模拟退火算法在薄膜光学常数反演中的应用

为了消除薄膜实际光学常数与理论光学常数差异对监控的影响，基于实测透射率光谱曲线，采用模拟退火（SA）算法对已镀膜层实际光学常数n、k、d进行数值反演；在应用模拟退火算法时，对于某一退火温度t，新解的查找范围根据新解的接受率来自适应控制，快速地找到更优的新解；当新解确定后，退温采用指数降温方式，其退温速率a的取值根据接受概率P的不同而变化，当连续退温后，满足终止条件，算法结束；算法经此改进后，应用在石英玻璃基底上镀制ZnS薄膜实例中，经验证，在较短的时间内找到n、k、d值，提高了优化速度与算法效率．

Application of the Simulated Annealing Algorithm to Film Optical Constant Inversion

The difference between the actual and theoretical optical constants has an effect on monitoring. On basis of the transmittance spectral curve the difference has been measured. A simulated annealing algorithm is applied to the inversion of optical constants n,k and d of layers deposited. Using the simulated annealing algorithm,the finding range of a new value is controlled adaptively according to the acceptance rate for finding the better new solution when the dropping temperature is t . After the new value is determined,the temperature decreases by the way of exponential drop, whose temperature rate varies with acceptance probability P; When the termination condition is satisfied after the temperature drops continuously, the algorithm stops. After the algorithm has been improved, it is applied to the example that membrane ZnS is deposited on the substrate of quartz glass. The values of n, k and d are obtained in a shorter time and the optimization speed and the algorithm efficiency are increased.