Selection of a Radiance Source for the Radiometric Calibration Facility at the CSIRO Earth Observation Centre

This report discusses the selection of a radiance source suitable for calibrating a diverse group of radiometers commonly used in CSIRO. The chosen system is based on an integrating sphere that enables the mapping of incident radiance against instrument response with known uncertainty. Commercially available candidate source systems are assessed against the physical and radiometric characteristics of the target instruments, with particular regard to the maximum radiance level required and the dimensions of the exit port. The Labsphere URS-600 was found to fit these requirements with the additional advantage of calibration traceable to the National Institute of Standards and Technology (NIST). A further design study was undertaken to ascertain whether a customised system would prove more attractive. However, the alternative system was found to provide inadequate radiant output and to be more expensive. Future work will focus on the development of a multispectral calibration reference system to monitor source performance.