Sök:

Sökresultat:

322 Uppsatser om Optical Coherence Tomography - Sida 1 av 22

OCT inom ögonsjukvård : noggrannhet hos mätfunktion

Denna rapport handlar om optisk koherenstomografi, Optical Coherence Tomography (OCT), en relativt ny teknik som blivit allt mer attraktiv på sjukhusens ögonkliniker. En OCT-apparat används bland annat för diagnosticering av ögonsjukdomar lokaliserade i gula fläcken och runt optiska disken. I maj 2007 köpte Ögonkliniken på Blekingesjukhuset in en 3D OCT-1000 av märket Topcon. Hos denna OCT-apparat finns en mätfunktion, Caliper, som mäter näthinnetjocklek. Studien i denna rapport syftade till att ta reda på vad Caliper mäter, hur den mäter och om den går att lita på.

OCT inom ögonsjukvård - noggrannhet hos mätfunktion

Denna rapport handlar om optisk koherenstomografi, Optical Coherence Tomography (OCT), en relativt ny teknik som blivit allt mer attraktiv på sjukhusens ögonkliniker. En OCT-apparat används bland annat för diagnosticering av ögonsjukdomar lokaliserade i gula fläcken och runt optiska disken. I maj 2007 köpte Ögonkliniken på Blekingesjukhuset in en 3D OCT-1000 av märket Topcon. Hos denna OCT-apparat finns en mätfunktion, Caliper, som mäter näthinnetjocklek. Studien i denna rapport syftade till att ta reda på vad Caliper mäter, hur den mäter och om den går att lita på. En OCT-undersökning utfördes på tio testpersoner.

Double integrating spheres: A method for assessment of optical properties of biological tissues

The determination of the optical properties of biological tissue is an important issue in laser medicine. The optical properties define the tissue´s absorption and scattering behaviour, and can be expressed by quantities such as the albedo, the optical thickness and the anisotropy coefficient. During this project, a measurement system for the determination of the optical properties was built up. The system consists of a double integrating sphere set-up to perform the necessary reflection and transmission measurements, and a computer algorithm to calculate the optical properties from the measured data. This algorithm is called Inverse Adding Doubling method, and is based on a one-dimensional transport model.

Optiska egenskapers påverkanav möjligheten att trycka eftermålvärden i ISO 12647-2.

This thesis investigates how the optical properties of paperboard influences printing with targets in ISO 12647-2. The targets for optical properties in ISO 12647-2 are defined for paperboard without optical brightening agents and fluorescent brightening agents wich makes it difficult to reach the targets when printing paperboard containing these agents.Seven different types of paperboard, some with and some without the agents, have been printed and instrumentally andvisually measured to see if there is any deviation from the standard targets and if it shows visually.The result shows that paperboard containing optical brightening agents and fluorescent brightening agents can print with targets in ISO 12647-2 but in many measurments the difference between the types of paperboard were to small to assess. The differences between the types of paperboard in the instrumental measurements did not fully correspond with the waythe panel appraised them visually..

OCT (Optical Coherense Tomography): Teknik och tillämpning

Före år 1895 kunde läkarna endast ställa en sannolik diagnos utifrån vad patienten kunde berätta och om det syntes någon förändring på utsidan av kroppen. Med röntgen blev det möjligt att se insidan av patienten utan att först skära upp densamma, man kan säga att säga att röntgen blev startskottet för diagnostisk avbildning.Vidareutvecklingen av röntgen gav CT (Computed Tomography) där röntgenrör och detektorer roterar runt patienten samtidigt som patientbordet förflyttas. Förutom CT utvecklades även MRI (Magnetic Resonance Imaging), PET (Positron Emission Tomography) och Ultraljud. Gemensamt för alla dessa olika metoder är att det produceras 3D-bilder.1990 kom en helt ny metod för diagnostisk avbildning, OCT (Optical Coherence Tomography), genom att mäta fasförskjutningen och intensitet av reflekterande ljus, ger det i realtid och oförstörande mätning (in vivo) en upplösning på 1 till 15 µm, mycket högre än alla andra vanliga bildåtergivningstekniker. OCT-maskinen kan jämföras med ultraljud, som använder reflektion av ljudvågor för tolkning [1].De första OCT-maskinerna var av typ TD (Time Domain), dessa hade låg upplösning och låg skanningshastighet.

Simulering av filtrerade skärmfärger

This report present a working model for simulation of what happens to colors displayed on screens when they are observed through optical filters. The results of the model can be used to visually, on one screen, simulate another screen with an applied optical filter. The model can also produce CIE color difference values for the simulated screen colors. The model is data driven and requires spectral measurements for at least the screen to be simulated and the physical filters that will be used. The model is divided into three separate modules or steps where each of the modules can be easily replaced by alternative implementations or solutions.

Hur skiljer sig tjockleken på retinas nervfiberlager mellan emmetroper, myoper samt hyperoper? : En OCT studie

Syfte: Syftet med studien var att utreda sambandet mellan ögats ametropi och tjockleken på retinas nervfiberlager (RNFL) med Optical Coherence Tomography teknik (OCT).Metod: I studien ingick 30 försökspersoner med olika typ av ametropi. En inledande mätning med autorefraktor genomfördes och styrkorna värderades därefter av i provbåge. På så sätt erhölls ett resultat på storleken på den eventuella ametropin. Därefter utfördes den huvudsakliga mätningen av nervfiberlagets tjocklek med OCT kameran OPKO Spectral OCT Slo på samtliga försökspersoners högerögon. Försökspersonerna delades in i fem olika grupper utifrån befintlig ametropi.Resultat: En signifikant korrelation mellan ögats ametropi och det retinala nervfiberlagrets tjocklek hittades då resultaten från alla 30 försökspersoner analyserades mot varandra.

Skillnaden i central och perifer retinal tjocklek mellan olika ametropier - en OCT-studie

Syfte: Syftet med studien var att, med hja?lp av Optical Coherence Tomography (OCT), underso?ka om det finns na?gon skillnad i central och perifer retinal tjocklek mellan olika ametropier.Metod: Studien omfattade 36 fo?rso?kspersoner, som grupperades beroende pa? ametropi i en myop, emmetrop och hyperop grupp. Av de 36 fo?rso?kspersonerna var det 15 myoper, 15 emmetroper och 6 hyperoper. En inledande ma?tning gjordes da?r fo?rso?kspersonernas objektiva refraktion uppma?ttes med autorefraktor och da?refter gjordes en avsta?mning i provba?ge fo?r att sa?kersta?lla refraktionen.

Asymptotiska egenskaper hos vissa kombinatoriska strukturer

In an attempt to develop a more cost-efficient material for solar   energy applications, nano-particles of nickel oxide composite in a silikatmatris manufactured with solar gelmethod and studied structurally by electron microscopy. Furthermore, the thin film optical properties characterized by Variable. Angel Spectroscopic Ellipsometry. Sol gelfilms suitability as a selective absorber surface is also analyzed by optical modeling..

Finns det skillnader i känsla av sammanhang mellan personer på monotona och icke -monotona arbetsplatser med hänsyn tagen till syskonplacering?

AbstractThe aim of this study was to examine whether there are differences in Sense of Coherence between people in monotonous and non ? monotonous jobs with regard to birth order. In this present study, 89 individuals from three different working organizations participated, of which 51 (57, 3 %) of them were men and 38 (42, 7 %) women. The results showed that in varying occupations, firstborn children showed a higher level of Sense of Coherence. In monotonus jobs, middle children prove to have the lowest level of Sence of Coherence.

Design and Analysis of an All-optical Free-space Communication Link

Free Space Optics (FSO) has received a great deal of attention lately both in the military and civilian information society due to its potentially high capacity, rapid deployment, portability and high security from deception and jamming. The main issue is that severe weather can have a detrimental impact on the performance, which may result in an inadequate availability. This report contains a feasibility study for an all-optical free-space link intended for short-range communication (200-500 m). Laboratory tests have been performed to evaluate the link design. Field tests were made to investigate availability and error performance under the influence of different weather conditions.

Känsla av sammanhang : En studie om KASAM i årskurserna 1, 3 och 6

Sense of coherence, SOC, is a way to study health and wellbeing in a salutogen perspective. SOC is a theory that Aaron Antonovsky came up with and it involves three elements; comprehensibility, manageability and meaningfulness. These three elements is a objective way to look at our existence. The aim of this study was to examine how high the pupils sense of coherence was in the grades 1, 3 and 6 in a school in Karlstad. And with the result as starting point have a discussion around the pedagogical consequences and which educational work procedures we can use to work with SOC in school.

Optisk karakterisering av tunna SiO2/NiO-filmer syntetiserade med en sol-gelmetod

In an attempt to develop a more cost-efficient material for solar   energy applications, nano-particles of nickel oxide composite in a silikatmatris manufactured with solar gelmethod and studied structurally by electron microscopy. Furthermore, the thin film optical properties characterized by Variable. Angel Spectroscopic Ellipsometry. Sol gelfilms suitability as a selective absorber surface is also analyzed by optical modeling..

Optisk sortering av matavfall : en jämförelse med en minskning av svinnet

The purpose of this study is to compare the energy related and environmental consequences of implementing optical sorting as a means of waste collection with those of reducing food waste. In addition to studying the possibility of implementing optical sorting in downtown Stockholm, the yielded amounts of energy from waste collection and reduced wastage will be calculated. This is done by way of literature reviews and interviews. The amount of energy that can be generated through optical sorting and biogas production via anaerobic digestion in downtown Stockholm is 29-44 TJ/year, compared to 118 TJ/year saved by completely eliminating food waste. The generated biogas can replace fossil fuels, but the required food waste contributes to increased greenhouse gas emissions as well as reduced bio diversity and eutrophication during the wasted food?s lifecycle.

Optimerade material för optiska komponenter i koncentrerande solfångare

The energy consumption continues to increase as the use of electronics and energy consuming equipment increases. The use of fossil fuels has to be phased out for this to be sustainable in the long run while the use of renewable energy continues to increase. A renewable energy source is solar energy but the production of heat and electricity are today very expensive compared to other energy sources and an important task for the solar energy market to grow is therefore to minimize the production cost of the solar collectors while increasing its efficiency to produce heat and/or electricity. One way to convert solar energy into heat is by using solar collectors and electricity can be produced by utilizing the produced heat, or by applying solar cells.This thesis aims to recommend a reflective material for the next generation solar collectors from Absolicon and to recommend a commercially available coating for the receiver tube of the solar collector. A market study has been carried out to investigate the cost-related aspects along with the optical and durable aspects for the optical material of the solar collector.

1 Nästa sida ->