Application of adaptive simulated annealing genetic algorithm in inverse of optical constants and thicknesses of the thin film

It is very important to measure thickness and optical constants accurately for film fabrication, research and application. With Cauchy dispersion model, the optical constants and thickness of thin film are inversed by fitting the curve of transmission spectrum using whole optical spectrum fitting based on adaptive simulated annealing genetic algorithm. The results of TiO₂ and SiO₂/TiO₂ thin films deposited by electron beam evaporation respectively are in good agreement with the measuring. The experimental result shows that the calculated transmittance of the film is consistent with the measured value. The thickness error is less than 2nm, and the refractive index error at 560nm is less than 0.03.