Evaluation of a Single‐monochromator Diode Array Spectroradiometer for Sunbed UV‐radiation Measurements^¶

Abstract

The suitability of a new technology single‐monochromator diode array spectroradiometer for UV‐radiation safety measurements, in particular for sunbed measurements, was evaluated. The linearity, cosine response, temperature response, wavelength scale, stray‐light and slit function of the spectroradiometer were determined and their effects on the measurement accuracy evaluated. The main error sources were stray‐light and nonideal cosine response, for which correction methods are presented. Without correction, the stray‐light may reduce the accuracy of the measurement excessively, particularly in the UV‐B range. The expanded uncertainty of the corrected UV measurements is estimated to be 14%, which is confirmed with the comparative measurements carried out with a well‐characterized double‐monochromator spectroradiometer. The measurement accuracy is sufficient for sunbed measurements, provided that all corrections described above have been done and the user of the instrument has a good understanding of the instrument's operating principles and potential error sources. If these requirements are met, the tested spectroradiometer improves and facilitates market surveillance field measurements of sunbeds.

Assessing scale‐wise similarity of curves with a thick pen: As illustrated through comparisons of spectral irradiance

“…Spectral (energy) irradiance (W m −2 nm −1 ) was measured with a CCD array spectroradiometer Maya 2000 Pro (Ocean Optics, Dunedin, FL, USA) attached via a fiber‐optic cable (FC‐UV400‐2 400‐μm, Avantes, Leatherhead, UK) to a D7‐H‐SMA cosine diffuser (Bentham Instruments Ltd., Reading, UK) with spectral range of 200–1,100 nm. The spectroradiometer was calibrated by the Finnish Radiation and Nuclear Safety Authority (STUK) (Ylianttila, Visuri, Huurto, & Jokela, ) prior to the measurements in early spring, to allow accurate recording of outdoor solar radiation from the UV‐B to the near‐infrared. A further stray‐light correction for the UV and “dark noise” correction were applied to each recording of solar spectral irradiance, through its repetition with a polycarbonate cap over the diffuser blocking solar UV radiation (UV‐B 280–315 nm plus UV‐A 315–400 nm) and a dark cap over the diffuser blocking UV and visible solar radiation.…”

Comment on “Extreme environments in the forests of Ushuaia, Argentina” by Hector D'Antoni et al.

“…Ocean Optics spectrographs are not suitable for measuring solar spectra in the UV‐B region without modifications because their stray light rejection is insufficient. Even in measuring sun‐bed irradiance, a much less demanding application, great care is needed in processing UV‐B data [ Ylianttila et al , 2005]. The multichannel (CCD type) detector in D'Antoni et al 's [2007] spectroradiometer may be particularly susceptible to spectral scattering [ Kostkowski , 1997], especially with the high flux from the background of sunlight.…”

Measurement of Photolysis Frequencies in the Atmosphere

“…In order to convert the measured signals into reasonable radiation data, sensitive stray-light corrections are needed in the UV-B, which requires a thorough analysis of the instrumental stray-light characteristics (e.g. Kanaya et al, 2003;Eckstein et al, 2003;Jäkel et al, 2005;Ylianttila et al, 2005).…”

“…Since spectrograph systems offer a number of advantages compared to scanning systems, more accurate methods for the stray-light correction in the UV-B are highly desirable and remain subject to ongoing research (e.g. Ylianttila et al, 2005).…”