AN INSTRUMENT FOR ACTION SPECTRUM STUDIES IN DERMATOLOGY

— An instrument designed for convenient determination of action spectra for cutaneous photo-responses in man and experimental animals is described. Light from 450 W Xe lamp is dispersed by a concave holographic grating. The spectrum from 244 to 616 nm is projected as a planar strip (2 times 17 cm) intercepted by a grid with 31 ports. The bandwidth at each port is 12 nm and the size of the port increases from about 4 × 4 mm to 6 × 8 mm from the low to high wavelength limits, respectively. Typical fluence rates in quanta m-2 s-1 are 4.0 times 1019 at 298 nm, 16 times 1019 at 394nm and 22 times 1019 at 538 nm. Responses due to delayed erythema in normal skin and to musk ambrette photoallergy and solar urticaria in patients skin have been elicited with this instrument.