Oscillations, Waves, and Interactions - GWDG

Dynamics of pulsed laser tissue ablation 225
Figure 5. (a) Development of a thermoelastic stress wave in water calculated for F0 =
2 J/cm 2 ; µa = 200 cm −1 and tp = 8 ns. (b) Pressure as a function of time at a depth of
50 µm. (Reprinted with permission from Ref. [45]. Copyright 1996 Springer).
tochemical mechanisms. In this article, we focus on the kinetics of phase transitions
in purely photothermal ablation processes such as in IR ablation. When UV lasers
are used, photochemical bond dissociation may contribute to ablation. For a detailed
discussion of the role of these photochemical processes, the reader is referred to a
recent review by two of the authors [6].
4.1 Phase diagrams
We use the pressure vs. temperature projection of the phase diagram for liquid and
gaseous water (Fig. 6) and the pressure vs. specific volume projection of the thermodynamic
phase diagram (Fig. 7) to discuss the thermodynamics of phase transitions.
The solid curve A–C on Fig. 6 represents those pressure/temperature pairs where
liquid and gaseous water are in equilibrium with each other and is known as the
“binodal”. The curve B–C–D, the “spinodal”, denotes a locus of states with infinite