Calibration and interpolation of the spectral responsivity of silicon photodiode-based detectors

The spectral responsivity of optical detectors is widely required in photometry, radiometry, and thermometry to absolutely measure the optical output of sources and the amount of optical radiation received at surfaces. Absolute calibration of the spectral responsivity requires a direct traceability to SI units. The method of traceable calibration of the spectral responsivity with very low uncertainties at the Physikalisch-Technische Bundesanstalt, the national metrology institute of Germany, is described for both, the experimental procedure and the subsequent mathematical analysis of the obtained measured values together with a statement of the uncertainty.