Design and characterisation of black-body sources for infrared wide-band Fourier transform spectroscopy

The design and characterisation of small and cost-effective reference black-body sources for radiometric calibration of Fourier transform spectrometers in the mid and far infrared is presented. The paper describes the optimisation of the absorbing black-coating material and the study of two types of cavity geometry, one designed for collimated beams and one for focused beams. These two reference sources have been developed for the Radiation Explorer in the Far InfraRed spectrometer covering the 100-1400 cm−1 spectral range. They are currently used on-board two prototypes for ground and stratospheric balloon based atmospheric emission measurements. An emissivity of better than 0.9999 is obtained for both type of cavity geometry giving a calibration error, depending only on the temperature gradient inside the blackbody, of less than 0.5 K.