A selective Pt-CdS photodiode to monitor erythemal flux.
The design and potential benefit of a solar ultraviolet (UV) radiometer reporting a maximum instantaneous flux of erythemally weighted heterogeneous energy is considered. The proposed device is electronically peak detecting; the user would ideally 'point and paint' the sun to find a localized maximum. A projected exposure time can be calculated from an instantaneous reading of erythemally weighted flux for a given minimal erythemal dose (MED) specified by the user. This calculation, though not necessarily providing a true exposure time, may be useful and informative in that it serves as a more 'recognizable' measure of erythemal flux and introduces a custom scale for each individual via their MED. Erythemal flux is calculated as the weighted integral sum [symbol: see text]j(lambda,t) epsilon(lambda) d lambda, where j (lambda, t) is the instantaneous angular integrated spectral irradiance accepted by human skin. This instrument proposal uses a single interference filter over a Pt-CdS photodiode; the interference filter is offered as a nominal design transmittance. The simulated response of the selective photodiode has a near-linear relation to the effective irradiance. Test inputs for evaluation purposes and to elucidate a transducer response are constructed from a spline interpolation of the World Radiation Center (WRC) spectrum and classic transmittance models. Our desired erythemal flux is offered in interconvertible UV Indexes (UVIs) as a function of zenith angle and atmosphere, characterized by elevation, ozone path, and turbidity.
Department of Electrical Engineering, University of Missouri-Rolla 65401, USA.
D L
DL
Richards
R E
RE
Davies
J L
JL
Boone
D019187:Cadmium Compounds; D002138:Calibration; D006801:Humans; D008962:Models, Theoretical; D011834:Radiation Monitoring / Q000295:instrumentation*; D012867:Skin / Q000528:radiation effects*; D013440:Sulfides
D019187:Cadmium Compounds; D013440:Sulfides; C034939:cadmium sulfide