Radiometric applications of Fourier-transform spectrometers

Filter radiometers are used as transfer standards in many radiometric measurements, and essentially comprise a detector, filter (interference or coloured glass) and high-precision aperture. An initial study into the use of Fourier-transform (FT) spectrometry has resulted in the attainment of medium accuracy (around 0.3 % to 0.7 %) calibration of assembled filter radiometers in a period of a few hours. This contrasts with a day for characterization using a grating instrument and the weeks required for high-resolution, high-accuracy, laser-based calibration. The technique measures the response of the radiometer to be calibrated against that of a standard detector, which in this case is a trap detector.