Investigation of comparison methods for UVA irradiance responsivity calibration facilities

A new method is described for comparing calibration facilities for broadband ultraviolet (UV) meters. The method is validated in a successful pilot comparison between five European laboratories performing UVA irradiance responsivity calibrations. Participating laboratories calibrated a broadband UVA detector using their ordinary procedures that differed both by calibration methods and radiation sources used. The pilot laboratory calculated different reference values for each laboratory based on the specified calibration methods and prior knowledge of the calibrated artefact. The results were in agreement within 5%, which demonstrates a factor of two improvement in the consistency of the results as compared with earlier intercomparisons.