Photomechanical basis of laser ablation of biological tissue

Abstract

The photomechanical model of laser ablation of biological tissue asserts that ablation is initiated when the laser-induced tensile stress exceeds the ultimate tensile strength of the target. We show that, unlike the one-dimensional thermoelastic model of laser-induced stress generation that has appeared in the literature, the full three-dimensional solution predicts the development of significant tensile stresses on the surface of the target, precisely where ablation is observed to occur. An interferometric technique has been developed to measure the time-dependent thermoelastic expansion, and the results for subthreshold laser fluences are in precise agreement with the predictions of the three-dimensional model.