CIE x048-PO20 PDF

Quality indexes are usually defined for measurement instruments in order to characterize some specific aspect of their performance. The V(A) spectral mismatch of photometers is evaluated by the general V(A) mismatch index, f1, whose value must be correlated with the average measurement error introduced by this spectral mismatch. The objective of this work is to assess the correlation of several indexes of this type with this average error of photometers. The difference between the studied indexes is that the spectral responsivity of the photometer is normalized with different factors to that defined for f1.  From this study, we conclude that the most suitable normalization in the definition of a f1-type quality index is not determined by the spectral distribution used in the calibration or by those of the light sources to be measured. The normalization factor presenting the best correlation in all studied cases was obtained by numerically minimizing the value of the index instead of by applying an explicit function,  as it is done in f1.