Light Environment Research Articles

Contrasting Dynamic Photoprotective Mechanisms under Fluctuating Light Environments between an Andean and a Mesoamerican Genotype of Phaseolus vulgaris L.

Plants have evolved various photosynthetic adaptations and photoprotective mechanisms to survive in fluctuating and extreme light environments. Many light-activated photosynthetic proteins and enzymes adjust to plant leaf anatomy and leaf pigments to facilitate these processes. Under excessive amounts of light, plants use non-photochemical quenching (NPQ) mechanisms to dissipate excess absorbed light energy as heat to prevent photoinhibition and, therefore, mitigate damage to the plant’s photosystems. In this study, we examined photosynthetic adaptations to the light environment in common beans using representative genotypes of the Andean (Calima) and the Mesoamerican (Jamapa) gene pools. We estimated their leaf chlorophyll fluorescence characteristics using dark- and light-adapted mature leaves from three-week-old plants. Our results indicated a higher chlorophyll fluorescence of the light-adapted leaves in the Mesoamerican genotype. NPQ induction was early and extended in the Andean genotype. A similar response in the Mesoamerican counterpart required high light intensity (≥1500 PAR). The NPQ relaxation was rapid in the Mesoamerican genotype (t1/2: 6.76 min) but sluggish in the Andean genotype (t1/2: 9.17 min). These results indicated variable adaptation to light environments between the two common bean genotypes and suggested different strategies for surviving fluctuating light environments that can be exploited for developing plants with environmentally efficient photosynthesis under light limitations.

Ambient light spectrum affects larval Mexican jumping bean moth (Cydia saltitans) behavior despite light obstruction from host seed

Spectral differences in ambient light can affect animal behavior and convey crucial information about an individual’s environment. The ability to perceive and respond to differences in ambient light varies widely by taxa and is shaped by a species’ ecology. Mexican jumping bean moths, Cydia saltitans, spend their entire larval period encased in fallen host seeds and contend with potentially lethal environmental temperatures when host seeds are in direct sunlight. We investigate if and how C. saltitans larvae in host seeds respond to lighting conditions associated with these thermal risks. In a temperature-controlled experiment, we identified that larvae demonstrated distinct behavioral (“jumping”) responses corresponding to four lighting treatments (white, red, green, and purple), despite extremely minimal light penetration through host seed walls. Red light induced the greatest larval activity (measured by probability of movement and by displacement from origin), suggesting that larvae have mechanisms to perceive low levels of red light and/or to detect subtle increases in heat produced by red/near infrared-biased light spectra, possibly providing them with an early-warning mechanism against thermal stress. Our findings highlight the interplay of environmental lighting, behavior, and potential thermosensory adaptations in a species with a visually constrained environment.

The effects of acoustic-light-thermal environment quality parameters on pedestrians’ overall comforts in residential districts

This study explored subjective responses towards various environmental quality parameters. It would be helpful to approach an overall comfort improvement relating to physics. In order to investigate the combined effects of sound, light and heat on the overall comfort of pedestrians, which could be evaluated by overall comfort vote, two residential areas in Yubei District, Chongqing (a Cfa city in China) were selected for field measurements and questionnaires. Three were three key findings were concluded based on subjective responses to environmental parameters via multiple linear regression. First, the average outdoor neutral temperature, mean neutral sound level and neutral illumination intensity were determined to be 26.6 °C (determined by physiologically equivalent temperature), 56.5 dBA (determined by A-weighted equivalent continuous sound level) and 21.4 klx (determined by LUX), respectively. Second, considering the effects of both physiology and psychology, thermal perceptions varied for acoustic and light environments. Residents partially had lower neutral temperatures at the noisy condition. Third, environmental quality factors had a significant effect on overall comfort. Positive correlation between physiologically equivalent temperature and overall comfort vote was found (sig < 0.000); while the effects of sound pressure and light intensity were not always significant. Hence, thermal stress played a significant role in people’s overall comfort. This study has explored the effects of three environment quality parameters on human perceptions. It provided better understanding against dwellers’ feelings under complex circumstances. Future urban design and planning works should consider the cooling factors regarding contextual acoustical and visual environments.

Exploring the causes of frequent accidents at highway tunnel exits: Coupling analysis of the slack effect and white hole effect in extra-long tunnels

In this paper, the causes of frequent traffic accidents at the exits of highway tunnels are investigated. This study recruited 34 subjects to conduct vehicle experiments using an illumination meter, eye tracker, Smarter Eye and OBD to measure the illumination, eye movement characteristics, driving trajectory, and speed while driving in a tunnel exit. A questionnaire was used to investigate drivers’ subjective feelings while driving. The change trend of each indicator in the area near the tunnel exit was analyzed, and the relationships among the light environment, driver physiology, driving behavior, and driver psychology were explored. The psychological and physiological inconsistency phenomenon and abnormal acceleration behavior were observed at the tunnel exit, and the slack effect was verified. As the tunnel exit area is driven through, with the rapid increase in illumination, the rate of change of the driver’s pupil area increases, and the distance between the vehicle and the tunnel sidewall increases. It is unreasonable that in a tunnel exit with a poor traffic environment, some drivers experience psychological slack and tend to increase their speed and accelerate out of the tunnel. The slack effect is observed in most drivers, approximately 79.4% of the total. The white hole effect interferes with drivers’ vision and reduces their ability to obtain traffic information. The slack effect reduces drivers’ attention and increases vehicle speed. A coupling effect exists between the white hole and slack effects, which together threaten traffic safety at the tunnel exit.

Research on the health performance improvement strategy of traditional dwellings in southern Henan province under the concept of healthy building

As the most basic unit of human life, the health attributes of dwellings have a significant impact on residents' health. Rural areas in Henan Province exhibit a high degree of "hollowing out," with permanent residents being highly sensitive to health issues. Therefore, studying the improvement strategies for the health performance of rural dwellings is of great significance to residents' health. This paper reviews the development of domestic healthy building concepts and relevant evaluation systems, and analyzes the correlation and mechanism between various building element indicators and health issues in dwellings based on relevant evaluation systems. Finally, drawing on modern healthy building concepts, the paper conducts a health performance analysis of traditional dwellings in southern Henan Province from four aspects: thermal environment, light environment, air quality, and sound environment, and proposes targeted improvement strategies.

SmartDampener: An Open Source Platform for Sport Analytics in Tennis

In this paper, we introduce SmartDampener, an open-source tennis analytics platform that redefines the traditional understanding of vibration dampeners. Traditional vibration dampeners favored by both amateur and professional tennis players are utilized primarily to diminish vibration transmission and enhance racket stability. However, our platform uniquely merges wireless sensing technologies into a device that resembles a conventional vibration dampener, thereby offering a range of tennis performance metrics including ball speed, impact location, and stroke type. The design of SmartDampener adheres to the familiar form of this accessory, ensuring that (i) it is readily accepted by users and robust under real-play conditions such as ball-hitting, (ii) it has minimal impact on player performance, (iii) it is capable of providing a wide range of analytical insights, and (iv) it is extensible to other sports. Existing computer vision systems for tennis sensing such as Hawk-eye and PlaySight, rely on hardware that costs millions of US dollars to deploy with complex setup procedures and is susceptible to lighting environment. Wearable devices and other tennis sensing accessories, such as Zepp Tennis sensor and TennisEye, using intrusive mounting locations, hinder user experience and impede player performance. In contrast, SmartDampener, a low-cost and compact tennis sensing device, notable for its socially accepted, lightweight and scalable design, seamlessly melds into the form of a vibration dampener. SmartDampener exploits opportunities in SoC and form factor design of conventional dampeners to integrate the sensing units and micro-controllers on a two-layer flexible PCB, that is bent and enclosed inside a dampener case made of 3D printing TPU material, while maintaining the vibration dampening feature and further being enhanced by its extended battery life and the inclusion of wireless communication features. The overall cost is $9.42, with a dimension of 21.4 mm × 27.5 mm × 9.7 mm (W × L × H) and a weight of 6.1 g and 5.8 hours of battery life. In proof of SmartDampener's performance in tennis analytics, we present various tennis analytic applications that exploit the capability of SmartDampener in capturing the correlations across string vibration, and racket motion, including the estimation of ball speed with a median error of 3.59 mph, estimation of ball impact location with accuracy of 3.03 cm, and classification of six tennis strokes with accuracy of 96.75%. Finally, extensive usability studies with 15 tennis players indicate high levels of social acceptance of form factor design for the SmartDampener dampener in comparison with alternative form factors, as well as its capability of sensing and analyzing tennis stroke in an accurate and robust manner. We believe this platform will enable exciting applications in other sports like badminton, fitness tracking, and injury prevention.

Amphiphilic Cationic Carbon Dots for Efficient Delivery of Light-Dependent Herbicide.

The inefficient delivery of herbicides causes unpleasant side effects on the ecological environment. Protoporphyrinogen oxidase (PPO)-inhibiting herbicides rely on the presence of external light to exert the activities and thus their performance in the field is extremely susceptible to the light environment. Here, taking acifluorfen (ACI) as a model PPO-inhibiting herbicide to enhance efficacy by boosting the utilization rate of sunlight, amphiphilic cationic CDs (CPC-CDs) from cetylpyridinium chloride (CPC) as a precursor, is first prepared as a supplementary light source generator, and subsequently co-assembled with ACI through non-covalent bond interactions to obtain the stable fluorescent nanoparticles (ACI@CPC-CDs). ACI@CPC-CDs with fascinating physicochemical properties can penetrate the leaves of weeds through the stomata and undergo a long-distance transport in the cell intervals. Under low light intensity, CPC-CDs can be applied as the internal light source to promote the formation of more singlet oxygen to damage the leaf cell membrane, consequently improving the herbicidal activity of ACI. Moreover, the safety evaluation of ACI@CPC-CDs demonstrates no risk to non-target organisms and the environment. Therefore, this work offers a promising strategy for the efficient delivery of light-dependent PPO-inhibiting herbicides and opens new insights into the application of CDs in the development of sustainable agriculture.

Design and Thermal-Optical Environment Simulation of Double-Slope Greenhouse Roof Structure Based on Ecotect

At present, most double-slope greenhouse shade systems utilize insulation quilts on a portion of the roof to enhance the light and thermal environment for winter production. However, this method often leads to challenges such as uneven light distribution and significant heat dissipation. To improve the uniformity of light distribution and optimize the light and thermal environment inside a shade room, this study employed Ecotect software 2011 for simulating and analyzing the light and thermal conditions of a double-slope greenhouse shade system. The study aimed to investigate the optimal spacing and width of roof windows. The results demonstrated that a double-slope greenhouse with roof windows of 300 mm width spaced at 3000 mm intervals achieved optimal performance. This configuration yielded a light distribution uniformity of 74.4% and an average temperature of 8.1 °C. Such conditions are conducive to creating an environment suitable for cultivating edible mushrooms, thereby enhancing the quality and consistency of mushroom production. This paper provides an effective method for designing the roof structure of double-slope greenhouses to enhance light capture, thermal regulation, and energy efficiency.

Indoor dynamic light/thermal environment of smart windows using ATO nanofluids in summer: An experimental study

Windows are crucial in regulating indoor daylighting, cooling, and heating to ensure suitable living conditions. However, conventional windows lack the capability for spectrum splitting and exhibit unpredictable light and heat management. This study introduces a smart window to propose a reversible function by utilizing Antimony Tin Oxide (ATO) nanofluids with near-infrared (NIR) selective absorption. An experimental study was conducted in a controlled chamber to evaluate these smart windows' dynamic light and thermal environment. The study examined the effects of ATO nanofluid concentrations at 10 ppm, 100 ppm, and 500 ppm. Results showed that the maximum indoor air temperature decreased by 4.35 °C, 2.78 °C, and 4.29 °C, respectively. Additionally, the maximum temperature differences on the outer surfaces of the exterior glass (EG) and the control glass (CG) were 4.27 °C, 3.78 °C, and 4.43 °C, respectively. When the smart window was oriented to the east, west, or north, the maximum indoor temperature differences between EG and CG were 1.37 °C, 2.9 °C, and 2.43 °C, respectively. This study demonstrates the potential of ATO nanofluid-based smart windows to enhance indoor environmental control through effective light and heat management.

Visual input regulates melanophore differentiation.

Developmental processes continue in organisms in which sensory systems have reached functional maturity, however, little research has focused on the influence of sensory input on cell and tissue development. Here, we explored the influence of visual system activity on the development of skin melanophores in Xenopus laevis. Melanophore number was measured in X. laevis larvae after the manipulation of visual input through eye removal (enucleation) and/or incubation on a white or black substrate at the time when the visual system becomes functional (stage 40). To determine the developmental process impacted by visual input, migration, proliferation and differentiation of melanophores was assessed. Finally, the role of melatonin in driving melanophore differentiation was explored. Enucleating, or maintaining stage 40 larvae on a black background, results in a pronounced increase in melanophore number in the perioptic region within 24 h. Time lapse analysis revealed that in enucleated larvae new melanophores appear through gradual increase in pigmentation, suggesting unpigmented cells in the perioptic region differentiate into mature melanophores upon reduced visual input. In support, we observed increased expression of melanization genes tyr, tyrp1, and pmel in the perioptic region of enucleated or black background-reared larvae. Conversely, maintaining larvae in full light suppresses melanophore differentiation. Interestingly, an extra-pineal melatonin signal was found to be sufficient and necessary to promote the transition to differentiated melanophores. In this study, we found that at the time when the visual system becomes functional, X. laevis larvae possess a population of undifferentiated melanophores that can respond rapidly to changes in the external light environment by undergoing differentiation. Thus, we propose a novel mechanism of environmental influence where external sensory signals influence cell differentiation in a manner that would favor survival.

Light environment and photosynthetic performance in Cornus officinalis: an analysis on SPAD value variations

Light environment and photosynthetic performance in Cornus officinalis: an analysis on SPAD value variations

Self‐Powered Luminescent Solar Concentrators‐Integrated Temperature Detection System with High Thermal Tolerance by Reversible Thermal Photoluminescence Luminophores

AbstractIt is still a challenge to prepare the red‐emissive perovskite‐polymer composite with high photoluminescence quantum yield (PLQY) and reversible thermal photoluminescence (RTPL), which is key for improving the thermal tolerance of luminescent solar concentrators (LSCs). In this work, the red‐emissive (661 nm) CsPb(Br0.25I0.75)3‐PMMA composite with high PLQY of 85.96% and favorable RTPL below 160 °C is reported via a strategy of the defect passivation by halide ligand additives. The composite film possesses excellent long‐term stability in air, water, and high temperature environments. Then, a self‐powered temperature detection system, which consists of LSCs and a temperature detection module based on the RTPL composite film, is fabricated. On one hand, RTPL composite makes LSCs of superior thermal tolerance even after 100 cycles of temperature between room temperature and 160 °C. On the other hand, RTPL composite in the opaque box of the temperature detection module can give rise to the signal light without the interference of ambient light. As a result, the self‐powered temperature detection system achieves the quantitative temperature data display at different environment lights for 24 h in a day.

Janus NbOBrI monolayer for efficient photocatalytic overall water splitting

Due to the presence of a built-in electric field, two-dimensional Janus materials can effectively reduce photogenerated carrier recombination while promoting carrier separation. In this work, the viability of Janus NbOBrI monolayer as a high-efficiency photocatalyst for water splitting was examined using first-principles calculations. The results demonstrate that the Janus NbOBrI monolayer exhibits appropriate band-edge potentials, significant visible light absorptions, high carrier separation efficiency and high enough carrier mobility along the Peierls distortion direction. Moreover, we have determined the variations in the Gibbs free energy for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) at various pHs, and found that the OER can occur spontaneously in the light environment. Applying -1.5 % uniaxial strain in the a(b) direction of the NbOBrI monolayer helps to increase the reduction potential and provide sufficient power for the HER, resulting in a solar-to-hydrogen (STH) efficiency of 8.9 % (9.3 %).

Evaluation of perception and analysis of energy saving potential of nighttime illumination in different types of residential areas: A case study of Dalian, China

The safety, comfort, and sustainability of the nighttime lighting environment in residential areas become increasingly the focus of social concern. This study integrates remote sensing observations, ground measurements, perception evaluations, and grading maps to compare the data of different residential areas, achieving perceptual performance assessment and energy-saving optimization of the lighting environment. The main researches include (1) Comparison of the Feeling of Safety (FoS) and Perceived Lighting Quality (PLQ) in the nighttime light environments of Dalian's residential areas by contrasting characteristics between high and low illuminated neighborhoods, new and old neighborhoods, open and enclosed neighborhoods, and internal and peripheral roads, (2)Establishment of a lighting environment perceptual evaluation model, proposing illuminance ranges for overall residential areas (6.67–17.97 lx), peripheral roads (8.79–24.50 lx), and internal roads (6.45–16.21 lx), (3) Construction a ground horizontal illuminance inversion model for Dalian and generate FoS and PLQ perception grading maps, (4) Within the scope of the study, the residential areas with insufficient, moderate, and excessive lighting account for 24 %, 56 %, and 20 %, respectively. This study provides effective strategies for reducing energy consumption, ensuring nighttime safety, and enhancing the comfort of living and helps to timely identify potential risk points that do not meet the perceptual standards.

Phenotypic variability of Montastraea cavernosa and Porites astreoides along a depth gradient from shallow to mesophotic reefs in the Cayman Islands

Phenotypic variability is the ability of the same species to express different phenotypes under different environmental conditions. Several coral species that exist along a broad depth distribution have been shown to differ in skeletal morphology and nutrient acquisition at different depths, which has been attributed to variability in response to differing levels of light availability. This study examined the phenotypic variability of two common depth generalist corals, Montastraea cavernosa and Porites astreoides, along a gradient from 10 to 50 m in the Cayman Islands, by examining changes in skeletal morphology, photophysiology, symbiont cell density, and chlorophyll concentration. Skeletal features of M. cavernosa were found to increase in size from 10 to 30 m, but returned to smaller sizes from 30 to 50 m, while P. astreoides skeletal features continued to increase in size from 10 to 40 m. No differences were observed in either symbiont density or chlorophyll concentration across depths for either species. However, all photophysiological parameters exhibited significant depth-dependent variations in both species, revealing adaptive strategies to different light environments. These results suggest that both species have high variability in response to depth. Patterns of skeletal morphology and photophysiology, however, suggest that M. cavernosa may be more variable in regulating photosynthetic efficiency compared to P. astreoides, which likely facilitates the broader depth distribution of this species.

Infrared and Harsh Light Visible Image Fusion Using an Environmental Light Perception Network.

The complementary combination of emphasizing target objects in infrared images and rich texture details in visible images can effectively enhance the information entropy of fused images, thereby providing substantial assistance for downstream composite high-level vision tasks, such as nighttime vehicle intelligent driving. However, mainstream fusion algorithms lack specific research on the contradiction between the low information entropy and high pixel intensity of visible images under harsh light nighttime road environments. As a result, fusion algorithms that perform well in normal conditions can only produce low information entropy fusion images similar to the information distribution of visible images under harsh light interference. In response to these problems, we designed an image fusion network resilient to harsh light environment interference, incorporating entropy and information theory principles to enhance robustness and information retention. Specifically, an edge feature extraction module was designed to extract key edge features of salient targets to optimize fusion information entropy. Additionally, a harsh light environment aware (HLEA) module was proposed to avoid the decrease in fusion image quality caused by the contradiction between low information entropy and high pixel intensity based on the information distribution characteristics of harsh light visible images. Finally, an edge-guided hierarchical fusion (EGHF) module was designed to achieve robust feature fusion, minimizing irrelevant noise entropy and maximizing useful information entropy. Extensive experiments demonstrate that, compared to other advanced algorithms, the method proposed fusion results contain more useful information and have significant advantages in high-level vision tasks under harsh nighttime lighting conditions.

Illumination Intelligent Adaptation and Analysis Framework: A comprehensive solution for enhancing nighttime driving fatigue monitoring.

Nighttime driving presents a critical challenge to road safety due to insufficient lighting and increased risk of driver fatigue. Existing methods for monitoring driver fatigue, mainly focusing on behavioral analysis and biometric monitoring, face significant challenges under low-light conditions. Their effectiveness, especially in dynamic lighting environments, is limited by their dependency on specific environmental conditions and active driver participation, leading to reduced accuracy and practicality in real-world scenarios. This study introduces a novel 'Illumination Intelligent Adaptation and Analysis Framework (IIAAF)', aimed at addressing these limitations and enhancing the accuracy and practicality of driver fatigue monitoring under nighttime low-light conditions. The IIAAF framework employs a multidimensional technology integration, including comprehensive body posture analysis and facial fatigue feature detection, per-pixel dynamic illumination adjustment technology, and a light variation feature learning system based on Convolutional Neural Networks (CNN) and time-series analysis. Through this integrated approach, the framework is capable of accurately capturing subtle fatigue signals in nighttime driving environments and adapting in real-time to rapid changes in lighting conditions. Experimental results on two independent datasets indicate that the IIAAF framework significantly improves the accuracy of fatigue detection under nighttime low-light conditions. This breakthrough not only enhances the effectiveness of driving assistance systems but also provides reliable scientific support for reducing the risk of accidents caused by fatigued driving. These research findings have significant theoretical and practical implications for advancing intelligent driving assistance technology and improving nighttime road safety.

Performance Characterization of an Illumination-Based Low-Cost Multispectral Camera.

Spectral imaging has many applications, from methane detection using satellites to disease detection on crops. However, spectral cameras remain a costly solution ranging from 10 thousand to 100 thousand euros for the hardware alone. Here, we present a low-cost multispectral camera (LC-MSC) with 64 LEDs in eight different colors and a monochrome camera with a hardware cost of 340 euros. Our prototype reproduces spectra accurately when compared to a reference spectrometer to within the spectral width of the LEDs used and the ±1σ variation over the surface of ceramic reference tiles. The mean absolute difference in reflectance is an overestimate of 0.03 for the LC-MSC as compared to a spectrometer, due to the spectral shape of the tiles. In environmental light levels of 0.5 W m-2 (bright artificial indoor lighting) our approach shows an increase in noise, but still faithfully reproduces discrete reflectance spectra over 400 nm-1000 nm. Our approach is limited in its application by LED bandwidth and availability of specific LED wavelengths. However, unlike with conventional spectral cameras, the pixel pitch of the camera itself is not limited, providing higher image resolution than typical high-end multi- and hyperspectral cameras. For sample conditions where LED illumination bands provide suitable spectral information, our LC-MSC is an interesting low-cost alternative approach to spectral imaging.

The Nurse-Implemented Chronotherapeutic Bundle in Critically Ill Children, RESTORE Resilience (R 2 ): Pilot Testing in a Two-Phase Cohort Study, 2017-2021.

Pilot test the nurse-led chronotherapeutic bundle in critically ill children, RESTORE Resilience (R 2 ). A two-phase cohort study was carried out from 2017 to 2021. Two similarly sized and organized PICUs in the United States. Children 6 months to 17 years old who were mechanically ventilated for acute respiratory failure. R 2 seven-item chronotherapeutic bundle, including: 1) replication of child's pre-hospital daily routine (i.e., sleep/wake, feeding, activity patterns); 2) cycled day-night light/sound modulation; 3) minimal effective sedation; 4) night fasting with bolus enteral daytime feedings; 5) early progressive mobility; 6) nursing care continuity; and 7) parent diaries. Children underwent environmental (light, sound) and patient (actigraphy, activity log, salivary melatonin, electroencephalogram) monitoring. Parents completed the Child's Daily Routine and Sleep Survey (CDRSS) and Family-Centered Care Scale. The primary outcome was post-extubation daytime activity consolidation (Daytime Activity Ratio Estimate [DARE]). Twenty baseline-phase (2017-2019) and 36 intervention-phase (2019-2021) participants were enrolled. During the intervention phase, nurses used the CDRSS to construct children's PICU schedules. Overall compliance with nurse-implemented R 2 elements 1-5 increased from 18% (interquartile range, 13-30%) at baseline to 63% (53-68%) during the intervention phase ( p < 0.001). Intervention participants were exposed to their pre-hospitalization daily routine ( p = 0.002), cycled day-night light/sound modulation ( p < 0.001), and early progressive mobility on more PICU days ( p = 0.02). Sedation target identification, enteral feeding schedules, and nursing care continuity did not differ between phases. Parent diaries were seldom used. DARE improved during the intervention phase and was higher pre-extubation (median 62% vs. 53%; p = 0.04) but not post-extubation (62% vs. 57%; p = 0.56). In the PICU, implementation of an individualized nurse-implemented chronotherapeutic bundle is feasible. Children who received the R 2 bundle had increased pre-extubation daytime activity consolidation compared to children receiving usual care. Given variation in protocol adherence, further R 2 testing should include interprofessional collaboration, pragmatic trial design, and implementation science strategies.

Untangling light in noisy luminous environments

Electric light sources, including displays and luminaires, often exhibit rapid light fluctuations called temporal light modulation (TLM). TLM can be seen as their electrical footprint. This work demonstrates that TLM can be remotely detected and used to perform in situ photometric and spectroradiometric measurements of very low light levels superimposed to intense backgrounds. Illuminance levels about 500 000 times smaller than the background were reliably measured by lock-in detection, allowing photometric measurements to be performed during daytime, even with sunny conditions. Using a new type of optical lock-in spectrometer, it becomes possible to retrieve spectral quantities through the TLM of the light source. The spectral distribution of an LED lamp was measured against a daylit background more than 1500 times brighter. Lock-in detection is an excellent technique to perform in situ measurements of electric light, even at very low level, in the presence of daylight and other background lights, opening interesting opportunities to characterize anthropogenic light pollution.