基于评价函数的宽光谱膜厚监控系统，由于实测光谱曲线和理论光谱曲线相背离，使得评价函数发散，监控失败。利用实测的膜层透射率光谱曲线，对于已镀层，利用模拟退火算法实时拟合其实际的光学常数，据此修正目标透射率曲线，并补偿吸收的影响，重新设计膜层数及预镀层厚度，获得新的评价函数，如此对评价函数进行逐层修正。实验结果表明，薄膜厚度监控误差可以达到10-2以下，精度完全可以满足实际要求。

In thin-film thickness wideband monitoring system based on merit function, because the measured spectrum curve deviates from the designed one, the merit function becomes divergence, which results in the failure of monitoring. Utilizing the thin-film transmittance spectrum curve measured, for the thin-film layer which has been deposited, its actual optical constants are fitted in real-time by simulated annealing algorithm to correct the merit function. Then the absorption effect of layers having been deposited on the layers to be deposited is compensated, and the layer number and thickness of the layers to be deposited are redesigned. The new merit function is achieved, by correction layer by layer. Experimental results show that the monitoring error of thin-film thickness may be less than 10-2, and the precision satisfies the practical requirement.