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 ∫j(λ,t)ε(λ)dλ, where j(λ,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.


Electrical and Computer Engineering

Keywords and Phrases

Erythemal flux; Solar ultraviolet radiometer

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Document Type

Article - Journal

Document Version


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© 2024 Elsevier, All rights reserved.

Publication Date

01 Nov 1998

PubMed ID