Abstract: An imaging system with nanosecond resolution was developed and used for investigation of excimer laser induced ablation. The photographic recordings were made by means of a videocamera equipped with a microscope. Dye laser pulses used for exposition were delayed appropriately with respect to the incidence of the excimer laser light. The movement of the plume ejected from the sample and the propagation of the mechanical waves developed in and above the sample were visualized. Using single recording pulses the distance-time functions were obtained. The velocity-time functions were calculated by derivation of those. Applying a Michelson interferometer for generating double exposing dye laser pulses with delay dt, the average velocity for dt could be measured directly. The propagation velocity of shock waves originating from the polymethyl-methacrylate surface was investigated by this technique in Schlieren arrangement. Velocities as high as 40 times the sound velocity in the air were measured. The material ablated from the polymethyl-methacrylate was observed in vacuum by single exposition transmission arrangement. During the excimer laser ablation of cornea several phenomena occur, such as shock wave in the air, shear wave on the surface, internal acoustic wave, plume ejection and so on. The characteristic velocities of these are shown. 7
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