Picosecond imaging of laser-induced ablation processes and production of microstructures by picosecond laser pulses

Picosecond laser pulses were used for microstructuring metals, ceramics and diamond. Using 40 ps laser pulses line patterns with a minimum line width in the range of 7 micrometer were formed in diamond without destroying the crystallinity. In Si₃N₄-ceramics holes were drilled with diameters smaller than 6 micrometer. Ultrathin copper and gold films of 1 micrometer thickness were removed from fused silica and silicon (100) without influencing the substrates. The ablation process was investigated by high-speed photography and pump-&- probe-measurements with a time resolution of 40 picoseconds. The measurements allow a detailed characterization of the melting, vaporization and solidification processes. Shock waves in the ambient atmosphere were detected and the energy in the shock wave was determined.