Pub Date : 2023-12-23DOI: 10.1177/14771535231212683
M. Figueiro, John D Bullough, A. Thayer, R. Nagare, MS Rea
With the growing interest in designing circadian-effective lighting, it is becoming increasingly important to determine how different lighting designs aimed at supporting circadian entrainment might also affect visual performance, preference, discomfort glare and lighting power density (LPD). These outcome measures were simultaneously examined in a controlled setting at night. Four ceiling lighting configurations, using combinations of direct and indirect lighting, were implemented along with one design that utilised local lighting. Every design delivered the same high level of circadian-effective lighting to participants. Saliva samples were obtained to measure nocturnal melatonin suppression. Two visual performance computer tasks together with subjective assessments of sleepiness, discomfort glare and preference were administered to participants. LPDs were determined. None of the lighting configurations created unacceptable levels of discomfort glare, and only one was above the required maximum allowable LPD. Lighting configuration had no differential effect on nocturnal melatonin suppression, visual performance and sleepiness. While the results show that a wide range of lighting approaches can meet visual, non-visual and energy objectives, the majority of participants preferred the local lighting over the ceiling-mounted lighting.
{"title":"Supporting visual and non-visual lighting design without increasing discomfort glare or lighting power density","authors":"M. Figueiro, John D Bullough, A. Thayer, R. Nagare, MS Rea","doi":"10.1177/14771535231212683","DOIUrl":"https://doi.org/10.1177/14771535231212683","url":null,"abstract":"With the growing interest in designing circadian-effective lighting, it is becoming increasingly important to determine how different lighting designs aimed at supporting circadian entrainment might also affect visual performance, preference, discomfort glare and lighting power density (LPD). These outcome measures were simultaneously examined in a controlled setting at night. Four ceiling lighting configurations, using combinations of direct and indirect lighting, were implemented along with one design that utilised local lighting. Every design delivered the same high level of circadian-effective lighting to participants. Saliva samples were obtained to measure nocturnal melatonin suppression. Two visual performance computer tasks together with subjective assessments of sleepiness, discomfort glare and preference were administered to participants. LPDs were determined. None of the lighting configurations created unacceptable levels of discomfort glare, and only one was above the required maximum allowable LPD. Lighting configuration had no differential effect on nocturnal melatonin suppression, visual performance and sleepiness. While the results show that a wide range of lighting approaches can meet visual, non-visual and energy objectives, the majority of participants preferred the local lighting over the ceiling-mounted lighting.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"200 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139161066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-29DOI: 10.1177/14771535231208933
GM Dotreppe, J. Audenaert, GH Scheir, P. Van Den Bossche, V. Jacobs
The near-field - far-field disparity of light sources leads to discussion within the lighting community. In the far-field, light sources are approximated by a point source with a luminous intensity distribution from which other photometric quantities can be computed. In the near-field, light sources must be considered as extended sources and no closed-loop analytical solutions can be found for the illuminance in off-axis directions. The illuminance allows to compute the apparent intensity used for the assessment of the limiting photometric distance (LPD), that is, the threshold between near- and far-field regions. Numerically, the illuminance can be determined through a discretisation of the luminous surface. This approach is verified for on- and off-axis directions through direct comparison with ray tracing simulations based on near-field goniophotometric measurements. A good match is observed for Lambertian and narrow beam light sources. Using the numerical approach, the LPD in all directions is assessed. For light sources of which the luminous intensity strictly decreases while moving away from the optical axis, the LPD decreases as well until a minimal value is reached. After this, the LPD increases again, in certain scenarios up to values resulting in the invalidity of the inverse square law.
{"title":"Off-axis limiting photometric distance of Lambertians and narrow beams","authors":"GM Dotreppe, J. Audenaert, GH Scheir, P. Van Den Bossche, V. Jacobs","doi":"10.1177/14771535231208933","DOIUrl":"https://doi.org/10.1177/14771535231208933","url":null,"abstract":"The near-field - far-field disparity of light sources leads to discussion within the lighting community. In the far-field, light sources are approximated by a point source with a luminous intensity distribution from which other photometric quantities can be computed. In the near-field, light sources must be considered as extended sources and no closed-loop analytical solutions can be found for the illuminance in off-axis directions. The illuminance allows to compute the apparent intensity used for the assessment of the limiting photometric distance (LPD), that is, the threshold between near- and far-field regions. Numerically, the illuminance can be determined through a discretisation of the luminous surface. This approach is verified for on- and off-axis directions through direct comparison with ray tracing simulations based on near-field goniophotometric measurements. A good match is observed for Lambertian and narrow beam light sources. Using the numerical approach, the LPD in all directions is assessed. For light sources of which the luminous intensity strictly decreases while moving away from the optical axis, the LPD decreases as well until a minimal value is reached. After this, the LPD increases again, in certain scenarios up to values resulting in the invalidity of the inverse square law.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"153 9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139211361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-29DOI: 10.1177/14771535231212404
V. Mantela, R. Nordlund, J. Askola, P. Kärhä, E. Ikonen
Flicker and stroboscopic effects caused by a temporally modulated light source may be harmful for the human visual system. Standardized measurement methods have been developed for the related temporal light artefacts of LED luminaires. It was found out that the performance of the International Electrotechnical Commission (IEC) recommended flickermeter implementation is highly dependent on sampling frequency. Novel digital implementations for the flickermeter and stroboscopic effect visibility measure (SVM) were created to remove any inaccuracies. The performance of the novel Aalto implementations does not depend on the sampling frequency when running the test waveforms of the IEC standard through the implementations. As compared with the IEC recommended digital implementations, Aalto flickermeter decreases the average error related to the test waveforms from −0.05 to +0.003, and Aalto SVM meter also decreases the average error by almost two orders of magnitude.
{"title":"Digital implementations for determination of temporal light artefacts of LED luminaires","authors":"V. Mantela, R. Nordlund, J. Askola, P. Kärhä, E. Ikonen","doi":"10.1177/14771535231212404","DOIUrl":"https://doi.org/10.1177/14771535231212404","url":null,"abstract":"Flicker and stroboscopic effects caused by a temporally modulated light source may be harmful for the human visual system. Standardized measurement methods have been developed for the related temporal light artefacts of LED luminaires. It was found out that the performance of the International Electrotechnical Commission (IEC) recommended flickermeter implementation is highly dependent on sampling frequency. Novel digital implementations for the flickermeter and stroboscopic effect visibility measure (SVM) were created to remove any inaccuracies. The performance of the novel Aalto implementations does not depend on the sampling frequency when running the test waveforms of the IEC standard through the implementations. As compared with the IEC recommended digital implementations, Aalto flickermeter decreases the average error related to the test waveforms from −0.05 to +0.003, and Aalto SVM meter also decreases the average error by almost two orders of magnitude.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139212190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-26DOI: 10.1177/14771535231181502
Y. Zhang, Y. Tu, L. Wang, Y. Shi
Visual fatigue has become a public health issue, while the relevant retinal mechanism and characteristics of blue light that induce visual fatigue have been rarely studied. In the retina, both short wavelength-sensitive (S) cones and melanopsin-containing intrinsically photoreceptive retinal ganglion cells (ipRGCs) are sensitive to blue light, and their responses are opposite in pupil mediation. Thus, effects of blue-enriched white light with different S-cone-opic Equivalent Daylight Illuminance (EDI) on visual fatigue was investigated, maintaining the same melanopic EDI to avoid interferences of melanopsin-containing ipRGCs. Two white illuminants (one with low S-cone-opic EDI, the other with high S-cone-opic EDI) were characterized based on α-opic EDI with the same correlated colour temperature and illuminance. Melanopic EDI was lower than S-cone-opic EDI of these two illuminants. Psychological, visual, physiological and cognitive performances were measured to investigate visual fatigue. Results showed that blue-enriched white light with high S-cone-opic EDI can induce visual fatigue. Participants felt more discomfort in their eyes under high S-cone-opic EDI along with the decline of tear film stability and changes of heart rhythm. Furthermore, the reaction time in a memory task increased significantly under high S-cone-opic EDI. The findings provide new insights into the optimization of indoor lighting environments for human health.
{"title":"Effects of blue-enriched white light with same correlated colour temperature on visual fatigue","authors":"Y. Zhang, Y. Tu, L. Wang, Y. Shi","doi":"10.1177/14771535231181502","DOIUrl":"https://doi.org/10.1177/14771535231181502","url":null,"abstract":"Visual fatigue has become a public health issue, while the relevant retinal mechanism and characteristics of blue light that induce visual fatigue have been rarely studied. In the retina, both short wavelength-sensitive (S) cones and melanopsin-containing intrinsically photoreceptive retinal ganglion cells (ipRGCs) are sensitive to blue light, and their responses are opposite in pupil mediation. Thus, effects of blue-enriched white light with different S-cone-opic Equivalent Daylight Illuminance (EDI) on visual fatigue was investigated, maintaining the same melanopic EDI to avoid interferences of melanopsin-containing ipRGCs. Two white illuminants (one with low S-cone-opic EDI, the other with high S-cone-opic EDI) were characterized based on α-opic EDI with the same correlated colour temperature and illuminance. Melanopic EDI was lower than S-cone-opic EDI of these two illuminants. Psychological, visual, physiological and cognitive performances were measured to investigate visual fatigue. Results showed that blue-enriched white light with high S-cone-opic EDI can induce visual fatigue. Participants felt more discomfort in their eyes under high S-cone-opic EDI along with the decline of tear film stability and changes of heart rhythm. Furthermore, the reaction time in a memory task increased significantly under high S-cone-opic EDI. The findings provide new insights into the optimization of indoor lighting environments for human health.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131275725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-16DOI: 10.1177/14771535231183884
L. Ahamadi, M. Matloobi, A. Motallebi-Azar
Light-emitting diodes (LEDs) offer the potential for physiological control of flowering and vegetative growth of ornamental potted plants such as African violet ( Saintpaulia ionantha Wendl.). In this experiment, we investigated the flowering and vegetative traits of African violet under 6 months of artificial illumination of four different spectra: monochromatic red, monochromatic blue, mixed red 75% plus blue 25%, and fluorescent light under 118 μmol m−2 s−1 ± 6 μmol m−2 s−1 photon flux for 12 h per day. Results showed that the number of days to the open flower stage was significantly influenced by irradiance. Although the blue-illuminated plants appeared to be significantly smaller and compact, they were superior in their most flowering qualities as they induced a pronounced effect on the flowering in terms of earliness, uniformity, consistency, the number of flowers, and the percentage of canopy covered with the flowers. We concluded that LEDs can be used as an effective tool to manipulate plant visual qualities without any further need for the application of conventional plant regulator chemicals, which are mostly identified as hazardous substances.
{"title":"Light source spectrum influences long-term flowering cycles and visual appearance in African violet (Saintpaulia ionantha Wendl.)","authors":"L. Ahamadi, M. Matloobi, A. Motallebi-Azar","doi":"10.1177/14771535231183884","DOIUrl":"https://doi.org/10.1177/14771535231183884","url":null,"abstract":"Light-emitting diodes (LEDs) offer the potential for physiological control of flowering and vegetative growth of ornamental potted plants such as African violet ( Saintpaulia ionantha Wendl.). In this experiment, we investigated the flowering and vegetative traits of African violet under 6 months of artificial illumination of four different spectra: monochromatic red, monochromatic blue, mixed red 75% plus blue 25%, and fluorescent light under 118 μmol m−2 s−1 ± 6 μmol m−2 s−1 photon flux for 12 h per day. Results showed that the number of days to the open flower stage was significantly influenced by irradiance. Although the blue-illuminated plants appeared to be significantly smaller and compact, they were superior in their most flowering qualities as they induced a pronounced effect on the flowering in terms of earliness, uniformity, consistency, the number of flowers, and the percentage of canopy covered with the flowers. We concluded that LEDs can be used as an effective tool to manipulate plant visual qualities without any further need for the application of conventional plant regulator chemicals, which are mostly identified as hazardous substances.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134405412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-25DOI: 10.1177/14771535231172100
J. Mundinger, K. Houser
Museum conservation guidelines restrict illuminance for sensitive artwork to levels that can cause objects to be perceived as less colourful, a phenomenon known as the Hunt effect. Previous colour rendering research identified red saturating gamuts that consistently increased perceived saturation and personal preference. A study was conducted to evaluate the visual experience of fine art illuminated by a red saturating gamut family constrained to be uniquely identified by their TM-30 gamut scores (denoted as [Formula: see text]) and position above or below the blackbody locus ( Duv). [Formula: see text] and Duv were systematically varied according to response surface methodology, designed to map second-order terms and interactions, with 96 ⩽ [Formula: see text] ⩽ 124 and −0.0212 ⩽ Duv ⩽ 0.0036, all at 3000 K and 50 lx. Thirty-one naïve participants each evaluated a pair of paintings in a mock art gallery under nine independently presented scenes along semantic scales corresponding to preference, saturation and naturalness. The study identified a response surface for preference that maps an interaction between [Formula: see text] and Duv, predicting Duv = −0.013 was preferred at [Formula: see text] and Duv = −0.005 was preferred at [Formula: see text]. Increasing [Formula: see text] consistently increased both personal preference and perceived saturation.
{"title":"Fine art under low illuminance: Gamut and tint","authors":"J. Mundinger, K. Houser","doi":"10.1177/14771535231172100","DOIUrl":"https://doi.org/10.1177/14771535231172100","url":null,"abstract":"Museum conservation guidelines restrict illuminance for sensitive artwork to levels that can cause objects to be perceived as less colourful, a phenomenon known as the Hunt effect. Previous colour rendering research identified red saturating gamuts that consistently increased perceived saturation and personal preference. A study was conducted to evaluate the visual experience of fine art illuminated by a red saturating gamut family constrained to be uniquely identified by their TM-30 gamut scores (denoted as [Formula: see text]) and position above or below the blackbody locus ( Duv). [Formula: see text] and Duv were systematically varied according to response surface methodology, designed to map second-order terms and interactions, with 96 ⩽ [Formula: see text] ⩽ 124 and −0.0212 ⩽ Duv ⩽ 0.0036, all at 3000 K and 50 lx. Thirty-one naïve participants each evaluated a pair of paintings in a mock art gallery under nine independently presented scenes along semantic scales corresponding to preference, saturation and naturalness. The study identified a response surface for preference that maps an interaction between [Formula: see text] and Duv, predicting Duv = −0.013 was preferred at [Formula: see text] and Duv = −0.005 was preferred at [Formula: see text]. Increasing [Formula: see text] consistently increased both personal preference and perceived saturation.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125553639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-18DOI: 10.1177/14771535231172085
J. Tan, F. Leon, N. Miller
There are multiple metrics used in research and industry to describe the visibility of temporal light modulation (TLM), colloquially referred to as ‘flicker’. However, the metrics are not straightforward to calculate, and the values sometimes vary according to sampling rates. This work addresses the vagaries in processing TLM waveform data and calculating the metrics. For each TLM metric, its sensitivity to sampling rate is presented, followed by recommendations for improving the reliability and consistency of calculated metrics. Appropriate sampling rates are proposed according to the nature of the waveform and metric. The analyses of this paper are based on ideal waveforms without noise or instability, but the effects of sampling rate also apply to real-world waveforms. Some metrics, such as the Stroboscopic Visibility Measure, were relatively stable (i.e. produced the same value regardless of sampling rate) – within the ranges for which they are defined – for sinusoidal and/or rectangular TLM waveforms. In contrast, short-term flicker indicator [Formula: see text] and perceived modulation [Formula: see text] values exhibited greater variability based on sampling rate. Metric values from sinusoidal waveforms were generally more stable than those from rectangular waveforms, although [Formula: see text] showed inconsistency even with sinusoidal TLM.
{"title":"Temporal light modulation: Data processing and metric calculations","authors":"J. Tan, F. Leon, N. Miller","doi":"10.1177/14771535231172085","DOIUrl":"https://doi.org/10.1177/14771535231172085","url":null,"abstract":"There are multiple metrics used in research and industry to describe the visibility of temporal light modulation (TLM), colloquially referred to as ‘flicker’. However, the metrics are not straightforward to calculate, and the values sometimes vary according to sampling rates. This work addresses the vagaries in processing TLM waveform data and calculating the metrics. For each TLM metric, its sensitivity to sampling rate is presented, followed by recommendations for improving the reliability and consistency of calculated metrics. Appropriate sampling rates are proposed according to the nature of the waveform and metric. The analyses of this paper are based on ideal waveforms without noise or instability, but the effects of sampling rate also apply to real-world waveforms. Some metrics, such as the Stroboscopic Visibility Measure, were relatively stable (i.e. produced the same value regardless of sampling rate) – within the ranges for which they are defined – for sinusoidal and/or rectangular TLM waveforms. In contrast, short-term flicker indicator [Formula: see text] and perceived modulation [Formula: see text] values exhibited greater variability based on sampling rate. Metric values from sinusoidal waveforms were generally more stable than those from rectangular waveforms, although [Formula: see text] showed inconsistency even with sinusoidal TLM.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115042115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-13DOI: 10.1177/14771535231173291
R. Viula, R. Bokel, M. Tenpierik
Daylighting is desirable in classrooms but can pose a challenge to classroom illumination when there is a risk of discomfort from glare from windows and sunlight. There are several metrics in use for the evaluation of discomfort from glare from daylight, but none has yet been validated based on the field-of-view conditions of classrooms. A previous study found that Daylight Glare Probability (DGP) produced a relatively better predictive power of the reported discomfort from glare in a classroom compared to other metrics. However, the metric tended to correlate weakly with the reported glare in positions away from the window light source in a classroom. This prompted the current investigation on the possibility of improving the DGP equation. The modified equation produced a significantly better fit to the subjective glare evaluations from a dataset comprising 184 evaluations from 49 participants collected in a classroom. The results suggest that DGP can be improved to predict the reported discomfort from glare for the conditions of board-based work in a classroom, particularly when a logarithmic form of the adaptation term is integrated in the equation.
{"title":"Prediction of discomfort from glare from daylight in classrooms","authors":"R. Viula, R. Bokel, M. Tenpierik","doi":"10.1177/14771535231173291","DOIUrl":"https://doi.org/10.1177/14771535231173291","url":null,"abstract":"Daylighting is desirable in classrooms but can pose a challenge to classroom illumination when there is a risk of discomfort from glare from windows and sunlight. There are several metrics in use for the evaluation of discomfort from glare from daylight, but none has yet been validated based on the field-of-view conditions of classrooms. A previous study found that Daylight Glare Probability (DGP) produced a relatively better predictive power of the reported discomfort from glare in a classroom compared to other metrics. However, the metric tended to correlate weakly with the reported glare in positions away from the window light source in a classroom. This prompted the current investigation on the possibility of improving the DGP equation. The modified equation produced a significantly better fit to the subjective glare evaluations from a dataset comprising 184 evaluations from 49 participants collected in a classroom. The results suggest that DGP can be improved to predict the reported discomfort from glare for the conditions of board-based work in a classroom, particularly when a logarithmic form of the adaptation term is integrated in the equation.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116001451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-10DOI: 10.1177/14771535231172687
A. Alshdaifat, NH Moadab, S. Fotios
A laboratory experiment was conducted to investigate the alerting effect of light under lighting conditions typical of road lighting. After a 2-h adaptation period, under lighting representing a domestic interior, participants were exposed for a further hour to one of four lighting conditions, with illuminance at the eye and spectral power distribution varied to give a melanopic equivalent daylight illuminance of <0.5 lx to about 10 lx. During this latter phase, half of the participants remained seated, and the other half walked on a treadmill. The dependent variables were reaction time to an acoustic detection task, melatonin levels derived from saliva samples, self-reported sleepiness and skin temperature. The results did not suggest that differences between the four lighting conditions had a significant effect on any of the dependent variables, confirming the results of a previous study conducted on a test track. This suggests that any alerting effect of road lighting is not significant for driving or walking in the evening.
{"title":"The impact of road lighting on road user alertness in the evening","authors":"A. Alshdaifat, NH Moadab, S. Fotios","doi":"10.1177/14771535231172687","DOIUrl":"https://doi.org/10.1177/14771535231172687","url":null,"abstract":"A laboratory experiment was conducted to investigate the alerting effect of light under lighting conditions typical of road lighting. After a 2-h adaptation period, under lighting representing a domestic interior, participants were exposed for a further hour to one of four lighting conditions, with illuminance at the eye and spectral power distribution varied to give a melanopic equivalent daylight illuminance of <0.5 lx to about 10 lx. During this latter phase, half of the participants remained seated, and the other half walked on a treadmill. The dependent variables were reaction time to an acoustic detection task, melatonin levels derived from saliva samples, self-reported sleepiness and skin temperature. The results did not suggest that differences between the four lighting conditions had a significant effect on any of the dependent variables, confirming the results of a previous study conducted on a test track. This suggests that any alerting effect of road lighting is not significant for driving or walking in the evening.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127856518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-08DOI: 10.1177/14771535231169904
N. Miller, E. Rodriguez-Feo Bermudez, L. Irvin, J. Tan
Solid-state light sources can be more prone to larger temporal light modulation (TLM) than conventional sources. TLM visibility depends on wave shape, frequency, modulation depth and duty cycle, and is affected by the sensitivity of the observer. TLM can be visible well above the critical flicker fusion frequency, when there is relative movement between the observer’s eyes and light source, lighted space or moving objects in the field of view. This human subjects experiment explored visibility of the stroboscopic effect (SE) versus the phantom array effect (PAE) with targeted tasks under 74 TLM waveforms. The results showed the SE visibility peaks between 90 Hz and 120 Hz, while the PAE visibility peaks between 500 Hz and 1000 Hz. The phantom array is visible to sensitive participants at 6000 Hz. Both effects are more visible under rectangular versus sinusoidal TLM, higher modulation, and when duty cycles are 10% or 30% versus 50%. Higher sensitivity participants, differentiated using the Leiden Visual Sensitivity Scale, rated TLM waveforms as more visible, especially those inherently harder to see. This work lays a foundation for a PAE metric and guides driver and dimmer designers toward electronic circuits that minimize the visibility of TLM in LED products.
{"title":"Phantom array and stroboscopic effect visibility under combinations of TLM parameters","authors":"N. Miller, E. Rodriguez-Feo Bermudez, L. Irvin, J. Tan","doi":"10.1177/14771535231169904","DOIUrl":"https://doi.org/10.1177/14771535231169904","url":null,"abstract":"Solid-state light sources can be more prone to larger temporal light modulation (TLM) than conventional sources. TLM visibility depends on wave shape, frequency, modulation depth and duty cycle, and is affected by the sensitivity of the observer. TLM can be visible well above the critical flicker fusion frequency, when there is relative movement between the observer’s eyes and light source, lighted space or moving objects in the field of view. This human subjects experiment explored visibility of the stroboscopic effect (SE) versus the phantom array effect (PAE) with targeted tasks under 74 TLM waveforms. The results showed the SE visibility peaks between 90 Hz and 120 Hz, while the PAE visibility peaks between 500 Hz and 1000 Hz. The phantom array is visible to sensitive participants at 6000 Hz. Both effects are more visible under rectangular versus sinusoidal TLM, higher modulation, and when duty cycles are 10% or 30% versus 50%. Higher sensitivity participants, differentiated using the Leiden Visual Sensitivity Scale, rated TLM waveforms as more visible, especially those inherently harder to see. This work lays a foundation for a PAE metric and guides driver and dimmer designers toward electronic circuits that minimize the visibility of TLM in LED products.","PeriodicalId":269493,"journal":{"name":"Lighting Research & Technology","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126089148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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