Fig. 1. Reflectances of an 8.5 nm gold thin film at different incidence angles. (a) S-polarization wave; (b) P-polarization wave

Fig. 2. Contour lines of the reflectances for P-polarized wave

Fig. 3. Flowchart of the inversion algorithm for optical parameters

Fig. 4. Optimization results of gold thin film thickness for various wavelength nodes and their probability density distribution. (a) Inversion results of thickness; (b) probability density distribution of thickness

Fig. 5. Gold thin film optical parameters obtained after two rounds of optimization using a global optimization algorithm based on reflectance. (a) Extinction coefficient; (b) refractive index

Fig. 6. Optimization results of sliver thin film thickness for various wavelength nodes and their probability density distribution. (a) Inversion results of thickness; (b) probability density distribution of thickness

Fig. 7. Sliver thin film optical parameters obtained after two rounds of optimization using a global optimization algorithm based on reflectance. (a) Extinction coefficient; (b) refractive index

Fig. 8. Absolute errors of thin film optical parameters between proposed algorithm and references. (a) 8.5 nm gold thin film; (b) 20 nm silver thin film