Efficiency of stone fragmentation by long pulses of a Q-switched Nd:YAG laser

The effect of long pulsed Nd:YAG laser (pulse duration 300 ns) with the fundamental and second harmonic wavelength on the fragmentation of different urological and gall stones has been investigated. With 200 and 400 micrometers fibers in a contact application, all types of stones could be fragmented with energies less than 120 mJ (400 micrometers fiber) or 45 mJ (200 micrometers fiber). By use of a double pulse-simultaneous application of second harmonic and fundamental radiation the efficiency of fragmentation could be increased and the energy threshold decreased.