Reconsidering the spectral distribution of light: Do people perceive watts or photons?

C Martinsons (1) , F Behar-Cohen (2, 3, 4, 5, 6) , T Bergen (7) , P Blattner (8) , M Herf (9) , C Gronfier (10, 11) , K Houser (12) , S Jost (13, 14) , M Nilsson Tengelin (15) , G Obein (16) , L Schlangen (17) , L Simonot (18, 19) , M Spitschan (20) , A Torriglia (2, 3) , J Zeitzer (21)

1 CSTB - Centre Scientifique et Technique du Bâtiment
2 CRC (UMR_S_1138 / U1138) - Centre de Recherche des Cordeliers
3 USPC - Université Sorbonne Paris Cité
4 AP-HP - Assistance publique - Hôpitaux de Paris (AP-HP)
5 OphtalmoPôle - Hôpital Cochin
6 Hôpital Foch [Suresnes]
7 PRL - Photometry and Radiometry Laboratory
8 METAS - Federal Institute of Metrology
9 F.lux Software LLC
10 CRNL - Centre de recherche en neurosciences de Lyon - Lyon Neuroscience Research Center
11 INSERM - Institut National de la Santé et de la Recherche Médicale
12 OSU - Oregon State University
13 ENTPE - École Nationale des Travaux Publics de l'État
14 LTDS - Laboratoire de Tribologie et Dynamique des Systèmes
15 RISE Research Institutes of Sweden
16 LNE - Laboratoire National de Métrologie et d’Essais
17 TU/e - Eindhoven University of Technology [Eindhoven]
18 CURIOSITY [Institut Pprime]
19 UP - Université de Poitiers = University of Poitiers
20 Max Planck Institute for Biological Cybernetics
21 Stanford University

The spectral distribution is a fundamental property of non-monochromatic optical radiation. It is commonly used in research and practical applications when studying how light interacts with matter and living organisms, including humans. In the field of lighting, misconceptions about the spectral distribution of light are responsible for unfounded claims, which pervade the scientific and technical communities. Starting from the definition of the spectral distribution, this paper describes the ambiguities and errors associated with a purely graphical analysis of the spectral distribution. It also emphasizes the importance of considering the particle nature of light in research involving both visual and non-visual effects, which implies using the spectral distribution expressed in the photon system of units, a system that has been seldom used in lighting research for historical reasons. The authors encourage lighting engineers and researchers to determine which system is best suited to their work and then proceed with the correct use of spectral distributions and of spectral weighting functions for applications involving optical radiation.

Keywords: OPTICAL RADIATION; LIGHT; SPECTRAL DISTRIBUTION

Keywords: LUMIERE; RAYONNEMENT OPTIQUE; DISTRIBUTION SPECTRALE

Domains: Optics [physics.optics]

C Martinsons, F Behar-Cohen, T Bergen, P Blattner, M Herf, et al.. Reconsidering the spectral distribution of light: Do people perceive watts or photons?. International Journal of Lighting Research and Technology, 2024, ⟨10.1177/14771535241246060⟩. ⟨hal-04569647⟩