薄膜光学常数的改进粒子群反演算法

Improved particle swarm optimization algorithm for optical constants of thin films

针对聚酰亚胺薄膜的光学常数进行反演计算,在传统粒子群算法的基础上引入模拟退火算法改进优化。基于改进后的算法由薄膜透射率测量数据反演求解薄膜在波长为450~2500 nm的折射率和消光系数。针对求解波长范围大、薄膜透射率数值变化剧烈的特点,采用基于透射率数值的分段方法并以平衡评价函数作为优化指标。根据菲涅尔方程使用反演计算得到的光学常数恢复出薄膜透射率的理论值,与实验测量值作对比。结果表明,相比传统算法,改进粒子群算法恢复出的计算透射率与测量值更加接近,具有更好的优化性能。

Inversion calculation was carried out for the optical constants of polyimide films.The simulated annealing algorithm was introduced to improve the behavior of traditional particle swarm optimization algorithm.Based on the improved algorithm,the refractive index and extinction coefficient of the film in the range of 450-2500 nm were solved by inversion using the film transmittance measurement data.According to the characteristics of large wavelength range and sharp change of film transmittance value,a subsection method based on the transmittance value was adopted and the balance evaluation function was taken as the optimization index.According to the Fresnel equation,the theoretical value of the transmittance of the film was recovered by using the optical constants calculated by inversion,and compared with the experimental values.The results show that,compared with the traditional algorithm,the calculated transmissivity recovered by the improved particle swarm optimization algorithm is closer to the measured value and has better optimization performance.