Fig. 12.

A three-stage mechanism for pulsed laser treatment of blood: I, initial non-ablative thermal impact; II, ablative impact; III, residual non-ablative thermal impact. Stage I: absorption of the first laser pulse by proteins induces non-ablative response (heating), but if the temperature is above the denaturation and coagulation threshold it will cause local aggregation of proteins and local increase of the concentration of proteins to the degree that the absorption of the 2nd, identical laser pulse will result in vapor bubble generation and transition to the ablative stage II; generation of the bubbles will disrupt the cellular membrane and will thus eject light-absorbing protein out of the cell, reducing its concentration below the ablation threshold and eventually terminating the bubble generation and returning to the residual thermal stage (III) with much lower temperatures than at stage I.