Calculation of the systematic error in spectroradiometric measurements in the IR

The paper presents an analysis and the results of calculation of the systematic error for the 6-15-micron spectral region - caused by a difference between the zero of the measurement scale of the recorder and the radiation zero - for measurements made with a single-beam spectroradiometer having a blackened Duralumin modulator. Idealized sources with a circular brightness indicatrix are discussed. It is shown that the systematic error can be of substantial value.