PHYSICAL PROBLEMS OF EXCIMER-LASER CORNEA ABLATION

ArF excimer laser ablation of corneal tissues (in vitro, pig) is inves tigated. Scanning electron microscopic analysis shows that the spatial resolution of the ablation is better than 1 mum. The etching rate and etched depth is found to be proportional to the logarithm of the lase r fluence and the number of shots, respectively. To investigate the dy namic processes a laser-based, ultrafast photographic arrangement was constructed having a temporal resolution of 1 ns. The maximum speed of the shock wave generated during ablation is found to be as high as 40 00 m/s. The ejection of the ablation plume with plume-front velocities in the range of 600 m/s is also observed. A new type of surface wave generated by the recoil forces of the ablated material is found. The a mplitude of this surface wave can be as high as 0.4 mm.