Laser hair removal

Laser hair removal is the process of removing unwanted hair by means of exposure to pulses of laser light that destroy the hair follicle. It had been performed experimentally for about twenty years before becoming commercially available in the mid-1990s. One of the first published articles describing laser hair removal was authored by the group at Massachusetts General Hospital in 1998. The efficacy of laser hair removal is now generally accepted in the dermatology community, and laser hair removal is widely practiced in clinics, and even in homes using devices designed and priced for consumer self-treatment. Many reviews of laser hair removal methods, safety, and efficacy have been published in the dermatology literature.

The primary principle behind laser hair removal 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, in the area that causes hair growth, the follicle, while not heating the rest of the skin. Light is absorbed by dark objects, so laser energy can be absorbed by dark material in the skin, but with much more speed and intensity. This dark target matter, or chromophore, can be naturally occurring or artificially introduced.

Melanin is considered the primary chromophore for all hair removal lasers currently on the market. Melanin occurs naturally in the skin, and gives skin and hair their color. There are two types of melanin in hair. Eumelanin gives hair brown or black color, while pheomelanin gives hair blonde or red color. Because of the selective absorption of photons of laser light, only black or brown hair can be removed. Laser works best with dark coarse hair. Light skin and dark hair are an ideal combination, being most effective and producing the best results, but new lasers are now able to target black hair in patients with dark skin with some success.

...
Wikipedia