A new solar spectrum source for absolute radiometric calibration of advanced multispectral sensors and hyperspectral imagers

A new solid-state source has been developed to emulate the solar spectrum for absolute radiometric calibration of advanced multispectral and hyperspectral imagers. The source is used in conjunction with quartz tungsten-halogen lamps (QTH) on an integrating sphere to provide a solar spectrum matching the AM1.5 spectrum from 385nm to 2500nm. The performance criteria required a source with “smooth” spectral shape to minimize spectral mismatch errors in the calibration as well as minimizing the differences between power in different bands to allow sensor arrays to be calibrated with equivalent integration times. A method has also been developed to quantify the “smoothness” of the calibration spectra and the expected error in the resulting spectral response calibration for measurement of various source spectra.