The acoustic resonance phenomena of metal halide lamps are investigated. A measuring system is set up to examine the effects of the acoustic resonance to the shape of the lamp arc, the lighting energy spectrum, the color temperature, the light output as well as electrical characteristics. Two ballast circuits are built to drive the lamps with the sine-wave current and the square-wave current, respectively. One ballast employs the series resonant inverter to output the sinusoidal lamp current. The other makes use of the full-bridge inverter to drive the lamps with the square-wave current. They are operated over a high-frequency range from 20kHz to 30kHz. For both ballast circuits, the operating frequency and the magnitude of the lamp current can be controlled independently. ¡@¡@The experiments are conducted on the 70-W metal halide lamps. The experimental results show that the spectral energy and the color temperature change more significantly as the acoustic resonance becomes more serious. These effects become less significant when the lamps are driven by the square-wave current. The degree of the acoustic resonance can be identified by detecting the variation of the lamp voltage or the output light. The investigated results of the thesis can provide useful information when a standard of the acoustic resonance is considered.

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This thesis proposes a novel driving circuit of the RGB light emitting diodes (LEDs) for the back-light source of the liquid crystal display. In stead of employing three dc-to-dc converters, a fly-back converter with three secondary windings is used to drive RGB-LED light bars. By adjusting the duty-ratio, the fly-back converter provides compromised voltages to RGB-LEDs in accordance with the operating modes of dimming control, so as to retain current magnitudes within the acceptable values. LEDs of three colors are dimmed by regulating the duty-ratios of three active power switches individually. By changing the ratio of the average currents of the three primary color LEDs, the color temperature range of driving can reach the requests of dimming control. As compared with a consumer product using the conventional driving circuit, the proposed circuit is obviously much simpler with less components and a higher efficiency.

A digital painter uses reference photography to add realism to a scene. This involves making n colors in a painting relate to each other more like n corresponding colors in a photograph, in terms of value and temperature. Doing this manually requires either experience or tedious experimentation. Color relationship transfer performs the task automatically, recoloring n regions of a painting so they relate in value and temperature more like n corresponding regions of a photograph. Relationship transfer also has applications in computational photography. In fact, it introduces a new paradigm for image editing in general, based on treating an image's fundamental relationships.

I takt med att e-handeln växer sig större behöver fysiska butiker blir allt mer upplevelseinriktad och leverera unika kundupplevelser för att inte mista sina kunder. Ljus och belysning är en viktig komponent för att påverka kundupplevelse, eftersom ljus direkt påverkar komfort och navigering i butiken. För att skräddarsy belysning för en specifik butik krävs expertis från en ljusdesigner. Finjusteringar av belysning på plats i butiken kan dock vara en utmaning även för ljusdesigners på grund av tidsbegränsning, mängden fel som kan uppstå i ljusinstallationen och avsaknaden av effektiva verktyg för att justera olika aspekter av ljus. Denna studie syftar till att förstå om ett mobilt verktyg för att justera ljusets färgtemperatur i realtid kan hjälpa en ljusdesigner vid installationen av belysning i en butik. För att förstå de utmaningar som är involverade i ljusdesigners arbete har två metoder använts. En deltagande observationsstudie och semistrukturerade intervjuer med tre ljusdesigners. Med kunskap från dessa metoder utfördes ett användarstudie där två versioner av en mobilapplikation för justera ljus testades. Detta utfördes för att dels undersöka användningen av en befintlig applikation och för att identifiera vilka element i den här typen av verktyg som är viktiga för en ljusdesigner. Denna studie indikerade att ett sådant mobilverktyg kan vara mycket användbart, men endast om det innehåller alla nödvändiga element som behövs för att finjustera en ljusinstallation. Studien visade även att en av de viktigaste komponenterna av ett sådant mobilt verktyg är möjligheten att justera färgtemperaturen på ljus, särskilt när man skapar belysning specifikt för en butik. En designövning utfördes för att undersöka hur användbara befintliga verktyg för att justera färgtemperatur är och hur sådana verktyg kan utformas för att passa en ljusdesigners behov. Baserat på resultatet av denna övning skapades en prototyp på ett verktyg för att justera färgtemperaturen av ljus. Denna prototyp utvärderades genom en formativ användarstudie samt ett frågeformulär för att utvärdera ett systems användbarhet. Enligt resultatet av testet uppfattades prototypen vara användbar. Sammantaget tyder resultaten från denna studie på att det finns ett behov av denna typ av mobila verktyg som effektivt kan hjälpa ljusdesigner i deras arbete. / With the significant growth of e-commerce, physical stores need to become more experience-driven, and delivering unique, high impact customer experiences is a core for their success. Lighting is an important element of customer experience, as it directly affects comfort and navigation. In order to customize lighting for a store,expertise from a light designer is needed. However, on-site lighting fine tuning is a challenge due to time restrictions, amount of error occurring to the light installation, and easy accessible tools for adjustments. This study aims to understand whether an mobile tool for adjusting color temperature of lights in realtime can assist a light designer when installing a light installation in a retail store. To understand the challenges involved in the work of lightning designers, two methods have been used. A participatory observational study and semistructured interviews with three light designers. Given that, an exploratory user test was performed, testing two versions of a lighting manager application in order to investigate the usage of an existing application and what elements in this kind of tool are of most importance for a light designer. The user tests indicated that a mobile tool like this could be very useful, but only if it contains all the necessary elements needed. The results show that one of the essential elements of such a tool regards options for adjusting color temperature, when creating specifically for a retail store. In order to investigate further how useful existing light color temperature tools are and how they could be designed to suit a light designer needs, a design exercise was performed. Through the result of this exercise a prototype of a color temperature tool was created. This prototype was evaluated through a formative user study. The usability of the prototype was evaluated through a System usability score evaluation questionnaire. According to the test, the prototype was found to be usable. All in all, the results of this study indicate that there is a need for this kind of mobile tools that can effectively assist light designers in their work.

A solar fiber optic lighting system, SP3 from the Swedish company Parans Solar Lighting AB, has been installed in a study area/corridor test site. A collector is tracking the sun during daytime, focusing the direct sun irradiance via Fresnel lenses into optical fibers, which guide the solar light into the building. The illumination properties of the system have been characterized. The energy saving due to reduced need of artificial lighting have been calculated and methods for balancing the artificial lights in the test site have been evaluated. The illumination at the test site using solar light was at least as high as when using the artificial lights and even higher at very clear days. The luminous flux output (500 lm) was somewhat lower than specified by the manufacturer (550 lm) at 100 000 lx direct sun illuminance. The output at 130 000 lx was high 767±33 lm the sunlight coupling efficiency 23 %. However, for a 20 m SP3 system the luminous flux output (400 lm) at 100 000 lx was higher than specified (350 lm). The SP3 system of Parans provides high quality solar light. It has a fuller spectrum close to the spectrum of the sun compared to the fluorescent lights at the test site. The correlated color temperature of the system was 5800±300 K and the color rendering index 84.9±0.5. The lighting energy saved due to decreased need for artificial light was estimated to 19 % in Uppsala which has 1790 annual sun hours. The savings in Italy, which has 3400 sun hours, is 46 %. Additional saving, especially in warmer countries can be obtained due to decreased need for cooling in the building as the solar luminaires provide negligible heat to the indoor air. Economical saving could also be realized by improved well-being of the occupants spending time under the solar luminaires. Three ways of balancing the artificial light due to sunshine fluctuations have been investigated. The global horizontal irradiance could not be used as a control signal for balancing the artificial lights but a pyranometer attached to the SP3 sun tracking collector was usable. Also the signal from an indoor luxmeter sensor could be used for balancing the light. However the signal from the light sensor which makes the SP3 collector to track the sun is probably the most cost effective method as it would serve two purposes; tracking the sun and balancing the artificial lights.

In this thesis we examine the feasibility of developing a white light source capable of producing colors between 2500 and 7500 Kelvin on the black-body radiator spectrum by simply adjusting amperage to a blue and ultraviolet (UV) light emitting diode (LED). The purpose of a lighting source of this nature is to better replicate daylight inside a building at a given time of day. This study analyzes the proposed light source using a 385 nm UV LED, a 457 nm blue LED, a 479 nm blue LED, a 562 nm peak cerium doped yttrium aluminum garnet (YAG:Ce) phosphor, and a 647 nm peak selenium doped zinc sulfide (ZnS:Se) phosphor. Our approach to this study initially examined optical performance of yellow-emitting phosphor (YAG:Ce) positioned at specific distances above a blue LED using polydimethylsiloxane (PDMS) as a substrate. An understanding of how phosphor concentration within the PDMS, the thickness of the PDMS, and how substrate distance from the LED die affected light intensity and color values (determined quantitatively by utilizing the 1931 CIE 2° Standard Observer) enabled equations to be developed for various lens designs to efficiently produce white light using a 457 nm peak wavelength LED. The combination of two luminescent sources (457 nm LED and YAG:Ce) provided a linear trend on the 1931 CIE diagram which required a red illumination source to obtain Kelvin values from 2500 to 7500. Red-emitting phosphor (ZnS:Se), selected to compliment the system, was dispersed with YAG:Ce throughout PDMS where they were stimulated with a blue LED thereby enabling all desired Kelvin values with differing concentration lenses. Stimulating ZnS:Se with the addition of a UV LED did not provide the ability to change the color value of the set up to the degree required. Many other factors resulted in the decision to remove the UV LED contribution from the multi-Kelvin light source design. The final design incorporated a combination of ZnS:Se and YAG:Ce stimulated with a blue LED to obtain a 2500 Kelvin value. A separate blue LED provides the means to obtain 7500 Kelvin light and the other color values in between, with a linear approximation, by adjusting the amperages of both LEDs. In addition to investigating the feasibility of obtaining the Kelvin values from 2500 to 7500, this thesis also examined the problem of ZnS:Se’s inability to cure in PDMS and a method to create a lens shape to provide equal color values at all points above a phosphor converted LED source. ZnS:Se was found to be curable in PDMS if first coated with a low viscosity silicon oil prior to dispersion within PDMS. The lens configuration consists of phosphors equally distributed in PDMS and cured in the shape of a Gaussian distribution unique to multiple factors in LED-based white light design.

Ljus påverkar människan psykiskologiskt och fysiskt, trots detta är de krav som idag finns på belysningen inte tillräckliga för att beakta de miljöegenskaper ljuset bidrar med. Ett visst ljus i kombination med en viss färg och material påverkar människan på olika sätt. De krav som ställs tar bara hänsyn till de tekniska aspekterna. Hur ljus estetiskt påverkar ett rum är en faktor detta arbete tar hänsyn till, då det påverkar människans välmående. Detta projekt behandlar två olika rum, ett rum för träning och behandling samt ett väntrum på en sjukgymnastikavdelning tillhörande Södersjukhuset i Stockholm. Dessa två rum har genomgått en ljusstudie och ljusplanering med syfte att skapa en ljussättning som är anpassad för sitt ändamål och som upplevs trivsam och behaglig. Vissa skillnader mellan projektets framtagna förslag och ett verkligt projekterat förslag har även jämförts. För att genomföra ljusstudien och ljusplaneringen har beräkningar utförts i belysningsprogrammet RELUX. På grund av att ljus inte enbart kan simuleras med hjälp av datorprogram har även fysiska modeller byggts för att analysera valet av färgtemperatur. Studiebesök på sjukgymnastpraktiker och träningsanläggningar har gjorts för att få inspiration. Även intervjuer med sjukgymnaster har gjorts för att få förståelse för vilka faktorer som måste tas hänsyn till vid en ljusplanering för denna typ av verksamhet. Litteraturstudier har gjorts för att få en djupare kunskap i hur ljus agerar i olika miljöer. Ljusplaneringen har resulterat i en jämn och god belysning i de två rummen. Kraven för belysning enligt SS-EN 12464–1:2011, har uppfyllts. Ljuskällornas färgtemperaturer har fastställts med hänsyn till färgerna i rummen, varmvit i väntrummet och neutral i tränings-/behandlingsrummet. Armaturer med uppljus och nedljus har valts i syfte att minska bländning och luminansskillnader. Downlights har valts för att belysa väggar och föremål. För att skapa en upplivande atmosfär i rummen har även dekorbelysning använts. Slutsatsen av detta arbete har visat att det är viktigt att ta hänsyn till en jämn belysning, anpassa belysningen och ljuskällans färgtemperatur efter färgsättning och material samt att anpassa belysningen efter alla synuppgifter som kan komma att krävas av personen som skall utföra arbetsuppgifter i rummet. / Light affects humans psychologically and physically, despite this the lighting requirements does not pay regard to the environmental characteristics that light contributes with. A specific light in combination with a specific color and material affects the human being in different ways. The lighting requirements only takes the technical aspects into account. In this project consideration will be given to how the light aesthetic affects the well-being. In this project two rooms will be processed, a waiting room as well as a room meant for rehabilitation. The rooms are placed in a building that includes physiotherapy at Södersjukhuset in Stockholm. The rooms have participated in a light study to create a light environment that is adjusted to its purpose as well as it is pleasantly perceived. Some differences between this lighting project and an actual lighting project have been compared. To perform this light study, various calculations have been done in the lighting planning software RELUX. Light can not solely be simulated with computer software, therefore physical models have been built to analyze the choice of color temperature. Visits to physiotherapy practices and training facilities have been done for inspirational purposes. Interviews with physiotherapists have also been done to reach a better understanding of what factors are needed to be taken under consideration while planning the lighting. Literature studies have been made to get a deeper knowledge in how light reacts in different environments. The lighting planning has resulted in an even lighting in both rooms. The requirements for lighting according to SS-EN 12464-1:2011 have been fulfilled. The different color temperatures of the light sources have been determined regarding the colors of the rooms, warm white in the waiting room and neutral in the rehabilitation room. Armatures with up and down lights have been chosen with the purpose of decreasing glare luminary differences. Downlights have been chosen to lighten up the walls and various objects. To create an uplifting atmosphere in the room, decor lighting have also been used. The conclusion of this work has shown that it is important to take luminance uniformity, adapt the light and color temperature to the room and its colors and materials into account. It is also important to adapt the light to all the different visual works that can take place in the room.

Tunable white-armaturer utgör idag en stor del av marknaden och förväntas öka ytterligare under de kommande åren. Då många leverantörer idag producerar och marknadsför sina egna lösningar för att skapa ett dynamiskt ljus kan det vara svårt att veta vilken standard dessa lösningar håller och hur väl den tekniska specifikationen stämmer överens med verkligheten. Syftet med denna studie har varit att undersöka om informationen mot beställare är tillräcklig samt om den redovisade data av Tunable White-armaturer är korrekt. Studien bygger på två delar. En experimentell undersökning genomfördes där fem tunable white-armaturers CRI (färgåtergivning) mättes mellan olika CCT-nivåer (färgtemperatur) och sedan jämfördes det med vad leverantörer har specificerat på deras hemsidor. En enkätundersökning genomfördes sedan som riktades mot 144 ljusdesigners i Sverige, varav 52 valde att besvara enkäten. Frågorna berörde redovisning av Tunable white-armaturer samt vikten av en god ljuskvalitet med inriktning på CRI. Resultaten från författarnas experimentella undersökning visar att alla tunable white-armaturer som testades skiftar i CRI under olika färgtemperaturintervaller. Den största skillnaden som mättes var på fabrikat 3 där det skiftade 9 CRI mellan 2700K-6000K. En jämförelse kunde sedan göras och visade att två av fem leverantörers specifikationer inte stämmer överens med vad som redovisats i respektive produktdatablad. Av att tyda svaren från enkätundersökningen kunde slutsatsen dras att det finns mycket skilda åsikter angående de tekniska specifikationerna gällande tunable white-armaturer. En del ansåg att det redovisas tillräckligt väl idag medan andra ansåg att det inte redovisas tillräckligt väl. Majoriteten ansåg att det är mycket viktigt med en god CRI när man föreskriver tunable white-armaturer i sina projekt. Man kunde också se att många ljusdesigners önskade att man redovisade färgåtergivning i TM-30-15 istället för CRI-metoden eller att man bör redovisa i givna färgtemperaturer. Det som kan fastställas av denna studie är att det finns en tendens till att vissa armaturleverantörer har sämre CRI än vad företaget i fråga redovisat. Denna studie enbart mätt TW-armaturer från fem företag verksamma i Sverige samt endast vid 100% ljusflöde. Författarna anser dock att denna studie kan leda till en diskussion om bättre redovisning av tunable white-armaturer behövs, samt ge läsaren en ökad förståelse för komplexiteten inom området. / Tunable white luminaires today form a large part of the market and are expected to increase further in the upcoming years. As many manufacturers today produce and market their own solutions to create a dynamic light, it can be hard to know what quality these solutions have and how well the technical specification is. The purpose of this study were to investigate whether the information to the user is sufficient and whether the presented data of tunable white luminaires is correct. This study is based on two parts. An experimental study where five tunable white luminaires CRI (color rendering) were measured between different CCT levels (color temperature) and then compared these to what providers have specified on their websites. The second part was a survey was conducted to 144 lighting designers based in Sweden, 52 of whom chose to answer the questionnaire. The questions concerned the presented information of tunable white luminaires as well as the importance of a good light quality focusing on CRI. The results from the authors experimental survey showed that all tunable white luminaires that where tested are changing in CRI under different color temperature intervals. The biggest difference that was measured was on manufacturer 3 where 9 CRI shifted between 2700K-6000K. A comparison could be made and showed that two of five of the suppliers specifications did not match with the authors measurements. By analyzing the answers from the survey, some conclusions could be drawn. There were very different opinions regarding the technical specifications of tunable white luminaires. Some felt that it is enough as it is today, while others felt that more information was needed. The majority considered it very important to have a good CRI when selecting tunable white luminaires in their projects. One could also see that many lighting designers wanted to present color reproduction in TM-30-15 instead of the CRI method or to present CRI at given color temperatures. What can be determined by this study is that there is a tendency for some luminaire suppliers to have worse CRI than presented. This study only measured tunable white fixtures from five companies operating in Sweden and only at 100% luminosity. However, the authors consider that this study could lead to a discussion about better specifications for tunable white luminaires, as well as giving the reader an increased understanding of the complexity of the subject.

The thesis deals with the pouring of epoxy materials over LED strips. The research part contains an introduction to photometry and summarizes the types of potting compounds along with their characteristics. The practical part delves into the effect different amount of pigment has on the photometric properties. This is assessed based on verified measurements performed with the help of a goniophotometer on samples with different amounts of pigment, which were created using an integration sphere. Furthermore, a brightness analysis and a long-term outdoor test were performed.