Tests of a balanced thermocouple and filter radiometer as a standard ultra-violet dosage intensity meter

Abstract

Data are given on the accuracy of the balanced thermocouple and filter radiometer as a standard ultraviolet dosage intensity meter. The erythema produced by the radiometrically measured amount of heterogeneous ultraviolet radiation is compared with that produced by a measured amount of homogeneous radiation of the emission line of mercury, at 297 m/x, which is used as a standard. This requires the determination of the ultraviolet spectral energy curve, and the total ultraviolet of wave lengths less than and including 313 m^t, of the source under test. An exact knowledge of the spectral erythemic response of the skin is also required (RP433) Sources differing markedly in ultraviolet spectral energy distribution were investigated, including as extremes the sun, and the so-called "cold quartz" mercury vapor lamp. * Figures in parentheses here and throughout the text indicate references given in the bibliography at the end of this paper. cobientz, stair] UltraViolet Filter Radiometry

Evaluation of ultraviolet solar radiation of short wave lengths

“…However, since, for the same person, skin sensibility is subject to a variation of 2 to 3 fold, this correction is of minor importance. If such a correction is made the agreement between the observed and the calculated erythemogenic efficiency is even closer than previously recorded [6]. 2.…”

“…The practical significance of this correction is that in the physiological (erythemal) tests the total ultraviolet solar energy required to produce a minimum perceptible erythema is probably 10 to 15 percent lower than previously published [4,6]. However, since, for the same person, skin sensibility is subject to a variation of 2 to 3 fold, this correction is of minor importance.…”

“…Subsequent tests of the balanced thermocouple and filter radiometer as a standard ultraviolet dosage intensity meter [6] on artificial sources justify the belief that the device is reliable, provided the ultraviolet spectral-energy distribution of the source is known with sufficient accuracy. In the case of the sun it was evident that the spectral-energy distribution, in the extreme ultraviolet, is not known with sufficient accuracy, and that it should be determined at the time of the physiological or biological application of the radiation stimulus.…”

Factors affecting ultraviolet solar-radiation intensities

“…In the above-mentioned tests (17), before exposure to heterogeneous ultraviolet radiation the skin-sensibility was standardized by exposure …”

“…It is to be noted that this method gives the relative (intensity) energy distribution for a given air mass, which information is sufficient for evaluating the integrated energy in a particular spectral band (6), (16), (17). The ordinates (intensities) of the spectralenergy curves for different air masses are on an arbitrary scale, which need not be the same for all the curves.…”