Illumination Area Research Articles

Liquid-metal-based three-dimensional microelectrode arrays integrated with implantable ultrathin retinal prosthesis for vision restoration

Electronic retinal prostheses for stimulating retinal neurons are promising for vision restoration. However, the rigid electrodes of conventional retinal implants can inflict damage on the soft retina tissue. They also have limited selectivity due to their poor proximity to target cells in the degenerative retina. Here we present a soft artificial retina (thickness, 10 μm) where flexible ultrathin photosensitive transistors are integrated with three-dimensional stimulation electrodes of eutectic gallium–indium alloy. Platinum nanoclusters locally coated only on the tip of these three-dimensional liquid-metal electrodes show advantages in reducing the impedance of the stimulation electrodes. These microelectrodes can enhance the proximity to the target retinal ganglion cells and provide effective charge injections (72.84 mC cm−2) to elicit neural responses in the retina. Their low Young’s modulus (234 kPa), owing to their liquid form, can minimize damage to the retina. Furthermore, we used an unsupervised machine learning approach to effectively identify the evoked spikes to grade neural activities within the retinal ganglion cells. Results from in vivo experiments on a retinal degeneration mouse model reveal that the spatiotemporal distribution of neural responses on their retina can be mapped under selective localized illumination areas of light, suggesting the restoration of their vision.

LED Arrays Design for Large Area and High Uniform Illumination

LED Arrays Design for Large Area and High Uniform Illumination

Illumination homogenization of highly coherent light source based on phase modulation

When using a fly’s eye lens system to homogenize highly coherent light sources, the interference effect between the sub-beams can cause a periodic speckle distribution of illumination intensity, thereby disrupting illumination uniformity. It has been shown that using a rotating optical phase-shift plate behind the fly’s eye lens can eliminate interference patterns, but it only demonstrates engineering realizations. And the theoretical analysis and technical guidance on the phase modulation method and statistical averaging method for fly’s eye lens homogenization systems are still lacking. In this work, a simulation model of fly’s eye random phase modulation homogenization system is developed and studied in detail. Each sub-beam of the fly’s eye lens is randomly phase-modulated to break the coherence condition, and the illumination intensity of multiple independent modulations is accumulated to eliminate the interference pattern. The more times the intensity is accumulated, the better the homogenization is. Meanwhile, studied in this paper are the influence of the diffraction effect on homogenization, and the influence of the sub-lens size and focal length on the homogenization, which result in the diffracting-type system and the imaging-type system respectively. For an imaging type system, it is necessary to ensure that the first fly’s eye lens is in the front focal plane of the second fly’s eye lens. By optimizing the parameters of the fly’s eye lens and using an imaging-type system with <i>p</i> = 1.8 mm and <i>f</i><sub>A</sub> = 9 mm, a Gaussian beam with the non-uniformity of 117% is homogenized into a flat-topped beam with the non-uniformity of 1.2% in a square illumination area of 100 mm<sup>2</sup>. This fly’s eye lens random phase modulation homogenization system has a simple structure, low energy loss, and good illumination uniformity, and can be used in systems that require high coherent laser input and high resolution. This technology can be used in the field of deep-ultraviolet mask defect detection.

Experimental approval of the working modes of the Sunbrick sun simulator

Commissioning and experimental testing of technical capabilities and modes of operation were carried out, and test measurements of light current-voltage characteristics of solar cells were carried out using a modern measuring complex based on the Sunbrick sun simulator. Automated measurement of the light-voltage-current characteristics of solar cells by the compensation method using the Keithley 2400 measuring device was implemented. During the approbation of the measuring complex based on the Sunbrick sun simulator, the possibility of reproducing different modes of simulator operation was tested and the ability to control radiation in terms of energy in the range from 100 to 1100 W/m2 and by spectral composition. It was established that the spatial unevenness of illumination for the investigated device is less than 2 % with an illumination area of more than 400 cm2. It is shown that the tested measuring complex allows for automated research of solar cells in irradiation regimes corresponding to both terrestrial irradiation conditions and extraatmospheric solar radiation conditions. The possibility of individual adjustment of each of the 36 channels of the emitting element in the range from 400 to 1100 nm has been tested, which adds flexibility in the use of the Sunbrick sun simulator during the study of both solar cells as a whole and the properties of functional semiconductor materials by irradiation with monochromatic or mixed illumination. It is shown that due to the rapidity of conducting research and the ability to immediately visualize the measured current-voltage characteristic on the computer screen, it is possible to significantly speed up the process of researching solar cells. Thus, it is possible to immediately divide the investigated solar cells into groups in relation to their efficiency and determine the presence of possible defects or damage in their structure.

Prompt Hole Extraction Suppresses V5+ Dissolution and Sustains Large-Area BiVO4 Photoanodes for Over 2100 h Water Oxidation.

Nanostructured bismuth vanadate (BiVO4) is at the forefront of emerging photoanodes in photoelectrochemical tandem devices for solar water splitting owing to the suitable band edge position and efficient charge separation capability. However, the (photo)chemical corrosion involving V5+ dissolution limits the long-term stability of BiVO4. Herein, guided by DFT calculations, we introduce an ALD-derived NiOx catalyst layer on BiVO4 to stabilize the surface Bi-O bonds, facilitate hole extraction, and thus suppress the V5+ dissolution. At the same time, the ALD NiOx catalyst layer could efficiently suppress the surface recombination and accelerate the surface OER kinetics, boosting the half-cell applied bias photon-to-current efficiency of BiVO4 to 2.05%, as well as a fill factor of 47.1%. By adding trace NaVO3 to the electrolyte, the NiOx/BiVO4 photoanode with an illumination area of 10.5 cm2 shows a record operational stability of more than 2100 h.

Analysis of Light Obstruction from Street Lighting in Road Scenes

As urban greenery improves and the ecological environment is continuously optimized, road facilities are also impacted to varying degrees. For example, as vegetation grows, it causes varying degrees of obstruction to the lighting facilities on the roads. This article is based on vehicle-mounted LiDAR data and focuses on the point cloud data characteristics of different objects. Using appropriate modeling techniques, it accurately models road surfaces, green belts, streetlights, and other objects. On the Lumion platform, this system creates a 3D visualization of road scenes and examines the interplay between objects and lighting space, analyzing lit areas. Leveraging the precise 3D spatial relationships found in point clouds, it determines the effective illumination area on the ground from streetlights after object obstruction, comparing it to the theoretical illumination area. This not only visualizes the road scene but also quantifies the lighting obstruction rate. Furthermore, it assesses the lighting conditions in road scenes based on illuminance distribution, offering scientific insights and suggestions for enhancing road lighting.

Plasma Treatment for Achieving Oxygen Substitution in Layered MoS2 and the Room-Temperature Mid-Infrared (10 μm) Photoresponse.

Highly sensitive photodetectors in the mid-infrared (MIR, 3-15 μm) are highly desired in a growing number of applications. However, only a handful of narrow-band-gap semiconductors are suitable for this purpose, most of which require cryogenic cooling to increase the signal-to-noise ratio. The realization of high-performance MIR photodetectors operating at room temperature remains a challenge. Herein, we report on plasma-treated few-layer MoS2 for room-temperature MIR (10 μm) photodetection. Oxygen plasma treatment, which is a mature microfabrication process, is employed. The ion kinetic energy of oxygen plasma is adjusted to 70-130 eV. A photoresponsivity of 0.042 mA/W and a detectivity of 1.57 × 107 Jones are obtained under MIR light (10 μm) illumination with an average power density of 114.6 mW/cm2. The photoresponse is attributed to the introduction of electronic states in the band gap of MoS2 through oxygen substitution. A graphene/plasma-treated MoS2/graphene device is further demonstrated to shorten the active channel while maintaining the illumination area. The photoresponsivity and detectivity are largely boosted to 1.8 A/W and 2.64 × 109 Jones, respectively. The excellent detective performance of the graphene/plasma-treated MoS2/graphene device is further demonstrated in single-detector MIR (10 μm) scanning imaging. This work offers a facile approach to constructing integrated MoS2-based MIR photodetectors.

Accurate color characterization of solar photovoltaic modules for building integration

Accurate and reproducible color characterization is essential for colored building integrated photovoltaic products, both for manufacturing quality control and assessing long-term color stability. However, existing characterization techniques struggle to accurately determine color when a surface is behind a transparent layer like a solar PV laminate. In this study, we compare different colorimetric techniques and propose an innovative colorimeter based on a fiber optic spectrometer and large area illumination to address this issue. Samples with varying transparent glass thicknesses and underlying colors are laminated and characterized using a scanner, an integrated sphere spectrometer, a commercial portable colorimeter, and the proposed large area illumination colorimeter. Results show that common scanners produce darker images and inaccurate color determination due to light losses in the glass. As glass thickness increases, reflectance decreases with the integrated sphere spectrometer and portable colorimeter. However, the large area illumination colorimeter exhibits only minimal signal reduction. High reflective foils experience more reflectance reduction with thicker glass than low reflective ones. All devices yield comparable results without the glass layer. The large area illumination colorimeter, compensating for light losses, proves to be a suitable solution for accurately measuring color under glass laminates using reflected light. For example, it reduces the color change from 57 (commercial portable colorimeter) to only 3 for an ivory colored glass laminate. This innovative tool has the potential to improve color characterization in building integrated photovoltaic products, enabling better manufacturing quality control and assessment of long-term color stability.

Open fringes interferograms generation through the phase contrast technique

Phase contrast imaging is a proven technique for sensing optical wavefronts and obtaining qualitative and quantitative insights into phase disturbances. Traditionally, this method involves introducing a phase mask at the Fourier transform plane of the phase object to create a synthetic reference wave that interferes with the analyzed phase disturbance. In this study, we incorporate an intensity-dependent photorefractive material, facilitating the self-induction of a Zernike-type phase filter. We introduce an innovative modification by inducing an angular offset between the synthetic reference wave and the phase distribution of the object. Effective implementation necessitates an illumination area larger than the phase object's support. This method stands out due to its resilience to environmental factors, shared by all common-path interferometers. Furthermore, it leverages open fringe interferograms, consolidating all essential phase information into a single image. This innovation streamlines phase retrieval, eliminating the need for multiple images, and extends applicability beyond small-phase object perturbations. We present results demonstrating the recovered phase distribution using the well-established Takeda technique for open fringe interferograms. This novel approach promises to enhance phase distortion analysis, offering versatility and simplicity in a variety of applications.

The Angular Use of Light in Architecture and the Concept of Space

In this study, the analysis of the understanding of space under the influence of light was made. The content of the study touched on the effect of light and space on human perception, both architecturally and computationally. The identity that the light adds to the space, the interaction of the material with the light, and the illusory properties of the light are explained. While examining these abstract concepts, the illumination area of the light was calculated with a computational application. The fact that light is one of the most effective elements used in space has revealed the necessity of designing form, material, and lighting together. It is understood that the effect of basic elements that make up space, such as form and material color, can be increased with angular lighting. It has been understood that if a textured surface is illuminated with a directional light, the visual effect of the surface will increase. However, it has been understood that a material with a smooth structure and a material with a rough structure cannot be illuminated with the same lighting method, and this visual effect will create negativity. For original lighting designs, it is necessary to make accented or homogeneous lighting according to the need, and it is possible to provide this with designed-planned lighting.

Long-range Fourier ptychographic imaging of the dynamic object with a single camera.

Fourier ptychographic imaging technology is a new imaging method proposed in recent years. This technology captures multiple low-resolution images, and synthesizes them into a high-resolution image in the Fourier domain by a phase retrieval algorithm, breaking through the diffraction limit of the lens. In the field of macroscopic Fourier ptychographic imaging, most of the existing research generally focus on high-resolution imaging of static objects, and applying Fourier ptychographic imaging technology to dynamic objects is a hot research area now. At present, most of the researches are to use camera arrays combined with multiplexed lighting, deep learning or other algorithms, but the implementation of these methods is complicated or costly. Based on the diffraction theory of Fourier optics, this paper proposes that by expanding and focusing the illumination area, we can apply Fourier ptychographic imaging technology with a single camera to moving objects within a certain range. Theoretical analysis and experiments prove the feasibility of the proposed method. We successfully achieve high-resolution imaging of the dynamic object, increasing the resolution by about 2.5 times. This paper also researches the impact of speckles in the illuminated area on imaging results and proposes a processing method to reduce the impact of speckles.

MLFFusion: Multi-level feature fusion network with region illumination retention for infrared and visible image fusion

Infrared image and visible light image fusion is widely used in night vision, surveillance, military and other fields. The focus of the fusion task is to integrate complementary information in visible and infrared light images and eliminate redundant information. In addition, most of the fusion tasks are performed in the harsh environment of low light, and it is worth studying how to maintain the lighting information of the fusion results. In order to solve the problems existing, firstly, we designs a multi-level feature module to fusion multi-source information. Different from the parallel layer fusion strategy of the traditional network, we proposed a fusion strategy combine parallel layers and depth layers. Secondly, we add attention computing to the feature extraction network to improve the performance of the feature extraction network. Thirdly, in order to make the fusion image have good illumination information, we design the area illumination retention module, improved the performance of the fusion algorithm in low-light environments. A large number of experiments show that the proposed method has excellent performance and will perform better in low light environment. In addition, the proposed algorithm also shows great potential in multi modal object detection.

The subject-environment interplay between runners from different Brazilian macro-regions.

Our purpose was to investigate the interplay between runners and their environment using a network approach. This cross-sectional study sampled Brazilian runners of both sexes, from the five macro-regions of the country. An electronic questionnaire was used to obtain information regarding age, sex, training volume, socio-economic level, place of residence, and running pace. Environmental indicators (public illumination, pavement, sidewalk, and green areas) were collected from available public information. Descriptive statistics were presented in mean (SD), and frequency (%). A network analysis was performed to evaluate the association between individual and environmental characteristics. Statistical analyses were performed in the JASP, considering p < 0.05. At North and Mid-West regions, public illumination presents the highest values for the expected influence (1.74 and 1.56), while in Northeast and Southeast, sidewalks present the highest values (2.13; 0.91). For betweenness centrality, in North, Northeast, and Mid-West regions, residency in the capital of a state presented a hub. In contrast, pavement, and training volume present higher values in the South and Southeast. Network topologies are different. Public illumination (North and Mid-West) and sidewalk (Northeast, Southeast) were the most important variables for runners. Continental size countries need specific approaches to improve physical activity levels and health outcomes that consider the cultural, historical, and environmental background.

Advancing sustainable solutions: Harnessing polyaniline/BiOCl/GO ternary nanocomposites for solar-powered degradation of organic pollutant and photocatalytic hydrogen generation

Recently, polyaniline-based photocatalysts have gained great attention due to their narrow band gap (E = 1.77 eV), which enables them to absorb a significant amount of visible light (∼43%) in the solar spectrum. In this study, we have synthesized a ternary nanocomposite (PANI/BiOCl/GO) through an oxidative polymerization approach, incorporating polyaniline (PANI), graphene oxide (GO), and bismuth oxychloride (BiOCl). Different weight percentages of composites (GO/BiOCl: 0.5%, 1%, 2.5%, and PANI: 99.5%, 99%, 97.5%) were prepared and named as 0.5PBG, 1PBG, and 2.5PBG, respectively. The ternary nanocomposite's successful development, crystallinity, purity, porosity, and optical properties were evaluated through several spectroscopic and surface analysis techniques, including UV–Vis-DRS, PL, XRD, XPS, BET, and EDS analysis. FESEM and HRTEM images unveiled the porous characteristics of PANI, the morphology of exfoliated GO layers, and the nanoplate-like structure of BiOCl. The ternary nanocomposite was finally tested for its ability to degrade an organic dye, rhodamine-b (Rhb), and in the process also generate solar-light-driven green hydrogen by water half-splitting. The composite achieved about 90% detoxification (assigned from GC-TCD by analyzing the evolved CO2 gas after degradation) and 96% color removal of Rhb dye within 120 min. The degradation of Rhb by 1PBG displayed a first-order reaction, featuring a rate constant 7.25 times higher than that observed for pure PANI, 3.8 times higher than for pure GO, and 3.9 times higher than for pure BiOCl. Thus, the ternary composites achieve a good amount of synergy. Significantly, this reaction rate constant is 4.7 times greater than the rate observed with commercially used TiO2–P25 photocatalyst. Various reaction parameters including solution pH, different illumination areas, catalyst dosage, and the study of scavengers were investigated to understand their effects on the degradation reaction. The photocatalyst's reusability effectiveness was evaluated over 6 cycles, and its stability was subsequently confirmed through XRD and ICP-OES analysis. The LC-MS study revealed the identification of various intermediates and end products following the degradation reaction. The nanocomposite also produced 1000 ppm of hydrogen gas with an apparent quantum efficiency (AQE) of 17.97% when CH3OH was used as a sacrificial agent, 500 ppm (AQE of 9.69%) in the acidic conditions, and 600 ppm (AQE of 11.63%) in the basic conditions. In a broader perspective, this endeavor paves the way for exploring fresh opportunities in the utilization of this ternary nanocomposite. Its potential extends beyond accelerating dye degradation to encompass diverse solar-driven applications as well.

In-line Raman spectroscopy for characterization of an industrial poultry raw material stream

In this work, we evaluated the feasibility of Raman spectroscopy as an in-line raw material characterization tool for industrial process control of the hydrolysis of poultry rest raw material. We established calibrations (N = 59) for fat, protein, ash (proxy for bone) and hydroxyproline (proxy for collagen) in ground poultry rest raw material. Calibrations were established in the laboratory using poultry samples with high compositional variation. Samples were measured using a wide area illumination Raman probe at varying working distance (6 cm, 9 cm, 12 cm) and probe tilt angle (0°, 30°) to mimic expected in-line variations in the measurement situation. These moderate variations did not significantly affect performance for any analytes. The obtained calibrations were tested in-line with continuous measurements of the ground poultry by-product stream at a commercial hydrolysis facility over the course of two days. Measurements were acquired under demanding conditions, e.g. large variations in working distance. Reasonable estimates of compositional trends were obtained. Validation samples (N = 19) were also reasonably well predicted, with RMSEPcorr = [0.14, 1.37, 2.36, 1.51]% for hydroxyproline, protein, fat and ash, respectively. However, there were indications that further calibration development and robustification of pre-processing would be advantageous, particularly with respect to hydroxyproline and protein models. It is the authors’ impression that with such efforts, potentially in combination with development of practical measurement setup, the use of Raman spectroscopy as a process control tool for the hydrolysis of poultry rest raw materials is within reach.

Vertical Multi-Junction Laser Power Converters with 61% Efficiency at 30 W Output Power and with Tolerance to Beam Non-Uniformity, Partial Illumination, and Beam Displacement

Stable and reliable optical power converting devices are obtained using vertical multi-junction laser power converters. They are based on the GaAs and the InP material systems and are used for power-over-fiber or power-beaming applications. This study demonstrates that, in addition to providing the overall best conversion efficiencies with output voltages ideal for various applications, these semiconductor photovoltaic devices are very tolerant to beam non-uniformity, partial illumination, or beam displacement variations. Examples are given with two tight beams, each covering as little as ~7% of the cell area. An optical input power of 10 W was converted with still an efficiency of Eff ~59.4%. For an input power of 20 W, the illuminated area was set to ~22% without significantly affecting the conversion efficiency of Eff ~60%. Remarkably, for a beam diameter at ~65% of the chip length (i.e., covering ~35% of the chip area), a converted power of 29.5 W was obtained using a 12-junction GaAs device with a conversion efficiency of 61%. For a 10 junction InP-based device, an efficiency of Eff = 51.1% was obtained at an output voltage reaching as high as Voc = 5.954 V for an average optical intensity of 69 W/cm2 and an illumination area of ~57%.

Elliptically polarized light photoelasticity based on LCD.

We propose a three-wavelength elliptically polarized light photoelasticity method for high efficiency and low-cost stress measurement. By illuminating the sample with two different forms of elliptically polarized light for each wavelength sources, twelve images are acquired. From these images, phase delay and the principal internal stress difference are precisely computed using developed algorithms. Our proposed method based on an LCD panel has the unrivalled advantage that elliptically polarized light can be automatically adjusted, which reduces the mechanical rotation of the system, in contrast to the traditional six-step phase-shifting photoelasticity method, which requires manual rotation for circularly polarized light. In addition, the system has the potential to theoretically expand the area of illumination infinitely, thereby expanding the measurement area. The viability of the suggested methods is confirmed with numerical simulation and stress measurement.

Optimized Design of Skylight Arrangement to Enhance the Uniformity of Indoor Sunlight Illumination

The use of skylights in buildings introduces natural light into the interior space, thereby reducing the reliance on artificial lighting and aligning with the principles of low carbon and environmental sustainability. To ensure optimal indoor lighting quality, it is essential to optimize the arrangement of skylights to strike a balance between high average illumination and uniformity of illumination. Recent initiatives by the Chinese government have emphasized the construction and renovation of numerous gymnasiums. In this research, a novel approach based on optimized algorithms was employed to design skylights and improve the uniformity of indoor illuminance. Simulation results demonstrated that the skylight arrangements derived from the optimization algorithms exhibited significantly higher levels of illumination uniformity, while maintaining comparable average illumination and skylight areas, when compared to conventional designs. Additionally, the study employed genetic algorithms to optimize the skylight arrangement for a specific gymnasium, resulting in a remarkable 32% increase in illumination uniformity. The study also accounted for obstacles and seating in the skylight design, and the genetic algorithm generated desirable skylight arrangements with respective increases of 32% and 21% in illumination uniformity for scenarios involving obstacles and seating. Overall, this study underscores the potential of optimized algorithms in the design of skylights for green buildings, offering valuable insights for future research endeavors in this field.

Features of the joint use of visible-range satellite and satellite radar data for monitoring arctic icebergs based on data from Franz Josef Land area

Given the availability of data, in order to monitor icebergs in the vast Arctic region, it is necessary to ensure an optimal ratio of the satellite radar data cost (with a wide swath and high spatial resolution) and the reliability of the results obtained. The aim of the study was to evaluate the effectiveness of using only non-commercial satellite information for monitoring icebergs. To achieve this goal, an iceberg detection technique was applied based on statistical criteria of searching for gradient zones in analyzing two-dimensional fields of satellite images. As a source of information, we used high spatial resolution satellite data obtained from non – commercial satellites Sentinel-1 (radar data) and Landsat-8 (visible spectral range data) with a pixel size of 40 × 20 and 15 m, respectively.Through comparison with the data of the visible spectral range of ultra-high resolution, the error was estimated of measuring the size of icebergs using the visible range equipment of the Landsat-8 satellite and the radar of the Sentinel-1 satellite. Based on the analysis of satellite data of the visible spectral range and radar data, the spatial dimensions of icebergs formed by the outlet glaciers of Franz Josef Land n 2020–2022 were estimated. The materials were collected for the period August-September, corresponding to the conditions of minimum ice extent in the Franz Josef Land area and sufficient natural illumination for using the data of the visible spectral range in the Arctic. In total, about 100 satellite images were analyzed. The sources of error in the satellite measurements are discussed, as well as the reasons for the impossibility in some cases to identify Franz Josef Land icebergs on radar images. It is shown that the largest contribution to the iceberg runoff of Franz Josef Land is made by outflow glaciers located on Georg Land, Wilczek Land, Gall, Salisbury and Champa islands. According to the results of the study, it is concluded that radar data with a pixel size of 40 m allow one to obtain essentially reliable information on the spatial distribution of icebergs in the water area. However, it is not possible to obtain a reliable function of the distribution of icebergs by size since most of the icebergs in the Franz Josef Land water area have small and medium sizes and are rarely identified in images of such spatial resolution.

Investigating the optical translucency of Spectralon using BSSRDF measurements.

Translucent materials have the property of reflecting light beyond the illumination point due to subsurface light propagation in the material. These reflectance properties can be characterized using the bidirectional scattering-surface reflectance distribution function (BSSRDF), a radiometric quantity that is a function of spatial, angular, spectral, and polarization parameters. At very small scales, we have observed that Spectralon, a commercial material widely used as a diffuse reflectance calibration standard, can be regarded as translucent. This can generate measurement errors and limit Spectralon's reliability as a calibration artefact for instruments that measure optical quantities on very small surfaces. To characterize the translucent properties of Spectralon, we have measured its BSSRDF using an experimental setup based on a goniospectrophotometer with a spatial scanning system for detection. In the present study, we show that Spectralon cannot be considered an opaque material at small scales (below 1mm). For instrument measuring on small areas, Spectralon can be used for calibration only when the illumination area and the observation area differ by more than 1mm in radius.