Pulsed infrared laser ablation of tissue: Effect of dynamic changes in the absorption coefficient of water

he physics of pulsed-infrared laser-tissue interactions was studied. An emphasis was placed on determining the effect of dynamic changes in the absorption coefficient of H;Ablation characteristics of Q-switched Er:YAG (;The thermodynamic equation of state for water was applied to calculate the peak temperature and pressure of the irradiated material based on the energy deposition calculated from the dynamic absorption model. The adiabatic expansion of the plume of ejecta demonstrates that the thermodynamic path of the water component passes over the vapor dome. Thus, an explosive expansion resulting in a continuous change in density of the supercritical fluid is proposed for the ablation mechanism.;The mechanical properties of the target tissue were seen to affect the dynamics of the ablation process. The mechanical ablative effects were mediated by high pressures causing elastic expansion of the surrounding non-ablated material during ablation. It was shown that the velocity and duration of ejection of ablative material depended on the amount of confinement by the surroundings and the initial energy of the explosion.;Thermal changes in the absorption coefficient of water was demonstrated at wavelengths near the fundamental bending mode band near...