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Leading the LED Revolution: EMPIR Project RevStdLED

In the dynamic landscape of lighting technology, the Metrology Research Institute is at the forefront of innovation, actively participating in the European Metrology Programme for Innovation and Research (EMPIR) Project RevStdLED. This projects seeked to revise and extend measurement methods for LED lamps, luminaires, and modules—a timely response to the surge of LED sources in lighting solutions.

Project Insight

As LED sources ascend to the status of the preferred light source technology in both consumer and industrial applications, a disparity has arosen. The prevailing measurement methods and analyses were grounded in classical tungsten filament lamps, resulting in spectral mismatch errors when assessing LED-based sources. The distinct spectral profiles of LEDs, showcased in Figure 2, underscore the need for transformative change. The core objective of EMPIR's RevStdLED project was to revamp existing measurement methods and analyses, aligning them with the shift in lighting technology.

Our Pioneering Role

Within this initiative, the Metrology Research Institute played a pivotal role. Our contributions encompass two significant areas:

1. Revision of Photometer Mismatch Index f1': As LED-based illumination gains prominence, the calculation of photometer mismatch index f1' demands reevaluation. Our efforts center on revising this index to accurately account for the unique attributes of LED-based lighting.
2. Determination of Spectral Correlations in Photometric Quantities: The shift towards LED technology necessitates a deep dive into spectral correlations within photometric quantities. This research utilized Monte Carlo methods to perform an uncertainty analysis of spectral integrals, focusing particularly on the uncertainty surrounding the spectral mismatch correction factor. A novel methodology is introduced to measure the effects of partial correlations among spectral irradiance values across various wavelengths. The findings suggest that uncertainty resulting from partial correlations significantly exceeds that arising from full spectral correlation or complete lack of correlation across different wavelengths. This revelation advances our understanding of uncertainty analysis in spectral integrals and emphasizes the importance of accounting for partial correlations to ensure accuracy in measurements.

Illuminating the Future

The RevStdLED project isn't just about measurements—it's about shaping the trajectory of lighting technology. By harnessing the potential of LED sources while recalibrating measurement paradigms, we're ensuring precision, accuracy, and innovation.

Advancing Toward Excellence

Join us on this transformative journey. As LED sources redefine the landscape of illumination, we're reshaping how we measure and analyze light. Stay connected to the revolution by following our progress in the EMPIR RevStdLED project, and witness how the boundaries of lighting technology are expanding under the guiding light of precision and excellence.

Revision of Photometer Mismatch index f1’: Metrology Research Institute contributed in the literary review and discussion of novel f1’ index with our own potential solution to the novel f1’ index. Our method would have used the standard deviation of the spectral mismatch correction factor as a performance indicator. In the end, however, in the practical context, the change of the relative spectral responsivity of the f1’ does not change significantly. As the f1’ has been used for a long time in the photometer manufacturing, changing the index could cause more problems that it would solve. One possibility is to add a complementary index that uses CIE reference spectrum L41 as the relative spectral responsivity instead of the Standard illuminant A in the original calculation of f1’ as a parallel index, which could be used after established in use for a longer period of time. 

References

Udo Krüger, Alejandro Ferrero, Ville Mantela, Anders Thorseth, Klaus Trampert, Olivier Pellegrino and Armin Sperling,” Evaluation of different general V(λ) mismatch indices of photometers for LED-based light sources in general lighting applications”, 2022 Metrologia 59 065003.

Udo Krüger, Alejandro Ferrero, Anders Thorseth, Ville Mantela and Armin Sperling, “General V(λ) mismatch index: History, current state and new ideas”, 2023 Lighting Research and Technology 554-5. pp 420-432.

Anders Thorseth, Udo Krüger, Alejandro Ferrero, Ville Mantela, Armin Sperling, and Olivier Pellegrino,”D5 : Evaluation of a complementary general V(λ) mismatch index”, 2023, DTU, Report

Ville Mantela, Janne Askola, Petri Kärhä and Erkki Ikonen,” Novel evaluation method for general photometer mismatch index f1’ ”, Abstracts of CIE 2021 Conference, September 27-29, 2021, pages 174-175 (Talk).

Y Rezazadeh, A Sperling, T Gerloff, U Krüger, A Ferrero, J Campos, O Pellegrino, J Dubard, and E Ikonen, “Uncertainty of evaluation of spectral mismatch correction factor” (submitted).