Urinary Tract Stone Disease pp 301-309
Laser Lithotripsy Physics
The physics of laser lithotripsy are reviewed. The principal mechanisms by which lasers fragment urinary calculi are photomechanical or photothermal. Photomechanical effects are produced in lasers with short pulse durations, typically <1 μs. Such lasers include pulsed dye, Q-switched alexandrite, and FREDDY lasers. Photothermal effects are produced in lasers with long pulse durations, typically >10 μs. Such lasers include Ho:YAG and Er:YAG. Different fragmentation is seen with photomechanical and photothermal lasers. Photomechanical lasers tend to be more efficient whereas photothermal lasers are slower but produce smaller fragments and fragment all compositions. The physics of optical fibers used for Ho:YAG lithotripsy is reviewed.