Coagulation of egg white by thermal feedback controlled CO₂ laser

Temperature feedback control during laser-assisted tissue coagulation was investigated and demonstrated using the egg white model. Dynamics of photothermal denaturation during CO₂ laser irradiation was observed by simultaneously controlling surface temperature and monitoring HeNe laser transmission of egg white samples. Once a quasi-constant surface temperature was established, transmission of egg white tended to decrease linearly with time. A first order rate process was observed. Our experiments demonstrated that thermal feedback can effectively control/limit photothermal damage.