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Optimising metameric spectra for integrative lighting to modulate the circadian system without affecting visual appearance

Zandi, Babak ; Stefani, Oliver ; Herzog, Alexander ; Schlangen, Luc J. M. ; Trinh, Quang Vinh ; Khanh, Tran Quoc (2022):
Optimising metameric spectra for integrative lighting to modulate the circadian system without affecting visual appearance. (Publisher's Version)
In: Scientific Reports, 11, Springer Nature, e-ISSN 2045-2322,
DOI: 10.26083/tuprints-00021246,
[Article]

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Item Type: Article
Origin: Secondary publication via sponsored Golden Open Access
Status: Publisher's Version
Title: Optimising metameric spectra for integrative lighting to modulate the circadian system without affecting visual appearance
Language: English
Abstract:

Smart integrative lighting systems aim to support human health and wellbeing by capitalising on the light-induced effects on circadian rhythms, sleep, and cognitive functions, while optimising the light’s visual aspects like colour fidelity, visual comfort, visual preference, and visibility. Metameric spectral tuning could be an instrument to solve potential conflicts between the visual preferences of users with respect to illuminance and chromaticity and the circadian consequences of the light exposure, as metamers can selectively modulate melanopsin-based photoreception without affecting visual properties such as chromaticity or illuminance. This work uses a 6-, 8- and 11-channel LED luminaire with fixed illuminance of 250 lx to systematically investigate the metameric tuning range in melanopic equivalent daylight illuminance (EDI) and melanopic daylight efficacy ratio (melanopic DER) for 561 chromaticity coordinates as optimisation targets (2700 K to 7443 K ± Duv 0 to 0.048), while applying colour fidelity index Rf criteria from the TM-30-20 Annex E recommendations (i.e. Rf ≥ 85, Rf,h1 ≥ 85). Our results reveal that the melanopic tuning range increases with rising CCT to a maximum tuning range in melanopic DER of 0.24 (CCT: 6702 K, Duv: 0.003), 0.29 (CCT: 7443 K, Duv: 0) and 0.30 (CCT: 6702, Duv: 0.006), depending on the luminaire’s channel number of 6, 8 or 11, respectively. This allows to vary the melanopic EDI from 212.5–227.5 lx up to 275–300 lx without changes in the photopic illuminance (250 lx) or chromaticity (Δu′v′ ≤ 0.0014). The highest metameric melanopic Michelson contrast for the 6-, 8- and 11-channel luminaire is 0.16, 0.18 and 0.18, which is accomplished at a CCT of 3017 K (Duv: − 0.018), 3456 K (Duv: 0.009) and 3456 K (Duv: 0.009), respectively. By optimising ~ 490,000 multi-channel LED spectra, we identified chromaticity regions in the CIExy colour space that are of particular interest to control the melanopic efficacy with metameric spectral tuning.

Journal or Publication Title: Scientific Reports
Volume of the journal: 11
Publisher: Springer Nature
Collation: 14 Seiten
Classification DDC: 600 Technik, Medizin, angewandte Wissenschaften > 600 Technik
Divisions: 18 Department of Electrical Engineering and Information Technology > Adaptive Lighting Systems and Visual Processing
Date Deposited: 09 May 2022 12:12
Last Modified: 09 May 2022 12:12
DOI: 10.26083/tuprints-00021246
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-212465
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/21246
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