scholarly journals Measuring the Effects of Light Distribution on Spatial Brightness

2021 ◽  
Author(s):  
◽  
James Sullivan
Keyword(s):  
Light Source ◽  
Process Model ◽  
Relative Strength ◽  
Light Distribution ◽  
Light Sources ◽  
Data Sets ◽  
Luminance Distribution ◽  
Direct View ◽  
Model Spaces ◽  
Mean Luminance

<p><b>By changing the light distribution it is possible to double the apparent amount of light in a space without any increase in its overall luminance. If one simply assumes that the apparent amount of light in a space — its spatial brightness — is described by its mean luminance (or similar measures) then substantial errors may be made.</b></p> <p>We carried out two experiments, measuring the brightness of 19 different model spaces. Our results demonstrate that making light distributions more non-uniform can make spaces appear both significantly brighter and significantly darker, depending on how the light distribution is changed. This challenges most existing studies in the field that argue that non-uniformity of the luminance distribution simply makes spaces look darker. Indeed, the observed pattern in brightness between our conditions cannot be consistently explained by a simple measure of the uniformity of the luminance distribution. We thus reject all previously proposed models of light distribution and spatial brightness.</p> <p>The best explanation of this and the apparent disagreements in the literature over the effects of non-uniformity appears to be that spatial brightness is affected by the qualitative appearance of the luminances in the space. Light sources and non-luminous surfaces have different effects. We propose a ‘duel’-process model of spatial brightness in which it is the sum of two opposed processes: the effects of the surfaces, and the effects of the light source(s). Non-uniform patterns of surface reflectance and illumination tend to make a space appear brighter. Non-uniformity as a result of a large difference between luminance of the light source(s) and the surfaces makes a space appear darker. If the light source is hidden from direct view its darkening effect is removed, which can make the space appear significantly brighter. Depending on the relative strength of these two processes, a non-uniform luminance distribution may thus appear either brighter or darker than a more uniform distribution.</p> <p>Additionally, we highlight issues demonstrated in both the failure of models previously proposed by the literature, and our exploration of potential implementations of the ‘duel’-process model. It is very easy to produce a good correlation with a defensible metric that will not generalise to other data sets. A metric having a good correlation in a study provides very little reason to actually believe it. If we wish to develop a model of the effects of light distribution that we can trust, we need to demonstrate its robustness by testing its underlying assumptions and showing them to be well supported. As we show, there is a large variety of these that need to be worked through.</p>

scholarly journals Measuring the Effects of Light Distribution on Spatial Brightness

2021 ◽  
Author(s):  
◽  
James Sullivan
Keyword(s):  
Light Source ◽  
Process Model ◽  
Relative Strength ◽  
Light Distribution ◽  
Light Sources ◽  
Data Sets ◽  
Luminance Distribution ◽  
Direct View ◽  
Model Spaces ◽  
Mean Luminance

<p><b>By changing the light distribution it is possible to double the apparent amount of light in a space without any increase in its overall luminance. If one simply assumes that the apparent amount of light in a space — its spatial brightness — is described by its mean luminance (or similar measures) then substantial errors may be made.</b></p> <p>We carried out two experiments, measuring the brightness of 19 different model spaces. Our results demonstrate that making light distributions more non-uniform can make spaces appear both significantly brighter and significantly darker, depending on how the light distribution is changed. This challenges most existing studies in the field that argue that non-uniformity of the luminance distribution simply makes spaces look darker. Indeed, the observed pattern in brightness between our conditions cannot be consistently explained by a simple measure of the uniformity of the luminance distribution. We thus reject all previously proposed models of light distribution and spatial brightness.</p> <p>The best explanation of this and the apparent disagreements in the literature over the effects of non-uniformity appears to be that spatial brightness is affected by the qualitative appearance of the luminances in the space. Light sources and non-luminous surfaces have different effects. We propose a ‘duel’-process model of spatial brightness in which it is the sum of two opposed processes: the effects of the surfaces, and the effects of the light source(s). Non-uniform patterns of surface reflectance and illumination tend to make a space appear brighter. Non-uniformity as a result of a large difference between luminance of the light source(s) and the surfaces makes a space appear darker. If the light source is hidden from direct view its darkening effect is removed, which can make the space appear significantly brighter. Depending on the relative strength of these two processes, a non-uniform luminance distribution may thus appear either brighter or darker than a more uniform distribution.</p> <p>Additionally, we highlight issues demonstrated in both the failure of models previously proposed by the literature, and our exploration of potential implementations of the ‘duel’-process model. It is very easy to produce a good correlation with a defensible metric that will not generalise to other data sets. A metric having a good correlation in a study provides very little reason to actually believe it. If we wish to develop a model of the effects of light distribution that we can trust, we need to demonstrate its robustness by testing its underlying assumptions and showing them to be well supported. As we show, there is a large variety of these that need to be worked through.</p>

scholarly journals Analysis on High-Power Seaport LED Luminaire with Uniform Light Distribution Based on Optimized Lens and Heatsink

2021 ◽  
Vol 11 (9) ◽  
pp. 4035
Author(s):  
Jinsheon Kim ◽  
Jeungmo Kang ◽  
Woojin Jang
Keyword(s):  
Light Source ◽  
High Power ◽  
Heat Dissipation ◽  
Light Emitting Diode ◽  
Light Distribution ◽  
Light Sources ◽  
Led Light ◽  
High Power Led ◽  
Distribution Requirement ◽  
Lighting Application

In the case of light-emitting diode (LED) seaport luminaires, they should be designed in consideration of glare, average illuminance, and overall uniformity. Although it is possible to implement light distribution through auxiliary devices such as reflectors, it means increasing the weight and size of the luminaire, which reduces the feasibility. Considering the special environment of seaport luminaires, which are installed at a height of 30 m or more, it is necessary to reduce the weight of the device, facilitate replacement, and secure a light source with a long life. In this paper, an optimized lens design was investigated to provide uniform light distribution to meet the requirement in the seaport lighting application. Four types of lens were designed and fabricated to verify the uniform light distribution requirement for the seaport lighting application. Using numerical analysis, we optimized the lens that provides the required minimum overall uniformity for the seaport lighting application. A theoretical analysis for the heatsink structure and shape were conducted to reduce the heat from the high-power LED light sources up to 250 W. As a result of these analyses on the heat dissipation characteristics of the high-power LED light source used in the LED seaport luminaire, the heatsink with hexagonal-shape fins shows the best heat dissipation effect. Finally, a prototype LED seaport luminaire with an optimized lens and heat sink was fabricated and tested in a real seaport environment. The light distribution characteristics of this prototype LED seaport luminaire were compared with a commercial high-pressure sodium luminaire and metal halide luminaire.

scholarly journals Elimination of the blinding effect in landscape luminaires

2018 ◽  
Vol 7 (2.13) ◽  
pp. 252
Author(s):  
Albert Ashryatov ◽  
Dinara Churakova
Keyword(s):  
Light Curve ◽  
Light Source ◽  
Light Flux ◽  
Light Distribution ◽  
Light Sources ◽  
Mirror Surface ◽  
Light Emitting ◽  
Lighting Technology ◽  
Initial Task ◽  
Flat Beam

The article presents one of the possible options for implementing the lighting technology "Flat beam" for landscape lighting purposes. One of the possible ways to control the light distribution of a number of light sources based on LEDs with different radiation patterns is considered. As a secondary optics, it is proposed to use a mirror surface that redistributes the light flux of an LED light source. It is indicated that, depending on the initial type of the light-emitting diodes light curve and the features of mounting the mirror surface, the resulting light distribution can vary widely, depending on the initial task that the designer sets for himself.  

The Mechanisms of the Trapping Effect of Artificial Light Sources Upon Animals

1960 ◽  
Vol 13 (1) ◽  
pp. 1-107 ◽  
Author(s):  
F.J. Verheijen
Keyword(s):  
Light Source ◽  
Light Trap ◽  
Light Distribution ◽  
Artificial Light ◽  
Light Sources ◽  
Human Beings ◽  
Optical Illusions ◽  
Apallic Syndrome ◽  
Trapping Effect ◽  
Living Organisms

AbstractAttempts were made to find out why insects and fishes can be captured with the help of lamps, why birds fly against lighthouse lanterns, and why in the laboratory phototaxis is preponderantly positive phototaxis. An extensive review of the literature revealed that none of the numerous old and new theories on photic orientation can account for either of these phenomena. Analysis of the abundance of data on the trapping effect of an artificial light source upon insects, fishes and birds has led to the working hypothesis according to which the low illumination intensity of the environment around such a light source interferes with normal photic orientation resulting in a drift of the animal towards the light source. The observed concentration of animals in the vicinity of a lamp is thought to be the statistical result of this drift. Experiments with insects (bees) demonstrated that an adequate screening of the light scattered from the sky, together with the elimination of the reflection of light by the environment really result in a disorientated drift towards the light source, even when this is the natural light source (the sun). Fishes and birds were forced to move towards a lamp under similar illumination conditions. Photic orientation is assumed to be accomplished by the goal-directed functioning of a number of hierarchically coordinated centres. The animal's movements are controlled by optic feedback based upon the normal differences in the intensities of the light stimuli acting upon the respective photosensitive surfaces. During more detailed orientation, fixation mechanisms are put in circuit by higher coordinating centres in response to sign stimuli. The normal values of these stimuli are determined by the normal angular light distribution in the animal's habitat, which is caused by: i. the nature of the light sources (sun, moon, stars); 2. the scattering and absorbing capacities of the media (the atmosphere and the water) ; and 3. the reflecting capacity of the environment. The abnormal feedback resulting from the abnormal angular light distribution around a lamp-brought about by the elimination of the factors 2 and 3-makes the animal deviate from the intended position or direction of locomotion. Moreover, the servomechanisms of lower coordination levels controlling the fixation movements of the eyes become a play-thing of the stimuli from the lamp that are quantitatively supernormal as compared with the adequate sign stimuli which normally activate the higher coordination centres of the fixation mechanisms. In this way these higher centres are more or less eliminated from the orientation process. Under extreme laboratory illumination conditions this results in a forced drift of the animal towards the lamp irrespective of factors which are incompatible with survival. Similar phenomena in human beings suffering from disturbance of the centres mediating eye movements, and in patients with far advanced cerebral degenerations (apallic syndrome) are thought to favour this concept. The implications of the present concept of photic orientation and disorientation are discussed with regard to the current concepts of pho- totaxis and photokinesis, the light trap technique, some optical illusions, and glaring lights in traffic. The tendency among cyberneticians to overrate the performances of life-imitating-e.g. "phototropic"- machines, which trifle with the complexity of living organisms, is criticized.

scholarly journals Optical System for Led Luminaire

2019 ◽  
pp. 62-67
Author(s):  
A. Kolesnyk
Keyword(s):  
Light Source ◽  
Light Emitting Diodes ◽  
New Technology ◽  
Light Distribution ◽  
Optical Systems ◽  
Light Sources ◽  
Optical Elements ◽  
Light Emitting ◽  
The Right ◽  
Led Luminaire

Lighting devices are an important element of a large number of technical systems, including road, living, industrial lighting, lighting systems of vehicles. It is known that the light instrument must fulfill two basic lighting tasks: to redistribute the light source of light source in the right way and to limit its dazzling effect. The introduction of light-emitting diodes (LEDs) for lighting necessitated a completely new quality in the construction of luminaires. The different production technology required new methods and designing tools. It also challenged designers with new problems to solve. LEDs are light sources emitting in one hemisphere, which requires a special approach to designing an LED lighting unit. However, for the illumination of premises with high spans or streets, roads such a light distribution is not suitable. For luminaires with solid-state light sources, other materials and new technology must be used; moreover, light distribution needs to be formed using different methods. This paper presents the design process of a LED luminaire from concept to implementation, exemplified by road lighting, and describes the methods and procedures used by the designer. Also, technological problems influencing the quality of the above lighting are addressed. Optical systems for LEDs are considered. The peculiarities of the use of secondary optical elements in the form of lenses for purpose of obtaining different diagrams of the spatial distribution of light intensity of light-emitting diodes are analyzed. Features and problems of calculation of secondary optical systems are considered. Massive collimators do not have to be elements that focus a narrow beam of light. They are able to form a beam in accordance with any accepted distribution that is appropriate for a given application. They are also able to form a beam in a specific way that is required for outdoor lighting luminaires. The stages of a project for designing a road luminaire require the application of the knowledge and experience gained in various research projects. The design methods described in this paper have been developed designing activity and are also to be used successfully in lighting production.  

scholarly journals Effective Light Source for Illuminating Overhead Guide Signs and Improving Roadway Safety

2016 ◽  
Author(s):  
Mohammed S. Obeidat ◽  
Malgorzata J. Rys
Keyword(s):  
Cost Analysis ◽  
Light Source ◽  
Light Emitting Diode ◽  
Operating Cost ◽  
Mercury Vapor ◽  
Light Distribution ◽  
Light Sources ◽  
Good Efficiency ◽  
Light Emitting ◽  
Roadway Safety

Driver safety is considered an important issue to departments of transportation. One way to increase highway safety is to improve the visibility of overhead guide signs for drivers. Visibility improving methods include the use of sign illumination or retroreflective sheeting materials. This paper focuses on sign illumination by comparing five light sources including high pressure sodium (HPS), metal halide (MH), mercury vapor (MV), induction lighting, and light emitting diode (LED). A laboratory experiment was conducted to compare effective light distribution of each light source and a cost analysis was performed to compare initial, maintenance, and operating cost components of the light sources. Results of the light distribution experiment indicated that HPS was the optimum light source followed by MH, induction lighting, MV, and LED. Induction lighting is a promising lighting technology which features good efficiency and long life. According to cost analysis, induction lighting was the most effective source, followed by the LED, HPS, MV, and MH. Of the five light sources considered, induction lighting provided the best overall performance when considering initial cost, operating cost, expected maintenance, and sign illuminance. Environmentally, LED does not contain mercury, and for those agencies that prefer using sources that are friendlier with the environment, the LED can be their best choice.

Organic Light Emitting Diodes - Innovative Light Sources

2019 ◽  
pp. 101-107
Author(s):  
Sergei A. Stakharny
Keyword(s):  
Light Source ◽  
Organic Light Emitting Diodes ◽  
Organic Leds ◽  
Light Sources ◽  
High Quality ◽  
Light Emitting ◽  
Organic Light ◽  
Lighting Systems ◽  
Physical Principles ◽  
Prospects Of Application

This article is a review of the new light source – organic LEDs having prospects of application in general and special lighting systems. The article describes physical principles of operation of organic LEDs, their advantages and principal differences from conventional non-organic LEDs and other light sources. Also the article devoted to contemporary achievements and prospects of development of this field in the spheres of both general and museum lighting as well as other spheres where properties of organic LEDs as high-quality light sources may be extremely useful.

scholarly journals Towards the Optimum Light Source Spectrum

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Andrew Chalmers ◽  
Snjezana Soltic
Keyword(s):  
Light Source ◽  
Large Scale ◽  
Source Spectrum ◽  
Light Sources ◽  
Luminous Efficacy ◽  
Light Emitting ◽  
Spectral Bands ◽  
Good Energy ◽  
Lighting Systems ◽  
Colour Rendering

This paper is concerned with designing light source spectra for optimum luminous efficacy and colour rendering. We demonstrate that it is possible to design light sources that can provide both good colour rendering and high luminous efficacy by combining the outputs of a number of narrowband spectral constituents. Also, the achievable results depend on the numbers and wavelengths of the different spectral bands utilized in the mixture. Practical realization of these concepts has been demonstrated in this pilot study which combines a number of simulations with tests using real LEDs (light emitting diodes). Such sources are capable of providing highly efficient lighting systems with good energy conservation potential. Further research is underway to investigate the practicalities of our proposals in relation to large-scale light source production.

Hybrid-Light-Source Stereolithography for Fabricating Macro-Objects With Micro-Textures

2021 ◽  
Author(s):  
Wenxuan Jia ◽  
Yuen-Shan Leung ◽  
Huachao Mao ◽  
Han Xu ◽  
Chi Zhou ◽  
...  
Keyword(s):  
Light Source ◽  
Dimensional Accuracy ◽  
Beam Width ◽  
Surface Structures ◽  
Light Sources ◽  
Scanning Method ◽  
Hardware System ◽  
Building Area ◽  
Micro Features ◽  
Display Resolution

Abstract Microscale surface structures are commonly found on macroscale bodies of natural creatures for their unique functions. However, it is difficult to fabricate such multi-scale geometry with conventional stereolithography processes that rely on either laser or digital micromirror device (DMD). More specifically, the DMD-based mask projection method displays the image of a cross-section of the part on the resin to fabricate the entire layer efficiently; however, its display resolution is limited by the building area. In comparison, the laser-based vector scanning method builds smooth features using a focused laser beam with desired beam-width resolution; however, it has less throughput for its sequential nature. In this paper, we studied the hybrid-light-source stereolithography process that integrates both optical light sources to facilitate the fabrication of macro-objects with microscale surface structures (called micro-textures in the paper). The hardware system uses a novel calibration approach that ensures pixel-level dimensional accuracy across the two light sources. The software system enables designing the distribution and density of specific microscale textures on a macro-object by generating projection images and laser toolpaths for the two integrated light sources. Several test cases were fabricated to demonstrate the capability of the developed process. A large fabrication area (76.8 mm × 80.0 mm) with 50 μm micro-features can be achieved with a high throughput.

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