Concept for improved radiometric calibration of radiance sources at the CHB facility

Abstract

The Calibation Home Base (CHB) is a facility for the calibration of airborne imaging spectrometers such as APEX, ROSIS and in the future ARES, and for field spectrometers. Absolute radiometric calibration in the spectral range of 350–2500 nm is currently based on an integrating sphere whose spectral radiance was calibrated by the German National Metrology Institute PTB. However, a single radiance source cannot meet the requirements of a multitude of sensors, hence CHB operates several sources. In order to enable consistent calibration at CHB, a transfer radiometer based system will be used in the future. Detectors are much more stable than lamps, hence a well-designed system based on accurate detectors can reach much higher absolute accuracy of radiometric calibration than a lamp based set-up. The concept of this system, its hardware components and the expected accuracies are presented.