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A technique is introduced for realizing spectral irradiance in the range between 286 nm and 901 nm. The scale is based on a temperature-controlled filter radiometer constructed from a three-element silicon trap detector, band-pass filters and a precision aperture. Seasoned FEL-type quartz halogen lamps are used as reference standards. In this method, direct traceability of the radiometer to the cryogenic radiometer gives an important advantage in the visible and near-infrared regions. Another advantage of this system is the procedure followed for measurement of the distance between the lamp filament and aperture surface of the filter radiometer. The expanded uncertainty (k = 2) of the spectral irradiance measurement is between 2.3% and 1.5% in the UV region, while the uncertainty is of the order of 0.6% above 400 nm.

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