The complex refractive index of the target material is derived from the reflectivity spectrum of the target material

The polarization characteristic of light is mainly determined by the complex refractive index of the target material, which is the fundamental cause of the polarization characteristic. The complex refractive index of the target material should be studied and measured first. In this paper, the reflectivity spectrum of the target material (the target material is mainly divided into metal and non-metal). Due to the influence of system noise measurement, the measurement of reflectance spectrum exist obvious ups and downs, in order to avoid the error influence on subsequent research, first of all, to get experimental data, based on the experimental data fitting, get rid of the noise be shaking experimental data, the data as the initial value. Then, different models are selected according to the properties of the materials, and a genetic algorithm is used to invert the model values. According to the experimental results, the measured metal experimental reflectivity spectrum jitter is obvious, so to correct the inversion, combined with the Kramers-Kronig relation, the complex refraction index is inverted. Finally, the inversion results of the two materials are compared with the experimental values, and the results are analyzed. The results show that the experimental values are in good agreement with the inversion values, which provides a theoretical basis for the subsequent research on the polarization characteristics of the target material.