The primary principle behind<unk>  is selective photothermolysis (SPTL), the matching of a specific wavelength of light and pulse duration to obtain optimal effect on a targeted tissue with minimal effect on surrounding tissue. Lasers can cause localized damage by selectively heating dark target matter, melanin, thereby heating up the basal stem cells in the follicle which causes<unk>  growth, the<unk>  follicle, while not heating the rest of the skin. Light is absorbed by dark objects but reflected by light objects and water, so laser energy can be absorbed by dark material in the<unk>  or skin, with much more speed and intensity than just the skin without any dark adult<unk>  or melanin. Melanin is considered the primary chromophore for all<unk><unk>  lasers currently on the market. Melanin occurs naturally in the skin and gives skin and<unk>  their color. There are two types of melanin in<unk> . Eumelanin gives<unk>  brown or black color, while pheomelanin gives<unk>  blonde or red color. Because of the selective absorption of photons of laser light, only<unk>  with color such as black, brown, or reddish-brown<unk>  or dirty blonde can be removed. White<unk> , light blonde and strawberry blonde<unk>  does not respond well. Laser works best with dark coarse<unk> . Light skin and dark<unk>  are an ideal combination, being most effective and producing the best results, but lasers such as the Nd:YAG laser are able to target black<unk>  in patients with dark skin with some success.<unk>  on dark skin on the face<unk><unk>  lasers have been in use since 1997 and have been approved for "permanent<unk>  reduction" in the United States by the Food and Drug Administration (FDA). Under the FDA's definition, "permanent"<unk>  reduction is the long-term, stable reduction in the number of<unk> s regrowing after a treatment regime. Indeed, many patients experience complete regrowth of<unk>  on their treated areas in the years following their last treatment. This means that although laser treatments with these devices will permanently reduce the total number of body<unk> s, they will not result in a permanent<unk>  of all<unk> .<unk>  has become popular because of its speed and efficacy, although some of the efficacy is dependent upon the skill and experience of the laser operator, and the choice and availability of different laser technologies used for the procedure. Some will need touch-up treatments, especially on large areas, after the initial set of 3–8 treatments.
Laser hair removal
Ultraviolet light therapy
Low-level laser therapy
Laser coagulation
GreenLight Laser Therapy
Laser surgery
Plesiotherapy
Climatotherapy