m) is a well-known infrared coherent light source as a tool in surgery. At this wave-length there is a high absorbance coefficient (860 cm–1), because of vibration mode resonance of H2O molecules.
Therefore, the majority of the irradiation energy is absorbed in the tissue and the temperature of the tissue rises
as a function of power density and laser exposure duration. In this work, the tissue damage caused by CO2 laser
(1–10 W, ~40–400 W cm–2, 0.1–6 s) was measured using 30 mouse skin samples. Skin damage assessment was
based on measurements of the depth of cut, mean diameter of the crater and the carbonized layer. The results
show that tissue damage as assessed above parameters increased with laser fluence and saturated at 1000 J cm–
2. Moreover, the damage effect due to high power density at short duration was not equivalent to that with low
power density at longer irradiation time even though the energy delivered was identical. These results indicate
the lack of validity of reciprocity (Bunsen–Roscoe) rule for the thermal damage.