Distribution characteristic of ejected particles from transmissive element induced by nanosecond laser

Optical instrument will be damaged when irradiated by high-energy laser. The damage process is accompanied by material fracture, structural collapse and particle ejecting, and the particles emitted will affect the performance of surrounding optical instruments. In this paper, a dual-beam pump-probe imaging system was built to obtain a transient image of the particles ejected form transmissive element induced by nanosecond laser. A particle receiving plate was placed behind the sample, so that the spatial distribution of the particles as well as the size and angular characteristics were analyzed. Then, the effects of different laser energies, different particle receiving distances and vacuum environment on the particle distribution were studied. In addition, combined with EDS spectrum detection technique, the characteristic of particles induced in the metal film was investigated. Also, the differences between different kinds of metal film and the influence of the vacuum environment were studied. The results show that the transmissive substrate emits micron-sized particles under laser induction, while atomic state particles or molten droplets from metal film. The distribution characteristics of the particles on the final receiving plate are mainly affected by the initial conditions. There is little change in the vacuum within a few pascals, and different metal films are also significantly affected by their own properties.....