Laser conditioning technique of mid-size laser spot

A novel laser conditioning method based on mid-size laser spot is introduced. A Nd: YAG laser with 10 J max energy 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 damage 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 430 mm×430 mm size optics. Experimental results indicate that a damage threshold of 27 J/cm² can be achieved after the conditioning procedure. The effect of this technique is well demonstrated.