深凹球面网栅恒定曝光量激光直写控制实现

Constant exposure dose control for laser direct writing of mesh in a deep concave spherical substrate

为在深凹球面内激光直写高质量网栅图形,必须实现写入过程恒定曝光量控制。首先介绍了深凹球面网栅激光直写设备原理,然后分析了任意纬线扫描运动状态,推导了工件尺寸、网栅参数、扫描速度间数学关系,最后建立了恒定曝光量扫描运动数学模型,开发了伺服控制软、硬件系统,确保了扫描角速度随纬度自动精确调整来保持线速度不变,实现了深凹球面网栅激光直写恒定曝光量控制,提高了写入线条质量。在矢跨比为0.31的深凹球面内制备了周期500μm的网栅,显影后测得线条线宽均匀,侧壁陡直,线宽误差≤±1%,网格周期误差≤±5%。

For the purpose of fabricating high-quality mesh in a deep concave spherical substrate by laser direct writing technique,the constant exposure dose control must be realized during the whole scanning process.Firstly,the principle of the equipment for fabricating mesh in a deep concave spherical substrate via laser direct writing technique was introduced.Then scanning motion states for writing arbitrary line of latitude were analyzed,and the formulas that expresses the mathematical relationships between the dimensions of the substrate,parameters of mesh and the scanning velocity were deduced.The mathematical model of scanning with constant exposure dose was built,and the servo control system including software and hardware was developed according to the mathematical model.The servo control system could tune the scanning angular velocity precisely according to the latitude of lines to maintain the linear velocity invariantly,so as to keep the exposure dose constant and improve the quality of lines.So far,constant exposure dose control was realized finally.Mesh with 500 μm gridding period was fabricated in a deep concave spherical substrate with a rise-span ratio of 0.31.Lines on the substrate have good uniformity,steep and straight side walls parallel to each other after development,and errors of line width and gridding period are within ±1% and ±5%,respectively.