影响球面激光直写线宽均匀度的关键技术

Key techniques influencing the linewidth evenness grade with laser direct writing on the spherical surface

为提高球面激光直写图形线宽均匀度,提出了球面激光直写四轴同心结构和同心扫描光学系统的方案。这种方案使得激光束经水平轴、垂直轴、光轴和工件中心轴相交于球心,经球心反射镜反射到球面工件表面上,形成激光曝光光斑。采用微小离焦探测和复合闭环控制的自动调焦技术与计算机并行工作的控制方法,确保了球面工件以垂直轴为轴心沿水平方向精密匀速旋转;激光笔绕水平轴以俯仰弧形轨迹移动且精准定位;激光束经写入物镜和调焦系统始终以圆形光点聚焦在球面上,实现了对球面任意纬度连续激光直写线条精度的可靠控制。原子力显微镜检测分析结果表明,在球面上激光直写出约3μm宽线条,线宽均匀度10%左右。

For improving the evenness grade of the line width of the laser direct writing figures on the spherical surface, the scheme of the four axes mutually intersecting at the center of the spherical surface and concentrically scanning optical system is proposed, which ensure that four axes including transverse axis, normal axis, optical axis and the center axis of work piece mutually intersect at the center of the spherical surface. As a result, the laser beam reflected from the center-mirror perpendicular focuses on the spherical surface with circular focus during .the period of laser direct writing. In the course of laser direct writing, the work piece spins around the normal axis along the level direction while the object lens spins around the transverse axis precisely. The control method of photo-electricity detection, automatic focusing and high-speed computer working in double harness is applied too, which realize the dependable control of the precision of laser direct writing line width on random latitude of the spherical surface, The section analysis of lines by the atomic force microscope proves that the evenness of lines with about 3μm line width has exceeded the request of the original design.