基于遗传算法的透射光谱法测量薄膜光学参数

摘要

基于多光束干涉理论建立了单层薄膜的透射率模型,并且得到了薄膜透射率与厚度及折射率之间的关系的数学模型,进而利用遗传算法求解该数学模型.根据薄膜透射光谱数学模型的特殊性,按照实际的精度需求,有针对性地选取了遗传算法中种群大小、交叉概率和变异概率等关键参数,并且针对透射光谱的具体情况,设计了离散化的适应度函数.最终的拟合结果表明,基于遗传算法的透射光谱法能够快速、准确地得到薄膜的光学参数.%Mathematic model of the transmitted spectrum of thin films was established by multi-beam interference theory.The relationship of transmittance,thickness and refractive index was built.Then the mathematic model could be solved with the genetic algorithm.In consideration of the special character of the optical film,value of key parameters of genetic algorithm would be a special choice.Key parameters included population size,crossover probability and mutation probability.Fitness function was designed to be discretized.Finally,the fitting results proved that the method could calculate the parameters of optical films at the same time.