Luminous intensity comparison based on new standard lamps with led reference spectrum

Abstract

Photometric calibrations are mainly based on the use of scientific grade incandescent standard lamps [CIE 2002]. Most of the measurement methods and reference spectra used in photometry were developed long before modern solid-state lighting (SSL) products were invented and introduced into the lighting market. In addition, phasing-out of incandescent lamps for lighting applications poses a metrological problem: all lamps and luminaires measured in practice differ completely in their behaviour with respect to spectral distribution, flicker and aging, as compared to incandescent lamps used in photometer calibrations. The European research project “Future photometry based on solid-state lighting products” (EMPIR 15SIB07 PhotoLED) has investigated the fundamental requirements for photometry based on white light-emitting diode (LED) sources. The project partners have analysed many hundreds of LED spectra and derived suitable LED reference spectra for photometric calibrations. In this article we present the practical advantages and disadvantages of luminous intensity standards based on white LEDs with very similar spectra to the hypothetical reference spectrum developed in the project. Furthermore, we discuss their suitability for metrological comparisons of the luminous intensity.