基于彩虹Airy理论分析了一阶彩虹强度分布的折射率和直径的灵敏度，并利用经验模态分解法对彩虹信号进行分解与重构，提出了一种有效分离彩虹强度中Airy信号和高频Ripple分量的方法。根据液滴的一阶彩虹分布，设计了液滴折射率和直径同步测量的彩虹?经验模态反演算法，该算法有很强的抗噪声特征。实验中测量了水滴和不同浓度乙醇液滴的一阶彩虹分布，研究结果表明，彩虹?经验模态法对液滴的折射率和直径测量精度分别为10^?4和1%。

Based on rainbow Airy theory, the sensitivity of the main Airy peak position and Ripple frequency to the refractive index and diameter was studied. Combined with empirical mode decomposition for rainbow signal, Airy signal and Ripple component were extracted from rainbow distribution. According to the first-order rainbow distribution of droplet, an inversion algorithm was designed to calculate the refractive index and diameter of droplet simultaneously, which with powerful feature of noise immunity. The first-order rainbow distributions from water and ethanol droplets with different concentrations were measured in the experiment. The results show that the refractive index and diameter measurement accuracy of the droplet by rainbow-empirical mode decomposition method are 10^?4 and 1% respectively.