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相对于传统多普勒鉴频器Fabry-Perot干涉仪,Mach-Zehnder干涉仪(MZI)具有透过率高、直线条纹易于探测、可进行视场展宽等优点.本文设计了基于条纹成像MZI的非相干多普勒测风激光雷达系统,构建了风速反演的数学模型,利用MZI视场展宽技术优化了激光雷达系统的性能.数值仿真实现了MZI鉴频系统干涉条纹图样的理想输出,采用Sine Sqr函数拟合法获取了高精度的多普勒频移前后干涉条纹的移动距离,并通过视场补偿减小了入射角对MZI光程差的影响,从而实现视场展宽.结果表明:采用Sine Sqr函数拟合法可获得在±100 m·s-1的径向风速范围内<0.45 m·s-1的风速误差,克服了条纹重心法反演风速不稳定性的缺点;视场展宽技术在不降低鉴频性能的情况下,能最大补偿1°的视场角.MZI条纹成像多普勒激光雷达应用技术的探讨将为中高层大气风速激光雷达测量系统的实际开发奠定良好的基础.
Compared with the traditional Doppler frequency discriminator Fabry-Perot interferometer, the Mach-Zehnder interferometer (MZI) has the advantages of high transmittance, straight line fringe detection, field-of-view broadening, etc. In this paper, A non-coherent Doppler wind-lidar system was constructed, the mathematical model of wind-velocity inversion was constructed, and the performance of Lidar system was optimized by using MZI field-broadening technique.The numerical simulation realized the ideal output of the interference fringe pattern of MZI- Sine Sqr function fitting method was used to obtain the moving distance of the interference fringes before and after the Doppler shift with high precision and the effect of incident angle on the optical path length difference was reduced by field compensation to realize the field broadening.The results showed that: The Sine Sqr function fitting method can obtain the wind speed error of <0.45 m · s-1 within a radial wind speed range of ± 100 m · s-1, overcomes the shortcomings of the instability of the wind velocity inversion by the fringe center of gravity method, Which can compensate maximum 1 ° field of view without degrading the frequency discrimination performance.The discussion on the application of MZI streak imaging Doppler lidar will lay a good foundation for the practical development of measurement system of middle and high level atmospheric wind lidar basis.