FASCAL 2 facility is solely dedicated to spectral irradiance scale realizations and calibrations. The spectral irradiance standards are calibrated using a high-temperature blackbody operating at nearly 3000 K. The temperature of the blackbody is determined using detector-based techniques traceable to the SIRCUS facility. The known spectral irradiances from the HTBB is used for the spectral irradiance responsivity calibration of a double-grating monochromator which is in turn used to calibrate calibration lamps.
Double-grating monochromator with photomultiplier tube, silicon diode and extended-InGaAs diode detectors are used to cover a range of wavelengths from 220 nm to 2500 nm. Four independent lamp stations are used for the calibrations.