Pub Date : 2022-01-22DOI: 10.1177/14771535211046521
L. Zaniboni, M. Sarey Khanie, G. Pernigotto, J. Toftum, A. Gasparella, B. Olesen
Visual comfort plays a central role in building occupants’ comfort, well-being and productivity. It is therefore fundamental to meet the occupants’ visual and lighting needs, carefully accounting for the room layout, usage and activities. In this framework, physiotherapy centres constitute a peculiar case since they are occupied by therapists and patients from different age groups, engaged in various activities performed in different positions in the rooms, and affected by different health issues. Lighting quality and satisfaction were monitored in four physiotherapy centres in Northern Italy and Denmark. Subjective assessments were compared with objective illuminance measurements at the task areas, and the sites were also analysed in terms of window and architectural features. Moreover, the interaction between visual and other environmental perceptions was studied. The results revealed: (1) positive influence of daylight access on the satisfaction of occupants; (2) occupants’ complaints about low lighting levels associated with artificial lighting being unable to provide 300 lx and natural light not balancing this lack of illumination; and (3) lower satisfaction among therapists, who also showed the tendency to assess their environmental perception more globally, since correlations between light and daylight satisfaction and other stimuli were observed when comfort issues were present.
{"title":"Lighting conditions in physiotherapy centres: A comparative field study","authors":"L. Zaniboni, M. Sarey Khanie, G. Pernigotto, J. Toftum, A. Gasparella, B. Olesen","doi":"10.1177/14771535211046521","DOIUrl":"https://doi.org/10.1177/14771535211046521","url":null,"abstract":"Visual comfort plays a central role in building occupants’ comfort, well-being and productivity. It is therefore fundamental to meet the occupants’ visual and lighting needs, carefully accounting for the room layout, usage and activities. In this framework, physiotherapy centres constitute a peculiar case since they are occupied by therapists and patients from different age groups, engaged in various activities performed in different positions in the rooms, and affected by different health issues. Lighting quality and satisfaction were monitored in four physiotherapy centres in Northern Italy and Denmark. Subjective assessments were compared with objective illuminance measurements at the task areas, and the sites were also analysed in terms of window and architectural features. Moreover, the interaction between visual and other environmental perceptions was studied. The results revealed: (1) positive influence of daylight access on the satisfaction of occupants; (2) occupants’ complaints about low lighting levels associated with artificial lighting being unable to provide 300 lx and natural light not balancing this lack of illumination; and (3) lower satisfaction among therapists, who also showed the tendency to assess their environmental perception more globally, since correlations between light and daylight satisfaction and other stimuli were observed when comfort issues were present.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":"331 1","pages":"377 - 408"},"PeriodicalIF":2.5,"publicationDate":"2022-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74078475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-03DOI: 10.1177/14771535211071133
K. S. Hickcox, S. Fotios, B. Abboushi, Naomi J Miller
While the de Boer scale is widely used to measure discomfort from glare, commonly in studies of pedestrian-scale outdoor lighting, its design has several problems that lead to noise in the data and in turn to continued disagreement about the prediction of discomfort. The de Boer scale is a 9-point categorical scale in which the odd numbered categories are labelled with magnitude descriptors (Figure 1). Problems with the scale include uncertainty about what the magnitude descriptors mean, inconsistent labelling of discomfort magnitudes between studies, in some versions it is not possible to respond that there is no discomfort, the anomaly that the higher number (9) is the lower degree of discomfort, and that it is uncertain where lies the borderline between comfort and discomfort (BCD). Note, for example, that while Schmidt-Clausen and Bindels cited de Boer and Schreuder as a source for their scale (Figure 1) the labels of points 7 and 9 were satisfactory and unnoticeable in that source. We propose here an alternative approach for rating discomfort from glare (Figure 2), as developed through discussions in the IESNA technical committee Discomfort Glare in Outdoor Nighttime Environments, and at the workshop on methods for measuring discomfort from glare at the CIE 2021 midterm conference. This is a twostep procedure. First, the subject is asked, “While viewing the scene as instructed, are you experiencing discomfort from glare?” with the response options being ‘Yes’ or ‘No’. This provides a participant with an equal opportunity to respond that discomfort is or is not being experienced. If the response to this first step is ‘Yes’, then the second step is to evaluate the degree of discomfort using a 6-point scale. In this scale, only the end points are labelled, with descriptors intended to be less ambiguous than those of the de Boer scale, and in which the higher number (6) corresponds to higher amount of discomfort. The two steps allow two approaches for analysing discomfort: the percentage of responses indicating that glare was experienced, and the mean rating for the second part. The two steps further allow analysis of the percentage of people expressing discomfort as a means of estimating the BCD. We offer this proposal in the hope that other researchers will consider using it, either as the main evaluation scale or in parallel with a researcher’s preferred scale. We do not propose that this will solve ongoing issues in the evaluation of discomfort from glare, but that it is an attempt to reduce the noise in responses. We do not propose that the scale originally devised by de Boer was incorrect, but that time and language translation Figure 1 Example of a 9-point scale used for evaluation of discomfort from glare. This version was used in the study by Schmidt-Clausen and Bindels
{"title":"Correspondence: A new two-step approach for evaluating discomfort from glare","authors":"K. S. Hickcox, S. Fotios, B. Abboushi, Naomi J Miller","doi":"10.1177/14771535211071133","DOIUrl":"https://doi.org/10.1177/14771535211071133","url":null,"abstract":"While the de Boer scale is widely used to measure discomfort from glare, commonly in studies of pedestrian-scale outdoor lighting, its design has several problems that lead to noise in the data and in turn to continued disagreement about the prediction of discomfort. The de Boer scale is a 9-point categorical scale in which the odd numbered categories are labelled with magnitude descriptors (Figure 1). Problems with the scale include uncertainty about what the magnitude descriptors mean, inconsistent labelling of discomfort magnitudes between studies, in some versions it is not possible to respond that there is no discomfort, the anomaly that the higher number (9) is the lower degree of discomfort, and that it is uncertain where lies the borderline between comfort and discomfort (BCD). Note, for example, that while Schmidt-Clausen and Bindels cited de Boer and Schreuder as a source for their scale (Figure 1) the labels of points 7 and 9 were satisfactory and unnoticeable in that source. We propose here an alternative approach for rating discomfort from glare (Figure 2), as developed through discussions in the IESNA technical committee Discomfort Glare in Outdoor Nighttime Environments, and at the workshop on methods for measuring discomfort from glare at the CIE 2021 midterm conference. This is a twostep procedure. First, the subject is asked, “While viewing the scene as instructed, are you experiencing discomfort from glare?” with the response options being ‘Yes’ or ‘No’. This provides a participant with an equal opportunity to respond that discomfort is or is not being experienced. If the response to this first step is ‘Yes’, then the second step is to evaluate the degree of discomfort using a 6-point scale. In this scale, only the end points are labelled, with descriptors intended to be less ambiguous than those of the de Boer scale, and in which the higher number (6) corresponds to higher amount of discomfort. The two steps allow two approaches for analysing discomfort: the percentage of responses indicating that glare was experienced, and the mean rating for the second part. The two steps further allow analysis of the percentage of people expressing discomfort as a means of estimating the BCD. We offer this proposal in the hope that other researchers will consider using it, either as the main evaluation scale or in parallel with a researcher’s preferred scale. We do not propose that this will solve ongoing issues in the evaluation of discomfort from glare, but that it is an attempt to reduce the noise in responses. We do not propose that the scale originally devised by de Boer was incorrect, but that time and language translation Figure 1 Example of a 9-point scale used for evaluation of discomfort from glare. This version was used in the study by Schmidt-Clausen and Bindels","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":"33 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2022-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85106806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-03DOI: 10.1177/14771535211051564
Z. Li, F. Zhang, X. Song, R. Dang
Spectral energy radiated by light sources is the primary source of colour damage in highly photosensitive artworks (HPAs). However, spectral power distributions differ for different light sources, and the absorption and reflection characteristics of different materials, when irradiated by each narrow spectral energy band, also differ. This could result in large differences in the degree of radiation damage for materials under the same lighting intensity. In this paper, the suitability of different light sources used to illuminate HPAs was experimentally investigated over a long period of time by irradiating nine types of typical HPA materials with 10 different narrow-band light sources. By analysing the colour difference data of the illuminated material against the amount of exposure, a mathematical model relating the spectral composition and the damage to the colour of HPA materials was obtained. Based on this, a colour damage evaluation equation for light sources used for lighting HPAs was proposed. Finally, the equations were discussed using an example.
{"title":"Evaluation methodology for light sources used to illuminate highly photosensitive artwork","authors":"Z. Li, F. Zhang, X. Song, R. Dang","doi":"10.1177/14771535211051564","DOIUrl":"https://doi.org/10.1177/14771535211051564","url":null,"abstract":"Spectral energy radiated by light sources is the primary source of colour damage in highly photosensitive artworks (HPAs). However, spectral power distributions differ for different light sources, and the absorption and reflection characteristics of different materials, when irradiated by each narrow spectral energy band, also differ. This could result in large differences in the degree of radiation damage for materials under the same lighting intensity. In this paper, the suitability of different light sources used to illuminate HPAs was experimentally investigated over a long period of time by irradiating nine types of typical HPA materials with 10 different narrow-band light sources. By analysing the colour difference data of the illuminated material against the amount of exposure, a mathematical model relating the spectral composition and the damage to the colour of HPA materials was obtained. Based on this, a colour damage evaluation equation for light sources used for lighting HPAs was proposed. Finally, the equations were discussed using an example.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":"37 1","pages":"529 - 545"},"PeriodicalIF":2.5,"publicationDate":"2022-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89646611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1177/14771535211071134
P. Boyce
It is frequently claimed that appropriate lighting can improve the wellbeing of people and change their mood. Such claims should be treated with caution, not because such effects do not occur but rather because such effects are matters of probability rather than certainty. There are three factors that contribute to the uncertainty. The first is simply a matter of definition. The Oxford Dictionary defines wellbeing as being healthy, happy or prosperous. This definition is so wide as to be useless for the identification of lighting effects. There is hardly any aspect of life that cannot contribute to an individual’s wellbeing, positively or negatively. With such a capacious definition it would be a miracle if the visual environment could not be shown to affect wellbeing so something more specific is required to be sure of any claimed effect. Mood is somewhat more closely defined as the way you are feeling at a particular time. This implies mood is a transient state of human emotion. Lighting can certainly influence mood. The second is the possibility of interference from aspects of life other than the visual environment. For example, a restaurant that is attractively lit for a romantic evening will not contribute to a positive mood if the couple cannot hear each other’s endearments. And it is not just the physical environment that matters. There is also the influence of human interaction. Entering a room filled with people one dislikes is likely to darken one’s mood, regardless of the way the room is lit. Mood is inherently labile. About the only situation when lighting can reliably change mood is when it causes visual discomfort. Then the salience of lighting increases and the probability of a negative effect on mood increases. However, very few lighting designers set out to cause visual discomfort. Claims of lighting’s beneficial effects onmood are generally framed in positive terms and it is these positive effects that are subject to interference. The third is the duration of the effect. The positive impact of lighting on mood is likely to be greatest for people unfamiliar with the installation, but how long will that effect be sustained. Familiarity is likely to reduce the impact of the lighting on mood, without any interference from other factors. Therefore, when considering claims of lighting enhancing wellbeing and mood, it is necessary to ask a number of questions. What is meant by wellbeing?What facets of mood are desired?Was mood only affected by the lighting in closely controlled laboratory conditions? How likely are these to occur in the real world? How will the lit space be used? Will people be familiar with the space? And so on. The main point to remember is that the further the outcome is from the operation of the visual system, the more likely it is other non-visual factors will interfere, or, to paraphrase the poet John Clare, the closer to the fountain, the purer runs the stream.
{"title":"Opinion: Wellbeing, mood and uncertainty","authors":"P. Boyce","doi":"10.1177/14771535211071134","DOIUrl":"https://doi.org/10.1177/14771535211071134","url":null,"abstract":"It is frequently claimed that appropriate lighting can improve the wellbeing of people and change their mood. Such claims should be treated with caution, not because such effects do not occur but rather because such effects are matters of probability rather than certainty. There are three factors that contribute to the uncertainty. The first is simply a matter of definition. The Oxford Dictionary defines wellbeing as being healthy, happy or prosperous. This definition is so wide as to be useless for the identification of lighting effects. There is hardly any aspect of life that cannot contribute to an individual’s wellbeing, positively or negatively. With such a capacious definition it would be a miracle if the visual environment could not be shown to affect wellbeing so something more specific is required to be sure of any claimed effect. Mood is somewhat more closely defined as the way you are feeling at a particular time. This implies mood is a transient state of human emotion. Lighting can certainly influence mood. The second is the possibility of interference from aspects of life other than the visual environment. For example, a restaurant that is attractively lit for a romantic evening will not contribute to a positive mood if the couple cannot hear each other’s endearments. And it is not just the physical environment that matters. There is also the influence of human interaction. Entering a room filled with people one dislikes is likely to darken one’s mood, regardless of the way the room is lit. Mood is inherently labile. About the only situation when lighting can reliably change mood is when it causes visual discomfort. Then the salience of lighting increases and the probability of a negative effect on mood increases. However, very few lighting designers set out to cause visual discomfort. Claims of lighting’s beneficial effects onmood are generally framed in positive terms and it is these positive effects that are subject to interference. The third is the duration of the effect. The positive impact of lighting on mood is likely to be greatest for people unfamiliar with the installation, but how long will that effect be sustained. Familiarity is likely to reduce the impact of the lighting on mood, without any interference from other factors. Therefore, when considering claims of lighting enhancing wellbeing and mood, it is necessary to ask a number of questions. What is meant by wellbeing?What facets of mood are desired?Was mood only affected by the lighting in closely controlled laboratory conditions? How likely are these to occur in the real world? How will the lit space be used? Will people be familiar with the space? And so on. The main point to remember is that the further the outcome is from the operation of the visual system, the more likely it is other non-visual factors will interfere, or, to paraphrase the poet John Clare, the closer to the fountain, the purer runs the stream.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":"12 1","pages":"4 - 4"},"PeriodicalIF":2.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72884858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1177/14771535211070917
{"title":"Corrigendum to Virtual reality in lighting research: Comparing physical and virtual lighting environments","authors":"","doi":"10.1177/14771535211070917","DOIUrl":"https://doi.org/10.1177/14771535211070917","url":null,"abstract":"","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":"52 1","pages":"93 - 93"},"PeriodicalIF":2.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79925289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-01DOI: 10.1177/14771535211070926
{"title":"Erratum to How can electric lighting contribute to human health and well-being?","authors":"","doi":"10.1177/14771535211070926","DOIUrl":"https://doi.org/10.1177/14771535211070926","url":null,"abstract":"","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":"432 1","pages":"95 - 95"},"PeriodicalIF":2.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77034382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-27DOI: 10.1177/14771535211058096
A. Eissfeldt, TQ Khanh
Multichannel LED luminaires with more than three channels offer the advantage to vary the spectrum and keeping the chromaticity steady. However, the optimisation calculations of various quality metrics are a challenge for real-time implementation, especially for the limited resources of a luminaire’s microcontroller. Here, we present a method in which a five-channel system is simulated with a quickly solvable 3-channel system by defining virtual channels, each consisting of two LED channels. An analysis of the influence of the parameterisation of the virtual valences on various quality metrics is presented. It shows how these parameters must be set at the time of the mixing calculation, in order to optimise the desired quality aspect. The mixing calculation can thus be carried out in real-time without high hardware requirements and is suitable for further developments, for example, to compensate for colour drift of the LEDs through sensor feedback.
{"title":"Algorithm for real-time colour mixing of a five-channel LED system while optimising spectral quality parameters","authors":"A. Eissfeldt, TQ Khanh","doi":"10.1177/14771535211058096","DOIUrl":"https://doi.org/10.1177/14771535211058096","url":null,"abstract":"Multichannel LED luminaires with more than three channels offer the advantage to vary the spectrum and keeping the chromaticity steady. However, the optimisation calculations of various quality metrics are a challenge for real-time implementation, especially for the limited resources of a luminaire’s microcontroller. Here, we present a method in which a five-channel system is simulated with a quickly solvable 3-channel system by defining virtual channels, each consisting of two LED channels. An analysis of the influence of the parameterisation of the virtual valences on various quality metrics is presented. It shows how these parameters must be set at the time of the mixing calculation, in order to optimise the desired quality aspect. The mixing calculation can thus be carried out in real-time without high hardware requirements and is suitable for further developments, for example, to compensate for colour drift of the LEDs through sensor feedback.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":"120 1","pages":"563 - 575"},"PeriodicalIF":2.5,"publicationDate":"2021-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85248616","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-27DOI: 10.1177/14771535211047220
MG Kent, J. Jakubiec
This article discusses ratings of visual discomfort from glare across different buildings located in Singapore. These data were used to determine if range effects influence the vertical illuminance values for the same ratings of visual discomfort when the category rating procedure is used. The effect occurs when maxima and minima vertical illuminance (i.e. the range) vary across buildings. Our analyses showed that with a higher vertical illuminance range in a building, the mean vertical illuminance value for the same criterion of visual discomfort also increased. The results suggest that the effect caused by different ranges of measured vertical illuminance present across the buildings biased the ratings of visual discomfort. Although these effects may be unavoidable in some buildings that have vastly different levels of light, the data suggest that the overall range of vertical illuminance must be carefully evaluated when predicting visual discomfort. Matching these conditions may enable vertical illuminance to provide more reliable evaluations of discomfort due to glare.
{"title":"An examination of range effects when evaluating discomfort due to glare in Singaporean buildings","authors":"MG Kent, J. Jakubiec","doi":"10.1177/14771535211047220","DOIUrl":"https://doi.org/10.1177/14771535211047220","url":null,"abstract":"This article discusses ratings of visual discomfort from glare across different buildings located in Singapore. These data were used to determine if range effects influence the vertical illuminance values for the same ratings of visual discomfort when the category rating procedure is used. The effect occurs when maxima and minima vertical illuminance (i.e. the range) vary across buildings. Our analyses showed that with a higher vertical illuminance range in a building, the mean vertical illuminance value for the same criterion of visual discomfort also increased. The results suggest that the effect caused by different ranges of measured vertical illuminance present across the buildings biased the ratings of visual discomfort. Although these effects may be unavoidable in some buildings that have vastly different levels of light, the data suggest that the overall range of vertical illuminance must be carefully evaluated when predicting visual discomfort. Matching these conditions may enable vertical illuminance to provide more reliable evaluations of discomfort due to glare.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":"44 1","pages":"514 - 528"},"PeriodicalIF":2.5,"publicationDate":"2021-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88285757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-09DOI: 10.1177/14771535211052451
DT Vu, H. Vu, S. Shin, NM Kieu, TQ Tien, NH Vu
We introduce a compact lenslet array principle that takes advantage of freeform optics to deploy a light distributor, beneficial for highly efficient, inexpensive, low energy consumption light-emitting diode (LED) lighting system. We outline here a simple strategy for designing the freeform lens that makes use of an array of the identical plano-convex lenslet. The light is redistributed from such lenslet, hinging on the principle of optical path length conservation, and then delivered to the receiver plane. The superimposing of such illumination area from every lenslet occurs on the receiver plane, in which the non-uniform illumination area located in the boundary should have the same dimension as the size of the freeform lenslet array. Such an area, insofar, is negligible due to their small size, which is the crux of our design, representing a large departure from the former implementations. Based on simulations that assess light performance, the proposed design exhibited the compatibility for multiple radiation geometries and off-axis lighting without concern for the initial radiation pattern of the source. As simulated, the LED light source integrated with such proposed freeform lenslet array revealed high luminous efficiency and uniformity within the illumination area of interest were above 70% and 85%, respectively. Such novel design was then experimentally demonstrated to possess a uniformity of 75% at hand, which was close to the simulation results. Also, proposed indoor lighting was implemented in comparison with the commercial LED downlight and LED panel, whereby the energy consumption, number of luminaires and illumination performance were assessed to show the advantage of our simplified model.
{"title":"A simple design of uniform LED illumination using catadioptric collimator and freeform lenslet array","authors":"DT Vu, H. Vu, S. Shin, NM Kieu, TQ Tien, NH Vu","doi":"10.1177/14771535211052451","DOIUrl":"https://doi.org/10.1177/14771535211052451","url":null,"abstract":"We introduce a compact lenslet array principle that takes advantage of freeform optics to deploy a light distributor, beneficial for highly efficient, inexpensive, low energy consumption light-emitting diode (LED) lighting system. We outline here a simple strategy for designing the freeform lens that makes use of an array of the identical plano-convex lenslet. The light is redistributed from such lenslet, hinging on the principle of optical path length conservation, and then delivered to the receiver plane. The superimposing of such illumination area from every lenslet occurs on the receiver plane, in which the non-uniform illumination area located in the boundary should have the same dimension as the size of the freeform lenslet array. Such an area, insofar, is negligible due to their small size, which is the crux of our design, representing a large departure from the former implementations. Based on simulations that assess light performance, the proposed design exhibited the compatibility for multiple radiation geometries and off-axis lighting without concern for the initial radiation pattern of the source. As simulated, the LED light source integrated with such proposed freeform lenslet array revealed high luminous efficiency and uniformity within the illumination area of interest were above 70% and 85%, respectively. Such novel design was then experimentally demonstrated to possess a uniformity of 75% at hand, which was close to the simulation results. Also, proposed indoor lighting was implemented in comparison with the commercial LED downlight and LED panel, whereby the energy consumption, number of luminaires and illumination performance were assessed to show the advantage of our simplified model.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":"44 1","pages":"546 - 562"},"PeriodicalIF":2.5,"publicationDate":"2021-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86842853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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