Parameter error analysis of dual-channel Mach–Zehnder interferometer for molecular Doppler wind lidar

Abstract

Based on the atmospheric molecular Doppler wind lidar system using dual-channel Mach–Zehnder interferometer (DMZI) double-edge detection, two important DMZI parameters, such as optical path difference and beam splitter transmittance, are analyzed. Furthermore, the changes in DMZI transmission response, wind speed sensitivity, and wind speed measurement errors of the lidar system caused by the errors of these two parameters are simulated. The ratio of the difference between the system measurement error caused by the non-optimal parameter and the optimal parameter to the system measurement error at the optimal parameter is defined as an error proportion factor, which can be used to quantitatively describe the variation of wind speed measurement error caused by the parameter errors. Numerical simulation shows that under the assumption that the horizontal wind speed is 20 m/s and the vertical detection height is 15 km, if this error proportion factor needs to be controlled to less than 1%, the difference δ_Δl0 between the actual and the optimal optical path difference should be controlled in the range of 0 ≤ δ_Δl0 < 3.16 mm. Similarly, if other parameters are optimal, the beam splitter transmittance of DMZI should be controlled in the range of 0.5 ± 0.0407, and the error proportion factor can be less than 1%. The results of this study not only provide theoretical guidance for the parameter selection of DMZI but also provide research ideas and methods for the error analysis of DMZI molecular Doppler lidar based on double-edge detection.