临界角法激光直写聚焦伺服系统静态特性研究

为同时提高金属网栅屏蔽效率及红外透过率,要求激光直写线条细且均匀.而工件面型误差、光刻胶涂布不均匀性、机械轴系误差等会造成写入焦斑离焦,影响线条线宽及均匀性.需引入聚焦伺服系统来实时探测并补偿离焦,确保写入光束实时聚焦在光刻胶面上.给出了临界角法调焦的原理,搭建了由探焦光路、离焦信号前放、压电陶瓷微位移执行机构组成的聚...

Static Characteristics of Auto-Focusing Servo System Based on Critical Angle Method for Laser Direct Writing

In order to improve the shielding effectiveness and infrared transmittance of metallic mesh,it is required to narrow the width of laser direct writing line and to improve its uniformity.The error of the shape of the concave spherical substrate,uneven thickness of the photoresist film,or shake of machine shafting could result in defocusing during laser direct writing,which will affect the line width and its uniformity.The promising approach to avoid defocusing is to detect and compensate the defocusing error via an auto-focusing servo system.Critical angle method was selected for detecting and compensating the defocusing error.The preamplifier was designed and the weak Focus Error Signal(FES) was amplified successfully.The auto focus servo system was established and the static characteristic curve of FES was demarcated.The static state experimental results show that the distinguishable displacement is ±40 nm with the linear range of about ±5 μm,which can satisfy the design requirements.