APD探测器的性能对激光雷达反演CO_2浓度误差影响研究

Influence of performances of APD detector on CO_2 concentration error retrieved by lidar measurement

星载积分路径差分吸收(IPDA)激光雷达是全天时全球范围内探测CO_2浓度的一种有效的方法,而作为接收系统关键元件的光电探测器对激光雷达系统性能有着较大的影响。雪崩光电二极管(APD)有着较大的动态范围与高的响应度,因此它在星载激光雷达中广泛应用。介绍了IPDA激光雷达和APD探测器的工作原理,并根据实际工作条件,测试了一款APD探测单元的响应度、动态范围、不同光功率下的信噪比等主要性能参数,分析了这些性能参数对星载激光雷达CO_2浓度的反演带来的影响。结果表明,在CO_2浓度为400 ppm(1 ppm=10^(-6)),吸收波段信号的探测器输出电压在280~980 mV范围内时,APD探测器本身的非线性和噪声造成的误差小于0.8 ppm。

Space-borne integrated path differential absorption(IPDA)lidar has been regarded as an efficient method to measure the concentration of the global atmospheric CO2 column concentration all day long.As a key part of the lidar receiver,the performance of the photodetector has a significant influence in the overall lidar system.Avalanche photodiode(APD)is widely used in space-borne lidar because of its large dynamic range and high responsivity.The basic theories of the APD detector and the IPDA lidar were briefly introduced.And taking the actual working conditions of the space-borne IPDA lidar into account,the actual performances of an APD detector such as the detector′s responsivity,dynamic range,linearity and the signal to noise ratio under different optical powers were tested.Then based on the experiment result,the influence caused by the performances of the detector on concentration inversion was analyzed.The result shows that,when the CO2 concentration is 400 ppm,and the on-line wavelength output voltage of the APD detector is between 280 mV and 980 mV,the CO2 concentration error caused by the non-linearity and noise of the APD detector is less than 0.8 ppm.