Spatial non-uniformity analyses of radiometric detectors to identify suited transfer standards for optical radiometry

The non-uniformity of responsivity of photodiodes and thermal detectors limits the accuracy of their calibration. Spatial non-uniformity properties of a pyroelectric radiometer, a thermopile detector, silicon, germanium and indium gallium arsenide photodiodes are investigated in the scope of our work. Silicon type photodiodes showed best uniformity characteristics among the analysed photodiodes and detectors. Significant changes have been found in the spatial responsivity close to the band gap of silicon. The spatial responsivity of thermopile detector was measured at two different wavelengths and no wavelength dependence was observed.