Uncertainty evaluation of spectral integrals for LED lamps

Partly correlated components in the spectral irradiance data form an essential problem in the uncertainty analysis of spectral integrals using Monte Carlo methods or other corresponding methods. We often know that the uncertainty is not fully correlated or fully uncorrelated between irradiance values at different wavelengths, but on the other hand, we do not know exactly what kind of correlation there is between these two extremes. Our new analysis method allows addressing the effect of correlations on spectral integrals of LED lamps in a practical and cost-effective way. A specific example is presented on the uncertainty evaluation of the spectral mismatch correction factor in the case of using the Predictable Quantum Efficient Detector (PQED) for LED illuminance measurement without V(lambda) filter. With the presented more reliable method, the uncertainty component related to spectral mismatch correction increases by a factor of 2 as compared with earlier estimates.