采用双离子溅射的方法，在硅、石英基底上制备了单层Ta2O5、SiO2及双层Ta2O5/SiO2光学薄膜。结合Cauchy色散模型，利用石英基底上单层Ta2O5及双层Ta2O5/SiO2薄膜透射光谱曲线，采用改进的遗传单纯形混合算法，获得了Ta2O5和SiO2薄膜材料在400~700 nm波段的光学常数。结果表明，理论分析值与实验测量值取得了很好的一致性，拟合出的单层Ta2O5薄膜折射率误差小于0.001，膜层厚度误差不超过1 nm；双层Ta2O5/SiO2薄膜最大折射率误差小于0.004，最大厚度误差小于2.5 nm。此外，还对400 ℃高温环境下双层Ta2O5/SiO2薄膜的微观结构、应力、表面形貌及光学性能变化进行了研究。

Single Ta2O5 and double layer Ta2O5/SiO2 films are deposited on Si and fused silica substrates by dual-ion-beam sputtering. With the Cauchy dispersion model, the optical constants of Ta2O5 and SiO2 thin films are obtained by fitting the transmission spectra of single Ta2O5 and double layer Ta2O5/SiO2 films using the combination of simplex and genetic algorithm (GA) optimization method. It shows that the results calculated by fitting the whole optical spectra are well consistent with the measuring values. The refractive index error and thickness error of single layer Ta2O5 film are less than 0.001 nm and 1 nm, respectively. In the case of double layer Ta2O5/SiO2 films，the maximum refractive index error and thickness error are in the range of 0.004 nm and 2.5 nm, respectively. In addition, the deposited double layer Ta2O5/SiO2 thin films are treated at 400 ℃ in air. The changes of microstructure, surface morphology and optical properties of the Ta2O5/SiO2 films are investigated.