电子束蒸发镀膜速率控制

Rate control in Electron-Beam Evaporated Optical Coatings

介绍了电子束蒸发镀膜速率控制的基本原理和方法,选取实际生产中大量使用且蒸发特性较难控制的SiO_2和HfO_2,对两者的电子束蒸发速率控制分别进行了实验研究。采用比例积分微分(PID)闭环反馈控制,通过Ziegler-Nichols工程经验公式进行原始参量整定,并在实验的基础上对控制器的原始参量进行调整以及对积分作用和微分作用进行分区处理,速率控制的实验结果表明,采用该参量整定方法并结合工艺流程的改进,能获得良好的速率控制。针对速率控制中存在的难点问题进行了分析,并提出改进措施:将速率控制和电子枪扫描控制相结合能进一步改善速率控制。

The basic principle and methods of rate control in e beam evaporated optical coatings are introduced. Rate control experiments are performed based on materials of SiO2 and HfO2, whose evaporation characteristics are hard to control. Using the proportion integral differential（PID） closed loop control, the original control parameters were set by Ziegler-Nichols experimental formula. Then the original parameters were adjused and the integral and derivative roles were delt with in subarea based on the experiment. The rate control experiment results show that good performance can be achieved by this tuning way combining with improved process flow. The problem existing in rate control are analyzed and the improving methods are proposed. Combining the rate control with egun sweep can luther improve the rate control performance.