Melanin absorbs light in the ultraviolet-1200nm range at the longer wavelenghths absorption is lower and penetration deeper than at shorter wavelenghths.eg Q-switched Nd:YAG 1064 nm laser emits light that penetrates 2-3 mm into dermis and is therefore suitable for the removal of deeper dermal pigmentation such as found in nevus of Ota.Shorter wavelenghths 532 nm and Ruby Laser 694 nm penetrates less than 1mm into skin is also full of ephelides and freckles and cafe-au-lait macules.Nd: YAG laser is effective in blue black tattoos but is relatively poorly absorbed by green pigments.
