Optimal Illumination Research Articles

Enhancing Optical Sectioning in Structured Illumination Microscopy With Axially Confined Fringe Modulation

AbstractOptical sectioning structured illumination microscopy (OS‐SIM) is a fast, minimally invasive 3D imaging technique that has found widespread application in the biosciences. It is based on sample illumination with several illumination fringe patterns featuring distinct mutual phase shifts, from which an axially sectioned image is reconstructed. Its optical sectioning capability is commonly attributed to the attenuation of the fringe modulation of light collected from planes displaced from the focal plane. However, in addition to this effect, which is governed solely by the detection optics, optical sectioning can be further enhanced by confining the fringe modulation axially via partially coherent illumination (PCI). To establish guidelines for optimal illumination field shaping, both theoretically and experimentally are investigated, the optical sectioning strength of OS‐SIM upon variation of the two key parameters, modulation period and angular spectrum of the incident illumination. By using PCI with OS‐SIM, nearly fivefold and 1.4‐fold enhanced axial resolution have achieved for scattering (non‐fluorescent) and fluorescent samples, respectively. This work elucidates the optical sectioning mechanism of OS‐SIM and provides a perspective for further optimization.

Color-multiplexed 3D differential phase contrast microscopy with optimal annular illumination.

Quantitative phase imaging (QPI) has become a valuable tool in the field of biomedical research due to its ability to quantify refractive index variations of live cells and tissues. For example, three-dimensional differential phase contrast (3D DPC) imaging uses through-focus images captured under different illumination patterns deconvoluted with a computed 3D phase transfer function (PTF) to reconstruct the 3D refractive index. In conventional 3D DPC with semi-circular illumination, partially spatially coherent illumination often diminishes phase contrast, exacerbating inherent noise, and can lead to a large number of zero values in the 3D PTF, resulting in strong low-frequency artifacts and deteriorating imaging resolution. To overcome the above drawbacks, we obtain the conditions for acquiring the optimal 3D PTF based on the analysis of the 3D imaging model and the derivation of the 3D PTF calculation process and propose a 3D DPC microscopy based on optimal annular illumination. The proposed optimal annular illumination pattern minimizes the missing frequency components in the 3D Fourier space, resulting in the best noise-robustness and significantly increased phase contrast. To expedite imaging speed, we utilize a 1/2 annular multiplexed illumination, reducing data acquisition volume by 75%. The 3D refractive index tomography of a simulated 3D phase object, unstained tongue sections, and oral epithelial cells demonstrates that our proposed method achieves the above advantages. In conclusion, we demonstrate a novel 3D DPC microscope that only requires replacing the illumination of a commercial microscope with a programmable LED array. The accurate 3D refractive index tomography and the compactness of the system setup allow the method to play a significant role in the biomedical field.

Анализ влияния освещенности на качество распознавания лазерной сетки машинным зрением

The main purpose of the study was to analyze the quality of laser grid shape detection in various ranges of illumination intensity for industrial application in conditions of underground and open-pit mining and on production sites. In particular, the dependences were established of the illumination level effect on the quality of the laser grid shape detection with the machine vision. Images were used as the study objects, while the subject was the machine vision algorithms and the values of the qualitative shape detection parameters. As a result, the authors have identified the conditions for the most effective shape detection of a laser grid projected onto the surface. In accordance with the developed methodology, the result of a series of laboratory tests was obtained with different light discreteness. In case of insufficient value of the parameter for a group of pixels, erosion and dilation operations were used, allowing to change the parameters of adjacent pixels to the values that would ensure the shape detection. The results are obtained in the form of qualitative dependence of the laser grid cells shape detection on illumination in laboratory conditions. The conclusion is made about the optimal illumination range, at which the quality of the laser grid shape detection is stable. The obtained results can be applied in various industries, including the mining industry, when measuring the objects volume with machine vision in combination with a laser grid.

A Study on Pendant and Blackboard Asymmetric Lens LED Luminaires for Optimal Illumination in Classrooms

This study examines the transformative impact of integrating pendant asymmetric lens (PAL) and blackboard asymmetric lens (BAL) LED luminaires to enhance classroom lighting, with the goals of replicating the ambient effects of natural daylight and promoting energy efficiency. This research focuses on improving the quality of learning environments through uniform, soft, and diffused lighting, which mimics sky-like illumination while adhering to sustainable energy practices. Advanced asymmetric lens LED luminaires are employed to achieve optimal lighting distribution, as indicated by luminous intensity distribution curves. Comparative analyses in diverse educational settings reveal significant improvements in ceiling illuminance, ranging from 935 to 1000 lx, and workspace illuminance from 660 to 720 lx, with reduced glare (UGR < 10). This results in bright, visually comfortable spaces conducive to learning. Additionally, the PAL and BAL solutions outperform conventional lighting systems like stretched ceilings and lightboxes by maintaining clear overhead spaces, eliminating shadows, and offering cost-effective solutions. This successful integration demonstrates a notable advancement in the development of energy-efficient, visually comfortable educational environments, contributing to the goals of sustainability and improved well-being for both students and teachers.

Optimal Illumination Distance Metrics for Person Re-identification in Complex Lighting Conditions

Person Re-identification is extensively applied in public security and surveillance. However, environmental factors like time and location often lead to varying lighting conditions in captured pedestrian images, significantly impacting identification accuracy. Current approaches mitigate this issue through lighting transformation techniques, aiming to normalize images to a standard lighting condition for consistent person re-identification results. Yet, these methods overlook the fact that different content may hold distinct identification values under diverse lighting conditions. To address this, we conducted an analysis on the identification distance between images of the same or different pedestrians under predefined lighting conditions. From this analysis, we introduce the concept of optimal lighting: a condition where the distance between image pairs is minimized compared to other lighting scenarios. We propose utilizing this optimal lighting distance in the image retrieval process for final ranking. Our study, validated on synthetic datasets Market-IA and Duke-IA, demonstrates that optimal lighting is independent of image texture information. Each image pair exhibits a unique optimal lighting, yet consistently shows a minimum distance value.

A Novel, Autonomous, Module-Based Surgical Lighting System

Optimal illumination of the surgical site is crucial for successful surgeries. Current lighting systems, however, suffer from significant drawbacks, particularly shadows cast by surgeons and operating room personnel. We introduce an innovative, module-based lighting system that actively prevents shadows using an array of swiveling, ceiling-mounted light modules. The intensity and orientation of these modules are autonomously controlled by novel algorithms utilizing multiple depth sensors mounted above the operating table. This paper presents our complete system, detailing the algorithms for autonomous control and the initial optimization of the light module setup. Unlike prior work that was largely conceptual and based on simulations, this study introduces a real prototype featuring 56 light modules and three depth sensors. We evaluate this prototype through measurements, semi-structured interviews (n=4), and an extensive quantitative user study (n=11). The evaluation focuses on illumination quality, shadow elimination, and suitability for open surgeries compared to conventional OR lights. Our results demonstrate that the novel lighting system and optimization algorithms outperform conventional OR lights for abdominal surgeries, according to both objective measures and subjective ratings by surgeons.

An illumination-guided dual-domain network for image exposure correction

Exposure problems, including underexposure and overexposure, can significantly degrade image quality. Poorly exposed images often suffer from coupled illumination degradation and detail degradation, aggravating the difficulty of recovery. These necessitate a spatial discriminating exposure correction, making achieving uniformly exposed and visually consistent images challenging. To address these issues, we propose an Illumination-guided Dual-domain Network (IDNet), which employs a Dual-Domain Module (DDM) to simultaneously recover illumination and details from the frequency and spatial domains, respectively. The DDM also integrates a structural re-parameterization technique to enhance the detail-aware capabilities with reduced computational cost. An Illumination Mask Predictor (IMP) is introduced to guide exposure correction by estimating the optimal illumination mask. The comparison with 26 methods on three benchmark datasets shows that IDNet achieves superior performance with fewer parameters and lower computational complexity. These results confirm the effectiveness and efficiency of our approach in enhancing image quality across various exposure scenarios.

Does the optimal level of illumination improve both visual functions and visual comfort in schoolchildren with low vision?

Lighting modification is commonly performed by optometrists and occupational therapists to enhance visibility and visual comfort among schoolchildren with low vision. The purpose of this study is to determine the optimal illumination level for visual function and visual comfort of schoolchildren with low vision and the relationship between them. A cross-sectional study was conducted to assess five levels of illumination ranging from 125 lux to 2000 lux to determine the optimal illumination for visual functions and visual comfort in schoolchildren with low vision from a special education school for blind in Malaysia. Purposive sampling was done to recruit forty-two schoolchildren with low vision for this study. Visual functions assessed were visual acuity, measured using the Early Treatment Diabetic Retinopathy Study LogMAR chart at distance and near, contrast sensitivity (CS) measured using the Pelli-Robson chart at distance and the Mars CS chart at near. Reading speed was determined using the Universiti Kebangsaan Malaysia Malay Language Related Word Reading Text test chart. Subjects were asked to rate their visual comfort using a validated questionnaire at the end of each measurement of visual functions and reading speed for the different illumination levels. Visual acuity and contrast sensitivity at distance and near, visual comfort and reading speed improved significantly with increase in illumination levels (p<0.05). However, the interaction between illumination level and level of low vision was not significant (p>0.05). Visual comfort was significantly associated with visual function (p<0.05), while direct association between visual comfort and illumination level was not significant (p>0.05). Optimal illumination for improvement of visual function, reading speed and visual comfort range from 276.67 lux to 701.59 lux. Majority of the schoolchildren with low vision had improved visual function, reading speed and visual comfort with increased illumination. Illumination of at least 600 lux is recommended for maximum visual functioning and visual comfort of schoolchildren with low vision.

Multi-objective optimization of switchable suspended particle device vacuum glazing for comfort and energy efficiency in school typologies under hot climate

This study focuses on the multi-objective optimization of a switchable Suspended Particle Device (SPD) vacuum glazing system to reduce energy use while ensuring thermal and visual comfort in schools located in arid desert environments. A detailed synergy analysis was performed on a representative floor from three school classroom typologies, comparing suspended particle device vacuum glazing in its OFF and ON states against conventional double-glazing with air gaps windows. This analysis employed an advanced simulation framework integrating Rhino-Grasshopper with Open Studio Model, Colibri 2.0, and Design Explorer2 software to evaluate energy consumption, Adaptive Comfort Percentage (ACP), and Useful Daylight Illuminance (UDI). Thermal comfort varied across typologies and orientations, with the atrium with skylight typology frequently meeting or approaching the 80 % Adaptive Comfort Percentage benchmark. However, the southern and eastern classrooms in the enclosed atrium with clerestory typology did not exceed a 39 % adaptive comfort percentage. The comprehensive parametric and multi-objective optimization simulation revealed that suspended particle device vacuum glazing in its 'OFF' state did not fulfill the UDI300lux–1000lux criteria across all typologies, even with maximal Window to Wall Ratio (WWR) and skylight ratio (SR). However, the enclosed atrium with clerestory, integrating SPD vacuum glazing with a 40 % Window to Wall Ratio configuration, emerged as particularly effective in achieving optimal useful daylight illuminance distribution, minimizing energy consumption, and ensuring satisfactory adaptive comfort percentage across various orientations. These findings underscore the potential of multi-objective optimization of suspended particle device vacuum glazing, combined with strategic Window to Wall Ratio adjustments, as a viable alternative to traditional glazing systems in hot desert climates. The adaptability of suspended particle device vacuum glazing highlights its significant potential for achieving thermal comfort, enhancing sustainable architectural design, and improving energy efficiency in educational buildings within extreme climate zones.

Natural low-illumination image enhancement based on dual-channel prior information

This paper proposes an adaptive image enhancement method that aims to effectively restore the brightness, detail, and natural color of various low-illumination images. To be specific, the method first constructs the initial dual-channel illumination map of the image. Next, the optimal illumination correction coefficient is calculated by the prior information entropy of the initial illumination map, which helps to correct potentially erroneous illumination estimates. To restore the illumination, gamma correction is used with the optimal illumination correction coefficient. Finally, an improved perfect reflection constraint model is used to restore the color of the image. Both visual analysis and quantitative comparison with state-of-the-art methods demonstrate the effectiveness of the method in terms of brightness adjustment, detail recovery, and color restoration.

Daylight illuminance levels, user preferences, and cognitive performance in office environments: Exploring an optimal illuminance range using virtual reality

This study investigates the impact of varied daylight illuminance levels on user preferences and cognitive performance in offices, employing a virtual reality platform and HDRI 360-degree panorama images, whose illuminance level was validated using simulation. With 46 participants, a cognitive task known as the Stroop-test was conducted under nine illuminance levels, ranging up to 1500 lux. Additionally, participants were surveyed to determine their preferred horizontal illuminance level at desk height. The results uncovered distinct user preferences, with the majority of participants favoring illuminance levels above 700 lux, specifically 1100 and 790 lux, for reading and work-related tasks. Notably, none of the participants opted for illuminance levels below 300 lux, indicating these levels were deemed insufficient for their tasks. An analysis of cognitive task performance revealed significant differences between various illuminance levels. Generally, increasing the illuminance level in an office building will increase the office workers’ task performance. As illuminance levels exceeded 300 lux, participants exhibited enhanced performance in tasks such as reading words (RW), naming colors (NC), and total Stroop-test performance (TT). The 700–1500 lux can be considered suitable illuminance level for high-precision tasks, and 300–700 lux can be considered the medium illuminance in office environments. Based on these findings, an optimal illuminance range of 900–1100 lux is recommended for office environments, aligning with both user preferences and performance. This study offers valuable insights for architects and researchers in the development of daylighting design guidelines aimed at enhancing employees' cognitive capabilities and satisfaction.

Optimal Selection of Distribution, Power, and Type of Luminaires for Street Lighting Designs Using Multi-Criteria Decision Model

This article introduces an innovative design method for public lighting systems that surpasses the limitations of conventional approaches, which rely on predefined lamp characteristics and spatial arrangements. By employing a linear additive model to solve a multi-criteria decision model, our study proposes an optimal design methodology considering several key aspects, including the distance between lamps, their type, power, and light distribution. The goal is to achieve optimal illumination that enhances visibility on public roads for drivers and pedestrians while simultaneously minimizing glare and installation costs and maximizing energy efficiency. The proposed methodology is implemented through an algorithm developed in MATLAB R2023b, with results validated through simulations in DIALux evo 12.0. This information is used to construct a decision matrix, assessed using the CRITIC method across 180 different scenarios within a specific case study. The findings demonstrate the effectiveness of multi-criteria decision-making as a tool for significantly improving the planning and design of lighting in public illumination systems, allowing for selecting the optimal combination of parameters that ensure the best lighting conditions.

Optimal Illumination: The BFF Light

Background: Optimal illumination for procedures performed without the operating microscope remains challenging for the surgeon within some subspecialties. We present a novel device that provides unmatched illumination for such procedures and highlight its use during scleral buckle placement. Methods: A mode of illumination prioritizing precision, flexibility, portability, and compatibility in various procedural settings was developed. Using such a prototype, a proof-of-concept assessment quantified the number of manual light adjustments vs ceiling-mounted spotlight adjustments required during scleral buckle placement. Results: The Brodie-Fekrat Flex (BFF) Light, an ultrabright LED light connected to a flexible gooseneck, can mount on surgical microscopes, wrist-rests, ceiling-mounted spotlight handles, and even exam chairs. During scleral buckle placement, the BFF Light did not require intraoperative re-adjustment once positioned, whereas ceiling-mounted spotlights were repositioned 5 times on average. Conclusions: The BFF light provides reliable, bright illumination during procedures that do not require the operating microscope. This versatile device may also have applications in the clinic setting, even beyond ophthalmology.

Unveiling the Spatiotemporal and Dose Responses within a Single Live Cancer Cell to Photoswitchable Upconversion Nanoparticle Therapeutics Using Hybrid Hyperspectral Stimulated Raman Scattering and Transient Absorption Microscopy.

Photodynamic therapy (PDT) provides an alternative approach to targeted cancer treatment, but the therapeutic mechanism of advanced nanodrugs applied to live cells and tissue is still not well understood. Herein, we employ the hybrid hyperspectral stimulated Raman scattering (SRS) and transient absorption (TA) microscopy developed for real-time in vivo visualization of the dynamic interplay between the unique photoswichable lanthanide-doped upconversion nanoparticle-conjugated rose bengal and triphenylphosphonium (LD-UCNP@CS-Rb-TPP) probe synthesized and live cancer cells. The Langmuir pharmacokinetic model associated with SRS/TA imaging is built to quantitatively track the uptakes and pharmacokinetics of LD-UCNP@CS-Rb-TPP within cancer cells. Rapid SRS/TA imaging quantifies the endocytic internalization rates of the LD-UCNP@CS-Rb-TPP probe in individual HeLa cells, and the translocation of LD-UCNP@CS-Rb-TPP from mitochondria to cell nuclei monitored during PDT can be associated with mitochondria fragmentations and the increased nuclear membrane permeability, cascading the dual organelle ablations in cancer cells. The real-time SRS spectral changes of cellular components (e.g., proteins, lipids, and DNA) observed reflect the PDT-induced oxidative damage and the dose-dependent death pattern within a single live cancer cell, thereby facilitating the real-time screening of optimal light dose and illumination duration controls in PDT. This study provides new insights into the further understanding of drug delivery and therapeutic mechanisms of photoswitchable LD-UCNP nanomedicine in live cancer cells, which are critical in the optimization of nanodrug formulations and development of precision cancer treatment in PDT.

Modelling the power threshold and optimum thermal deformation of indirectly liquid-nitrogen cryo-cooled Si monochromators.

Maximizing the performance of crystal monochromators is a key aspect in the design of beamline optics for diffraction-limited synchrotron sources. Temperature and deformation of cryo-cooled crystals, illuminated by high-power beams of X-rays, can be estimated with a purely analytical model. The analysis is based on the thermal properties of cryo-cooled silicon crystals and the cooling geometry. Deformation amplitudes can be obtained, quickly and reliably. In this article the concept of threshold power conditions is introduced and defined analytically. The contribution of parameters such as liquid-nitrogen cooling efficiency, thermal contact conductance and interface contact area of the crystal with the cooling base is evaluated. The optimal crystal illumination and the base temperature are inferred, which help minimize the optics deformation. The model has been examined using finite-element analysis studies performed for several beamlines of the Diamond-II upgrade.

Causally Aware Generative Adversarial Networks for Light Pollution Control

Artificial light plays an integral role in modern cities, significantly enhancing human productivity and the efficiency of civilization. However, excessive illumination can lead to light pollution, posing non-negligible threats to economic burdens, ecosystems, and human health. Despite its critical importance, the exploration of its causes remains relatively limited within the field of artificial intelligence, leaving an incomplete understanding of the factors contributing to light pollution and sustainable illumination planning distant. To address this gap, we introduce a novel framework named Causally Aware Generative Adversarial Networks (CAGAN). This innovative approach aims to uncover the fundamental drivers of light pollution within cities and offer intelligent solutions for optimal illumination resource allocation in the context of sustainable urban development. We commence by examining light pollution across 33,593 residential areas in seven global metropolises. Our findings reveal substantial influences on light pollution levels from various building types, notably grasslands, commercial centers and residential buildings as significant contributors. These discovered causal relationships are seamlessly integrated into the generative modeling framework, guiding the process of generating light pollution maps for diverse residential areas. Extensive experiments showcase CAGAN’s potential to inform and guide the implementation of effective strategies to mitigate light pollution. Our code and data are publicly available at https://github.com/zhangyuuao/Light_Pollution_CAGAN.

Leading Light: The Impact of Advanced Lighting Technologies on Indonesia's Office Industry

Addressing concerns over resource scarcity and environmental sustainability necessitates a global shift towards sustainable energy, notably facilitated by adopting Light-Emitting Diode (LED) lamps. This transition is pivotal for ensuring global energy security and aligning with sustainability goals. This study endeavors to comprehensively analyze potential energy savings achievable through the transition from Fluorescent (FL) lamps to LED lamps within industrial offices. Emphasis is placed on highlighting the central role of energy efficiency. Utilizing false color rendering as a visual guide, the study systematically identifies areas where FL lamps inadequately illuminate. The findings prompt recalculations for determining optimal room illumination achievable through implementing LED lamps. Lux calculations are then employed to showcase the superior illumination offered by LED lamps, revealing consistent monthly cost savings of 35%, particularly when harmonized with Building Management System (BMS) control in industrial office buildings. The study's results indicate that LED lamps provide superior illumination, yielding a noteworthy 35% monthly cost savings, especially when integrated with BMS control. Lamps contribute modestly (21-30%) to overall energy consumption, while air conditioning commands a substantial 60%, underscoring the critical need for advanced lighting technology. This need is emphasized, particularly with Solar PV as a sustainable energy source. Understanding technological developments, especially in BMS, is crucial to optimize energy efficiency in industrial offices. The imperative implementation of LED lighting technology is a critical solution to address resource scarcity and environmental concerns in industrial offices. The efficacy of LED lamps in achieving significant energy savings, especially when coupled with advanced systems like BMS and complemented by renewable energy sources such as Solar PV. The conclusion stresses the significance of staying abreast of technological advancements to foster sustained progress towards energy-efficient and environmentally conscious practices within industrial environments.

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.

Investigating the influence of perforated façade skins on indoor illuminance level: a case study

ABSTRACT Building shading systems is crucial to both avoid indoor overheating during summer and control daylight inflow. This is particularly relevant in exposed glazed façade during summer, where the risk of excessive solar radiation and light entering the building is elevated. The study proposes the use of Dialux software to support the design of sun-shading devices with the two-fold objective of reducing the risk of glare along the façade side and avoiding a dark effect on the opposite side. The procedure is based on a multiple-design approach that simulates the effect of diverse shading panel configurations on indoor illuminance distribution. Then the procedure is implemented on a residential case study in Bologna (Italy) resulted in having a limited depth and thus a high risk of excessive illuminance. The results demonstrate that Dialux is sensitive to changes in the openness factor and geometry of the panel. The multiple simulations allowed the optimal illuminance level of around 300 lux for more than 70% of the case study room surface while containing the area exceeding the optimal level under 1000 lux to less than 20% and to avoid reaching the minimum threshold of 100 lux through a shading system with Openness Factor ranging between 11 and 15%. The workflow can serve not only as a tool for addressing and verifying the design choices but as a design support means itself. Due to its structure and easiness of inputting data and modelling stage, the methodology has a high replicability potential.

High-resolution display screen as programmable illumination for Fourier ptychography

We introduce a new programmable illumination strategy for Fourier ptychographic microscopy (FPM), utilizing a high-resolution organic light-emitting diode (OLED) display screen at the vicinity of the sample to achieve super-resolution and quantitative phase imaging of biological samples. High-density pixels in the OLED screen allow for the angle-scanning illumination required for FP by placing the sample slide directly on the screen, where multiple images of the sample are captured while scanning the pixels on the screen. We discuss the design of the OLED-FP illumination and the corresponding image reconstruction strategies and experimentally validate the super-resolution and phase imaging capabilities of FP using a smartphone screen as illumination. Further, we extend our method to patterned illumination strategies, which multiplexes multiple illumination pixels to achieve full-field FP imaging with a reduced number of measurements, where we identify an optimal illumination pattern and density to maximize the imaging speed without sacrificing the image quality. Our approach offers a simple and compact programmable illuminator that can effectively transform any microscope into a compact FPM with resolution improvement and phase imaging capabilities.