Hello enrgyturtle. Excellent question. Lasers and other light based devices like IPL (not a laser) work by selectively targeting different parts of the skin. For example, one wavelength of light (810 nanometers, a Diode laser) is very effective at targeting the melanin in the hair follicle so is excellent for permanent hair removal. Another wavelength (532 nanometers, KTP laser) is excellent for targeting small blood vessels. So each type of laser light is preferentially absorbed in one part of the skin. It's called "Selective photothermolysis" and it's the way lasers work :).
