数字微镜阵列扫描曝光图形在某些方向的边缘存在约一个像素的锯齿, 对此设计自由曲面光学透镜, 将其安装在距离数字微镜阵列窗口玻璃1 mm附近, 使微镜阵列成像线性错位, 在保持原有线宽和光刻效率的情况下, 平滑曝光图形边缘.理论分析了微镜阵列成像线性错位形式及其表达式.根据物像映射原理, 用Matlab软件计算出自由曲面光学透镜面形初始数据, 通过Zemax软件优化得到理想透镜模型, 模拟了安装该透镜模型前后曝光图形效果.结果表明：在±2 μm容差范围内, 安装该透镜且曝光总能量为原来的0.9倍时, 曝光图形的横线边缘锯齿由0.14个像素缩小至0~0.01个像素, 斜线边缘锯齿由0.338个像素缩小至0.110~0.125个像素, 且线长变化范围为－0.153~0.05个像素, 线宽变化范围为－0.058~0.153个像素, 变形范围不影响10~30 μm pcb板的制作精度.该方法可同时提高能量利用率, 降低光源成本.

The scanning exposure patterns by Digital Micro-mirror Device(DMD) array in some directions have a saw-tooth edge of one pixel, to solve this problem a free surface optical lens is designed and installed at 1 mm distance of DMD window glass. The imaging of the microscopy array has a linear dislocation which caused by free surface optical lens. When the original line width and photolithography efficiency are invariable, the edges of the exposure pattern are smoothed. The linear dislocation form is analyzed theoretically. Based on the mapping principle, the initial data of the free surface is calculated by Matlab. The model of the ideal lens shape is constructed and optimized by Zemax. And the exposure effect with and without the lens is simulated. The results show that within the tolerance range of 2 μm, the dash saw-tooth edge of the exposure pattern is reduced from 0.14 pixel to 0~0.01 pixel, the slash edge of the saw-tooth is reduced from 0.338 to 0.110~0.125 pixel, and the change of the line length and width range respectively from －0.153 to 0.05 pixel, and from －0.058 to 0.153 pixel, when the energy decreases to 0.9 times of the original after installing the lens. The deformation range of the pixels and scribe line meets the manufacture precision of PCB which is about 10~30 μm. The proposed method has the advantage of reducing exposure energy demand and light source cost.