An extension of the three-zone model to predict depth of tissue damage beneath Er:YAG and Ho:YAG laser excisions.

Pulsed lasers such as Er:YAG and Ho:YAG with outputs at mid-infrared wavelengths emit radiation which may be transmitted by fibre to a treatment site. The thickness of soft-tissue damage beneath excisions made by these lasers is predicted using an extension to a model previously devised for CO2 laser radiation. The minimum achievable thickness occurs at a water absorption peak and at such high irradiance that heat cannot diffuse significantly compared with the radiation penetration depth. This minimum thickness is estimated to be in the order of 10 microns for the Er:YAG laser.