Calibration of IR detectors can be carried out at NPL between 1 and 3 um with an uncertainty of 3 %. This is based on the use of a cryogenic radiometer. As high wavelengths up to 20 um, the uncertainty is estimated to be up to 20% which is much too high.
The project consists in establishing another absolute calibration point at 10.6 um (corresponding to the CO2 laser)
An absolute spectral responsivity scale has been established at two wavelengths, 1.3 and 10.5 um, using laser radiation, with an uncertainty of less than +/- 2.5% over the spectral range 1 um to 20 um.