中等口径光斑激光预处理

Laser conditioning technique of mid-size laser spot

介绍了一种基于中等口径光斑的新型激光预处理技术。采用基频最大输出10J的Nd:YAG调Q激光器,获得了直径5mm、能量密度满足预处理需求的中等口径光斑。较之于小光斑处理方案,采用中等光斑进行扫描,可以显著压缩大口径光学元件的预处理总耗时。为了验证效果,搭建了实验平台,在陪镀片上开展了光斑扫描与损伤阈值测量实验,设计了合理的中等光斑预处理流程,并对阈值提升效果进行了验证。在此基础上,开展了正式元件的预处理实验,采用大行程二维电动位移台,对430mm×430mm口径的金属铪蒸发工艺高反膜元件进行了夹持和扫描。实验结果表明,经处理后的高反薄膜元件初步达到了27J/cm2的阈值水平,证明了该技术对薄膜抗损伤能力的提升效果。

A novel laser conditioning method based on mid-size laser spot is introduced. A Nd：YAG laser with 10 J max en- ergy output at 1064 nm is adopted to form a 5 mm, fluence-qualified beam spot. Compared with the small-size spot type, this method has significant advantage in time saving. Experimental setup is built for verification. First, laser scanning and d^lmage testing are carried out on small samples. The results demonstrate an obvious effect of laser conditioning, and the best flowchart for large-aperture optics is also verified. Furthermore, the conditioning experiment to large-aperture optics with reflective film prepared by hafnia evaporating is done. A 2D-motorized motion stage is applied for the handling and scanning of 430mm×430mm size optics. Experimental results indicate that a damage threshold of 27 J/cm^2 can be achieved after the conditioning proce dure. The effect of this technique is well demonstrated.