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1
Standingford, David William Fin. "Optimal lifting surfaces, including end plates, ground effect & thickness /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phs785.pdf.
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Ziemann, Paul [Verfasser]. "Optimal thickness of shells with an application to cylindrical bodies / Paul Ziemann." Greifswald : Universitätsbibliothek Greifswald, 2016. http://d-nb.info/1113751959/34.
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Perman, Daniel. "Optimal väggisoleringstjocklek på hyresfastighet vid begränsad byggyta." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-26411.
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Miljömedvetenheten och ökat intresse för energieffektiva hus har gjort att byggnader isoleras som aldrig förr. Oftast är det på lång sikt ganska så lätt att räkna hem en ökad isoleringsmängd och det är just den ekonomiska vinsten som brukar lyftas fram som det främsta argument varför en beställare bör välja den tjockare isoleringen. För en beställare av hyresfastigheter är det oftast ekonomin som avgör ifall ett projekt ska påbörjas eller inte och denna studie ska därför vara en hjälp till att välja den mest ekonomiska isoleringstjockleken i väggar. Syftet med denna studie är att utreda var den optimala väggisoleringstjocken hamnar på en hyresfastighet med flerfamiljsbostäder som byggs på en begränsad byggyta. Inte sällan finns det krav på maximal byggyta från kommunen och då innebär det att ju tjockare isoleringen är desto mindre blir den uthyrningsbara boytan. Kvalitativa intervjuer låg till grund för att bestämma några vanligt förekommande ytterväggskonstruktioner som isoleringen sedan skulle optimeras på. Dessa ytterväggar placerades på en teoretisk referensbyggnad som därefter energiberäknades med hjälp av handberäkningar där matematiska uttryck för en varierande isoleringstjocklek användes. De teoretiska ytterväggarna kalkylerades därefter med hjälp av kalkylprogrammet Sektionsdata. En livscykelkostnadsanalys utfördes sedan där historisk statistik på hyror, energipriser och räntor utnyttjades. Slutligen kunde en optimal isoleringstjocklek hittas för varje väggtyp. Väggkonstruktionerna som valts var två betongväggar och två träregelväggar, båda med puts respektive tegel. Optimal isoleringstjocklek för väggkonstruktionen betongstomme med tegel hamnade på 84mm. För väggkonstruktionen betongstomme med puts hamnade optimal isoleringstjocklek på 88mm. För väggkonstruktionerna med trästomme kunde en optimal isoleringstjocklek inte hittas eftersom väggarnas uppbyggnad med två respektive tre isoleringsskikt gjorde att väggarna förblev överisolerade i ett ekonomiskt perspektiv även vid minsta möjliga tjocklek på isoleringsskiktet som skulle optimeras. Studien visar på att det med dagens byggregler ger en stor vinst att hålla nere på väggisoleringstjockleken på flerfamiljsbostäder som byggs på en begränsad byggyta.Environmental awareness and increased interest in energy-efficient housing have made the buildings more insulated in Sweden. Usually, it is quite easy to calculate a profit from a greater amount of insulation, in the long term. This is usually the seller’s main argument to why the client should choose the thicker insulation. For a client that wants to build a rental property, it is usually the economy that determines whether a project should be started or not. Hopefully this study will be a help to choose the most economic insulation thickness in walls. The purpose of this study is to investigate where the optimum of wall insulation thickness is in an apartment building for renting which is built on a limited area. Quite often there are requirements for a maximum building area from the municipality, which means that the rentable living space will come smaller when the insulation gets thicker. Qualitative interviews were used to determinate the common wall constructions which the insulation would be optimized for. These walls were placed in a theoretical reference building in which the energy use were estimated using hand calculations where mathematical expressions of a variety of insulation thickness were used. Thereafter, the prices of the walls were calculated using a spreadsheet program called Sektionsdata. A life cycle cost analysis was performed in which the historical statistics on rents, energy prices and interest rates were used. Finally, the optimal insulation thickness was found for each wall type. The wall types chosen were a wall of concrete and brick, a wall of concrete and rendering, a wall of wood and brick and a wall of wood and rendering. Optimal insulation thickness of the wall with concrete and brick ended up at 84mm. For the wall of rendered concrete, the optimal insulation thickness ended up at 88mm. The optimal insulation thickness of the walls of wood could not be found as the wall structure with two and three insulation layers made the walls too isolated in an economic perspective even at a minimal thickness of the layer that was going to be optimized. The study shows that with current building codes in Sweden it is profitable to keep down the wall insulation thickness in an apartment building for renting, built on a limited area.
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Trail, Nicholas. "Imaging Profilometry For In Situ Measurement of Plasma Spray Coating Thickness." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/560844.
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Thermal Barrier Coatings (TBCs), and plasma spray coatings in general, require critical control over the deposited thickness to achieve reliable coating performance. Currently, the plasma spray industry quantifies thickness by sampling the part before and after TBC deposition. Approximate thickness is thus inferred from previous runs. However, process variability can allow errors to propagate in this result that leads to wasted time and resources, and can ultimately lead to non-reliant coatings. To this end, an in situ optical fringe profilometer is developed that enables coating thickness measurements across a 2-dimensional surface. The initial profilometer concept is explored through requirements and trade studies, leading to a hardware and algorithm design family and prototype build to capture and compare real-world data to simulation and model predictions. This initial result shows a viable path-forward and the ability to achieve micrometer-scale depth resolution. Modifications and alterations to the in situ profilometer are then explored to improve the performance limits achievable. In specific, industrial spray coatings operate by dropping fine-grain media into a high pressure gas line aimed through a plasma torch to impart enough thermal and kinetic energy to stick to the part surface. This presents a challenging operational environment for an optical depth measurement sensor, working with a variable high-temperature blackbody stray light source; constant part rotation and plasma gun movement; and a non-isolated vibration environment. As such, the concept of the profilometer is further adapted specific to this end-purpose, by developing and reviewing both dual-fringe projection and plenoptic imaging. These techniques allow an improvement to both the system micro- and macroscopic depth retrieval limits, allowing a method to solve for an extended range of phase ambiguities and relax object focus requirements (respectively). The end result is a system concept and algorithm design that presents a feasible manner for automated in situ geometry and depth measurements in the plasma spray industry. The in situ fringe profilometer work described herein allows a flexible path to recover object depth information remotely, and is especially relevant for asymmetric and complex non-planar geometries, which are experiencing renewed interest with additive manufacturing processes and generally quite common to the thermal spray industry.
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Ciamacca, Marisa Lynn. "Foveal Phase Retardation Correlation with Henle Fiber Layer Thickness." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492631647528424.
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Shelley, Paul H. "Optical low coherence reflectometry for process analysis /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/8666.
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Lehman, Bret M. "Validation of Optical Coherence Tomography-Based Crystalline Lens Thickness Measurements in Children." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1242248244.
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Varkentin, Arthur [Verfasser]. "Thickness determination of melanocytic nevi by means of optical coherence tomography / Arthur Varkentin." Hannover : Gottfried Wilhelm Leibniz Universität, 2018. http://d-nb.info/1161096787/34.
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Schäfer, Michael, Katharina Loewe, André Ehrlich, Corinna Hoose, and Manfred Wendisch. "Comparison of simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus." Universität Leipzig, 2019. https://ul.qucosa.de/id/qucosa%3A74176.
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Two-dimensional horizontal fields of cloud optical thickness derived from
airborne measurements of solar spectral, reflected radiance are compared with semiidealized large eddy simulations (LESs) of Arctic stratus performed with the Consortium for Small-scale Modeling (COSMO) atmospheric model. The measurements were collected during the Vertical Distribution of Ice in Arctic Clouds (VERDI) campaign carried out in Inuvik, Canada, in April/May 2012. The input for the LESs is obtained from collocated dropsonde observations of a persistent Arctic stratus above the sea-icefree Beaufort Sea. Simulations are performed for spatial resolutions of 50 m (1.6 km by 1.6 km domain) and 100 m (6.4 km by 6.4 kmdomain). Macrophysical cloud properties, such as cloud top altitude and vertical extent, are well captured by the COSMO simulations. However, COSMO produces rather homogeneous clouds compared to the measurements, in particular for the simulations with coarser spatial resolution. For both spatial resolutions, the directional structure of the cloud inhomogeneity is well represented by the model. This study was first published by Schäfer et al., 2018.Zweidimensionale horizontale Felder optischer Dicken abgeleitet aus flugzeuggetragenen Messungen der spektralen, solaren, reflektierten Strahldichte über Arktischem Stratus werden mit teilidealisierten Large Eddy Simulationen (LES) im Atmosphärenmodel des Consortium for Small-scale Modeling (COSMO) verglichen. Die Messungen stammen von der Vertical Distribution of Ice in Arctic Clouds (VERDI) Kampagne in Inuvik, Kanada, im April/Mai 2012. Fallsonden- Beobachtungen eines beständigen arktischen Stratus über dem eisfreien Beaufort Meer bilden die LES-Eingangsdaten. Die Simulationen wurden mit räumlichen Auflösungen von 50 m (1.6 km 1.6 km Gebiet) und 100 m (6.4 km 6.4 km Gebiet) durchgeführt. Makroskopische Wolkeneigenschaften (Wolkenhöhe, -ausdehnung) wurden von COSMO erfasst. Allerdings produziert COSMO verglichen zu den Beobachtungen (besonders bei grober räumlicher Auflösung) eher homogenere Wolken. Gerichtete Strukturen der Inhomogenitäten wurden mit beiden räumlichen Auflösungen gut erfasst. Diese Studie wurde als erstes von Schäfer et al., 2018 veröffentlicht.
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Walpert, Madeleine Jane. "Retinal thickness in adults with Down's syndrome : relationship with age, cognition and dementia." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274945.
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People with Down’s syndrome (DS) are known to experience premature ageing and have a high propensity for clinical diagnosis of dementia due to Alzheimer’s disease (AD). In DS there is a unique and natural model of over-expression of amyloid-beta (Aβ) protein, the accumulation of which is proposed to be the central early event in the pathogenesis of AD. In DS, AD neuropathology is universally seen in the brain from the fourth decade. Identifying biomarkers are essential to the evaluation of future treatment trials. The retina has been shown to experience changes in patients with AD, such as retinal thinning, compared to age-matched controls. As an extension of the brain, the retina can be quickly and non-invasively imaged and may provide a proxy measure of brain changes in AD. Using optical coherence tomography (OCT), cross-sectional retinal examinations were completed in 50 people with DS aged 18 years and over. Comparisons between retinal thickness of the DS and control groups were examined, as well as the effect of age on thickness in both groups. For the DS group, further investigations were made into the relationships between retinal thickness and (i) cognitive performance, (ii) diagnosis of dementia, (iii) cortical thickness and, (iv) presence of Aβ binding in the brain. Contrary to expectations, people with DS had thicker retina compared to age-matched controls. In addition, normal age-related retinal thinning was not seen in the DS group. People with DS have a life-long overproduction of Aβ, deposits of which have been previously imaged in the retina. Aβ may be responsible both directly, through physical mass, and indirectly through inflammation as a response to Aβ, for increased retinal thickness in people with DS. Consequently, retinal thickness in DS may be a proxy measure of Aβ deposition in the retina. As part of a collaborative study, brain Aβ binding was measured using positron emission tomography neuroimaging in a subset of the DS group. Individuals with positive Pittsburgh compound [11C]-PIB (PIB) binding to Aβ displayed a trend towards having thinner retina than those with negative PIB binding. These results indicate that a shift towards thinning retina in people DS may reflect changes in brain pathology. Future studies are discussed which aim to investigate Aβ and Aβ driven pathology in the retina.
11
Hakhumyan, Hrant. "Study of optical and magneto processes in Rb atomic vapor layer of nanometric thickness." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00764958.
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Using a narrow-band resonant fluorescence spectra from a nano-cell with a thickness of L= [lambda]/2, and VSOP resonances formed at a thickness L =[lambda] ([lambda] is the wavelength of the resonant radiation), for the first time it was experimentally investigated the behaviour of the frequency and intensity (transition probabilities) of the atomic hyperfine structure transitions between the 85Rb, 87Rb, D1 and D2 lines Zeeman sublevels in external magnetic fields in range 5 - 7000G. The behaviour of tens of previously unstudied atomic transitions was analyzed and it is demonstrated that the intensities of these lines can both greatly increase, and decrease (tenfold). For the first time it is demonstrated that, in the case of partial pressure of neon buffer gas up to 6~torr into the nano-cell of thickness L = [lambda] filled with Rb, VSOP resonances are recorded confidently, while the addition of 0.1~torr neon buffer gas in a cell of a centimeter thickness leads to the complete disappearance of VSOP resonances formed with the help of the widely used technique of saturated absorption. It is demonstrated for the first time that the spectral width of the resonant fluorescence spectra of the rubidium nano-cell with thickness L= [lambda]/2, for all values of the neon buffer gas pressures is much narrower (6-8 times) compared with the resonant fluorescence spectra of an ordinary centimeter cell containing rubidium with the same pressures of neon
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Compagnon, Maxime. "Ink-Jet Printing of Color Optical Filters for LCD Applications." Thesis, Högskolan Dalarna, Materialteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:du-2244.
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At the age of multi-media, portable electronic devices such as mobile phones, personal digital assistant and handheld gaming systems have increased the demand for high performance displays with low cost production. Inkjet printing color optical filters (COF) for LCD applications seem to be an interesting alternative to decrease the production costs. The advantage of inkjet printing technology is to be fast, accurate, easy to run and cheaper than other technologies. In this master thesis work, we used various disciplines such as optical microscopy, rheology, inkjet printing, profilometering and colorimetry. The specific aim of the thesis was to investigate the feasibility of using company-A pigment formulation in inkjet production of COF for active matrix LCD applications. Ideal viscosity parameters were determined from 10 to 20mPa·s for easy inkjet printing at room temperature. The red pigments used are fully dispersed into the solvent and present an excellent homogenous repartition after printing. Thickness investigations revealed that the printed COF were equal or slightly thicker than typically manufactured ones. The colorimetry investigations demonstrated color coordinates very close to the NTSC red standard. LED backlighting seems to be a valuable solution to combine with the printed COF regarding to the spectrum and color analysis. The results on this thesis will increase the understanding of inkjet printing company-A pigments to produce COF for LCD applications.
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Noe, Susan Cunningham. "A prism coupling study of optical anisotropy in polymide including moisture, stress, and thickness effects." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12915.
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Schäfer, M., E. Bierwirth, A. Ehrlich, F. Heyner, and M. Wendisch. "Retrieval of Cirrus Optical Thickness and Assessment of Crystal Shape from Ground-Based Imaging Spectrometry." Universität Leipzig, 2013. https://ul.qucosa.de/id/qucosa%3A16411.
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An imaging spectrometer (AisaEAGLE) is applied for ground-based measurements of downward spectral radiance fields with high spatial (1024 spatial pixels within 36.7° field of view), spectral (488 spectral pixels, 400-970 nm, 1.25 nm full width at half maximum) and temporal (4-30 Hz) resolution. The calibration, measurement, and data evaluation procedures are introduced. A method is presented that retrieves the cirrus optical thickness tci using the spectral radiance data collected by AisaEAGLE. On the basis of four measurement cases during the second campaign of the Cloud Aerosol Radiation and tuRbulence of trade wInd cumuli over BArbados (CARRIBA) project in 2011 the spatial inhomogeneity of the investigated cirrus is characterized by the standard deviation of the retrieved tci, as well as the width of the frequency distribution of the retrieved tci. By comparing measured and simulated downward solar radiances as a function of scattering angle, a first estimation of the detected cirrus ice crystal shape is given and used in the retrieval of tci.Ein abbildendes Spektrometer (AisaEAGLE) wurde bodengebunden zur Messung von Feldern abwärts gerichteter spektraler Strahldichten mit hoher räumlicher (1024 Raumpixel auf 36.7° FOV), spektraler (488 spektrale Pixel, 400-970 nm, 1.25 nm FWHM) und zeitlicher (4-30 Hz) Auflösung verwendet. Die Kalibrierungsprozedur, das Messverfahren sowie die Datenauswertung werden hier vorgestellt. Weiter wird eine Methode zur Ableitung der Zirrus optischen Dicke tci unter Verwendung dieser bodengebundenen spektralen Strahldichtedaten vorgestellt. Auf der Grundlage von vier Messzeiträumen während der zweiten Kampagne des Cloud Aerosol Radiation and tuRbulence of trade wInd cumuli over BArbados (CARRIBA) Projektes in 2011 wird die räumliche Inhomogenität der untersuchten Zirren durch die Standardabweichung der abgeleiteten tci, wie auch der Breite ihrer Häufigkeitsverteilungen charakterisiert. Vergleiche der gemessenen Strahldichten mit Simulationen abwärts gerichteter solarer Strahldichten als Funktion der Streuwinkel ermöglichen eine erste Abschätzung der Eiskristallform im detektierten Zirrus und gehen in die Ableitung der tci ein.
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Wilson, Robin. "Developing a novel method to retrieve high spatial resolution Aerosol Optical Thickness (AOT) from satellite data." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/374707/.
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Aerosol Optical Thickness (AOT) data have many important applications including atmospheric correction of satellite imagery and monitoring of particulate matter air pollution. Current data products are generally available at a kilometre-scale resolution, but many applications require far higher resolutions. For example, particulate matter concentrations vary on the scale of tens of metres, and thus data products at a similar scale are required to provide accurate assessments of particle densities and allow effective monitoring of air quality and analysis of local air quality effects on health. This thesis describes the development of a novel method which retrieves per-pixel AOT values from high-resolution (30m) satellite data, and this method is the main novel contribution to scientific knowledge of this PhD. This method is designed to work over a wide range of land covers including both bright and dark surfaces - and requires only standard visible bands, making it applicable to a range of data from sensors such as Landsat, DMC, SPOT and Pleiades. The method is based upon an extension of the Haze Optimized Transform (HOT), which was originally designed for estimating the haziness of each pixel in a satellite image, based upon the distance from a `Clear Line' in feature space. In this research, the HOT method is adapted and used to estimate AOT instead. Significant extensions include Monte Carlo estimation of the `Clear Line', object-based correction for land cover, and modelling of the HOT-AOT relationship using radiative transfer models. Validation against ground and satellite measurements, as well as simulated data, shows that 40-50% of the pixels have an error within ±0.1, not much lower than many presently available low-resolution products, with further work likely to improve the accuracy. Two example applications show the potential of this method for per-pixel atmospheric correction and monitoring the spatial pattern of particulate matter pollution. This novel method will enable many new applications of AOT data that were impossible with low-resolution data.
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Ueda, Naoko. "Macular Choroidal Thickness and Volume of Eyes With Reticular Pseudodrusen Using Swept-Source Optical Coherence Tomography." Kyoto University, 2016. http://hdl.handle.net/2433/215412.
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Final publication is available at http://www.sciencedirect.com/science/article/pii/S0002939414000488Kyoto University (京都大学)
0048
新制・課程博士
博士(医学)
甲第19586号
医博第4093号
新制||医||1014(附属図書館)
32622
京都大学大学院医学研究科医学専攻
(主査)教授 大森 孝一, 教授 宮本 享, 教授 横出 正之
学位規則第4条第1項該当
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Rajai, Payman. "Measurement of Refractive Index and Thickness of Multi Layer Systems Using Fourier Domain Optical Coherence Tomography." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34792.
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A multilayered system is a good model for many optical systems. An optical
coherence tomography (OCT) system can provide fundamental information about
the refractive index distribution of the sample and enables images to be corrected
for geometric accuracy, but this requires the separation of refractive index and
physical thickness for each layer from the measured optical paths. In this thesis a
novel approach for simultaneous extraction of index and thickness of multi layer
systems and the last medium index of refraction in a single experiment using only
the object’s spectral response available by any Fourier Domain OCT system without
using any additional outside measurements is introduced. The method is based on a
novel matrix equation that uses the reflected spectrum from the object and the
measured optical thickness. In the presence of slight error of measuring optical
thickness, the parameters extraction has wavenumber dependency. A novel method
is used to select the suitable set of spectral components that reduces the extracted
parameters error. The parameters extraction method is followed by a fitting process
for optimized results. The method works the best for low contrast index distribution
even in the presence of relatively large optical thickness measurement error.
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Mok, Kwok-hei. "The characterization of retinal nerve fiber layer thickness in normal, high-tension and normal-tension glaucoma using optical coherence tomography." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31381005.
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ALJhayyish, Anwer K. "Optimizing Slab Thickness and Joint Spacing for Long-Life Concrete Pavement in Ohio." Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1550099928352708.
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Swan, Philip. "Development of an optical technique for on-line measurement of the thickness distribution of blow moulding parisons." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61319.
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In the extrusion blow moulding process, the strength and weight of a hollow article, such as a bottle, is controlled by an open loop control process called parison programming. The article thickness is increased and decreased by opening and closing the gap of the annular die from which the parison is extruded. The die gap is regulated according to a gap-time profile which an operator determines during start up by trial and error.An optical sensor has been developed which can measure the thickness profile of the parison on-line just prior to its enclosure in the mould. The device will help operators to program the gap-time profile for optimum use of plastic by providing rapid feedback on the formation of the parison. It also represents an important step toward the development of closed loop control for container thickness distribution.
The device determines thickness by striking the parison at an angle with a laser beam and measuring the separation between the beams that reflect from the outer and inner surfaces of the parison wall. A prototype was built and tested. The prototype uses three lasers at different angles and can make up to 250 point measurements during a one second scan. A personal computer uses specially developed software to reconstruct the profile of the parison wall from the raw data with an accuracy of $ pm$5%.
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Wissel, Tobias [Verfasser]. "Tissue thickness estimation from backscattered light : a novel concept for optical head tracking in radiotherapy / Tobias Wissel." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2017. http://d-nb.info/1125057858/34.
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Muraoka, Yuki. "Age- and Hypertension-Dependent Changes in Retinal Vessel Diameter and Wall Thickness: An Optical Coherence Tomography Study." Kyoto University, 2014. http://hdl.handle.net/2433/188665.
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Mok, Kwok-hei, and 莫國熙. "The characterization of retinal nerve fiber layer thickness in normal,high-tension and normal-tension glaucoma using optical coherencetomography." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31381005.
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Zhang, Xuan ZHANG. "Polymer Films With Enhanced Through Thickness Optical Transmission and Compression Modulus with Electric Field Aligned Glass Fiber/Bubbles." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1463961142.
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Röling, Christian. "Anwendungsbezogene Weiterentwicklung der abbildenden Ellipsometrie." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://hdl.handle.net/11858/00-1735-0000-0023-3F1F-5.
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Thomas, Paul J. S. "Ellipsometry, reflectance and modulated spectroscopy of bulk and multi-layer semiconductor structures." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/844284/.
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Vertical-cavity surface-emitting lasers (VCSELs) are complex multi-layer structures whose operating characteristics are highly sensitive to variations in layer thickness and composition. They contain an active region of one or more quantum wells sandwiched between highly reflecting mirrors. Non-destructive optical characterisation techniques including reflectance spectroscopy, spectroscopic ellipsometry and photomodulated reflectance have been used to examine these structures and various components of them. In addition, the relatively novel technique of photomodulated spectroscopic ellipsometry has been examined in comparison with photomodulated reflectance in the characterisation of bulk, multi-layer and quantum well material. The distributed Bragg reflectors of VCSELs provide the high reflectance required over a selected wavelength range. Optical measurements were used to determine important information concerning layer thicknesses and compositions, which were confirmed with X-ray diffraction and transmission electron microscopy. The techniques were also used to provide important information concerning growth and uniformity, which could be readily applied for feedback to growers or for device fabrication. Novel reflectance and photomodulated reflectance measurements made on a range of laser structures designed to operate over a range of wavelengths from 650 nm to 1 ?m were used to examine the characteristics of the reflectors and the active region of the lasers. The cavity mode observed clearly indicates the lasing wavelength, and the interaction of the cavity and quantum well has been interpreted using new lineshapes. The cavity mode and quantum well resonance observed in photomodulated reflectance has been shown to provide a clear indication of where devices can be fabricated successfully from non-uniform material. The identification of the cavity and quantum well features has also enabled important information concerning the changes in structure and therefore in device performance with temperature and pressure. Measurements have also been able to provide important information to explain the variation in performance of some devices.
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Schäfer, Michael. "Optical Thickness Retrievals of Subtropical Cirrus and Arctic Stratus from Ground-Based and Airborne Radiance Observations Using Imaging Spectrometers." Doctoral thesis, Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-207395.
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The development and application of new cloud retrieval methods from ground–based and airborne measurements of spectral radiance fields above heteorogeneous surfaces is introduced. The potential of imaging spectrometers in remote–sensing applications is evaluated. The analyzed spectral radiance fields were measured during two international field campaigns in the visible wavelength range (400–970 nm) with high spatial (<10m) resolution. From ground–based measurements, high ice clouds were observed and from airborne measurements Arctic stratus. From the measurements, cloud optical thickness is retrieved with high spatial resolution and the horizontal cloud inhomogeneities are investigated. Depending on the measurement configuration, different uncertainties arise for the retrieval of the cloud optical thickness. A reduction of those uncertainties is derived by a specification of the ice crystal shape to improve the retrieval of the optical thickness of high ice clouds. The ice crystal shape is obtained independently from the angular information of the scattering phase function features, imprinted in the radiance fields. A performed sensitivity study reveals uncertainties of up to 90%, when neglecting this information and applying a wrong crystal shape to the retrieval. For remote-sensing of Arctic stratus, the highly variable surface albedo influences the accuracy of the cloud optical thickness retrieval. In cloudy cases the transition of reflected radiance from open water to sea ice is not instantaneous but horizontally smoothed. In general, clouds reduce the reflected radiance above bright surfaces in the vicinity of open water, while it is enhanced above open sea. This results in an overestimation of to up to 90% in retrievals of the optical thickness. This effect is investigated. Using observations and three-dimensional radiative transfer simulations, this effect is quantified to range to up to 2200 m distance to the sea-ice edge (for dark-ocean albedo of αwater = 0.042 and sea-ice albedo of αice = 0.91 at 645 nm wavelength) and to depend on macrophysical cloud and sea-ice properties. The retrieved fields of cloud optical thickness are statistically investigated. Auto–correlation functions and power spectral density analysis reveal that in case of clouds with prevailing directional cloud structures, cloud inhomogeneities cannot be described by a universally valid parameter. They have to be defined along and across the prevailing cloud structures to avoid uncertainties up to 85%Im folgenden wird die Entwicklung und Anwendung neuer Ableitungsverfahren von Wolkenparametern, basierend auf bodengebundener und flugzeuggetragener spektraler Strahldichtemessungen über heterogenen Untergründen, vorgestellt und das Fernerkundungspotential abbildender Spektrometer evaluiert. Die spektralen Strahldichtefelder wurden während zweier internationaler Feldkampagnen im sichtbaren Wellenlängenbereich (400–970 nm) mit hoher räumlich Auflösung (<10m) gemessen. Bodengebundene Messungen wurden genutzt, um hohe Eiswolken zu beobachten und flugzeuggetragenen um arktischen Stratus zu beobachten. Aus den Messungen werden räumlich hochaufgelöste wolkenoptische Dicken abgeleitet und anschließend horizontale Wolkeninhomogenitäten untersucht. Die Ableitung der wolkenoptischen Dicke birgt je nach Messkonfiguration verschiedene Unsicherheiten. Eine Reduzierung der Unsicherheiten wird durch die Vorgabe einer Eiskristallform zur Verbesserung der Ableitung der optischen Dicke hoher Eiswolken erreicht. Diese werden unabhängig aus den winkelabhängigen, in das gemessene Strahldichtefeld eingeprägten Eigenschaften der Streuphasenfunktion, abgeleitet. Bei Vernachlässigung dieser Information und Wahl der falschen Eiskristallform, treten Fehler in der abgeleiteten optischen Dicke von bis zu 90% auf. Bei der Fernerkundung von arktischem Stratus beeinflusst die sehr variable Bodenalbedo die Genauigkeit der Ableitung der optischen Dicke. Beim Übergang von Meereis zu Wasser, findet die Abnahme der reflektierten Strahldichte im bewölktem Fall nicht direkt über der Eiskante, sondern horizontal geglättet statt. Allgemein reduzieren Wolken die reflektierte Strahldichte über Eisflächen nahe Wasser, während sie über dem Wasser erhöht wird. Dies führt zur Überschätzung der wolkenoptischen Dicke über Wasserflächen nahe Eiskanten von bis zu 90 %. Dieser Effekt wird mit Hilfe von Beobachtungen und dreidimensionalen Strahlungstransferrechnungen untersucht und es wird gezeigt, dass sein Einfluss noch bis zu 2200 m Entfernung zur Eiskante wirkt (für Meeresalbedo 0.042 und Meereisalbedo 0.91 bei 645 nm Wellenlänge) und von den makrophysikalischen Wolken- und Meereiseigenschaften abhängt. Die abgeleiteten Felder der optischen Dicke werden statistisch ausgewertet, um die Inhomogeneität der Wolken zu charakterisieren. Autokorrelationsfunktionen und Leistungsdichtespektren zeigen, dass Inhomogenitäten von Wolken mit vorranging richtungsabhängiger Struktur nicht mit einem allgemeingültigen Parameter beschrieben werden können. Es sind Inhomogenitätsmaße entlang und entgegen der jeweiligen Wolkenstrukturen nötig, um Fehler von bis zu 85% zu vermeiden
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Li, Yan. "Image Processing and Clinical Applications of Anterior Segment Optical Coherence Tomography." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1212436115.
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Gong, Shengjie. "An Experimental Study on Micro-Hydrodynamics of Evaporating/Boiling Liquid Film." Doctoral thesis, KTH, Kärnkraftsäkerhet, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-50216.
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Study of liquid film dynamics is of significant importance to the understanding and control of various industrial processes that involve spray cooling (condensation), heating (boiling), coating, cleaning and lubrication. For instance, the critical heat flux (CHF) of boiling heat transfer is one of the key parameters ensuring the efficiency and safety of nuclear power plants under both operational and accident conditions, which occurs as the liquid layers (microlayer and macrolayer) near the heater wall lose their integrity. However, an experimental quantification of thin liquid film dynamics is not straightforward, since the measurement at micro-scale is a challenge, and further complicated by the chaotic nature of boiling process. The object of present study is to develop experimental methods for the diagnosis of liquid film dynamics, and to obtain data for the film instability under various conditions. A dedicated test facility was designed and constructed where micro conductive probes and confocal optical sensors were used to measure the thickness and dynamic characteristics of a thin liquid film on various heater surfaces, while a high speed camera was used to get visual observation. Extensive tests were performed to calibrate and verify the two thickness measuring systems. The micro conductive measuring system was proven to have a high reliability and repeatability with maximum system error less than 5µm, while the optical measuring system is capable of recording the film dynamics with spatial resolution of less than 1 mm. The simultaneous measurement on the same liquid film shows that the two techniques are in a good agreement with respect to accuracy, but the optical sensors have a much higher acquisition rate up to 30 kHz, which are more suitable for rapid process. The confocal optical sensors were therefore employed to measure the dynamic thickness of liquid films (ethanol, hexane and water) evaporating on various horizontal heater surfaces (aluminum, copper, silicon, stainless steel and titanium) to investigate the influences of heat flux, the surface and liquid properties on the film instability and the critical thickness. The critical thickness of water film evaporating on various surfaces was measured in the range of 60-150 mm, increasing with the increased contact angle or increased heat flux (evaporating rate) and also with the decreased thermal conductivity of the heater material. The data suggest the conjugate heat transfer nature of the evaporating liquid film dynamics at higher heat fluxes of interest to boiling and burnout. In the case of hexane on the aged titanium surface with contact angle of ~3o, the liquid film is found resilient to rupture, with film oscillations at relatively large amplitude ensuing as the averaged film thickness decreases below 15 µm. To interpret our experimental findings on liquid film evolution and its critical thickness at rupture, a theoretical analysis is also performed to analyze the dynamics of liquid films evaporating on heater surfaces. While the influences of liquid properties, heat flux, and thermal conductivity of heater surface are captured by the simulation of the lubrication theory, influence of the wettability is considered via a minimum free energy criterion. The thinning processes of the liquid films are generally captured by the simulation of the lubrication theory. For the case with ideally uniform heat flux over the heater surface, the instability of the liquid film occurs at the thickness level of tens micro meters, while for the case of non-uniform heating, the critical thicknesses for the film rupture are closer to the experimental data but still underestimated by the lubrication theory simulation. By introducing the minimum free energy criterion to considering the influence of surface wettability, the obtained critical thicknesses have a good agreement with the experimental ones for both titanium and copper surfaces, with a maximum deviation less than ±10%. The simulations also explain why the critical thickness on a copper surface is thinner than that on a titanium surface. It is because the good thermal conductivity of copper surface leads to uniform temperature distribution on the heat surface, which is responsible for the resilience of the liquid film to rupture. A silicon wafer with an artificial cavity fabricated by Micro Electronic Mechanical System (MEMS) technology was used as a heater to investigate the dynamics of a single bubble in both a thick and thin liquid layer under low heat flux (<60 kW/m2). The maximum departure diameter of an isolated bubble in a thick liquid film was measured to be 3.2 mm which is well predicted by the Fritz equation. However, in a thin liquid layer with its thickness less than the bubble departure diameter, the bubble was stuck on the heater surface with a dry spot beneath. A threshold thickness of the liquid film which enables the dry spot rewettable was obtained, and its value linearly increases with increasing heat flux. In addition, another test section was designed to achieve a constant liquid film flow on a titanium nano-heater surface which helps to successfully carry boiling in the liquid film from low heat flux until CHF. Again, the confocal optical sensor was employed to measure the dynamics of the liquid film on the heater surface under varied heat flux conditions. A statistical analysis of the measured thickness signals that emerge in a certain period indicates three distinct liquid film thickness ranges: 0~50 µm as microlayer, 50~500 µm as macrolayer, 500~2500 µm as bulk layer. With increasing heat flux, the bulk layer disappears, and then the macrolayer gradually decreases to ~105 µm, beyond which instability of the liquid film may lose its integrity and CHF occurs. In addition, the high-speed camera was applied to directly visualize and record the bubbles dynamics and liquid film evolution. Dry spots were observed under some bubbles occasionally from 313 kW/m2 until CHF with the maximum occupation fraction within 5%. A dry spot was rewetted either by liquid receding after the rupture of a bubble or by the liquid spreading from bubbles’ growth in the vicinity. This implies that the bubbles’ behavior (growth and rupture) and their interactions in particular are of paramount importance to the integrity of liquid film under nucleate boiling regime.QC 20111205
VR-2005-5729, MSWI
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Simon, Darren, and s3027589@student rmit edu au. "Chemistry and Morphology of Polymer Thin Films for Electro-Optical Application." RMIT University. Applied Sciences, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070123.122707.
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Thin polymer films and their properties have been investigated. The characteristics of crystalline polymers according to film thickness have been improved using polycaprolactone (PCL). The melting enthalpy of PCL has increased when the film thickness decreased and the peak melting temperature showed no significant changes with film thickness. Film thickness variation influenced surface roughness and crystal size. Optical microscope images showed the rougher surface of thicker films. The spinning time has shown no influence on film thickness and no significant changes to surface roughness. Thin films of block copolymers were used in the surface modification study; films studied included poly(styrene-b-butadiene-b-styrene) (SBS) and poly(styrene-b-isoprene-b-styrene) (SIS) and their surface modifications have been controlled using different methods of treatment. Films of SIS heated at different temperatures have shown different surface texture and roughness. Films treated at low temperature (45 °C) had smooth surfaces when compared with films heated at high temperature (120 °C and 160 °C). Phase separation of SIS heated at (120 °C and 160 °C) caused bulges of different sizes to cover the surface. The height and width of the bulges showed variation with film thickness and heating. Substrate interaction with SBS and SIS block copolymer films showed different surface texture when using the same type of substrate and different texture were obtained when SBS solutions were spun onto different substrates. It has been demonstrated that using different solvents in copolymer preparation caused different texture. Thermal and surface property variations with film thickness have been improved using amorphous polymers. Surface roughness of poly(methyl methacrylate) PMMA and disperse red 1-poly(methyl methacrylate) DR1-PMMA, PMMA has improved using thickness variation. Glass transition temperature measurement has increased when film thickness was increased. The glass transition temperature (Tg) and surface roughness of UV15 UV - curable coating polymer has been modified using UV curing and heating methods. Tg variation was observed when curing time and curing intensity were changed causing the optical properties of the polymer to be more variable. A plasma etcher caused wrinkles to occur on the surface of unheated UV15. Tg of UV15 increased when curing time increased. The Fourier Transform Infrared Spectroscopy (FTIR) spectra of cured UV15 film have shown peak variations of the ester and carbon double bond regions over the range of 1850-1700 cm-1. Urethane-Urea (UU) Polymer thin films were used to investigate optical properties and develop an optical waveguide. Absorption and transmission properties of light using non-linear optical (NLO) polymer was investigated and used in optical waveguide fabrication. Refractive indices were measured to examine UU films at two different wavelengths. A UU film of 1 µm thickness caused a maximum absorption at max = 471 nm also obtained at 810 nm wavelength. Many methods of fabrication were used; photolithography, plasma etching in a barrel reactor and thin film deposition using sputtering and evaporation. Etched depths from 1 μm to 100 μm were obtained. An optical waveguide has been prepared using plasma etching of a cured UV15 as a cladding layer on a silicon substrate.
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MAXIMO, ARTHUR. "Comparação entre soldagem de chapas finas de tântalo e monel 400 com laser pulsado de Nd:YAG e com laser contínuo de fibra." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23912.
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Submitted by Maria Eneide de Souza Araujo (mearaujo@ipen.br) on 2015-10-07T12:39:18Z
No. of bitstreams: 0Made available in DSpace on 2015-10-07T12:39:18Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Pallikarakis, Christos A. "Development of temporal phase unwrapping algorithms for depth-resolved measurements using an electronically tuned Ti:Sa laser." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/23918.
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This thesis is concerned with (a) the development of full-field, multi-axis and phase contrast wavelength scanning interferometer, using an electronically tuned CW Ti:Sa laser for the study of depth resolved measurements in composite materials such as GFRPs and (b) the development of temporal phase unwrapping algorithms for depth re-solved measurements. Item (a) was part of the ultimate goal of successfully extracting the 3-D, depth-resolved, constituent parameters (Young s modulus E, Poisson s ratio v etc.) that define the mechanical behaviour of composite materials like GFRPs. Considering the success of OCT as an imaging modality, a wavelength scanning interferometer (WSI) capable of imaging the intensity AND the phase of the interference signal was proposed as the preferred technique to provide the volumetric displacement/strain fields (Note that displacement/strain fields are analogous to phase fields and thus a phase-contrast interferometer is of particular interest in this case). These would then be passed to the VFM and yield the sought parameters provided the loading scheme is known. As a result, a number of key opto-mechanical hardware was developed. First, a multiple channel (x6) tomographic interferometer realised in a Mach-Zehnder arrangement was built. Each of the three channels would provide the necessary information to extract the three orthogonal displacement/strain components while the other three are complementary and were included in the design in order to maximize the penetration depth (sample illuminated from both sides). Second, a miniature uniaxial (tensile and/or compression) loading machine was designed and built for the introduction of controlled and low magnitude displacements. Last, a rotation stage for the experimental determination of the sensitivity vectors and the re-registration of the volumetric data from the six channels was also designed and built. Unfortunately, due to the critical failure of the Ti:Sa laser data collection using the last two items was not possible. However, preliminary results at a single wavelength suggested that the above items work as expected. Item (b) involved the development of an optical sensor for the dynamic monitoring of wavenumber changes during a full 100 nm scan. The sensor is comprised of a set of four wedges in a Fizeau interferometer setup that became part of the multi-axis interferometer (7th channel). Its development became relevant due to the large amount of mode-hops present during a full scan of the Ti:Sa source. These are associated to the physics of the laser and have the undesirable effect of randomising the signal and thus preventing successful depth reconstructions. The multi-wedge sensor was designed so that it provides simultaneously high wavenumber change resolution and immunity to the large wavenumber jumps from the Ti:Sa. The analysis algorithms for the extraction of the sought wavenumber changes were based on 2-D Fourier transform method followed by temporal phase unwrapping. At first, the performance of the sensor was tested against that of a high-end commercial wavemeter for a limited scan of 1nm. A root mean square (rms) difference in measured wavenumber shift between the two of ~4 m-1 has been achieved, equivalent to an rms wavelength shift error of ~0.4 pm. Second, by resampling the interference signal and the wavenumber-change axis onto a uniformly sampled k-space, depth resolutions that are close to the theoretical limits were achieved for scans of up to 37 nm. Access of the full 100 nm range that is characterised by wavelength steps down to picometers level was achieved by introducing a number of improvements to the original temporal phase unwrapping algorithm reported in ref [1] tailored to depth resolved measurements. These involved the estimation and suppression of intensity background artefacts, improvements on the 2-D Fourier transform phase detection based on a previously developed algorithm in ref [2] and finally the introduction of two modifications to the original TPU. Both approaches are adaptive and involve signal re-referencing at regular intervals throughout the scan. Their purpose is to compensate for systematic and non-systematic errors owing to a small error in the value of R (a scaling factor applied to the lower sensitivity wedge phase-change signal used to unwrap the higher sensitivity one), or small changes in R with wavelength due to the possibility of a mismatch in the refractive dispersion curves of the wedges and/or a mismatch in the wedge angles. A hybrid approach combining both methods was proposed and used to analyse the data from each of the four wedges. It was found to give the most robust results of all the techniques considered, with a clear Fourier peak at the expected frequency, with significantly reduced spectral artefacts and identical depth resolutions for all four wedges of 2.2 μm measured at FWHM. The ability of the phase unwrapping strategy in resolving the aforementioned issues was demonstrated by successfully measuring the absolute thickness of four fused silica glasses using real experimental data. The results were compared with independent micrometer measurements and showed excellent agreement. Finally, due to the lack of additional experimental data and in an attempt to justify the validity of the proposed temporal phase unwrapping strategy termed as the hybrid approach, a set of simulations that closely matched the parameters characterising the real experimental data set analysed were produced and were subsequently analysed. The results of this final test justify that the various fixes included in the hybrid approach have not evolved to solve the problems of a particular data set but are rather of general nature thereby, highlighting its importance for PC-WSI applications concerning the processing and analysis of large scans.
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Schäfer, Michael [Verfasser], Manfred [Gutachter] Wendisch, and Thomas [Gutachter] Trautmann. "Optical Thickness Retrievals of Subtropical Cirrus and Arctic Stratus from Ground-Based and Airborne Radiance Observations Using Imaging Spectrometers / Michael Schäfer ; Gutachter: Manfred Wendisch, Thomas Trautmann." Leipzig : Universitätsbibliothek Leipzig, 2016. http://d-nb.info/1240483007/34.
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Edman, Jennifer. "Deriving characteristics of thin cirrus clouds from observations with the IRF lidar." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76574.
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Cirrus clouds play an important role in radiative transfer, and thus have impact on the energy balance of the atmosphere and the climate of the Earth. Furthermore, they occur often and cover large areas globally at any time. Nevertheless, cirrus clouds are poorly studied, especially in the polar regions. Cirrus clouds are present in a large amount of the 14 years of data produced by the lidar at the Swedish Institude of Space Physics (IRF), but has not been studied to a large extent. A lidar is an active remote sensing instrument using a laser. This master's thesis develops and improves programs for analysis of cirrus clouds from this lidar data. It also performs analysis of six case studies chosen from the available data, and statistics of these six cases. The parameters calculated for each date are the cloud top, base and mean altitude, the geometrical thickness, the depolarisation ratio, the backscatter ratio (BSR), the backscatter coefficient, the extinction coefficient, the optical thickness and the number of cloud layers. No clear correlation between the optical thickness and the cloud top, base or mean altitude was found. There seems to be a weak correlation between increased optical thickness and increased geometrical thickness, which is not unreasonable. The mean cloud layer top altitude was 11.82 km and the mean cloud base was 10.36 km. The mean optical thickness for a cloud layer was 1.46 km, and the average of the cloud layer mean altitude was 11.09 km. It should be noted that the statistical analysis is based on only six cases with a total observation time of no more than 37 hours. A far larger dataset is needed in order to obtain any statistically signicant conclusions. The effect of averaging is studied, and it is concluded that averaging over altitude reduced the noise and facilitated the interpolation more than averaging over time did. Different approaches to obtain the molecular backscatter coefficient are compared, as well as the effect on the simulated molecular signal. Two of these approaches calculate the molecular backscatter coeffcient with input of the temperature and pressure either as continuously measured ground vales from the weather station at IRF or as radiosonde profiles for a specific time. In the other two, the molecular backscatter coeffcient is obtained from ECMWF data and from the standard atmosphere. Differences in the range 12-35% between the methods are found. Different approaches to calculate the backscatter ratio (BSR) are also compared. At cirrus altitudes, the decrease in the signal due to the molecular cloudfree part of the atmosphere is still strong, and finding the top and base separately by comparison with the standard deviation of the signal is proven a better method than interpolating between the point where the signal starts to increase and the point where it reaches the same signal value again. Height-normalising the signal provides a more robust method. For thin cirrus, the signal is not significantly attenuated above the cloud layer, and it is found that a method based on the ratios between the measured signal and the simulated molecular signal at cloud top and base did not produce reliable results for the optical thickness. In addition to analysing data and data processing methods, new data processing tools in MATLAB have been developed and existing functions have been improved. These will be valuable for continued studies with the IRF lidar, for cirrus as well as PSCs and thick and/or low-altitude clouds.
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Yoon, Jongmin [Verfasser], Wolfgang von [Akademischer Betreuer] Hoyningen-Huene, John P. [Akademischer Betreuer] Burrows, and Justus [Akademischer Betreuer] Notholt. "Global and regional trends of Aerosol Optical Thickness derived using satellite- and ground-based observations / Jongmin Yoon. Gutachter: John P. Burrows ; Justus Notholt. Betreuer: Wolfgang von Hoyningen-Huene." Bremen : Staats- und Universitätsbibliothek Bremen, 2012. http://d-nb.info/1071993712/34.
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Dieudonné, Xavier. "Etude d'empilements multicouches colloidaux préparés par voie sol-gel : propriétés optiques et mécaniques." Thesis, Tours, 2011. http://www.theses.fr/2011TOUR4022/document.
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Les procédés de dépôt de couches minces optiques par voie physique ou par voie sol-gel présentent par nature des limitations pour la réalisation de revêtements épais (>1 µm) et ont alors recours à des empilements multicouches pour la préparation de miroirs diélectriques ou de polariseurs. C'est pour ces raisons qu'il est intéressant d'étudier les conditions permettant d'augmenter l'épaisseur critique des films sol-gel notamment. Après avoir étudié la capacité d'empilements des couches colloïdales, trois principaux paramètres ont été identifiés permettant d'augmenter l'épaisseur critique d'empilements monomatériaux et multimatériaux. Ces paramètres sont : l'épaisseur déposée,les interactions chimiques entre les particules et le temps de séchage du film. Ils influencent la microstructure des empilements et par conséquent les propriétés optiques et mécaniques. En contrôlant tous ces paramètres, nous avons montré qu'il est possible de préparer des empilements colloïdaux de fortes épaisseurs ouvrent la voie à la préparation sol-gel de miroirs de hautes performances et/ou de polariseurs. En outre, un développement spécifique de méthodes de caractérisations optiques et mécaniques a été nécessaire pour l'étude de ces films sol-gel, à la fois minces et fragilesMain optical deposition processes, physical vapor deposition or sol-gel, exhibit difficulties of achieving thick coatings (>1 µm) and to build multilayer stacks (dielectric mirrors, polarizers). For these reasons, we have studied the conditions to enable a significative increase of deposited sol-gel films thickness. Three main parameters have been evidenced enabling the control of the stacking ability : single layer deposited thickness, chemical interactions beetween nanoparticles and coating drying time. We have shown that these parameters depend on the sol composition and on deposition conditions (process) and that the microstructure of single material stacking is influenced. Optical and mechanical properties of sol-gel films have been studied and optimized regarding these different material and process parameters. For this reason, optical and mechanical characterization techniques have been specifically developed and can now be used for fragile and thin film characterization. In controlling all these parameters, it is now possible to prepare multilayer colloidal stack with high thicknesses enabling the fabrication of high-performance mirrors and polarizers
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Sung, Yen-Peng, and 宋彥朋. "Asymptotically Optimal Thickness Bounds of Generalized Bar Visibility Graphs." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/84701459805661359153.
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碩士國立臺灣大學
資訊工程學研究所
97
Given a set of disjoint horizontal line segments (call bars), d(b1, b2) of two bars b1 and b2 is the minimum number of the other bars that the vertical line segments whose endpoints are at b1 and b2 passing through. A graph G is a bar k-visibility graph if G can be represented as a set of disjoint bars such that any two vertices are adjacent in G if and only if d(u, v) ≤ k, where u and v are the associated bars with those vertices. A graph G is a semi bar k-visibility graph if G can be represented as a set of disjoint bars whose left endpoints have the same x-coordinates such that any two vertices are adjacent in G if and only if d(u, v) ≤ k, where u and v are the associated bars with those vertices. The thickness of G is the minimum number of planar subgraphs whose union is G. Dean et al. gave the best previously known upper bound 3k(6k + 1) on the thickness of bar k-visibility graphs. Hartke et al. proved that the largest complete graph in bar k-visibility graphs is K_4k+4, so the upper bound on the thickness of bar kvisibility graphs is at least ⌈(2k +3)/3⌉. Felsner and Massow gave an upper bound on the thickness of semi bar 1-visibility graphs. Felsner and Massow proved that K_2k+3 is the largest complete graph in semi bar k visibility graphs, so the upper bound on the thickness of semi bar k visibility graphs is at least ⌈(2k + 5)/6⌉. We reduce the upper bound to 3k + 3 on the thickness of bar k-visibility graphs, and give an upper bound 2k for semi bar k-visibility graphs.
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Lee, Chih-Yun, and 李之云. "Ergonomics mattress topper evaluation for determining an optimal firmness and thickness combination." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/09206741158705351768.
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碩士國立清華大學
工業工程與工程管理學系
101
The selection of a bedding system has direct relationship with sleeping quality. Putting a mattress topper on bed in use is also a common practice to increase sleeping comfort. Thus, the ergonomic study of a mattress topper is an important issue. Forty healthy male subjects were recruited in this study. The experiment involves a combination of 3 different firmness (firm, medium, soft) and 4 thickness (3, 5, 7, 10 cm) levels. For each subject, pressure distribution, temperature distribution, microclimate, electromyography, spinal posture, accompany with subjective ratings were collected to determine the optimal firmness and thickness mattress topper combination. The results showed that the firm mattress toppers had higher pressure in every position. The medium ones also had higher temperatures and it had an increasing trend with time. The microclimate temperature was higher on medium and soft toppers, and it was also proportional to time. But the microclimate humidity was inversely proportional to time. The electromyography of trapezius was lower on soft ones, and the EMG of biceps femoris was lower on firm ones. The slope of spine was lowest on firm ones at T1-T4, T4-T6 and T6-T8. The thick mattress toppers had higher temperatures. The humidity was the lowest at 5 cm, and the slope of spine was smallest at 3 cm. Subjective ratings revealed that the firm mattress toppers were perceived as the firmest and most supportive, while the soft ones had the greatest conformity. Finally, among all 12 combinations, 3 or 7 cm soft and 3 cm medium mattress toppers showed better performance in most physiological indexes, and was considered as the preferred combinations.
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Lee, Horng-Won, and 李宏文. "A Theoretical Study of Optimal Biofilm Thickness for Different Substrate Utilization Kinetics." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/99484564983999814686.
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碩士淡江大學
水資源及環境工程所
82
The application of fixed microbial films in water and wastewater treatment processes such as trickling filters, rotating biological contactors and biological fluidized beds have been developed rapidly during the past several years. Recently, there are so many biofilm models with different substrate utilization kinetic expressions, have been thoroughly discussed by mamy authers, such as zero-order, first-order, Monod kinetics for non- substrate inhibition or Haldane kinetics, Luong kinetics for substrate inhibition. Instead of emphasizing the influence of different substrate concentrations on the substrate utilization rate of biofilm, this study is interested in finding out optimal biofilm thicknesses for different substrate utilization kinetics under constant substrate concentration. The results demonstrate that it is preferable to use thin biofilms for non-substrate inhibitive Monod kinetics biofilms and to keep biofilm at the optimal thickness for substrate inhibitive Haldane kinetics or Luong kinetics biofilms in order to remain high volumetric substrate removal rate.
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Liang, Jin-Tiao, and 梁金條. "Optimal Design of UBM Thickness and Solder Shape for WLCSP by Taguchi Method." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/70547238774708705889.
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碩士國立成功大學
工程科學系碩博士班
93
The Wafer Level Chip Scale Package (WLCSP) has increasingly been becoming popular, because it has some advantages, such as high power, high efficiency and high density. Though WLCSP electronic signal (I/O density) can be improved, the reliability reduces. Among affecting factors of package reliability, solder joints are considered as the main keys. This study uses Surface Evolver to construct Non-Solder Mask Defined model, and ANSYS for simulation. The Chen model of mixing type is adopted to analyze solder joints with under bump metallurgy (UBM), which is between the solder joint and the chip. This paper focuses on 95.5Sn3.8Ag0.7Cu lead-free solder joints with UBM in a WLCSP. First, utilize Surface Evolver to predict the solder joint shape after reflow, and then use finite element analysis ANSYS 7.0 to build up two-dimensional and three-dimensional models under thermal cycling to investigate deformations of entire package, and changes of stress-strain hysterisis curve for solder joints. Then the accumulated equivalent creep strain puts into modified Coffin-Manson formula to calculate the fatigue life of WLCSP. The model in this study is different from Liu’s model. In Liu’s model, the meridian arc of solder joint is arbitrarily taken, but in this study, Surface Evolver is utilized to predict the post-reflow solder joint shape before putting it into ANSYS for further simulation. The comparison between these two models is also introduced. Additionally, the variations of UBM thickness, solder pad radius and solder volume are made to observe their effects on WLCSP reliability. Finally, Taguchi Method is introduced to find optimal control factors for WLCSP reliability. According to the results, the factor response table, graphs are made to seek the most significant control factor and the optimal level set to improve WLCSP reliability. The complication of this study could give manufacturers some suggestions for the application of lead-free UBM solder joint, hopefully cutting cost, enhancing WLCSP reliability, and shortening manufacturing period, and improving the cutting edge of the products.
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Wei, Wen-Fu, and 魏文福. "The Study of Optimal Thickness Combination of Ceramic Composite Material under Ballistic Impact." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/68353399777695392493.
Full textAbstract:
碩士國防大學理工學院
兵器系統工程碩士班
102
The goal of this study is to explore the optimal thickness combination of ceramics/Kevlar composite material under the considerations of weight, volume and ballistic resistance capability. Firstly, the ballistic tests were performed by using 0.30 inch Armor Piercing (AP) bullets. Assuming the kinetic energy loss of projectile is the energy absorption of target plates, the regression equation of target thickness and ballistic resistance capability by regression analysis was established. Secondly, the optimal thickness combination of ceramics/Kevlar composite material under the constraint of areal density, total thickness and ballistic resistance capability was obtained by using Lagrange Multiplier Method. Finally, the finite element software ANSYS/LS-DYNA was also used to perform a simulated analysis on the penetration performance. The results from simulation were then compared with the experimental results to verify the reliability. Through the analysis, there was an interaction with the influence of energy absorption due to the thickness of ceramic and Klevlar fiber laminate. Therefore, there was an optimal thickness combination of ceramics/Kevlar composite material under the considerations of areal density or total thickness. On the other hand, the maximum energy absorption increase with the increasing of the constraint of areal density and total thickness. This relationship can be used to get the optimal thickness combination of ceramics/Kevlar composite material under the constraint of impact energy.
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Ho, Cheng-Ying, and 何政穎. "Ultrathin-ENEPIG Surface Finish in Low Impedance Soldering: Metallurgical Reactions, Bonding Strength, and Optimal Ni(P) Thickness Evaluation." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/99953397274183492670.
Full textAbstract:
博士國立清華大學
材料科學工程學系
103
The continuing thrust toward high-density and high-performance electronic devices has spurred development of more reliable solder joints in flip-chip technology. Successful solder joints not only give rise to metallurgically stable and mechanically robust but also ensure the electrical and signal delivery with excellent quality. Recently, Electroless Ni(P)/Electroless Pd(P)/Immersion Au (ENEPIG) has been widely used as surface finish for metal bond pad because of its many superior comprehensive performances. However, the amorphous electroless Ni(P) layer in ENEPIG dramatically increase the electrical resistance of solder joints and lead to pronounced signal degradation and conductor loss. Thus, it is urgently needed to search for another alternative surface finish which is suitable for low impedance soldering. ENEPIG with ultrathin electroless Ni(P) deposit (ultrathin-ENEPIG) was used to decrease the electrical impedance. The Ni(P) layer in ultrathin-ENEPIG was designed in submicron meter scale (0.05-0.31 µm) and expected to be completely exhausted after the first reflow process. The electrical impedance in ultrathin-ENEPIG was about an order magnitude lower than that in conventional ENEPIG. The next question is that what the optimal Ni(P) thickness is in ultrathin-ENEPIG regarding both the stability of mechanical bonding strength and superior electrical conductivity. In this study, the results of high speed impact test vehicle depicted that ultrathin-ENEPIG with 0.18 and 0.31µm electroless Ni(P) layer performed well owing to their limited growth of interfacial IMC. However, after 1000 hr thermal aging, the bonding strength of ultrathin-ENEPIG with 0.31 µm Ni(P) layer degraded abruptly because of the Kirkendall voids formation resulted from the huge difference in the diffusivity between Cu and Sn. On the other hand, the phase transformation from Ni3P to Ni2Sn1+xP1-x in ultrathin-ENEPIG with 0.18 µm Ni(P) layer eliminated the Kirkendall voids and further avoided the bonding strength degradation after thermal aging. Moreover, the needle-like interfacial IMC was proved to provide interlocking mechanics from fast crack propagation and improved the mechanical performance in the final part of the study. In summary, although ultrathin-ENEPIG indeed provided ultra-low electrical impedance, the mechanical bonding strength may decay faster than conventional ENEPIG. Notwithstanding, it is suggested that 0.18 µm would be the optimal Ni(P) thickness due to its limited growth of interfacial IMC, better bonding strength maintenance after prolonged thermal aging, and interlocking mechanics caused by the needle-like (Cu,Ni)6Sn5 IMC morphology.
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Le, Roux Andre Rayne. "The performance of base metal ceramic alloy restorations with reference to variances in thickness in metal and porcelain in order to establish optimal thickness ratios to maxize strength and aesthetic characteristics." Thesis, 2000. http://hdl.handle.net/10321/1909.
Full textAbstract:
Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Dental Technology, Technikon Natal, 2000.The greatest problem in maximizing strength and aesthetic characteristics of metal ceramic restorations arises when there is a lack of available space to allow sufficient thickness of metal alloy and porcelain. This generally results in the metal alloy being reduced to its minimum to allow adequate porcelain thickness. The minimum thickness to which noble metal alloys can safely be reduced, is generally accepted to be 0.3 mm due to previous clinical time-dependent trial and error. Agreement regarding the minimum thickness to which base metal alloys can safely be reduced is still under dispute possibly because base metal alloys have not had the same duration of clinical exposure. The objectives of the present study were: 1. To determine the influence thickness variations of the base metal alloy would have on strength characteristics of metal ceramic restorations and thereby establishing the minimum thickness to which base metal alloys can safely be reduced. 2. To determine the influence thickness variations of porcelain would have on strength and aesthetic characteristics of metal ceramic restorations and thereby establish the minimum thickness to which the porcelain thickness can safely be reduced. 3. To determine which base metal alloy to porcelain thickness ratios would be most suited in order to maximize strength and aesthetic characteristics in metal ceramic restorations where the amounts of available space for the alloy and porcelain are varied. For objective (1) Tensile strength tests to determine and compare the ability of various alloy thickness to resist porcelain fracture were performed in Newtons. For objective (2) Tensile tests to determine and compare the ability of various porcelain thickness to resist porcelain fracture were performed in Newtons.
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YU-LUNTSAI and 蔡侑侖. "Development of A Contactless Micron-Sized PCB Copper Foil Thickness Measuring System and Design of Optimal Sensing Coil with Multiple Quality Characteristics." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/wmk942.
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Huang, Ting-Yun, and 黃婷筠. "Influence of optical thickness error in spectrum." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/98938084284013927964.
Full textAbstract:
碩士國立中央大學
光電科學與工程學系
105
During the process of optical thin film deposition, if certain layer has optical thickness error, then final spectrum will change. This thesis aims to discuss the influence on spectrum due to the optical thickness error. Layers which influence the spectrum are named as “sensitive layers”. There are two aspects to consider the sensitive layers, one is the characteristics of thin film and the other is regarding to the optical monitoring method. Optical monitoring method used in this thesis are level monitoring and admittance loci monitoring.
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Chen, Chih-Cheng, and 陳志成. "Optical aberrations caused by non-uniform film thickness." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/94299034843213688655.
Full textAbstract:
碩士明新科技大學
電子工程研究所
96
This paper is composed of two parts, first the film thickness uniformity of the dome-type substrate is studied by simulating film thickness distribution theory . The other part optical aberrations caused by non-uniform film thickness are investigated by using Zernike polynomials fittings and simulations of film thickness distributions in different coating parameters.
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Chen, Chih-Hui, and 陳志輝. "Thickness dependent optical properties of a silver nanorod array." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/276q6f.
Full textAbstract:
碩士國立臺北科技大學
光電工程系研究所
98
Silver nanorod arrays (NRA) with different thicknesses are deposited using glancing angle deposition (GLAD) technique by electron beam evaporation. The transmission and the reflection coefficients of silver films for p-polarized light and s-polarized light are measured at the wavelength of 532nm, 639 nm and 690nm by walk-off and polarization interferometers. The equivalent electromagnetic parameters of the silver nanorod arrays are obtained by the two coefficients. Due to the magnetic effect, the real part of the equivalent permittivity and equivalent permeability of the silver film can be tuned by varying the thicknesses of the silver nanorod arrays. Compared with the finite-difference time-domain method (FDTD) simulation, we can find that the inverse magnetic resonance intensity directly proportional to the wavelength in the visible regime. In this experiment, the real part of equivalent refractive index for the P-polarized light is negative at the three thicknesses.
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Liu, Yi-Hong, and 劉奕宏. "Optical Constant and Thickness Measurements through Multi-wavelength Interferometry." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/88318613106113659640.
Full textAbstract:
碩士國立中央大學
光電科學研究所
98
In this thesis, there were two major parts, software and the hardware parts, for measuring the optical constants and thickness of the thin film. For the software, we used novel Genetic Algorithm to design our program. For the hardware, we proposed a polarization phase shifting interferometer based on Twyman-Green interferometer structure. In our arrangement, the low coherence light source is composed of a mercury lamp, which is a polychromatic light source and covering the visible spectral range, and a narrow band pass filter to create a Gaussian power spectral density source. We chose five color filters (532nm, 580nm, 632nm, 690nm, 730nm) for selecting wavelengths. In the polarization interferometer, a novel pixelated mask with a micro-polarizer phase shifting array was placed just in front of the CCD, so that we can use single shot to extract phase information and it is effective to reduce environmental vibration. Then we can get the spectrums from U4100 spectrometer made by HITACHI, and use genetic algorithm to write a fitting program to get the refractive index and thickness of single-layer thin film. We used two parts, transmittances only and transmittances plusing with phases, to process our problems. All the researches need only five phases and spectrums can derive multi-wavelength refractive index and thickness. The measurement results were compared with the results obtained by SOPRA ellipsometer. The results meet reasonable values in both refractive index and thickness.
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Yen-Pin, Lin, and 林妍蘋. "High-Precision Measurement of Optical Material Refractive Index and Thickness." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/01594728064649415435.
Full textAbstract:
碩士遠東科技大學
機械研究所
96
This study is a non-destructive and easy operational of optical material quality measurement technique for determining the refractive index of the wave plate and the variable concentration liquid. This measurement system comprises a laser interferometer、PSD and optical path to finish high-accurate of optical quality measurement. The results show that the error between the birefringence wave plate of thickness 465 and experiment data 464.957 by using laser interferometer method is the 0.043 . The measurement thickness of the wave plate by using the variable optical path difference method is 464.91 . The relative function between the alcohol concentration and the refractive index is about the quadratic. The relative error between the experimental refractive index and the analysis refractive index is about 0.000234035. For the refractive index measurement of the Glucose concentration (9.09%), the relative error between the experimental refractive index and the analysis refractive index is about 0.00027. In this paper, the optical path measurement of the laser interferometer can be applied to determent multi-characteristics of optical material. When the PSD component is applied to system measurement the characteristics of optical material can be obtained. In future, the measurement method can be applied to commercial products.
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Huang, Hung Yang, and 黃宏仰. "Un-doped layer thickness on the optical properties of GaN LED." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/26416853261947049883.
Full textAbstract:
碩士元智大學
電機工程學系
98
Owing to the lattice mismatching, 13.8%, between GaN and Al2O3, the GaN LED on Al2O3 substrate results in high defect density, which including dislocations will substantially degrade the light-emitting efficiency, lifetime, reliability, and ESD capability. To improve this problem, the present work study the influence of the Un-intentionally doped GaN (U-GaN) layer thickness on optoelectronic properties. The defect density is 3.85 E+10 cm-2 when the thickness of u-GaN is 1um. When the thickness of U-GaN is 2um and 3um, the defect densities decrease 47.2% and 52.7% respectively. The better quality of 3um u-GaN than 2um U-GaN is shown in the XRD (X-Ray Diffraction) measurement. To improve this problem, the present work study the influence of the Un-intentionally doped GaN (U-GaN) layer thickness on optoelectronic properties. The defect density is 3.85 E+10 cm-2 when the thickness of u-GaN is 1um. When the thickness of U-GaN is 2um and 3um, the defect densities decrease 47.2% and 52.7% respectively. The better quality of 3um u-GaN than 2um U-GaN is shown in the XRD (X-Ray Diffraction) measurement.