UVR photodiodes are small and inexpensive, but are they good? In 2002, we submitted a photodiode-based dosimeter to be tested in the Third International Solar UV Radiometer Calibration Campaign (UVC-III) in Davos, Switzerland. Our submission was a prototype, and it was plagued with problems; preliminary results looked bleak. While the campaign was ongoing, we studied a duplicate instrument in our New Zealand lab, and we discovered several dependencies that have not been described before now. When we remotely applied our findings to the instrument in Davos, the sudden improvement caused much surprise: our instrument now compared favorably to some of the more expensive radiometers in the campaign!
Soon after this success, we were asked to collaborate in the MeLiDos consortium, which seeks to define best practice for UVR and visible light dosimetry. This includes guidance for how dosimeters should be characterized and qualified for research.
In this talk, we will discuss how environmental factors affect the accuracy of UVR photodiodes, and how these factors can be compensated for. [We will briefly outline the goals of the MeLiDos consortium.] If time permits, we will tell the story of how we accidentally measured column ozone with a photodiode and a hairdryer.
Note to conveners: if another presentation will discuss MeLiDos, then the bracketed sentence should be omitted from this abstract. It is a big project, and deserves its own presentation.