CIE 167 – Action spectroscopy of skin with tunable lasers

In order to determine action spectra with high accuracy, improved experimental methods are needed. This concerns the irradiation sources as well as quantitative measurements of the skin reactions. We reevaluated action spectra for erythema and pigmentation in humans with a tunable, highly monochromatic irradiation source and with an instrumental measurement of skin reactions. The irradiation system consisted of an excimer laser pumped dye laser and an ultraviolet fiber optic system. The skin colour after irradiation was determined with a colorimeter using the CIELUV system. By applying laser a very high spectral resolution in action spectra could be obtained. For example, the maximum of the erythema action spectrum in the ultraviolet-B range was measured at 298,5 nm and an additional maximum was found at 362 nm in the ultraviolet-A region. Our results suggest a photochemical mechanism boundary at 330 nm. The erythema and pigmentation curves are compared with spectra from the literature determined with conventional irradiation sources (lamps and monochromators), with the current standard erythema curve of the CIE, as well as with other photobiological action spectra; especially with spectra for UV damage and tumor induction in the UV-A.

The research note is written in English, with a short summary in French and German. It consists of 14 pages with 3 figures and 1 table.