Vapor bubble dynamics and collapse energetics produced by different laser lithotripters

Vapor bubble dynamics in laser lithotripsy are central to stone ablation efficiency, retropulsion, safety, and clinical outcomes. Pulse profile and duration govern bubble morphology, collapse pressure, and influence contribution of collapse in stone damage. Distinct collapse mechanisms shape fragmentation, dusting, and retropulsion. Using high-speed imaging, hydrophone measurement, and ablation matrices, three laser lithotripters were compared. Holmium:YAG produces short-duration, shark-fin pulses with high peak power that generate large pear-shaped bubbles, collapsing forcefully (~10⁻⁴ J) to yield strong fragmentation but with high retropulsion. Thulium fiber laser, with long rectangular low-peak-power pulses, produces a stream of smaller bubbles with chaotic oscillations that collapse gently (~10⁻⁶ J), enabling efficient dusting with minimal displacement. Pulsed Thulium:YAG supports captive and fragmenting modes, providing hybrid performance with mid-range collapse energies. Recognizing these collapse regimes reaffirms cavitation as a vital contributor to stone damage, complementing photothermal effects and shaping fragmentation, dusting efficiency, and clinical performance.