理论分析表明,双边缘瑞利测风激光雷达技术中,信号通道分光精度影响风速测量精度。因此,在风速误差计算上,需考虑分光比误差,且尽量选择分光稳定性好的仪器。在激光雷达中,常常利用光纤分束器与分束片进行分光。分束片的分光受大气退偏振效应影响,分光不稳定;而光纤分束器分光比需测量,存在测量误差。分析可得,在纯分子散射环境下,由于退偏振效应引起分光片的相对变化为0.07%-0.63%;实验测得多模光纤分束器分光比均值为1.018,标准偏差为0.4%,分析比较后选用分光稳定较好的光纤分束器。最后,进行了瑞利多普勒激光雷达与探空气球的联合测风实验,实验结果表明两者风场分布吻合得较好。
Theoretical analysis shows that splitting ratio of signal paths affects the accuracy of wind speed measurement in dual edge Rayleigh wind measurement technology.Therefore,the splitting error should be calculated when evaluating the wind speed error,and one suitable spectroscopic instrument should be selected as much as possible.Multimode optical fiber beamsplitter and beamsplitter are usually used in lidar.As for beamsplitter,its splitting ratio is affected by the depolarization of the atmosphere.As for the multimode optical fiber beamsplitter,its splitting ratio is affected by the measurement error.According to the analysis,the range of relative beamsplitter change is from 0.07% to 0.63% due to depolarization effects in pure molecular scattering environment.However,the mean value of multimode optical fiber beamsplitter is 1.018,and the standard deviation is 0.4%.Therefore,multimode optical fiber beamsplitter is used in lidar.Finally,the Rayleigh Doppler lidar combined with balloon wind test,the test results show the wind field in good agreement.