[Optical radiation and its effect on the skin]

Optical radiation ranges from short wave ultraviolet via visible light to the far infra-red. Both natural and artificial light sources may cause desired and undesired effects, both on the skin and on the organism as a whole. The nature and extent of such effects depend primarily on the energy of the photons, the absorption capacity of the chromophores, the mean depth of penetration, and on the density and dose of the radiation. The present paper discusses the mechanisms of action and desired and undesired effects in the organism, including therapeutic applications, separately for ultraviolet radiation, visible light and infrared radiation.