An absolute detector-based spectral radiance source

We describe an absolute, spectrally tunable, detector-based broad-band radiometric calibration source whose uncertainties in spectral radiance may approach those of reference detectors, on the order of 0.1 % (k=1). This uncertainty in the spectral radiance of the source is a factor of two lower than the current uncertainty in radiance sources disseminated by the National Institute of Standards and Technology, USA (NIST). These low uncertainties in radiance calibration sources are required for satellite sensors supporting climate change missions. For example, the uncertainty requirements for the Climate Absolute Radiance and Refractivity Observatory (CLARREO) sensor are approximately 0.2 % (k=1) in the silicon range. The conceptual framework of the source, characterization and radiance validation data and trending of the source radiance over time are described.