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For the laser-driven lighting, traditional phosphor ceramics (PCs), such as Y 3 Al 5 O 12 : Ce3+ (YAG: Ce) PC and Lu 3 Al 5 O 12 : Ce3+ (LuAG: Ce) PC, usually show a wide "cyan cavity" due to the ultra-narrow emission bandwidth (∼2 nm) of the blue laser diode (LD). In this regard, the attainable color rendering (Ra) is always <90 even via the combination of "YAG: Ce/LuAG: Ce + CaAlSiN 3 :Eu2+". Evidently, the "cyan gap" is the bottleneck issue to attain high-color-quality laser-driven lighting. As such, we develop a novel cyan-green-emitting garnet-structured solid-solution Lu 3- x Sc x Al 2- y Sc y Al 3- z Sc z O 12 : Ce3+ (abbreviated as LuScAG: Ce) PCs, derived from the LuAG: Ce PC. A comparative study is conducted to unearth its microstructure, luminescence properties and promising availability. It can be found that the LuScAG: Ce PCs shows large full width at half maximum (FWHM) and abundant cyan emission. Upon material optimization, bright cyan-green emission can be generated with internal quantum efficiency (IQE) of 87.4 % and FWHM of 87.17 nm. Remarkably, this new material yields high-power emitting light with luminous flux (LF) of 3230 lm and luminous efficacy (LE) of 89.7 lm/W upon 36.0 W blue LD driven in rotatory excitation mode, which can serve as an efficient laser color converter. As expected, due to the achieved affluent cyan emissive components of developed LuScAG: Ce PCs, the lighting source based on "LuScAG: Ce PC + CASN: Eu phosphor-in-glass film (PiGF)" shows high color quality with Ra of 90.6 and R12 (related with the cyan cavity) of 85.0. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to evaluate illumination properties in an in-vitro kidney calyx model in saline. Design and methods: We evaluated a series of contemporary flexible ureteroscopes including the Storz Flex-Xc and Flex-X2s, Olympus V3 and P7, Pusen 7.5F and 9.2F, as well as OTU WiScope using a 3D-printed closed pink kidney calyx model, submerged in saline. A spectrometer was used for illuminance and color temperature measurements at different openings located at center (direct light), 45° (direct and indirect light) and 90°(indirect light) to the axis of the scope. Results: Maximum illuminance was at the center opening for all scopes (range: 284 to 12,058 lx at 50% brightness and 454 to 11,871 lx at 100% brightness settings). The scope with the highest center illuminance (Flex-Xc) was 26 times superior to the scope with the lowest illuminance (Pusen 7.5Fr) at 100% brightness setting. For each scope, there was a peripheral illuminance drop ranging from − 43 to − 92% at 50% brightness and − 43% to − 88% at 100% brightness settings, respectively (all p < 0.01). Highest drop was for the P7 and the Pusen 9.2F. All scopes had illuminance skew, except the V3. All scopes had a warm color temperature. Conclusion: Illumination properties vary between ureteroscopes in an enclosed cavity in saline, and differs at center vs 45° and 90° positions within scopes. Peripheral illuminance drop can be as high as − 92%, which is undesirable. This may affect the choice of ureteroscope and light brightness settings used in surgery by urologists. [ABSTRACT FROM AUTHOR]

Display technologies have been developed to adjust the display brightness and color under different viewing conditions, providing better viewing experiences to users. Solutions have been proposed to adjust the display white point according to the ambient light condition, which roots into the underlying chromatic adaptation mechanism in the human visual system. This study was carefully designed to reveal the necessity to consider the ambient light level and display luminance together, which affects the viewing mode, when adjusting the adaptive display white point. The results clearly suggested that when the display luminance was greater than the ambient light diffuse white luminance, the display was viewed in the self‐luminous mode and the display white point was not significantly affected by the ambient light chromaticities. In contrast, when the display luminance was lower than the ambient light diffuse white luminance, the display was viewed in the surface mode and the ambient light chromaticities had a significant effect on the display white point, especially when the surround ratio was high. Adaptive display shifts the display white point and other colors accordingly based on the ambient conditions. In addition to the ambient light color, it needs to consider the ambient light illuminance and also the relationship between ambient light illuminance and display luminance. [ABSTRACT FROM AUTHOR]

After dark, pedestrians may experience discomfort from glare caused by outdoor lighting. While several models for measuring discomfort have been proposed, there is no consensus as to which model should be used. The performances of different models were investigated using datasets from four independent studies, comparing the degree of association between model predictions and subjective ratings, and the ability of a model to distinguish between discomfort and non-discomfort situations. The models tested are those proposed by Petherbridge and Hopkinson in 1950, Schmidt-Clausen and Bindels in 1974, Bullough et al. in 2008 and Lin et al. in 2014 and 2015. They also include two quantities: direct illuminance at the eye from the glare source and average source luminance. Of the models tested, the best performance was found using either the model proposed by Bullough et al. in 2008 or by direct illuminance at the eye. [ABSTRACT FROM AUTHOR]

The optimal illuminance from road lighting for pedestrian reassurance after dark is that beyond which further increase in illuminance has no significant effect on reassurance. Previous studies have not revealed a precise estimate of optimal illuminance. The current study investigates the use of segmented regression for defining optimal illuminance, applied to 25 662 reassurance evaluations by 380 test participants who recorded their reassurance assessments in 253 locations in three cities in Israel. Segmented regression led to models which better fit the empirical data than their unsegmented counterparts and offered precise estimates of optimal illuminance, these ranging from 8.9 lx to 26 lx, depending on location. [ABSTRACT FROM AUTHOR]

This paper conducts a comprehensive analysis of the light environment in different areas of residential houses located in Beijing's Guangyuanli neighborhood. The main objective of this study is to assess the contribution of natural daylight to residential illuminance, with the aim of providing a foundation for reducing energy consumption and enhancing light comfort. While previous research predominantly focused on sensor deployment in single scenes such as offices and classrooms, these approaches are inadequate for multi-scene analysis of daylight in residential areas. Moreover, traditional deployment methods can negatively impact the quality of life and everyday living experience. To overcome these limitations, a prediction model is developed to estimate ceiling and window illuminance, as well as work surface illuminance in various scenes within residential buildings. The Dialux software is employed for data simulation, and a GA-optimized BP neural network is utilized to train the model, establishing the mapping relationship between input variables and corresponding illuminance outputs. By inputting sensor values from different scenarios into the model, the predicted daylight illuminance values can be obtained. This predictive approach facilitates the evaluation of light comfort and energy consumption reduction in different functional areas of residential buildings. [ABSTRACT FROM AUTHOR]

We produce the green phosphor Ca14-xEuxMg2[SiO4]8 (CEMSO) to be a part of the white light emitting diodes (WLEDs), short for diodes that generate white illumination. It has wide emission spectra, reaching highest value as 505 nm when excited at the wavelength of 400 nm, which is caused by the 4f 65d-4f 7 shift (excited state to ground state) in an ion of Eu2+. The dipoledipole interactivity appeared to be main energy shift method for the electric multipolar nature in CEMSO. We determine the critical distance to be 12.9 Å as well as 14.9 Å via a critical Eu2+ concentration and theory of Dexter regarding the energy shift. The CEMSO is integrated into the phosphor compound of yellow-phosphor/silicone for producing the UV-LED (395 nm). The impacts of CEMSO concentrations on UV-LED performances are determined. Significant improvements in chromatic uniformity and luminous output of the WLED are reported. The color rendering index (CRI) is not promoted, but this can be addressed by combining CEMSO green phosphor with red-luminescence materials, for example, red quantum dots or red phosphors. [ABSTRACT FROM AUTHOR]

A new phosphor-in-glass film (PiGF) color converter with high heat dissipation capability was proposed for high-power laser illumination. To intensify heat conduction, a composite structure was fabricated by welding the PiGF to a copper block through a silver layer. The PiGF converter was found to have a high quantum yield and similar fluorescence lifetime as the original phosphors. The optical characteristics of this material were investigated by varying the thickness of PiGF and the lase power. Under the excitation of 8.78W laser power, the PiGF converter with 100 μm film thickness enables a luminous efficacy of 187.9 lm/W, a CCT of 6150 K, and a perfect chromaticity coordinate of (0.3174, 0.3351). In addition, a maximum luminous flux of 4449 lm was obtained when the laser power reached 27.42 W. Besides, The PiGF converter displayed low working temperature and stable optical performance under the sustained excitation test, which indicates that the PiGF converter exhibits excellent opto-thermal performances. In general, an effective solution is put forward for the heat dissipating obstacle of laser lighting. [ABSTRACT FROM AUTHOR]

(Y 1-x-y Ho x Yb y)OF/polyacrylonitrile (YOF-H u Y v /PAN) composite fibers prepared by electrostatic spinning have been demonstrated to possess effective upconversion (UC) luminescence and sensitive temperature feedback properties for laser display and real-time temperature monitoring in complex environments. When the excitation power density is increased to 73 mW/mm2, the total luminous flux reaches 3.35 mlm, demonstrating that the Ho3+/Yb3+ co-doped YOF nanocrystals embedded in the composite fibers are efficient luminous materials. The quantum yields (QYs) of green and red emissions from Ho3+ are derived to be 2.97 × 10−5 and 1.40 × 10−5 respectively when the pump power density arrives at 73 mW/mm2 under 977 nm laser, and the high photon generation efficiency ensures sufficient fluorescence intensity for tracing temperature feedback. The maximum relative sensitivities appear at 303 K, while the absolute sensitivity (S A) and relative sensitivity (S R) of the nanofibers retain 13.77% K−1 and 0.34% K−1 at 433 K respectively, demonstrating that the nanofibers have superior optical temperature sensing properties. The composite fibers with effective luminescence and high temperature sensitivity as luminescent materials provide a potential option for the field of laser display and temperature sensing. YOF-HY/PAN flexible nanofibers with effective luminescence and real-time temperature monitoring provide a new attempt in the field of non-contact temperature sensing. [Display omitted] • YOF-Ho/Yb nanocrystals have quantum yields on the order of 10−5 for laser display. • UC luminous flux is identified as 3.35 mlm under 977 nm laser with 73 mW/mm2. • Low signal background and high thermal sensitivity are achieved in flexible fiber. • Non-thermal coupled energy levels of Ho3+ are applied for temperature sensing. • Composite fiber provides a feasible strategy for extending the application scenes. [ABSTRACT FROM AUTHOR]

All-inorganic phosphor-in-glass (PiG) converter withstanding high power laser excitation has garnered attention for laser-driven white lighting, while its poor heat dissipation and low fluorescence conversion efficiency has been serious challenges in high-brightness white lighting. Herein, a thermally robust PiG film converter with a sandwich phosphor structure and microstructure interface was designed for ultrahigh-brightness laser-driven white lighting. The yellow-emitting YAG PiG film was thermocompression bonded to microstructure sapphire (MS) and planar alumina (PA) to construct the MS-PiG-PA converter. The YAG PiG film possess higher luminescence intensity than YAG phosphor and was tightly attached to sapphire and alumina without microcracks. Benefiting from the double-sided heat dissipation design and microstructure interface light field strengthening effect, the MS-PiG-PA converter emits ultrahigh luminous flux white light (5197 lm) at power density of 30 W/mm2 and displays excellent CRI and CCT stability. The MS-PiG-PA converter has a lower working temperature, higher saturation threshold and luminous efficacy. [ABSTRACT FROM AUTHOR]

Energy reduction is a great challenge in road lighting applications. Replacing high-pressure sodium vapor (HPSV) with light-emitting diodes (LED) is a viable approach to reducing energy consumption. However, a total replacement can incur a significant capital cost. This study aims to investigate the effects on light distribution by replacing HPSV lamps with LED lamps in HPSV luminaires using Light Intensity Distribution (LID) curve measurement and Backlight, Uplight and Glare (BUG) rating evaluation to reduce the adoption costs. While LED lamps have high illumination rates, the structural differences from HPSV lamps can affect the LID curve and original lighting design. Therefore, it is crucial to study photometric dispersion after retrofitting light sources. Both lamps were installed into similar HPSV luminaires to assess photometric performance using goniophotometer measurements. The HPSV lamp outperforms the LED lamp in terms of luminous flux (11.13%) and light intensity (7.69%), whereas the LED lamp outperforms the HPSV lamp in terms of efficacy rating (68.67%) and wattage used (47.61%). The findings indicate that retrofit LED luminaires have an LOR of 46.77% lower than the HPSV luminaires. The light distribution pattern is maintained but reduced to 40 to 50% for the main usable light angles. The reduced performance is caused by the lamp structure, which occupies a large area inside the luminaire housing, obstructing proper light distribution. Although overall energy consumption is reduced, similar illumination levels cannot be maintained. These outcomes can assist authorities and manufacturers with alternative methods of reducing costs while maintaining lighting levels. [ABSTRACT FROM AUTHOR]

The natural light environment in polar regions is different in that there are midnight sun and polar night rather than a regular year-round alternation of day and night. Existing research has reported that the scientific modulation of interior light parameters can reduce the negative effects on the circadian rhythm and improve brain functions of the staff members at polar stations, from basic physiological mechanisms to higher cognitive functions, such as perception, learning, memory, and thinking. Currently, the appropriate balance of visual and nonvisual aspects that allow lighting conditions to be applied in a manner conducive to human well-being, health and functioning is still to be investigated, and accurate analysis of the influence rules of functional lighting's vertical illuminance at eye level on cognitive performance remains an unresolved and important issue. This study analyses the effects of the vertical illuminance at eye level of functional lighting on the cognitive performance indicators toward the target population through simple reaction time task, cancellation test, and stroop test, and concludes that vertical illuminance levels of 260 ~ 300 lx at eye level contributed to improved cognitive performance. The study also verifies that comfort and satisfaction indices of subjective perceptions are significantly and strongly correlated with cognitive function indicators, and slightly better than the relaxation index. However, the attention index is not significantly correlated with cognitive function indicators. This study can provide data reference for the light design and operational decisions of buildings in Antarctica and the Arctic to promote wider application and impact. [ABSTRACT FROM AUTHOR]

This is a systematic review of studies assessing the effects of polychromatic (white) ambient light on mood in healthy adults. We hypothesized that higher melanopic equivalent daylight illuminances (EDI) would be associated with better mood. The search identified 2,994 publications, of which 14 met inclusion criteria. The resulting database included the spectral power distributions, illuminances, mood measures, and methods. We used the CIE S026 toolbox to calculate the five α-opic EDI values to characterize the light exposures in each study. Regression models tested the associations between predictors α-opic EDI, duration, and timing, and the outcome, mood. The results showed that none of the five α-opic values were significantly associated with mood (all estimates <0.044, p >.490). A longer duration of light exposure (all estimates <0.154, p <.018) and timing of light exposure in the morning (all estimates <0.233, p <.001) were associated with better mood, but these effects did not persist after adjusting for the data being nested within studies. Average mood scores remained reasonably consistent across different α-opic EDI profiles, suggesting that exposure profiles might not influence mood. Notably, none of the studies included had an experimental condition with a peak for melanopic EDI greater than the other α-opic EDI values, therefore the hypothesized association between melanopic EDI and mood could not be tested. Future research designs should contrast selected light parameters to identify the photoreceptors involved in the processes of interest. [ABSTRACT FROM AUTHOR]

Moonlight exerts profound ecological, behavioural and physiological effects on animals. However, lunar cycles are characterised by complex changes in the illuminance and timing of illumination, making it challenging to re‐create and manipulate moonlight cycles in the laboratory using artificial lights. As a result, ecological experiments on the effects of moonlight cycles are uncommon, and existing studies often oversimplify the re‐creation of moonlight. This limitation extends to experimental studies of the effects of light pollution on nocturnal animals, which often fail to adequately represent natural nocturnal light.To address the lack of open‐source solutions for re‐creating and manipulating moonlight cycles, we developed the software‐hardware system MoonShine. This has two components: (1) MoonShineR, an R package with additional R scripts, which predicts moonlight ground illuminance (in lux) at defined intervals, for a specified location and time range; (2) MoonShineP, a Python program running on a Raspberry Pi computer, which uses the illuminance values from MoonShineR to gradually dim and brighten a diffused array of individually addressable LEDs, allowing realistic natural light regimes to be re‐created in a laboratory environment. MoonShine includes multiple features to re‐create and manipulate light cycles. It supports colour‐shifting of the LED light (by adjustment of RGBW intensity ratios) to approximate the spectrum of natural moonlight, and to mimic habitat‐specific conditions or certain types of light pollution.We tested the accuracy of MoonShineR's moonlight illuminance predictions by comparison to field radiometer measurements at equatorial and temperate latitude sites. We demonstrated the accuracy of MoonShineP's moonlight re‐creation, by comparing its measured LED illuminances to the intended values and its measured LED spectrum against natural moonlight.MoonShine allows researchers to re‐create a range of natural nocturnal lighting scenarios in the laboratory. It can be used to re‐create full natural moonlight cycles with a relatively realistic spectral composition, generate manipulated moonlight schedules, or simulate light pollution. Furthermore, the moonlight illuminance predicted by MoonShineR is useful for field ecologists who require moonlight as a quantitative model predictor. Finally, to provide laboratory‐housed animals with full diurnal light cycles, MoonShine allows researchers to re‐create natural twilight and sunlight regimes. [ABSTRACT FROM AUTHOR]

To ensure high-quality lighting in indoor spaces, many objective parameters have been suggested in building codes and standards all over the world. Despite the emergence of luminance-based metrics, the average horizontal illuminance (Eav) remains popular in practice. For the case of relatively small rooms with one or two point light sources, it is often intended to determine the point with horizontal illuminance equal to Eav. It is also intended to have the computation for various room scenarios, so that the outcome can be predicted using a simple model. This study, therefore, aims to propose a method to identify the location of point of Eav on horizontal plane in cuboid rooms with various sizes, with one or two point light sources, and to further verify the theoretical concept. To achieve the objective, scenarios and assumptions are described using mathematical tools, followed with verification using grid computations and Monte Carlo simulation of 10,000 random scenarios. Logarithmic models to predict Eav value and its representative location are proposed. The room length-to-width ratio is found more influential, compared to the source luminous intensity characteristics, in affecting the location of point of Eav. [ABSTRACT FROM AUTHOR]

Introduction. In modern society, different types of lighting fixtures with a variety of shapes, colours and brightness are widely used. However, not all of them effectively fulfil their functions and can negatively affect human health. Optimal lighting parameters are identified, taking into account safety and energy efficiency. Key aspects include the analysis of the spectra of incandescent, fluorescent and LED lamps using a spectrometer and assessing their impact on the vision and mental health of employees working in an office space through a written survey.Materials and methods. The illuminance, luminous flux and economy of workstations in office premises were analyzed.Results. The analysis of the obtained results allowed to determine the rationality of application of the investigated spectra of different types of lamps. The results of the research will be useful both for specialists and manufacturers in the field of lighting engineering, as well as end users.Conclusions. Recommendations for the use of LED lamps as the main source of lighting in office-type premises are given. These lamps provide an almost uniform spectrum, which creates optimal conditions for vision and reduces the negative impact on mental health. It is proposed to supplement the workspace lighting with individual light sources in the form of desk lamps of a yellowish shade at each employee's workplace. LED lamps are not only energy efficient, but also contribute to the formation of a comfortable and safe working environment.

The images captured by forest nighttime imaging devices are prone to degradation and noise issues due to environmental constraints. This paper proposes a novel framework based on the self‐calibrating illumination framework to improve image quality. The framework consists of four specific steps: (1) addressing non‐uniform degradation by estimating illuminance components through non‐uniform MaxRGB, (2) extracting rich information using multi‐scale inflationary convolution, (3) analyzing the relationship between different input levels and the initial level and progressively adjusting the luminance components using a channel self‐calibration module to achieve continuous improvement in luminance, and (4) designing a reflectance optimization module that enhances illuminance while suppressing noise through a regularization model. To evaluate the proposed method, a dataset comprising 1000 forest night images is constructed using an image simulation strategy. The effectiveness of this method was validated on both synthetic and real datasets, demonstrating its ability to significantly enhance nighttime forest images. When compared to six other algorithms, this method outperformed them in eight evaluation metrics, including a peak signal‐to‐noise ratio metric of 22.839 and a structural similarity metric of 0.909. The experimental results clearly indicate that this method excels in enhancing image quality and fidelity. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of window films on indoor environmental conditions and electricity consumption of air conditioning. The research focused on the performance of different window films (HAG, RG), taking into account variations from different building orientations. The findings of this research indicated that building orientation could significantly influence the duration of direct sunlight entering the interior, with the areas closer to the glass being more susceptible to the effects of outdoor temperature and solar radiation. The clear glass with heat-absorbing film (HAG) and reflective film (RG) both reduced the indoor temperature and indoor illuminance while increasing indoor comfort. The RG could accumulate less heat on the glass surface compared with the HAG. The glass temperature of the RG will be lower than the HAG. The electricity-saving ratios of the HAG were 1.4%, 1.9%, 1.4%, and 1.2%, respectively, when facing the east, south, west, and northwest orientations compared with the clear glass (OG). The electricity-saving ratios of the RG were 3%, 4.2%, 4.2%, and 10.3%, respectively. [ABSTRACT FROM AUTHOR]

This article reports on the development, validation, workflow and implementation of a simplified method for evaluating the non-visual (melanopic) potential of daylight in typical side-lit rooms. The method is suitable for climatic areas with a dominant occurrence of cloudy skies. The non-visual daylight evaluation tool is based on a modified average daylight factor method. A simplified daylighting model improves the calculation of the vertical daylight factor and the passage of daylight through a vertical lighting opening. The proposed calculation method makes it possible to determine the illuminance of a vertical plane in the interior. The method is based on the uniform sky and the external diffuse horizontal illuminance at the location of interest. The outputs of the tool can also be used to quickly estimate visual levels of daylight. The article also proposes a classification of the availability of melanopic daylight in side-lit rooms, which is based on the outputs of the proposed calculation method. [ABSTRACT FROM AUTHOR]

Mood affects an individual's performance, whether relaxed/tense or alert/fatigued. This article was based on research to study a correlation between the lighting setting with relaxed-tense and alert/fatigued moods in the workplace by observing the illuminance level, the correlated color temperature (CCT), and the overhead/peripheral placement of lighting. The research was conducted with two online image-based questionnaire evaluations of 7 different lighting settings specifying their illuminance level, CCT, and placement as overhead or peripheral lighting depicted in images from the DIALux simulation. In the first questionnaire, subjects were asked to rate the difference between the two lighting displays being compared and the combination of the seven lighting settings. In the second questionnaire, subjects were also asked to rate their relaxed-tense and alert-fatigued perceptions of the lighting diplayed in the image. The results of these two questionnaires were analyzed by multidimensional scaling and correlation analysis. This image-based research concluded that a relaxed/tense perceived mood correlated negatively with the CCT, and an alert/fatigued perceived mood correlated negatively with the illuminance level and the CCT. [ABSTRACT FROM AUTHOR]

Rapid detection of fish freshness is of vital importance to ensuring the safety of aquatic product consumption. Currently, the widely used optical detecting methods of fish freshness are faced with multiple challenges, including low detecting efficiency, high cost, large size and low integration of detecting equipment. This research aims to address these issues by developing a low-cost portable fluorescence imaging device for rapid fish freshness detection. The developed device employs ultraviolet-light-emitting diode (UV-LED) lamp beads (365 nm, 10 W) as excitation light sources, and a low-cost field programmable gate array (FPGA) board (model: ZYNQ XC7Z020) as the master control unit. The fluorescence images captured by a complementary metal oxide semiconductor (CMOS) camera are processed by the YOLOv4-Tiny model embedded in FPGA to obtain the ultimate results of fish freshness. The circuit for the YOLOv4-Tiny model is optimized to make full use of FPGA resources and to increase computing efficiency. The performance of the device is evaluated by using grass carp fillets as the research object. The average accuracy of freshness detection reaches up to 97.10%. Moreover, the detection time of below 1 s per sample and the overall power consumption of 47.1 W (including 42.4 W light source power consumption) indicate that the device has good real-time performance and low power consumption. The research provides a potential tool for fish freshness evaluation in a low-cost and rapid manner. [ABSTRACT FROM AUTHOR]

Continual two-year measurements of daylight illuminance were performed in order to evaluate the daylighting of a model room. The key research idea was to study room orientation and its effect on daylight availability by using real measurements from a physical scale model. Firstly, differences between the illuminance in the north- and south-oriented rooms were compared. Secondly, a characteristic annual profile of the external horizontal illuminance data was determined. Finally, the median external diffuse illuminance data from measurements were compared with values based on the values recommended in the standard. The goal of the research was focused on the evaluation of a regional daylight climate model applicable for daylight evaluations. The results of the daylight illuminance measurements showed the importance of climatic daylight data for indoor daylighting in building design performance. [ABSTRACT FROM AUTHOR]

T8 LED tubes with adjustable brightness and color temperature are installed in the workshop for workers to adjust their lighting independently. The illuminance of the workers' working surface is dynamically monitored for one year, and the collected illuminance data are quantitatively analyzed to explore the suitable illuminance threshold and color temperature preference for workers in real scenes. The illuminance value is divided according to time period and season, which provides reference for the development of intelligent buildings. For the three workflows in the post-finishing workshop, the lighting environment was optimized based on the uniformity of illumination, and the optimal height of the lighting arrangement was determined. The optimal luminaire placement height for the bar tacking machine was found to be 1.28 m, for the auxiliary workbench it was 1.02 m, and for the ironing table it was 1.2 m. [ABSTRACT FROM AUTHOR]

A rapid checkerboard pattern change is used to elicit pattern-reversal visual evoked potentials (PR VEPs). CRT or LCD monitors do not allow immediate reversal of the entire pattern. The study aimed to construct a new stimulator whose characteristics approximate an instantaneous reversal and verify whether the improvement is reflected in PR VEPs. A new stimulator using a matrix of 12 × 48 independent white square LEDs was designed and compared with LCDs and CRTs. The effect on the PR VEP peak times and amplitudes of N70, P100, and P140 waves was evaluated in ten subjects. The LED stimulator showed significantly better performance in the rate of change of illuminance, change of pattern, luminance settling and stability. The PR VEP amplitudes of N75, P100, and N140 did not show significant differences. The sum of interpeak amplitudes was significantly larger for the LCD than for the other monitors. The peak times of the waves evoked by the LED were shorter than those evoked by the LCD and CRT for the N75 wave and a check size of 30´. LED stimulators are a better alternative to CRTs for PR VEPs than current LCDs. LEDs also seem to be better than CRTs, but further research is necessary to obtain significant results. [ABSTRACT FROM AUTHOR]

Blue laser diodes (LDs), owing to their high electro-optical conversion efficiency, strong directivity, and small size under high power, have paved new paths in the semiconductor lighting and display industry. Blue LDs are expected to replace LED lighting in laser displays, automotive headlights, and other advanced lighting fields. In this study, the Lu 3 Al 5 O 12 : Ce3+ phosphor-in-silica glass (LuAG: Ce-PiSG) is fabricated using spark plasma sintering at 1060 °C. This method enables rapid sintering while maintaining the stability of the silica glass matrix, resulting in high transparency and minimal destruction of the crystal structure of the LuAG: Ce phosphor. The phosphor-converted LDs made from LuAG: Ce-PiSG exhibit high luminous efficacy (298 lm·W−1) and luminous flux (1069 lm). The results show that LuAG: Ce-PiSG has significant potential for application as a robust, high-efficiency phosphor conversion material for high-brightness laser lighting applications. [ABSTRACT FROM AUTHOR]

Exploring the microhabitat determinants of organisms distribution and functional traits differences can help us better understand the importance of intraspecific variations in ecological niches. Investigations on animals functional niche primarily focused on differences among species and tended to neglect the potential variability within species, despite the fact that the ecological and evolutionary importance of intraspecific variations was widely recognized. In this study, we examined the influence of microhabitat features on the intraspecific variability of the distribution and functional traits of a highest elevational distributed lizard species Phrynocephalus erythrurus. To do so, field work was conducted between July and August, 2020 and August and September, 2021 in Namtso watershed in central Xizang, China. Specifically, 11 transects were sampled for P. erythrurus individuals, which were measured for a set of 10 morphological traits. Moreover, 11 microhabitat variables that potentially affect the distribution of lizards were also measured for each transect. Our results indicated that juveniles, males, and females exhibited different functional traits, allowing them to occupy distinct functional space. The distribution of juveniles, males, and females was determined by different microhabitat variables such as illuminance and air temperature. More importantly, these variables also determined the intraspecific functional traits variability in this lizard species. All of these results supported previous claims that intraspecific traits variation should be incorporated into functional ecological studies, and diverse microhabitat features should be conserved to maintain high intraspecific diversity. Future studies can focus on the food analysis to explore the linkage between functional traits and resources utilization within animal populations. [ABSTRACT FROM AUTHOR]

Appropriate daylight control could maximize occupants' visual comfort, potentially saving energy. However, the deployment of daylight control systems (DLCSs) is not happening, mainly due to the complex system calibration and the frequent reluctance of occupants toward automatic control systems that exclude their participation. In this paper, a human-in-the-loop DLCS is presented. The system is designed to allow the users to have direct interaction via smartphone Bluetooth communication, enabling them to set the lighting values deemed most comfortable nimbly. Special attention has been paid to the power consumption of the DLCS, especially in standby mode. Accessibility of configuration has been taken into consideration, leading to the choice of a wireless configured device. The performance of the prototype DLCS was evaluated experimentally in a side-lit room and compared with that of a commercial controller. The illuminance on a reference work plane was measured during the operation of the systems to observe the controllers' effect on the lamp's luminous flux while simultaneously considering the variation of daylight conditions. Moreover, the energy performance of the systems was studied to obtain information about the energetic effectiveness and convenience of the studied DLCSs. The main results showed that the proposed system could maintain the required target illuminance values on the work plane as daylight conditions vary: the maximum deviation measured using the prototype never exceeded 11 lx. In comparison, the commercial controller reached peaks of 220 lx. Moreover, the energy consumption of the prototype (resulting equal to 370 mVA) was lower than the consumption of the commercial system (equal to 600 mVA), allowing for increased energy savings over the long period. The more straightforward configuration allows the user to better interact with the DLCS. [ABSTRACT FROM AUTHOR]

Occupants' spatial adjustment (OSA) is one of the critical adaptive behaviours in buildings because it affects occupants' comfort and contents of view. However, OSA for contents of view management from facade (e.g. sky, other construction, and greenery) have not been quantified to be integrated into other aspects of multi-objective building design, particularly façade design. The current study develops a design methodology and a correspondent plugin tool to incorporate OSA and content view calculation for visual comfort improvement. To this end, first, a test cell and outdoor and indoor environment were modelled, and façade geometric variables and OSA variables (location and direction of occupant's sight) were set. After that, images were captured from hypothetical occupants' locations inside in different directions of sight while façade transformation alternatives were recorded to the occupants' content view images. Next, python image processing was linked to the Grasshopper modelling environment for content view analysing and quantification to be integrated into the optimisation process linked with visual comfort objectives. The designed methodology helped improve occupants' visual comfort by optimising façade form and managing OSA for optimum daylight availability, glare minimisation, and enhancing occupants' content view. Illuminance and discomfort glare probability (DGP), useful daylight illuminance (UDI), and spatial daylight autonomy (sDA) were used to shed light on the daylight performance of the proposed scenarios. Results demonstrated that a unique OSA and integrated façade configuration at any point in time and seasons that are suitable for the occupant's daylight availability management, decreases perceived glare, and enhances the content view. [ABSTRACT FROM AUTHOR]

Composite ceramic phosphor (CCP) is a candidate light-conversion material to obtain the high-quality laser lighting source. Phosphors based on the transmissive configuration model could not simultaneously meet the requirements of angular color uniformity and high thermal stability. In this study, a novel composite structure ceramic was designed, including Al2O3-YAG:Ce/YAG layered ceramic with a size of 1 mm × 1 mm for lighting, and Al2O3 ceramic (φ = 16.0 mm) was used as the wrapping material due to its outstanding thermal stability. The prepared ceramics exhibited excellent thermal performance and no yellow ring phenomenon. Through this design, we achieved the match of the intensity distribution of the blue and yellow lights, resulting in a high angular color uniformity of 0.9 with a view angle of ±80°. All ceramics showed no luminous saturation phenomenon, even the laser power density was increased up to 47.51 W/mm2. A high-brightness white-light source with a luminous flux of 618 lm, a luminous efficiency of 126 lm/W, a CCT of 6615 K, and a CRI of 69.9 was obtained in the transmissive configuration. In particular, the surface temperature of the ceramic was as low as 74.1 - under a high laser radiation (47.51 W/mm2). These results indicate that Al2O3/Al2O3-YAG:Ce/YAG composite structure ceramic is a promising luminescent material in the high-power laser lighting applications. [ABSTRACT FROM AUTHOR]

Phosphor-glass composites (PGC) are excellent candidates for highly efficient and stable photonic converters; however, their synthesis generally requires harsh procedures and long time, resulting in additional performance loss and energy consumption. Here we develop a rapid synthetic route to PGC within about 10 seconds, which enables uniform dispersion of Y3Al5O12:Ce3+ (YAG:Ce) phosphor particles through a particle self-stabilization model in molten tellurite glass. Thanks for good wettability between YAG:Ce micro-particles and tellurite glass melt, it creates an energy barrier of 6.94 × 105 zJ to prevent atomic-scale contact and sintering of particles in the melt. This in turn allows the generation of YAG:Ce-based PGC as attractive emitters with high quantum efficiency (98.4%) and absorption coefficient (86.8%) that can produce bright white light with luminous flux of 1227 lm and luminous efficiency of 276 lm W−1 under blue laser driving. This work shows a generalizable synthetic strategy for the development of functional glass composites. Phosphor-glass composites can serve as efficient and stable photonic converters, but their synthesis generally requires harsh and time-consuming procedures. Here, the authors report an alternative synthesis route that requires only a few seconds and is based on particle self-stabilization. [ABSTRACT FROM AUTHOR]

For white-light emitting diode (WLED) applications, a green-to-orange emission nitridosilicate-based phosphor is created. The observed wide-band radiation in the green-orange range is caused by Eu2+ and Yb2+ at the trap point of a doubly doped SrSi2O2N2:Eu2+,Yb2+ (SSON:Eu,Yb) nitridosilicate phosphor. The green-color radiation's decay duration was measured to validate the energy transfer among activator ions. The co-doping various ratios' influence of activator ions on luminescence features was investigated. The resulting phosphor's radiation is a function of the activator ion concentrations and raising the Yb2+ concentration causes red-color radiation to dominate the green radiation. To generate white illumination, the resulting phosphor was coupled with an InGaN blue-LED chip having a pumping wavelength of 450 nm. Two stages were taken to achieve hue balance management. Initially, the green to orange proportion was tuned by varying the Eu2+ and Yb2+ ions' concentrations. At the second stage, the Commission Internationale de L'Eclairage, International Commission on Illumination (CIE) coordinates were changed from [0.2805; 0.2014] to [0.4071; 03789] by raising the amount of phosphor powder used. White illumination produced under optimal conditions has a hue rendering indicator of 89. The designed single-stage dual-hue-releasing nitridosilicate phosphor and blue-LED chip displayed remarkable hue steadiness over a wideband of forwardbias currents (100 to 500 mA at 3 V). [ABSTRACT FROM AUTHOR]

The use of CaO:Tb3+ with light green emission on for improvement of both luminescent output and chromatic fidelity of the white light emitted from a light-emitting diode (LED). The CaO:Tb3+ is combined with the yellowemitting phosphor of YAG:Ce3+ to provide sufficient colored spectral proportion for the white light generation, enhancing the color performance. The phosphor combination is utilized for the three most applied LED structures: conformal, in-cup, and remote phosphor structures. The changes in optical properties of these three LEDs are monitored with adjustments in the proportion of CaO:Tb3+. The higher proportion of the green phosphor results in higher scattering efficiency in all structures, offering better color coordination and stronger luminous flux. The color quality scale is somehow reduced when CaO:Tb3+ concentration is more than a certain level. Therefore, depending on the phosphor configuration of the white lightemitting diode (WLED), the concentration of CaO:Tb3+ should be modified to achieve a good color rendition with improved color consistency and luminous properties. [ABSTRACT FROM AUTHOR]

This article deals with problems related to electromagnetic compatibility, which is a very important issue due to the fact of ensuring the proper coexistence of devices and systems in a given electromagnetic environment. The devices manufactured today can, on the one hand, be a source of electromagnetic disturbance emissions and, on the other hand, be susceptible to disturbance signals from the environment. A large group of receivers in which electronic specialised circuits are used are LED lamps. The operation of an RGB LED lamp due to higher harmonic current emissions has been analysed in this paper. Lamp tests were carried out in several stages. In each of them, the values of the generated higher harmonics were analysed and related to the parameters of the current flowing through the lamp. It was shown how the parameters of the current pulse affect the generated harmonics when the value of the luminous flux was changed, its colour was changed, or the built-in function was turned on. It is also shown how, for example, changing the value of an electronic component in the lamp's power supply changes the parameters of the current and thus the value of the generated higher harmonics. [ABSTRACT FROM AUTHOR]

Highly transparent Ho:Y2O3 ceramics for laser diode lighting were prepared using the vacuum sintering method with 0.3 at.% Nb2O5 as a sintering additive. The microstructures, transmittance, and luminescence properties of the Ho:Y2O3 ceramic samples were investigated in detail. The transmittance levels of all samples with various Ho3+ concentrations reached ~81.5% (2 mm thick) at 1100 nm. Under the excitation of 363 nm (ultraviolet) or 448 nm (blue) light, Ho:Y2O3 transparent ceramic samples showed that green emission peaked at 550 nm. The emission intensity was strongly affected by the concentration of Ho3+ ions, reaching its highest level in the sample doped with 1 at.% Ho3+. The CIE coordinates of the luminescence were in the green region (i.e., the CIE coordinates of the sample doped with 1 at.% Ho3+ were [0.27, 0.53] and [0.30, 0.69], under the excitation of 363 nm and 448 nm light, respectively). The possibility of its application as laser diode lighting was reported. Under the excitation of 450 nm blue laser, the sample doped with 0.5 at.% Ho3+ had the best performance: the saturated luminous flux, lumen efficiency, and the luminescence saturation power densities were 800 lm, 57.7 lm/W, and 17.6 W/mm2, respectively. Furthermore, the materials have high thermal conductivity and mechanical strength due to their host of rare-earth sesquioxide. Thus, Ho:Y2O3 transparent ceramics are expected to be a promising candidate for green-light-emitting devices for solid-state lighting, such as laser diode lighting. [ABSTRACT FROM AUTHOR]

Phosphor conversion materials with excellent thermal stability and broad-spectrum is critical to obtaining laser lighting devices with high luminous flux and CRI. In this paper, high thermally stable green AlN-Lu 3 Al 5 O 12 :Ce (ASL) and red AlN–CaAlSiN 3 :Eu (ASR) composite phosphor ceramics were prepared by embedding phosphor into AlN ceramic matrix. With mass ratio of phosphor increasing, luminescence intensity and quantum efficiency gradually increased, and the maximum internal quantum efficiency reached 62.8 % and 78.9 % for ASL and ASR, respectively. Under laser exciting in reflection mode, ASL-20 and ASR-50 got the max luminous emittance of 2827.5 lm/mm2 and 268.7 lm/mm2 with a saturation laser power density of 60.4 W/mm2 and 16.7 W/mm2, respectively. The diffusion coefficient of Ca, Al, Si between AlN and CASN grains was 2–4 magnitude higher than that of Lu, O, N between AlN and LuAG grains, confirming facile solid solubility of AlN and CASN. Finally, luminescence performances of green-red color wheel fabricated by ASL and ASR were evaluated. When the area ratio of green to red was 2:1, the color wheel yielded the biggest CRI of 82.6. This work presents a facile strategy for fabricating high thermally stable AlN-based composite phosphor ceramic and its application in high-quality laser lighting and display devices. [ABSTRACT FROM AUTHOR]

Because the human eye cannot visually detect the results of direct bilirubin test papers accurately and quantitatively, this study proposes four different highly collimated mini light-emitting diodes (HC mini-LEDs) as light sources for detection. First, different concentrations of bilirubin were oxidized to biliverdin by FeCl3 on the test paper, and pictures were obtained with a smartphone. Next, the red, green, and blue (RGB) channels of the pictures were separated to average grayscale values, and their linear relationship with the direct bilirubin concentration was analyzed to detect bilirubin on the test paper noninvasively and quantitatively. The experimental results showed that when green HC mini-LEDs were used as the light sources and image analysis was performed using the G channel, for a direct bilirubin concentration range of 0.1–2 mg/dL, the G channel determination coefficient (R2) reached 0.9523 and limit of detection was 0.459 mg/dL. The detection method proposed herein has advantages such as rapid analysis, noninvasive detection, and digitization according to RGB grayscale changes in the images of the detection test paper. [ABSTRACT FROM AUTHOR]

Dichromatic phosphor-in-glass films (PiFs) are recognized as ideal color converters for high-quality laser lighting, but photon reabsorption among multiple phosphor degrades the luminescence performance. Therefore, there is urgent to design a suitable PiF structure to alleviate this problem. Herein, the green-emitting phosphor YAGG:Ce and the orange-yellow-emitting phosphor GdYAG:Ce are mixed with silicate glass powder respectively, and print on the sapphire plate with high thermal conductivity (TC) to prepare spatially separated structure PiF (SS-YG PiF). Under the excitation of blue LD with power of 6.15 W, the luminous flux (LF) of SS-YG PiF reaches 1020.4 lm, and the corresponding luminous efficiency (LE) reaches 165.92 lm/W and CRI∼80. Notably, the perfect white light color coordinates (0.3354, 0.3253) are obtained at 6.15 W. In addition, SS-YG PiF has a lower surface temperature and a higher TC (9.89 W m−1K−1), reflecting the excellent luminescence performance and thermal properties of SS-YG PiF. [ABSTRACT FROM AUTHOR]

Interferometers used for high-precision spectroscopic measurements are considered. The choice of a holographic interferometer is supported because of it implements the spatial-spectral method of holographic interferometry. With this holographic interferometer one can measure in real time the displacements of the phase center of a coherent light flux over a wide dynamic range and record the measured data in digital form. Based on the mathematical relations elucidated by the authors in previous publications, and based on the results of experimental studies, we have been able to numerically estimate the sensitivity of a holographic interferometer to spatial movements of phase centers (focus points) of light fluxes—point light sources that form a holographic interferogram. We establish the dependence of the normalized level of light flux intensity in the central region of the holographic interferogram on the displacement of a real point light source along the normal to the plane of the Fourier hologram. From the results of mathematical simulation we show that the sensitivity of a holographic interferometer to the movements of a real point light source normal to the plane of the Fourier hologram depends on the optical circuit parameters of the holographic interferometer when exposing the hologram and on the measurement parameters. In this case, the sensitivity of a holographic interferometer to specific movements of a real point light source can only be estimated experimentally. We propose to increase the sensitivity of a holographic interferometer by using a thin converging lens in its optical design. A mathematical relation has been obtained and studied for the gain coefficient of the phase advance of a light flux with a spherical wavefront. Given the known parameters of the thin converging lens in the optical circuit, we can use this relationship to numerically estimate the increase in sensitivity of a holographic interferometer that implements the spatial-spectral method of holographic interferometry. It is shown that the sensitivity of the holographic interferometer to the displacement of an imaginary point light source normal to the plane of the Fourier hologram is 2.86 times greater than its sensitivity to the same movement of a real point light source. It has been established that the sensitivity of holographic interferometer with a volumetric Fourier hologram and a thin converging lens in its design can be increased by no less than an order of magnitude compared with the sensitivity of known optical interferometers. The results of assessing the sensitivity of the holographic interferometer implementing the spatial-spectral method of holographic interferometry to displacement of point sources of real and imaginary light fluxes, as well as the resulting ratio for the gain coefficient of the phase advance of the light flux by the thin converging lens, will be useful for high-precision measurements of linear and angular movement of objects, as well as in the construction of photonic device structures. From the results of the study based on the holographic interferometer, an experimental sample of an acousto-electric transducer has been developed and manufactured, which has high sensitivity over wide dynamic and frequency ranges and is intended for use in acoustic locations of unmanned aerial vehicles. [ABSTRACT FROM AUTHOR]

Background: We aimed to study the optical and retinal modifications that occur after adapting to different lighting conditions including photopic, mesopic, scotopic, blue light and red light conditions. Methods: Thirty young healthy subjects with a mean age of 23.57 ± 3.45 years were involved in the study (both eyes included). They underwent aberrometry and optical coherence tomography at both the central and peripheral retina with the 3 × 3 mm2 macular cube protocol before starting adaptation to the illuminations (baseline) and after remaining for 5 min under the five different lighting conditions inside a controlled lighting cabinet. Results: Significant myopization (p = 0.002) was observed under scotopic and mesopic lighting conditions, while hypermetropization occurred under the influence of blue LED light. In the central retina, a significant thickening of the inner temporal (p = 0.025) and outer inferior (p = 0.021) areas was observed in the scotopic area, and the thickening increased even more under blue and red light. The mean central thickness decreased significantly under photopic lighting conditions (p = 0.038). There was an increase in the mean volume of the central retinal area with red light and a reduction in the volume under photopic lighting (p = 0.039). In the peripheral retina, no significant thickness changes were observed after adapting to any of the lighting conditions (p > 0.05). Regarding morphological changes, a significant increase in retinal eccentricity (p = 0.045) and the shape factor (p = 0.036) was found. In addition, a significant correlation was found only between the eccentricity and volume of the central retina in scotopic conditions (r = −0.265; p = 0.041), meaning that a higher volume was associated with lower retinal eccentricity. Conclusions: When exposed to different lighting conditions, the retina changes in shape, and ocular refraction is modified to adapt to each condition, revealing the phenomenon of night myopia when transitioning from photopic to scotopic regimes. [ABSTRACT FROM AUTHOR]

Low-light image enhancement plays an important role in computer vision applications, which is a fundamental low-level task and can affect high-level computer vision tasks. To solve this ill-posed problem, a lot of methods have been proposed to enhance low-light images. However, their performance degrades significantly under nonuniform lighting conditions. Due to the rapid variation of illuminance in different regions in natural images, it is challenging to enhance low-light parts and retain normal-light parts simultaneously in the same image. Commonly, either the low-light parts are underenhanced or the normal-light parts are overenhanced, accompanied by color distortion and artifacts. To overcome this problem, we propose a simple and effective Retinex-based model with reflectance map reweighting for images under nonuniform lighting conditions. An alternating proximal gradient (APG) algorithm is proposed to solve the proposed model, in which the illumination map, the reflectance map, and the weighting map are updated iteratively. To make our model applicable to a wide range of light conditions, we design an initialization scheme for the weighting map. A theoretical analysis of the existence of the solution to our model and the convergence of the APG algorithm are also established. A series of experiments on real-world low-light images are conducted, which demonstrate the effectiveness of our method. [ABSTRACT FROM AUTHOR]

The paper presents a simple method of measuring the luminous flux value dedicated to LED light sources. This method uses information about a spatial radiation pattern of the lighting source under test and the results of illuminance measurements at the axis of this source. The method is described and the results of the measurements obtained using this method and the classical method are compared and discussed. Tests have been carried out for LED modules of different geometries. The measurement error of the considered method is analysed. [ABSTRACT FROM AUTHOR]

A space occupant's real-time exposure to light reaching his/her eyes has been a concern in lighting research and design practice. Following the parallel fundamental research in Part 1, Part 2 of this study explored a way to use a Canon 550D fitted with the Sigma 4.5 mm F2.8 circular fisheye lens to estimate the luminous flux arriving at the entrance pupil from the visible luminous environment. By taking two 180° HDR images at the same camera position but in different aiming directions and merging them into a single luminance map covering the observer's entire binocular visual field (214° horizontally and 125° vertically), the monocular and binocular luminance map can be generated with the aid of the dynamic visual field model proposed in Part 1. In a field verification experiment, the luminous flux passing through the entrance pupil in the preset scenes and gaze angles was estimated. Individual luminous contribution from an object or a region of interest within the occupant's dynamic binocular visual field or subfields was also calculated. This study expanded the capacity of HDR photography in lighting measurement to capture binocular luminous flux entering human eyes as input for optimizing human-light interaction in various luminous environments. [ABSTRACT FROM AUTHOR]

A space occupant's real-time exposure to light reaching his/her eyes has been a concern in lighting research and design practice. This study assumed a schematic eye to estimate the luminous flux received by the entrance pupil from the visible luminous environment. As the first part of this study, this paper focused on the fundamentals of luminous flux calculation that considers real-time human eye reactions. The research work includes: (a) developing a dynamic binocular/monocular visual field model that takes the eye movement into account, based on a conventional visual field model in orthomode, (b) retrieving the apparent area of the entrance pupil of the schematic eye, and (c) quantifying the light passing through the entrance pupil from the luminous environment fallen in the binocular/monocular visual field. The fundamental theory was tested in a theoretical uniform lighting scene to calculate the luminous flux emitted from the human visual field along multiple gaze directions at different light levels. A foundation was thus laid to estimate the real-time luminous flux passing through the entrance pupil with the aid of the camera as disclosed in Part 2 of the present study. [ABSTRACT FROM AUTHOR]

In this study, we introduce a novel design of a remote edge-lit backlight structure featuring blue laser diodes (LDs). These LDs were integrated into a remote yellow phosphor layer on a light guide plate (LGP). Blue light emitted by the LDs passes through the LGP and spreads to the remote phosphor layer, generating white light output. Owing to the incorporation of a scattering layer between sequential LGPs, the remote edge-lit backlight structure facilitates the expansion of the output surface of the LGP by combining multiple individual LGPs. Two- and three-LGP remote edge-lit backlight structures demonstrated acceptable white illuminance uniformity. The proposed architecture serves as a viable solution for achieving uniform illumination in planar lighting systems using blue LDs; thus, this structure is particularly suitable for linear lighting or slender backlighting instead of display stand applications. [ABSTRACT FROM AUTHOR]

The use of photovoltaic (PV) panels in interior spaces is expected to increase due to the proliferation of low-power sensor devices in the IoT domain. PV models are critical for estimating the I–V curves that define their performance at various light intensities. These models and the extraction of their parameters have been extensively studied under outdoor conditions, but their indoor illumination performance is less studied. With respect to the latter, several studies have used the parameter-scaling technique. However, the model's accuracy degrades when the light level decreases. In this study, we propose a simple PV modeling technique that can be applied at various illuminance levels by only using characteristic points (short-circuit current, open-circuit voltage, and maximum-power voltage points) at a reference illumination level. The model uses the characteristic point translation technique to translate the reference characteristic points to other operating conditions. Then, parameter extraction technique is used to extract the model's parameters. The proposed model's accuracy is verified using two commercial PV panels and different indoor lighting technologies. The results indicate that the proposed model outperforms the other examined works in terms of accuracy, with an average improvement of 15.75%. [ABSTRACT FROM AUTHOR]

This study proposes a three-lens design with a short lens length and explores the curved imaging plane and performs a relative illumination analysis. There are two ways to reduce the lens length: shortening the back focal and lens group lengths. We derived the relevant parameter relationships of three lenses using the first-order geometric optics theory. The optical lens length can be controlled within 2 mm. The shorter the lens length, the larger the angle of the chief ray in the image space, resulting in an increase in the field curvature and astigmatism. Third-order Seidel aberrations can be effectively reduced by a curved image plane. We also derived the equations for relative illuminance, solid angle, surface transmittance, and internal transmittance for the short three-lens design. The optical lens design uses a curved image plane to shorten the distance from the off-axis beam image space to the image plane and reduce the incident angle of the chief ray on the image plane. The formula and design results verified by Code V software (version 11.2) show that both the solid angle and relative contrast of the lens can be increased. For the proposed three-lens design with a short lens length, the semi-field angle is 32°, F/# is 2.7, the effective focal length is 1.984 mm, the image plane area is 2.16 mm × 1.22 mm, and the curvature radius of the concave image plane is 3.726 mm. Moroever, the MTF (100 lp/mm) is larger than 52%, the lateral color aberration is less than 2.12 μm, the optical distortion is less than 2.00%, and the relative illumination is greater than 68%. [ABSTRACT FROM AUTHOR]