在真空蒸发镀膜过程中，元件面形的改变主要决定于基底应力(包括自重应力与残余应力)在镀膜前后的分布状态。通过建模定性分析发现，基底的自重应力在薄膜沉积前后施加并撤除的状态变化，会导致薄膜与基底界面产生相互制约的应力，由此引起的基底形变幅度微小，基本可忽略不计; 因此，基底的残余应力是导致真空蒸镀过程中基底面形变差的主要因素。在抛光前对基底进行精密退火处理，可以有效地消除由基底残余应力引起的无规则形变。

In vacuum evaporating deposition, the surface deformation of the optical elements was primarily affected by the substrate stress redistribution including the gravitational stress and the residual stress before and after deposition. A model was built to analyze the effects of substrate stress, the results proved that an interaction stress in the substrate-film interface induced by the gravitational stress in the substrate in the vacuum evaporating deposition produced very little deformation of the substrate. Therefore, the irregular deformation of the optical element induced in vacuum evaporating deposition was determined by the residual stress of the substrate mostly. The experimental results show that the irregular deformation of the substrate caused by the residual stress can be eliminated by fine annealing the substrate before being polished.