Dissertations / Theses on the topic 'Goniophotometr'

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.
Includes bibliographical references (p. 23-24).
The investigation of innovative window materials for redirecting light and thermal sources is an important component of the field of daylighting. The Heliodome system developed in the Building Technology department is a new type of goniophotometer for analyzing the spectral and angular properties of these materials. The Heliodome system relies on two cameras to transmit images to a user interface in order to provide immediate feedback to users. A filter wheel that divides the spectrum of visible and infrared light into separate wavebands for performing spectral analysis also needs to be integrated into the system to optimize the operation of the system by one user. The subject of this thesis is a control system that unifies the operation of the heliodome system. A wireless system has been developed to enable communication between the main user interface and the system camera without restricting the system's freedom of motion. Also, motors were selected and added to the filter wheel system to automate the filter changes and eliminate inaccuracy in the system. The modifications will enable the separate components of the Heliodome system to operate cohesively and allow architecture students to control the separate components from a single interface.
by Javier Burgos.
S.B.

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.

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.
"June 2007."
Includes bibliographical references (p. 21).
To enable the fast and accurate cataloging of material samples, I designed a filtration device for selecting specific visible and near-infrared light wavelengths related to the red, green, and blue sensitivity peaks of a visible detection camera and the pixel response for a near-infrared camera. This filter device functions in conjunction with the Department of Architecture's Daylighting Laboratory goniophotometer to profile the complete reflection and transmission properties for sample building materials. The resulting data is used in computer simulations and material optimization. The goniophotometer uses two types of detection cameras, color and infrared, to measure the light that is transmitted or reflected off a sample of material. The spectral sensitivity variances of the cameras create inaccuracies in the resulting data when full-spectrum light is used. To remove these inaccuracies, the light is filtered into smaller sections of the full spectrum and the data is recombined by software, to remove these inaccuracies. The device to filter the light is the subject of this thesis. The final filter design uses a geneva drive to index wheels containing pairs of high-pass and low-pass filters into the light path between the light source and the test specimen.
(cont.) The device satisfies the design specifications dictated by the usability, function and spatial constraints. This design should prove to be very reliable and flexible through its continued use in studying building materials. As the project is advanced, future work includes installation of the control system and integration into the software used to coordinate the goniophotometer components.
by Timothy David Koch.
S.B.

The thesis deals with the design of a goniophotometer and the GUI (Graphical User Interface), capable of evaluating the photometric parameters of light sources and luminaires. The introduction contains theoretical information about photometry, photometric parameters, light sources, lamps, as well as the theory of measuring these parameters, and basic globally used data formats, designed to store the parameters of light sources. The core of this thesis, then describes the hardware, that makes up the proposed device, and the software needed to control the measurement process, visualization and storing the results. The conclusion is an evaluation of the functionality of the described device, and the measurements that were mediated by it, and an overall summary of the results achieved.

Avhandlingen behandlar de teoretiska och praktiska aspekterna av att använda spektrala vinkelupplösta reflektansmätningar för optisk karakterisering av fiberbaserade material såsom papper och kartong. En spektral goniofotometer används för att mäta det reflekterade ljusets vinkelfördelning. En stor del av arbetet utgörs av att utvärdera instrumentets noggrannhet, samt utreda hur de vinkelupplösta mätningarna skall utföras på bästa sätt för att erhålla en så fullständig karakterisering som möjligt. Det reflekterade ljuset består av tre komponenter; ytreflektans, bulkreflektans samt fluorescens. En fullständig karakterisering förutsätter att dessa tre komponenter kan analyseras separat, vilket i detta arbete görs genom nyutvecklade metoder. En metod har utvecklats för separation av ytreflektans och bulkreflektans. Metoden bygger på att analysera hur den totala reflektansen förändras vid ökande absorption i det reflekterande materialet. Absorptionen kontrolleras genom inkjet-tryckning där tryckfärg appliceras på substratet i sådan mängd att bulkreflektansen helt släcks ut. Genom att kombinera mätningar på tryckt och otryckt substrat kan de båda komponenterna separeras. Trots att ytreflektansen från ett matt papper är liten i förhållande till bulkreflektansen, så visar resultaten att den ökar markant med ökande betraktningsvinkel och kan därmed ha stor inverkan på den totala reflektansen. Bidraget från fluorescens kan kvantitativt analyseras genom att kombinera mätningar utförda med respektive utan UV-filter. Vinkelupplösta mätningar och Monte Carlo-simuleringar av fluorescensens vinkelfördelning visar att dess anisotropi är relaterad till det medeldjup vid vilket fluorescensen emitteras. Resultaten förklarar observerade skillnader och motstridigheter i tidigare rapporterade studier kring huruvida fluorescens kan anses vara Lamberskt fördelad. Samtliga goniofotometriska mätningar är utförda med ett kompakt, kommersiellt tillgängligt, dubbelstråleinstrument. För att undersöka instrumentets lämplighet för absoluta reflektansmätningar utförs en analys av dess mätnoggrannhet. Resultaten visar att instrumentets kompakta storlek i kombination med den anisotropa reflektansen från papper introducerar systematiska fel av samma storleksordning som den totala mätnoggrannheten. Dessa fel uppstår på grund av den relativt stora detektorapertur som måste användas vid mätningar av diffus reflektans, vilket är karakteristiskt för papper och kartong. Resultaten visar även att felen är störst vid flacka mätvinklar och för prover med hög grad av anisotropisk reflektans, och en geometrisk korrektionsmetod för denna typ av systematiska fel föreslås. Spektrala och vinkelupplösta mätningar medför per automatik stora mängder mätdata. Genom att använda strålningstransportteori som en matematisk modell för hur ljus sprids i papper kan mätdatat reduceras till en uppsättning beskrivande materialparameterar. Att uppskatta dessa optiska parametrar utifrån vinkelupplösta reflektansmätningar är i sig ett komplicerat problem, vilket dessutom är känsligt för mätfel och val av mätvinklar. Detta inversa problem analyseras i detalj, och speciellt hur valet av mätvinklar kan reduceras utan att försämra förutsättningarna för estimeringen. Simuleringar visar att mätningarna kan begränsas till infallsplanet, eller till och med enbart framåtriktningen, så länge tillräckligt flacka mätvinklar är inkluderade i mätsekvensen.
This thesis is about measuring and modelling light reflected from paper by using goniophotometric measurements. Measuring bidirectional reflectance requires highly accurate instruments, and a large part of the work in this thesis is about establishing the requirements that must be fulfilled to ensure valid data. A spectral goniophotometer is used for measuring the light reflected from paper and methods are developed for analyzing the different components, i.e. the fluorescence, surface reflectance and bulk reflectance, separately. A separation of the surface and bulk reflectance is obtained by inkjet printing and analyzing the total reflectance in the absorption band of the ink. The main principle of the method is to add dye to the paper until the bulk scattered light is completely absorbed. The remaining reflectance is solely surface reflectance, which is subtracted from the total reflectance of the undyed sample to give the bulk reflectance. The results show that although the surface reflectance of a matte paper is small in comparison with the bulk reflectance, it grows rapidly with increasing viewing angle, and can have a large influence on the overall reflectance. A method for quantitative fluorescence measurements is developed, and used for analyzing the angular distribution of the fluoresced light. The long-standing issue whether fluorescence from turbid (or amorphous) media is Lambertian or not, is resolved by using both angle-resolved luminescence measurements and radiative transfer based Monte Carlo simulations. It is concluded that the degree of anisotropy of the fluoresced light is related to the average depth of emission, which in turn depends on factors such as concentration of fluorophores, angle of incident light and the absorption coefficient at the excitation wavelength. All measurements are conducted with a commercially available benchtop sized double-beam spectral goniophotometer designed for laboratory use. To obtain reliable results, its absolute measurement capability is evaluated in terms of measurement accuracy. The results show that the compact size of the instrument, combined with the anisotropic nature of reflectance from paper, can introduce significant systematic errors of the same order as the overall measurement uncertainty. The errors are related to the relatively large detection solid angle that is required when measuring diffusely reflecting materials. Situations where the errors are most severe, oblique viewing angles and samples with high degree of anisotropic scattering, are identified, and a geometrical correction is developed. Estimating optical properties of a material from bidirectional measurements has proved to be a challenging problem and the outcome is highly dependent on both the quality and quantity of the measurements. This problem is analyzed in detail for optically thick turbid media, and the study targets the case when a restricted set of detection angles are available. This is the case when e.g. an unobstructed view of the sample is not possible. Simulations show that the measurements can be restricted to the plane of incidence (in-plane), and even the forward direction only, without any significant reduction in the precision or stability of the estimation, as long as sufficiently oblique angles are included.

The changes in light interaction between healthy and diseased tissues have been investigated as a potential diagnostic application. Here we attempt to differentiate between healthy and pathological gastrointestinal tissues using quantitative analysis of optical coherence tomography (OCT) data and goniophotometry. A goniophotometer was constructed and calibrated using titanium oxide and microsphere phantoms. Measurements were carried out on human gastrointestinal tissue sections collected using the methodology described below. The anisotropy factor g was extracted from the scattering curves by fitting the Henyey-Greenstein function. Measurements on human samples were in the forward scattering range with g 0.6-0.7, in agreement with the literature. Optical coherence tomography imaging was carried out on gastrointestinal tissues collected from patients undergoing elective surgery or endoscopy at St. Mary's Hospital, London. In total 146 patients were included. Data was processed using gradient analysis of signal attenuation and morphological analysis with kNN classification. Results were correlated with histological diagnoses. Gradient analysis results were statistically significant across most categories, showing particularly good differences in the gradient distributions between healthy and diseased oesophageal tissues. Morphological analysis and kNN classification produced sensitivity and specificity values for healthy oesophagus and cancer in surgical specimens reaching 100%/97.87% and 99.99%/99.91% respectively and high accuracy in detecting Barrett's oesophagus in endoscopic specimens, with sensitivity and specificity values of 99.80% and 99.02%. Results in rectal tissue where also noteworthy, with detection of dysplasia reaching a sensitivity and specificity of 99.55%/96.01%. Despite limitations in our work, we have shown that the detection of gastrointestinal pathologies using quantitative analysis of OCT data is a promising technique with good ex vivo results. Transferring the methodology to the in vivo domain holds a lot of potential as a future quick and reliable diagnostic technique.

La quête d'un photoréalisme accru en synthèse d'images passe par l'amélioration de la modélisation géométrique des scènes, des algorithmes de calcul de l'éclairement global, et des modèles locaux de réflexion. Ces modèles locaux de réflexion sont représentés par les BRDFs (fonctions de distribution de la réflectance bidirectionnelle). Nous étudions dans ce mémoire un certain nombre de modèles analytiques de BRDFs et les comparons à des mesures réelles de BRDFs. Cette étude nous montre que la diversité du réel ne saurait être prise en compte par un modèle unique de BRDF, et la nécessité d'utiliser directement des mesures de BRDFs en calcul d'images. Nous présentons alors les méthodes existantes pour représenter ces mesures, et introduisons une nouvelle méthode particulièrement adaptée au cas particulier des BRDFs. Cette méthode est basée sur des fonctions à support local et une approche hiérarchique. Afin de valider ces recompositions de BRDFs, nous introduisons aussi un critère d'erreur permettant de comparer les BRDFs entre elles. Afin de relier BRDFs mesurées et BRDFs informatiques, nous présentons un appareil informatique simulant le comportement d'un goniophotomètre existant, appareil servant à mesurer des BRDFs. Ce goniophotomètre virtuel nous permet de valider des modèles analytiques de BRDFs, et de comparer des BRDFs réelles et leur _équivalent simulé à partir de relevés sur les matériaux_

Práce se zabývá měřením křivek svítivosti světelných zdrojů a svítidel konvenčními a nekonvenčními metodami. Úvodní část práce je věnována popisu zrakového systému a základních fotometrických veličin. Hlavní teoretická část je zaměřena na popis současných metod měření křivek svítivosti a nových metod měření pomocí jasového analyzátoru. Současně jsou pro jednotlivé metody uvedeny zdroje nejistot, které ovlivňují výsledky měření. Těžiště práce spočívá v návrhu metodiky měření křivek svítivosti z jasových skenů svítidla a následném ověření tohoto postupu vlastním měřením. Dále bylo provedeno srovnání naměřených výsledků navrženým postupem, s výsledky konvenčního měření na goniofotometru s luxmetrem.

This thesis is focused on the theoretical and practical introduction to the verification procedures used today for obtaining luminosity curves of lamps. The introduction acquaints readers with the photometric variables. Consequently, it is theoretically described procedure for constructing luminance curves by zonal flow and further familiarization with the near-field photometry. For the practical part was chosen several lights. These lamps were measured by luxmeter first from a very close photometric distance from lights, and then from large distance. The next step was to obtain pictures of luminaries in planes C 0 to 345 ° (with a step of 15 °) of the angle gamma from 0 to 180 ° (in steps of 5 °). The measured data were processed by zonal flow and through programs LumiDISP and Matlab. The partial result of this thesis is to verify whether it is possible to use the luminance analyzer for obtaining luminosity curves, it means, if the luminosity curve obtained through luminance analyzer will comply with the curves obtained through a luxmeter. Further work should ascertain the feasibility of acquired photographs lamps from a very close photometric distance could create luminosity curve for any location and distance from the observer to measured lamps.

碩士
國立高雄科技大學
機械與自動化工程系
107
Comfortable ambient lighting, in addition to providing the basic needs of our daily lives, provides an efficient, safe and energy-efficient visual environment. Among all the factors affecting the quality of lighting, the most important factor is the light distribution curve characteristics of the lighting fixture. The light distribution curve and the light distribution data are very important for the lighting design. Lamp manufacturers should provide customers with light distribution or light distribution data for light sources or lamps, but many manufacturers do not have equipment similar to the light curve meter. Because a set of instruments is expensive and requires a large test space, the average company is not willing to buy, but for measuring light distribution data, the light curve meter is a must. 　　For the purpose of designing a goniophotometer, this study compares the design of several mechanical structures with the current distribution of goniophotometers and improves the shortcomings of commercially available goniophotometers. In the adjustment of the luminosity center of the luminaire, a rotating mechanism that can adjust the angle is used to solve the problem, which not only improves the accuracy of the measurement, but also greatly reduces the time required for the luminaire to perform the light distribution measurement. 　　Finally, in the measurement distance of the goniophotometer, this paper also proposes a method to shorten the measurement distance, which reduces the measurement distance, in addition to solving the space for the factory equipment, and the difference between the measurement distance data for shortening. Very little. The goniophotometer designed in this paper cooperates with the method of shortening the measurement distance to develop a space-saving cost-setting curve meter, which improves the technical level of the optical measurement system and greatly helps the domestic measurement industry.

碩士
國立交通大學
機械工程學系
100
This thesis designed a type-C goniophotometer to improve the disadvantages of the current goniophotometer by some design of mechanical structure. By the use of a fine-tuned mechanism, the center of luminaire could be adjusted. Set up a hood in front of the illuminance meter to reduce the stray light and use a synchronously rotating mechanism to eliminate the cosine error caused by the incident angle that light launch into the illuminance meter by. In addition, changing the measurement mode of goniophotometer, the required time to measure the light distribution curve of the luminance was significantly reduced. Finally, this thesis proposes a new alignment method which can be easy and fast to complete the alignment of a goniophotometer.

碩士
正修科技大學
電機工程研究所
95
This thesis presents the GMS-2000 rotating mirror goniophotometer to measure candlepower distribution for luminaires. The most advanced rotating mirror theory is adopted in the GMS-2000 Goniophotometer which can ensure that measured luminaires always be in practical situation. It meets the requirements of CIE (Commission Internationale de I’Eclairage), & IESNA (Illuminating Engineering Society of North America). It also can achieve measuring way C-γ, A-?and B-β. It can measure photometric parameters of luminaires for road lighting, interior lighting and projecting lighting, such as spatial intensity distribution, intensity distribution curve on each section(represent by right-angled coordinates or polar coordinates), spatial iso-intensity curve, iso-illuminance distribution curve on the plane, luminance limitation curve, zonal flux, glare grade, luminaire efficiency, effective beam angle, upward luminous flux ratio, downward luminous flux ratio, total luminous flux, effective luminous flux, utilization factor and electric parameters (voltage, current, wattage, power factor) and etc. The GMS-2000 system can complete automatically muti-coordinates intensity distribution measurement, and the measured data file satisfies the international standard format and can be transferred directly by other luminaire or lighting design software. With large elliptical plane mirror in the GMS-2000 system, the measurement position of luminaire is in consistent with practical status. Moreover, the burning point of the light source keeps unchanged, meeting the measurement requirements of various high intensity discharge (HID) lamps such as mental halide lamp, high-pressure mercury vapour lamp, and high-pressure sodium lamp etc. The test results have shown that the GMS-2000 goniophotometer system can obtain precision measurement results, and the feasibility of applying the GMS-2000 system to measure spatial candlepower distribution for luminaire has been demonstrated.

碩士
國立中央大學
光電科學與工程學系
104
Screen image synthetic whole-field optical distribution meter overcomes the shortcoming of time consuming of goniophotometer in the current market. It use camera to capture a wide range of light distribution with only one shot. By using rotator to change the picturing aspect, we can synthesize the whole images with aid of image fusion system to form the whole field optical distribution. Moreover, we add light source to illuminate the sample, and rotate the sample to change incident angle to obtain the BSDF measurement result. In this thesis, in order to measure the optical distribution and BSDF using one instrument. We increase the distance between the sample and the camera up to 50 cm. Besides, in order to reduce the volume of the instrument, the screen size is set as 601×496 (mm2), and the rotational part is the sample with light source instead of the imaging system. Since the screen size is limited, the total number of pictures is increased to cover the whole field. Here, we proposed an optimized solution to minimize the total number of pictures in semi-sphered field measurement. BSDF measurement and whole field optical distribution measurement distribution are accomplished with one instrument. The size of the light source in one dimension for the whole field optical distribution measurement achieve 5 cm.

碩士
元智大學
光電工程學系
106
This study designed and implemented a goniophotometer for measuring the intensity of a small-size light source in zenith angle (θ) and azimuthal angle (φ). A half-hemisphere shell of 15-cm radius was designed and manufactured with a 3D printer. There are 30 photodiodes on the shell as light sensors so that the zenith angle resolution is 3°. A 4096-step step motor loaded with a light source horizontally rotates so that the azimuthal angle resolution can be less than 0.1°. The light source was driven by 100 Hz square wave. The photo-current generated by a light-illuminated photodiode was converted into voltage signal with a trans-impedence amplifier. Voltage signal was converted into digital signal after a two-stage voltage amplifier. After calibration, the relative light intensity was detected from the digital signal. The design of amplifiers and calibration process are described. Two measurement examples of light emitting diodes were shown. In comparison with commercially available goniophotometer, the goniophotometer designed in this study has the potentials of small size, low cost, and short measurement time.

碩士
國立中央大學
光電科學與工程學系
104
The relative intensity distribution curve is necessary for engineers to design optical system. Traditionally we use goniophotometer to obtain data. It works but takes much time. Much necessary space also costs too high. In such a way, users are concerned about the emergence of alternatives. With great progress both on the software and the hardware in recent years, the possibility of imaging luminance measurement device (ILMD) is getting promising. Through theory research and experiments, this study presents a systematic design includes mechanical design and algorithms to obtain relative intensity data of a LED just by one snap. To improve system stability, we have done hardware calibration (CCD noise, gray value response, image distortion and Vignetting ) for CCD and lens system to make sure only right data can be input to main algorithm. To improve the accuracy of the system, the calibration algorithm is including finding real incidence angle, BTDF, transmittance, absorption rate, solid angle normalization, and cosine law function.