The wavelength of Nd: YAG targets pigment to heat it and denature the molecule. This cause the body's immune system to absorb the pigment naturally. This delivers unblemished skin that appears and feels rejuvenated.
On different settings, Nd: YAG can also target broken veins. It heats up the blood in the veins destroying and clotting at the same time which are then reabsorbed naturally by the body, often with immediate results.
Non-ablative laser usually results in effective dermal regeneration over a number of repeat sessions. It does not destroy tissues (non-ablative) so the downtime is remarkably low.
On the other hand, ablative fractional laser (Co2) results in marked dermal regeneration over a far shorter timespan because more energy is imparted to skin there is also a higher downtime which is usually capped at 5-7 days. Energy imparted to the skin excites a controlled inflammatory response. Cells that make-up the dermis and maintain it are recruited to the area. Such cells include fibroblasts which lay down new collagen and eventually reorient it according to the grain of the skin. When collagen and other ground substances (e.g. elastin) are deposited this results in plumped, rejuvenated more elastic and youthful skin.
On yet another setting Co2 laser can be used to resurface the skin and this can include sun-damaged areas leaving behind in-tact dermis from which new skin grows. Considering that this skin is perfectly matched to surrounding areas, the aim of rejuvenation is achieved.