The real advantage of these wavelengths is that they are delivered through a glass fiber, therefore they can be passed through an endoscope. Even though they can't cut as good as a CO 2 laser they are able reach areas the CO 2 laser can't. More necrosis means better control of bleeding, but too much increases healing time. The CO 2 laser provides a nice balance for general incisional work. This is the power delivered per unit area, expressed usually as watts per square centimeter.
Power density depends on the set power, the spot size, and the distance of the tip from tissue.
If the power is held constant, a larger spot size produces s smaller relative impact on tissue than a smaller spot size, because the power is spread over a larger area. This is what a 0.4 mm tip looks like at when attached to the hand piece. Distance of the tip from the tissue target This diagram shows the effect of tip size and target distance on tissue spot size. The arrow points to the three different exposure settings on the machine. The top is single exposure, the middle is repeat, and the bottom is continuous.