Concerns about temporal light modulation (TLM) from LEDs are beginning to turn into consensus-based metrics and guidance. One important point of consideration is how to establish performance criteria based on metrics like the stroboscopic visibility measure and the phantom array visibility measure. This brief paper describes a new technical memorandum, TM-39, from the Illuminating Engineering Society, including how the committee developed the specification levels it proposes. For such documents to be effective, the broader lighting industry needs to understand what meeting the thresholds will and will not accomplish; this paper provides an important explanation of proper interpretation and limitations. Finally, it suggests future research that can continue to strengthen the methods being used to limit TLM and improve lighting quality.
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References
1.
MartinsonsCVeitchJALoughranS, et al. Solid-State Lighting: Review of Health Effects. Paris, France: International Energy Agency, 2024.
2.
MantelaVNordlundRAskolaJ, et al. Improvement of temporal light artefact effects in commercial LED lamps. Lighting Research and Technology2024; 56: 790–799.
3.
Institute of Electrical and Electronics Engineers (IEEE). IEEE 1789-2015 Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers. Piscataway, NJ: Institute of Electrical and Electronics Engineers, 2015.
4.
National Electrical Manufacturers Association (NEMA). NEMA 77-2017 Temporal Light Artifacts: Test Methods and Guidance for Acceptance Criteria. Rosslyn, VA: National Electrical Manufacturers Association, 2017.
5.
Commission Internationale de l’Eclairage (CIE). CIE 249:2022 Visual Aspects of Time-Modulated Lighting Systems. Vienna, Austria: Commission Internationale de l’Eclairage, 2022.
6.
TanJMillerNJRoyerMP, et al. Temporal light modulation: a phantom array visibility measure. Lighting Research and Technology. First published April 2024. DOI: 10.1177/14771535241239611.
7.
Illuminating Engineering Society (IES). ANSI/IES TM-39-25: Quantification and Specification of Visual Responses to Temporal Light Modulation (a.k.a. Flicker). New York, NY: Illuminating Engineering Society, 2025.
8.
BodingtonDBiermanANarendranN.A flicker perception metric. Lighting Research and Technology2016; 48: 624–641.
9.
PerzMSekulovskiDVogelsI, et al. Stroboscopic effect: contrast threshold function and dependence on illumination level. Journal of the Optical Society of America A2018; 35: 309.
10.
PerzMBeeckmanPSekulovskiD.Acceptability criteria for the stroboscopic effect visibility measure. CIE 2017 Midterm Meetings. Jeju, South Korea, 2018: 453–459.
11.
Dam-HansenCCoyneSIsoardiG, et al. Minimising the uncertainties in the calculation of stroboscopic effect visibility measure. Proceedings of the CIE Symposium on Advances on the Measurement of Temporal Light Modulation, 2022: CIE-X049.
12.
MillerNIrvinLRoyerM, et al. Visibility and annoyance of the phantom array effect varies with age and history of migraine. Lighting Research and Technology2024; 56: 676–706.
13.
VeitchJAVan RoonPD’AngiulliA, et al. Effects of temporal light modulation on cognitive performance, eye movements, and brain function. Leukos2024; 20: 67–106.
14.
ZhaoXHouDLinY, et al. The effect of stroboscopic effect on human health indicators. Lighting Research and Technology2020; 52: 389–406.
15.
KangHLeeCSKimJG, et al. Saccadic eye movement speed is related to variations in phantom array effect visibility. Scientific Reports2023; 13: 11576.
16.
SekulovskiDPerzMVogelsI.Modeling the visibility of the stroboscopic effect. Proceedings of the CIE Symposium on Lighting Quality and Energy Efficiency, 2012: 439–449.
17.
MillerNRodriguez-Feo BermudezEIrvinL, et al. Phantom array and stroboscopic effect visibility under combinations of TLM parameters. Lighting Research and Technology2024; 56: 707–733.
18.
National Electrical Manufacturers Association (NEMA). American National Standard for Lighting Equipment – Temporal Light Artifacts. ANSI C82.77-6-2023. Rosslyn, VA: National Electrical Manufacturers Association, 2023.
19.
SekulovskiDPoortSPerzM, et al. Effects of long-term exposure to stroboscopic effect from moderate-level modulated light. Lighting Research and Technology2020; 52: 775–789.
20.
PerzM.Opinion: Setting the stroboscopic visibility threshold. Lighting Research and Technology2020; 52: 322–322.
21.
Directorate-General for Energy European Commission. 32019R2020 Laying down ecodesign requirements for light sources and separate control gears pursuant to Directive 2009/125/EC of the European Parliament and of the Council and repealing Commission Regulations (EC) No 244/2009, (EC) No 245/2009 and (EU) No2019.
22.
VeitchJAMartinsonsC.Detection of the stroboscopic effect by young adults varying in sensitivity. Lighting Research and Technology2020; 52: 790–810.
23.
WilkinsAJNimmo-SmithISlaterAI, et al. Fluorescent lighting, headaches and eyestrain. Lighting Research and Technology1989; 21: 11–18.
24.
VeitchJAMccollSL.Modulation of fluorescent light: flicker rate and light source effects on visual performance and visual comfort. Lighting Research and Technology1995; 27: 243–256.
25.
JaenMSandovalJColomboE, et al. Office workers visual performance and temporal modulation of fluorescent lighting. Leukos2005; 1: 27–46.
26.
JaénEMColomboEMKirschbaumCF.A simple visual task to assess flicker effects on visual performance. Lighting Research and Technology2011; 43: 457–471.
27.
LaycoxCAThompsonRHaggertyJA, et al. Flicker and reading speed: effects on individuals with visual sensitivity. Perception2024; 53: 512–528.
