低高度的瑞利散射信号标定共振荧光信号,获得相对数密度曲线和信噪比(SNR)曲线。仿真结果显示,在积分时间为30min,距离分辨为50km,亚稳态He原子[He(2~3S)]密度最低的情况下,在250~530km高度范围内,相对误差小于2%,SNR大于40。结果证明系统设计的参数可以满足高层大气He原子密度的探测要求,对将来系统的实现有一定参考价值。
In order to meet the detection index of Helium (Lidar) laser radar system, the measurement of He atomic density in the atmosphere of 200 ~ 1000km is achieved, and the parameters and performance of the Heidelity detection Lidar system are designed (including the laser emission part, the optical receiving part, the data Acquisition and control). The relationship between the number of received photons and the distance under different metastable He density, different integration time and different distance resolution is compared. The density of metastable He has the strongest influence on the signal intensity. Resonance fluorescence signals were calibrated with lower height Rayleigh scattering signals to obtain relative number density curves and signal-to-noise ratio (SNR) curves. The simulation results show that the relative error is less than 2% in the range of 250 ~ 530 km with the lowest density of metastable He atoms [He (2 ~ 3S)] at integration time of 30 min and distance resolution of 50 km, 40. The results show that the parameters of the system design can meet the detection requirements of He atomic density in the upper atmosphere and have certain reference value for the realization of the future system.