抄録
In processing of metal using femtosecond pulse laser, we discovered a novel phenomenon of behavior of debris. The process has five phases: in the first phase, no debris are generated even under irradiation of the femtosecomd laser ; in the second phase, smoke-like debris burst out from the processed point ; in the third phase, large debris blast off in a radial pattern from the processed point ; in the forth phase, the splattered debris decelerate its velocities and some debris already scattered around the outside of the visualized area reverses the motion direction, rushing toward the center of the processed point ; in the fifth phase, all scattered debris rush toward the processing point.
