Ambient Illumination Research Articles

Design and Application of Indoor Intelligent Light Emitting Diode Lighting

In this research, an indoor intelligent light emitting diode (LED) lighting device is designed, which includes environmental brightness detection module, temperature detection module, display module and LED driving module. S5052 photodiode is selected for environmental brightness level, which can work normally in the environment of −25 °C to 75 °C, and the analog signal is converted into recognizable digital signal through MCP3204 A/D converter. The DS18B20 sensor is selected to measure the temperature, which is connected with the single chip microcomputer to collect the indoor temperature signal. Adopting constant current drive mode, HV9910 LED driver chip is selected to convert 220 V AC power supply into 5 V DC power supply, and AD1585 chip is used as reference power supply to suppress the fluctuation of DC power supply. The display module takes STC12C5A60S2 single chip microcomputer as the control module, and integrates MAX810 special reset circuit, 2-channel PWM and 8-channel 10-bit A/D converter, thus simplifying the peripheral circuit. During the test, the single chip microcomputer is initialized, the intelligent control part is embedded with data analysis technology, and the modular debugging method is adopted, and the illumination brightness value meets the expectations under different conditions. The ambient temperature is compared with the test temperature to keep consistent. Based on PWM method, dimming is carried out, and two environments are set (the first one is to maintain the ambient light illumination of 300lx, and the other one is to maintain the ambient light illumination of 100lx). The results show that the designed system is suitable for different lighting environments and can adjust the indoor lighting brightness adaptively.

Robust point cloud registration for map-based autonomous robot navigation

Robust point cloud registration for map-based autonomous robot navigation

Machine learning approach for ambient-light-corrected parameters and the Pupil Reactivity (PuRe) score in smartphone-based pupillometry.

The pupillary light reflex (PLR) is the constriction of the pupil in response to light. The PLR in response to a pulse of light follows a complex waveform that can be characterized by several parameters. It is a sensitive marker of acute neurological deterioration, but is also sensitive to the background illumination in the environment in which it is measured. To detect a pathological change in the PLR, it is therefore necessary to separate the contributions of neuro-ophthalmic factors from ambient illumination. Illumination varies over several orders of magnitude and is difficult to control due to diurnal, seasonal, and location variations. We assessed the sensitivity of seven PLR parameters to differences in ambient light, using a smartphone-based pupillometer (AI Pupillometer, Solvemed Inc.). Nine subjects underwent 345 measurements in ambient conditions ranging from complete darkness (<5 lx) to bright lighting (≲10,000 lx). Lighting most strongly affected the initial pupil size, constriction amplitude, and velocity. Nonlinear models were fitted to find the correction function that maximally stabilized PLR parameters across different ambient light levels. Next, we demonstrated that the lighting-corrected parameters still discriminated reactive from unreactive pupils. Ten patients underwent PLR testing in an ophthalmology outpatient clinic setting following the administration of tropicamide eye drops, which rendered the pupils unreactive. The parameters corrected for lighting were combined as predictors in a machine learning model to produce a scalar value, the Pupil Reactivity (PuRe) score, which quantifies Pupil Reactivity on a scale 0-5 (0, non-reactive pupil; 0-3, abnormal/"sluggish" response; 3-5, normal/brisk response). The score discriminated unreactive pupils with 100% accuracy and was stable under changes in ambient illumination across four orders of magnitude. This is the first time that a correction method has been proposed to effectively mitigate the confounding influence of ambient light on PLR measurements, which could improve the reliability of pupillometric parameters both in pre-hospital and inpatient care settings. In particular, the PuRe score offers a robust measure of Pupil Reactivity directly applicable to clinical practice. Importantly, the formulae behind the score are openly available for the benefit of the clinical research community.

A flexible bimodal self-powered optoelectronic skin for comprehensive perception of multiplexed sensoring signals

Multi-modal electronics skin that mimics collaborative operation of natural skin establishes a substantial foundation for next-generation smart healthcare, biomimetic science and related interdisciplinary fields. However, the power consumption of multi-channels and the decoupling complexity of fused-information that determine the effectiveness of the system still remain enormous challenge. Here, a bimodel self-powered optoelectronic fusion system with a vertical integration structure to achieve mechanical and illumination perception is reported, enabling simultaneous monitoring of human motion signal and environmental illumination. This device comprises a photo-conductive layer of MAPbI3-PVA and a teflon (PTFE) friction layer of TENG-based sensor, characterizing the mechanical and illuminance information in the form of pulse electrical signals and continuous resistance variation curves, respectively. This bimodel sensor exhibits the highest photoelectric responsivity of 64 mA/W and saturated output power of 156 μW/cm2 within the visible illumination range. Moreover, the environmental and mechanical stability of the device have been significantly improved, which is attributed to the inherent flexibility and hydrophilicity of PVA wrapped in perovskite grains. Finally, A 3×3 bimodel array is attached onto the volunteer's cervical vertebra for classifying motion posture and ambient illuminance by monitoring the surface tension distribution under different lighting conditions, validating the feasibility and promotion potential for application scenarios.

Key HPI axis receptors facilitate light adaptive behavior in larval zebrafish

The vertebrate stress response (SR) is mediated by the hypothalamic–pituitary–adrenal (HPA) axis and contributes to generating context appropriate physiological and behavioral changes. Although the HPA axis plays vital roles both in stressful and basal conditions, research has focused on the response under stress. To understand broader roles of the HPA axis in a changing environment, we characterized an adaptive behavior of larval zebrafish during ambient illumination changes. Genetic abrogation of glucocorticoid receptor (nr3c1) decreased basal locomotor activity in light and darkness. Some key HPI axis receptors (mc2r [ACTH receptor], nr3c1), but not nr3c2 (mineralocorticoid receptor), were required to adapt to light more efficiently but became dispensable when longer illumination was provided. Such light adaptation was more efficient in dimmer light. Our findings show that the HPI axis contributes to the SR, facilitating the phasic response and maintaining an adapted basal state, and that certain adaptations occur without HPI axis activity.

P‐3.10: A Model‐based Study on Perceived Brightness under Various Ambient Illuminance Levels

P‐3.10: A Model‐based Study on Perceived Brightness under Various Ambient Illuminance Levels

Wettability and Bactericidal Properties of Bioinspired ZnO Nanopillar Surfaces.

Nanomaterials of zinc oxide (ZnO) exhibit antibacterial activities under ambient illumination that result in cell membrane permeability and disorganization, representing an important opportunity for health-related applications. However, the development of antibiofouling surfaces incorporating ZnO nanomaterials has remained limited. In this work, we fabricate superhydrophobic surfaces based on ZnO nanopillars. Water droplets on these superhydrophobic surfaces exhibit small contact angle hysteresis (within 2-3°) and a minimal tilting angle of 1°. Further, falling droplets bounce off when impacting the superhydrophobic ZnO surfaces with a range of Weber numbers (8-46), demonstrating that the surface facilitates a robust Cassie-Baxter wetting state. In addition, the antibiofouling efficacy of the surfaces has been established against model pathogenic Gram-positive bacteria Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli). No viable colonies of E. coli were recoverable on the superhydrophobic surfaces of ZnO nanopillars incubated with cultured bacterial solutions for 18 h. Further, our tests demonstrate a substantial reduction in the quantity of S. aureus that attached to the superhydrophobic ZnO nanopillars. Thus, the superhydrophobic ZnO surfaces offer a viable design of antibiofouling materials that do not require additional UV illumination or antimicrobial agents.

A robust non-contact heart rate estimation from facial video based on a non-parametric signal extraction model

Remote photoplethysmography (rPPG) is a non-contact method to extract heart rate (HR) pulse signals from facial videos. However, challenges persist due to head motion disturbances and ambient illumination variations. To address these issues, a novel non-parametric signal extraction model is proposed for HR estimation using the webcam camera. We first select the better-quality RGB signal from the divided face regions through the ranking of signal-to-noise ratio (SNR). Then, we use blind source separation and skin reflection modeling to eliminate the effect of ambient illumination. Finally, we employ a non-parametric signal extraction model named circulant singular spectrum analysis (CiSSA), with frequency-based decomposition and energy-driven reconstruction, to extract the HR-related pulse signal effectively. To evaluate the performance of our method, we conducted the validation experiments on three datasets, including two public datasets (UBFC and PURE dataset) and one self-collected dataset (ILVA dataset). Our method outperformed significantly on all three datasets, achieving Mean Absolute Deviation (MAD) of 2.42, 1.36, and 2.84 bpm, Root Mean Square Error (RMSE) of 1.89, 2.24, and 3.58 bpm, and Pearson Correlation Coefficients (PCC) of 0.98, 0.98, and 0.93, respectively. The experimental results demonstrate that our method achieves comparable performance, particularly in scenarios involving severe head motion disturbances and variations in ambient illumination.

Solution-processed CsPbBr3 perovskite films via CsBr intercalated PbBr2 intermediate for high-performance photodetectors towards underwater wireless optical communication

All inorganic CsPbBr3 perovskite is regarded as a promising candidate of halide perovskites and has attracted great attention due to its superior optoelectronic properties and stability. However, the low and unbalanced solubility of precursors and uncontrollable crystallization result in poor coverage and impurity phases in CsPbBr3 polycrystalline films, hindering the application in optoelectronic devices. In this work, a facile CsBr intercalated nanostructured intermediate based two-step method is reported for simultaneously achieving good morphology and pure phase of CsPbBr3 films. With the CsBr intercalation, the intermediate films deposited in the first step exhibit porous nanostructure and CsxPb2Br4+x crystal phase. This unique porous morphology and crystal structure favor CsBr solution penetration and Cs+ ion diffusion. First-principles calculations are conducted to investigate the phase diagram of intermediates and the diffusion kinetics of Cs+ ions in the various polymorphs. The key role of CsBr intercalation is confirmed for achieving high-quality CsPbBr3 perovskite films with features of pinhole free, pure phase, large grains, and high crystallinity. Photodetectors based on optimized CsPbBr3 films exhibit excellent performance with a peak EQE of 83%, responsivity of 0.35 A/W, and specific detectivity of 1.25×1013 Jones. Fast response speed is also achieved with rise/fall time of 1.41 μs and 2.06 μs and −3 dB bandwidth up to 800 kHz. Moreover, CsPbBr3 PD shows great potential in the application of underwater wireless optical communication due to its low background noise current under ambient light illumination. Overall, this work paves the way for further research on optoelectronic devices and their applications based on CsPbBr3 films.

Design and Evaluation of Wireless DYU Air Box for Environment-Monitoring IoT System on Da-Yeh University Campus

This paper presents an original wireless DYU Air Box of an environment-monitoring IoT (EMIoT) system on a campus to offer information on environmental conditions through the public ThingSpeak IoT platform for stakeholders including all the students and employees on the Da-Yeh University (DYU) campus in Taiwan. Firstly, the proposed wireless heterogeneous multi-sensor module aggregates BME680, SCD30, PMS7003, and BH1750 sensors with a TTGO ESP32 Wi-Fi device based on the I2C and UART interface standards of series communication. Through the DYU-802.1X Wi-Fi network with the WPA2 Enterprise security directly, the wireless multi-sensor monitoring module further forwards the observation data of environmental conditions on campus via the DYU-802.1X Wi-Fi network to the public ThingSpeak IoT platform, which is a cloud service platform to aggregate, visualize, and analyze live sensing data of air quality index (AQI), concentrations of PM1.0/2.5 and CO2, brightness, ambient temperature, and relative humidity (RH). The results illustrate the proposed DYU Air Box for monitoring the indoor environmental conditions on campus and validate them with sufficient accuracy and confidence with commercialized measurement instruments. In this work, the wireless smart environment-monitoring IoT system features monitoring and automatic alarm functions for monitoring AQI, CO2, and PM concentrations, as well as ambient illumination, temperature, and RH parameters and collaboration and interoperability through the Enterprise Intranet. All the organizational stakeholders interested in the environmental conditions of the DYU campus can openly access the information according to their interests. In the upcoming future, the information of the environmental conditions in the DYU campus will be developed to be simultaneously accessed by all the stakeholders through both the public ThingSpeak IoT platform and the private EMIoT system.

Enhancing legibility in educational settings: Optimizing projection illuminance for varied indoor ambient illuminance

Projectors are common display devices in the educational setting. However, dim projector lightbulbs or well-lit classrooms may cause blurriness in the projected image. To determine the optimal projection light under different ambient light conditions, the conjoint effects of projection illuminance and ambient illuminance on the legibility of projection images indoors were investigated. Participants (N = 96) were randomly assigned to one of six indoor ambient light conditions (0, 40, 80, 120, 160, and 200 lx) and performed a visual search task under several projection illuminance conditions (200, 250, 300, 350, and 400 lx). The accuracy and correct response time on the task were collected to evaluate the participants’ visual performance to represent legibility. The optimal projection illuminance (high visual accuracy and fast reaction) was 400 lx (944 ANSI lumen) under all ambient light conditions. To avoid low legibility (accuracy<0.6) and maintain acceptable legibility (accuracy>0.7), the projection illuminance should be increased as the indoor ambient light increases.

An approach to ensure joint illumination &amp; communication performance of a forward error corrected indoor visible light communication (VLC) system in presence of ambient light interference

Abstract In recent time of looming radio frequency (RF) spectrum crisis, visible light communication using lighting infrastructure emerged as a potential alternative at an indoor environment. This paper addresses the setback associated with ambient light interference in an indoor Visible Light Communication (VLC) system to ensure joint communication and illumination performance inside an office room. A novel VLC architecture with suitable white light emitting diode (WLED) luminaire arrangement is presented to minimize the dispersion of signal to interference plus noise ratio (SINR) across the room. Luminaires are categorized in two groups viz. data transmitting illuminants and illuminants for lighting purpose. The first group is dedicated to transmit data as well as serves the purpose of illumination. The other set creates only ambient illumination to achieve quality lighting attributes. The proposed forward error corrected receiver configuration discards the ambient light noise originated by the illuminants that serve the ambient illumination. Tail biting convolutional encoder and viterbi decoder are used at the encoding section of the transmitter and decoding section of the receiver respectively to improve bit error rate. Results obtained through MATLAB simulation shows better average bit error rate (BER) in the order of 10−8 measured at uniformly distributed 25 grid points over the working plane. At the same time achieved average horizontal illuminance with good uniformity comply with ISO recommendation.

Effects of Screen Color Mode and Color Temperature on Visual Fatigue under Different Ambient Illuminations

Viewing electronic screens for a long time can cause visual fatigue, even induce eye problems such as refractive errors, dry eyes, etc. The relationship between screen display and visual fatigue has received much attention. This article aims to study the optimal display color temperature and color mode under two common ambient illuminations—normal office lighting (450 lux) and dark environment (3 lux). In a 2 × 2×3 experimental design, 36 participants evaluated the effects of two display color modes (light mode and dark mode) and three screen color temperatures (2800 K, 4500 K, and 6500 K) on visual fatigue under two ambient illuminations. We used eye movement tracking technology to collect blink rate and pupil diameters as objective indicators and used the Richter scale to collect subjective visual fatigue and preference score as subjective indicators. Results showed that at 450 lux, lower visual fatigue was found in the dark mode, 4500 K and 6500 K. At 3 lux, the visual fatigue was lower in the dark mode and 4500 K color temperature. Whether at daytime or night, the 2800 K color temperature resulted in the highest visual fatigue. Our findings complement the research on screen display and visual fatigue. They have practical implications for reducing visual fatigue caused by prolonged viewing of electronic screens.

Photo-oxidative Crack Propagation in Transition Metal Dichalcogenides.

Monolayered transition-metal dichalcogenides (TMDs) are easily exposed to air, and their crystal quality can often be degraded via oxidation, leading to poor electronic and optical device performance. The degradation becomes more severe in the presence of defects, grain boundaries, and residues. Here, we report crack propagation in pristine TMD monolayers grown by chemical vapor deposition under ambient conditions and light illumination. Under a high relative humidity (RH) of ∼60% and white light illumination, the cracks appear randomly. Photo-oxidative cracks gradually propagated along the grain boundaries of the TMD monolayers. In contrast, under low RH conditions of ∼2%, cracks were scarcely observed. Crack propagation is predominantly attributed to the accumulation of water underneath the TMD monolayers, which is preferentially absorbed by hygroscopic alkali metal-based precursor residues. Crack propagation is further accelerated by the cyclic process of photo-oxidation in a basic medium, leading to localized tensile strain. We also found that such crack propagation is prevented after the removal of alkali metals via the transfer of the sample to other substrates.

Crystalline engineering of FAPbI3 via pyrrolidinium ionic liquid for stable perovskite solar cells with 21.72% efficiency.

Improving the crystallinity of formamidinium triiodide (FAPbI3) perovskite layer is one of the most effective approaches to increase the photovoltaic performance and stability of FAPbI3-based solar cells (FSCs). In the current study, FAPbI3 layers were fabricated through a sequential deposition method. The morphology and crystalline properties of the FAPbI3 layers were modified by controlling the lead iodide (PbI2) precursor by adding pyrrolidinium (Pyr) material into the PbI2 layer and modulating the FAPbI3 crystallization. The Pyr contributed to obtain (001)-preferred FAPbI3 orientation with no yellow photo-inactive phase. Subsequently, it reduced the unreacted PbI2 phase in the perovskite layer and suppressed the defect density, resulting in extended carrier lifetimes and improved ambient air and illumination stabilities. The Pyr-mediated FSCs recorded a champion efficiency of 21.72%, which is higher than that of control FSCs with a maximum efficiency of 19.08%. The developed Pyr-mediated method offers a practical and effective approach to fabricate stable and efficient FSCs.

An Average Amplitude Regulation Scheme for Ambient Illuminance Adaptation in Retinal Prosthesis

An Average Amplitude Regulation Scheme for Ambient Illuminance Adaptation in Retinal Prosthesis

Metalens for Accelerated Optoelectronic Edge Detection under Ambient Illumination.

Analog systems may allow image processing, such as edge detection, with low computational power. However, most demonstrated analog systems, based on either conventional 4-f imaging systems or nanophotonic structures, rely on coherent laser sources for illumination, which significantly restricts their use in routine imaging tasks with ambient, incoherent illumination. Here, we demonstrated a metalens-assisted imaging system that can allow optoelectronic edge detection under ambient illumination conditions. The metalens was designed to generate polarization-dependent optical transfer functions (OTFs), resulting in a synthetic OTF with an isotropic high-pass frequency response after digital subtraction. We integrated the polarization-multiplexed metalens with a polarization camera and experimentally demonstrated single-shot edge detection of indoor and outdoor scenes, including a flying airplane, under ambient sunlight illumination. The proposed system showcased the potential of using polarization multiplexing for the construction of complex optical convolution kernels toward accelerated machine vision tasks such as object detection and classification under ambient illumination.

Assessments of Mean Reflectance Surface Exitance and Contrast in a Museum: Comparison Between Simulation, Calculation and Field Measurements

Museums are artistic centers that attract people as tourist destinations, allowing them to appreciate art, and learn about history, culture, society, and science. The visual presentation of museum spaces is crucial in enhancing the appeal to visitors. It is closely tied to visual appearance and ambient illumination of the space, which can be represented by Mean Room Surface Exitance (MRSE). The objectives of this research are to determine the lighting specifications in exhibition spaces by considering lighting metrics, including MRSE and contrast, and to compare the MRSE values obtained from the calculation, simulation, and measurements from field experiments. The findings of this research indicate that the type of luminaire that can be used is a spotlight with a TAIR (Target-to-Ambient Illuminance Ratio (TAIR) of 3:1 or higher, particularly if the object needs to appear brighter than its surroundings. The error between the experimental and simulated results with the DIALux evo simulation tool was relatively low at 1.4%. However, the error between the experimental results and the calculated results was relatively high, at 25.25%, which is caused by the TAIR factor. The lowest contrast error was obtained for the displayed statue, with a 4% error in the calculation method and 0% error in the simulation method. The highest contrast error was obtained for the wall, with a 66% error in the simulation method due to differences in the room size of the simulation model and the actual space.

Luminance and Detail Enhancement for HDR Images Based on Surround-Aware Perceptual Quantization Under Ambient Illumination

The lighting conditions of mobile devices could severely affect the viewing experience of the displayed image, such as loss of details and contrast, especially for high dynamic range (HDR) contents. In this paper, a content independent luminance and detail enhancement method is proposed for HDR images under ambient illumination. The perceptual luminance at the given lighting conditions is first quantified based on the human visual adaption. Combining the quantization curve and the display model, the mapping operator for the luminance channel could then be efficiently constructed. Both psychophysical evaluation and objective measurement indicate that the proposed method significantly improves the perceptual quality of HDR images under ambient illumination.

The influence of illumination regimes on the structure of ant (Hymenoptera, Formicidae) community composition in urban habitats

The reliance on visual cues can vary among ant species living in different habitats, and is mostly influenced by the level of ambient illumination and the morphological adaptations of ant species that can determine their period of daily activity. Thus, different illumination regimes might affect ant community composition in habitats with different ambient illumination intensities. Despite this, in the literature, information is scarce about the effects of ambient illumination on ant activity. In the present study, we investigated the effect of ambient illumination intensity on the activity of ant species and their community composition under herbaceous and woody plants in 24 localities from Kyiv and Kyiv region, Ukraine. Our results showed that the ambient illumination properties of the habitat type affect the presence of ant species and the activity of their workers. In open habitats, the maximum ambient illumination had a negative effect, whereas in closed, woody habitats the maximum ambient illumination and tree circumference generally had a positive effect on the number of non-dendrobiotic ant individuals found on individual plants. The dendrobiotic species were less affected by the maximum illumination intensity. Although, in closed habitats, the effect of the previous variables and their interaction had species-specific aspects. Based on the former, we can tell that more structured forest habitats can provide broader illumination intensity ranges, allowing more ant species to coexist. However, similar illumination intensity ranges can lead to overlaps in the activity of ant species under the same illumination conditions, especially in open habitats. The outcomes of these interactions are highly influenced by larger trees that besides lowering illumination intensities, can enhance ant worker activity and promote species coexistence.