为了去除布里渊雷达系统中 Fabry-Perot标准具的谱线展宽对谱特征参数测量精度的影响, 本文提出了一种双参数拟合结合单参数拟合的方法。该方法首先根据 F-P标准具的谱线展宽原理, 采用双参数 L-M算法进行拟合, 分析了拟合参数中拟合向量初始值和最大迭代次数对拟合精度的影响; 然后针对其中一个拟合参数结果不稳定的问题, 选择附加一个单参数拟合来提高测量精度。实验结果表明, 该方法可以使谱特征参数测量精度稳定在 MHz量级, 保证了 0.1℃的温度测量精度。

In Brillouin lidar system based on the Rayleigh-Brillouin scattering (RBS) and Fabry-Perot (F-P) etalon, the spectral broadening of F-P etalon could produce measurement error of spectrum characteristics. A fitting procedure based on the combination of the dual-parameter fitting and single-parameter fitting for removing the broadening effect is proposed in this paper. Firstly, based on the analysis of the broadening effect of F-P etalon on the spectrum, a dual-parameter Levenberg-Marquardt (L-M) algorithm fitting is proposed and the effects of the initial values of the fitted parameters and the iteration steps in the fitting are analyzed. Then to deal with one parameter’s floating, an extra single-parameter fitting procedure is proposed to improve the measurement accuracy. Experiments show that the fitted results can be stable in the magnitude of MHz and the measurement accuracy of temperature can be improved to 0.1 ℃.