Evaluation of different general V(λ) mismatch indices of photometers for LED-based light sources in general lighting applications

The general V(λ) mismatch index, f₁′, of a photometer quantifies the deviation between its determined relative spectral responsivity, s_relλ, and its nominal responsivity, the spectral luminous efficiency function for photopic vision, V(λ). LED-based light sources now dominate in general lighting, displacing incandescent and fluorescent lamps. Furthermore, the calibration of photometers will very likely see the replacement of the reference CIE standard illuminant A with CIE reference spectrum L41. The article evaluates the consequences. Should we also change the definition of the general V(λ) mismatch index? Based on performance criteria, the individual indices are evaluated using various datasets with the help of statistical analyses. As a result, the authors can conclude that the current definition works very well even under changed calibration and application conditions and does not need to be changed. Other evaluated indices for a new index definition perform only slightly better in some cases, but do not generate generally better properties.