Dissertations / Theses: 'Light scattering'

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Malkovskiy, Andrey Victorovich. "Light Scattering of Nanostructured Materials." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1303760576.

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Zangrando, David Duane. "Light scattering studies of proteoglycans." Case Western Reserve University School of Graduate Studies / OhioLINK, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=case1055947716.

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Li, Qinghe. "Light scattering of semitransparent media." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22686.

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Ricks, Douglas Wayne. "Light scattering from binary optics." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186258.

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Binary optics is a new technology that makes use of the principle of diffraction instead of reflection or refraction to change an incident wavefront. This technology takes advantage of the recent progress in microlithography. There are many new and exciting applications for binary optics, and we can also expect to see the replacement of some conventional optical elements with binary optics. In many ways a binary optic behaves like a diffraction grating with a period that changes continually over the surface of the optic. We find that energy is scattered into different diffraction orders, and there is scattering similar to "grass", "ghosts", "errors of run", "accidental errors of amplitude", and diffuse scattering from surface roughness, just like there is from a diffraction grating. There are vector theories and scalar theories of diffraction. In this dissertation we give the conditions under which the various theories are applicable. We derive a formula for scattering from binary optics with slightly rough surfaces. By comparing this theory to computer simulations of scattering from binary optics we show that the theory can account for random fabrication errors. Formulas are also derived to predict the scattering from systematic errors. The author designed and built an instrument to measure scattering at small angles, and we show that measured scattering from binary optics can be predicted by the theories developed.

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Atthipalli, Gowtam. "Light Scattering by Colloids Larger than Wavelength of Light." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1185471826.

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Linder, Tomas, Torbjörn Löfqvist, Coppel Ludovic Gustafsson, Magnus Neuman, and Per Edström. "Lateral light scattering in fibrous media." Mittuniversitetet, Avdelningen för naturvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-18657.

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Lateral light scattering in fibrous media is investigated by computing the modulation transfer function (MTF) of 22 paper samples using a Monte Carlo model. The simulation tool uses phase functions from infinitely long homogenous cylinders and the directional inhomogeneity of paper is achieved by aligning the cylinders in the plane. The inverse frequency at half maximum of the MTF is compared to both measurements and previous simulations with isotropic and strongly forward single scattering phase functions. It is found that the conical scattering by cylinders enhances the lateral scattering and therefore predicts a larger extent of lateral light scattering than models using rotationally invariant single scattering phase functions. However, it does not fully reach the levels of lateral scattering observed in measurements. It is argued that the hollow lumen of a wood fiber or dependent scattering effects must be considered for a complete description of lateral light scattering in paper.
PaperOpt

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Nordam, Tor. "Scattering of light from weaklyrough surfaces." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for fysikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20288.

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A formalism is introduced for the non-perturbative, purely numerical, solution of the reduced Rayleigh equation for the scattering of light from two-dimensional penetrable rough surfaces. In the papers included in this thesis, we apply this formalism to study the scattering of p- or s-polarised light from two-dimensional dielectric or metallic randomly rough surfaces, or from two-dimensional randomly rough thin dielectric films on metallic substrates, by calculating the full angular distribution of the co- and cross-polarised intensity of the scattered light. We present calculations of the mean differential reflection coefficient for glass and silver surfaces characterised by (isotropic or anisotropic) Gaussian and cylindrical power spectra, and find a good match with experimental results, as well as results obtained from another numerical method. We also present a numerical calculation of the Mueller matrix for scattering from rough surfaces, based on the same method. We investigate the optical phenomena of enhanced backscattering, enhanced forward scattering and satellite peaks. Enhanced backscattering is a well known phenomenon, and is used as one among several indicators of correct results. The phenomenon of enhanced forward scattering has not previously been investigated in two-dimensional systems. We demonstrate its presence, and provide an explanation for why it is qualitatively different from the same phenomenon in one dimension. Regarding satellite peaks, there has been a dispute in the literature, where one group found they should be present in scattering from a thin dielectric film on a metallic substrate, while another group found they should not. We have demonstrated their presence, and shown how the one-dimensional phenomenon of satellite peaks become “satellite rings” in the two-dimensional case. The proposed method is found, within the validity of the Rayleigh hypothesis, to give reliable results. For a non-absorbing metal surface the conservation of energy was explicitly checked, and found to be satisfied to within 0.03%, or better, for the parameters assumed. This testifies to the accuracy of the approach and a satisfactory discretisation. We also perform a numerical investigation of the range of validity of the reduced Rayleigh equation for scattering from two-dimensionally rough silver and perfectly conducting surfaces. The advantage of using a numerical solution of the reduced Rayleigh equation, rather than a rigorous numerical method such as the surface integral method, lies in the required computational resources. The main limitation of these methods for considering two-dimensionally rough surfaces are their memory requirements. To calculate the scattering amplitude for a typical system studied in this thesis, by the reduced Rayleigh equation, requires 12 GB of memory. To solve a similarly sized system with a rigorous method requires one or two orders of magnitude more. The limitation of the reduced Rayleigh equation is that it can only be applied to weakly rough surfaces, due to the assumption of the Rayleigh hypothesis.

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Douglas, James Stewart. "Light scattering from ultracold atomic gases." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:0aa4ede3-8b6e-45d4-a112-a2d18271307c.

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Systems of ultracold atoms in optical potentials have taken a place at the forefront of research into many-body atomic systems because of the clean experimental environment they exist in and the tunability of the system parameters. In this thesis we study how light scattered from these ultracold atomic gases reveals information about the state of the atomic gas and also leads to changes in that state. We begin by investigating the angular dependence of light scattered from atoms in optical lattices at finite temperature. We demonstrate how correlations in the superfluid and Mott insulator states affect the scattering pattern, and we show that temperature affects the number of photons scattered. This effect could be used to measure the temperature of the gas, however, we show that when the lattice band structure is taken into account the efficiency of this temperature measurement is reduced. We then investigate light scattering from small optical lattices where the Bose-Hubbard Hamiltonian can be solved exactly. For small lattices, scattering a photon from the atomic system significantly perturbs the atomic system. We develop a model of the evolution of the many-body state that results from the consecutive scattering and detection of photons. This model shows that light scattering pushes the system towards eigenstates of the light scattering measurement process, in some cases leading to a superposition of atomic states. In the second half of this thesis we study light scattering that depends on the internal hyperfine spin state of the atoms, in which case the scattered light can form images of the spatial atomic spin distribution. We demonstrate how scattering spatially correlated light from the atoms can result in spin state images with enhanced spatial resolution. We also show how using spatially correlated light can lead to direct measurement of the spatial correlations of the atomic spin distribution. We then apply this theory of spin-dependent light scattering to the detection of different spin states of ultracold gases in synthetic magnetic fields. We show that it is possible to distinguish between ground states in the quantum Hall regime using light scattering. Moreover, we show how noise correlation analysis of the spin state images can be used to identify the correlations between atoms and how a variant on phase-contrast imaging can reveal the relationship between the atomic spins.

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Broky, John. "Inverse Problems in Multiple Light Scattering." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5608.

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The interaction between coherent waves and material systems with complex optical properties is a complicated, deterministic process. Light that scatters from such media gives rise to random fields with intricate properties. It is common perception that the randomness of these complex fields is undesired and therefore is to be removed, usually through a process of ensemble averaging. However, random fields emerging from light matter interaction contain information about the properties of the medium and a thorough analysis of the scattered light allows solving specific inverse problems. Traditional attempts to solve these kinds of inverse problems tend to rely on statistical average quantities and ignore the deterministic interaction between the optical field and the scattering structure. Thus, because ensemble averaging inherently destroys specific characteristics of random processes, one can only recover limited information about the medium. This dissertation discusses practical means that go beyond ensemble averaging to probe complex media and extract additional information about a random scattering system. The dissertation discusses cases in which media with similar average properties can be differentiated by detailed examination of fluctuations between different realizations of the random process of multiple scattering. As a different approach to this type of inverse problems, the dissertation also includes a description of how higher-order field and polarization correlations can be used to extract features of random media and complex systems from one single realization of the light-matter interaction. Examples include (i) determining the level of multiple scattering, (ii) identifying non-stationarities in random fields, and (iii) extracting underlying correlation lengths of random electromagnetic fields that result from basic interferences. The new approaches introduced and the demonstrations described in this dissertation represent practical means to extract important material properties or to discriminate between media with similar characteristics even in situations when experimental constraints limit the number of realizations of the complex light-matter interaction.
Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics

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Sharpe, Donal J. "Laser light scattering from liquid surfaces." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282336.

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Lecler, Sylvain. "Light scattering by sub-micrometric particles." Université Louis Pasteur (Strasbourg) (1971-2008), 2005. https://publication-theses.unistra.fr/public/theses_doctorat/2005/LECLER_Sylvain_2005.pdf.

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L’objectif de ce travail a été de contribuer à la compréhension physique de l’interaction de la lumière visible avec des particules sub-microniques, en particulier en champ proche. Deux phénomènes particuliers ont été étudiés, la possibilité de concentrer la lumière en un jet photonique et les couplages électromagnétiques entre particules proches. La théorie de Lorenz-Mie et l’algorithme de la T-matrice, qui est une extension pour simuler rigoureusement l’interaction de la lumière avec plusieurs sphères, ont été utilisés pour les simulations. Dans les deux cas, les équations de Maxwell ont été résolues analytiquement. En premier lieu, nous avons observé la possibilité qu’avaient des sphères diélectriques de focaliser jusqu’à la limite de diffraction et de fortement concentrer l’énergie en champ proche. Cette focalisation en champ proche a lieu quand le rayon de la sphère a une taille comparable avec la longueur d’onde, mais aussi pour des sphères de taille plus grande. Quand le point focal est juste sur la surface de la sphère ou à quelques longueurs d’onde devant, la largeur (FWHM) du faisceau peut être plus petite que la longueur d’onde, le faisceau est faiblement divergent et l’énergie peut être fortement concentrée. Un tel faisceau focalisé a été appelé un jet photonique. Nous avons montré son existence pour des particules sphériques et avons décrit ses principales propriétés en fonction des propriétés optiques de la sphère. Plusieurs applications possibles ont été présentées. Cette concentration d’énergie en champ proche a posé la question des couplages électromagnétiques qui peuvent intervenir entre particules au coeur d’un agrégat de sphères diélectriques. Pour étudier ces couplages, nous avons simulé des couples de particules. L’étude a été réalisée avec des couples de sphères diélectriques et des couples de sphères conductrices parfaites et ceci pour plusieurs orientations. Notre but a été de proposer une interprétation physique des phénomènes de couplages qui peuvent avoir lieu entre deux particules proches. Pour un couple de particules qui serait orthogonal au vecteur d’onde de l’onde plane incidente, une comparaison avec des trous d’Young a été faite. En diffusion simple, l’intensité diffusée en champ lointain peut être décrite en terme d’interférences et de diffraction. Nous avons étendu cette comparaison aux cas où il y a diffusion multiple et nous avons montré que les interactions dues à la diffusion multiple influaient essentiellement sur la fraction de l’onde incidente qui interagissait avec les particules. Nous avons également considéré le cas où le couple de particules serait parallèle au vecteur d’onde de l’onde plane incidente. En diffusion multiple et dans la direction de rétro diffusion, nous avons mis en évidence un phénomène d’ombrage dans le cas de sphères conductrices parfaites, qui fait décroître l’intensité des interférences observées. A l’inverse, un effet de type Fabry-Perot (résonances d’une cavité) a été observé pour un couple de particules diélectriques, effet qui fait augmenter l’intensité des interférences observées et qui pourra être utilisés pour des applications futures.

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Pawlikowski, Laura J. "Light scattering from solutions of nanoparticles." Tallahassee, Fla. : Florida State University, 2008. http://purl.fcla.edu/fsu/lib/digcoll/undergraduate/honors-theses/341804.

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Thesis (Honors paper)--Florida State University, 2008.
Advisor: Dr. John C. Telotte, Florida State University, College of Engineering, Dept. of Biomedical Engineering. Includes bibliographical references.

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Nouisiainen, Timo. "Light scattering by nonspherical atmospheric particles." Helsinki : University of Helsinki, 2002. http://ethesis.helsinki.fi/julkaisut/mat/fysik/vk/nousiainen/.

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14

Turbil, Colette. "Light Scattering from Complex Rough Surfaces." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS205.

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Lorsque la lumière interagit avec un objet, deux phénomènes peuvent avoir lieu : la lumière peut être absorbée ou déviée par l’objet, ce dernier phénomène étant généralement qualifié de diffusion de la lumière. Malgré l’intérêt de la communauté scientifique au cours des dernières décennies, la diffusion de la lumière induite par des surfaces rugueuses reste un problème complexe à traiter, ceci étant principalement dû à la grande multidisciplinarité requise pour l’étude du phénomène. Ce travail multidisciplinaire est basé sur l’étude de quatre différents domaines scientifiques qui doivent être considérés en parallèle pour traiter le phénomène de diffusion de la lumière de manière globale. Une vingtaine d’échantillons, fabriqués au laboratoire ou par des procédés industriels, sont sélectionnés pour leurs différentes apparences visuelles. Leur morphologie est caractérisée grâce à trois dispositifs expérimentaux, qui permettent ainsi de décrire la rugosité sur quatre décades de fréquences spatiales. Ensuite, la distribution angulaire de l’intensité lumineuse diffusée par les échantillons est mesurée, et confirme la grande variété des propriétés optiques des surfaces examinées. Finalement, ces données expérimentales sont utilisées et comparées aux résultats de deux types de modèles de diffusion de la lumière, l’un basé sur l’optique géométrique et l’autre sur l’optique physique. L’étude montre que les propriétés optiques des échantillons étudiés peuvent être assez fidèlement reproduites par le modèle de diffusion de la lumière basé sur l’optique physique. En revanche, le modèle basé sur les lois de l’optique géométrique ne parvient pas à produire des résultats satisfaisants
When light interacts with an object, two types of phenomena can occur: light can be either absorbed or redirected by the object. The latter phenomenon is generally referred to as light scattering. Despite the significant efforts over the past decades of the scientific community, light scattering from rough surfaces remains a complex problem. This is partly due to the high degree of multidisciplinary that is required for its study. The present multidisciplinary study is related to four scientific domains that must be examined to consider the full light scattering phenomenon. First, a large panel of a rough surface, elaborated by ourselves in the laboratory or manufactured industrially, is selected for its wide range of visual aspect. The morphology of the samples are characterized using three experimental tools which allow us to describe their surface morphologies over four decades of spatial frequencies. Then the angular intensity distributions of the light scattered from the samples are measured which confirm the wide variety of optical properties of the samples. Finally, these reliable and representative experimental data are compared to the results of different light scattering models, based on both the physical and the geometrical optics approaches. The main conclusion we drew from this work is that for the examined surfaces, the light scattering can be approximated fairly well by a model based on the physical optics approach, while at the same time, geometrical optics models are not able to give an adequate description of the same scattering data

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Hayakawa, M., T. Kinoshita, and A. I. Sanda. "Hadronic Light-by-Light Scattering Effect on Muon g -2." The American Physical Society, 1995. http://hdl.handle.net/2237/7156.

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Hayakawa, M., T. Kinoshita, and A. I. Sanda. "Hadronic light-by-light scattering contribution to muon g-2." The American Physical Society, 1996. http://hdl.handle.net/2237/7136.

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Schaudt, Kimberly Jean. "Light scattering in dielectric disk arrays and atomic scattering by helium." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185932.

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The exact scalar wave solution for light scattering from a general dielectric disk array is found. The exact solution as well as a numerical solution is also given for an array of three dielectric disks, whose centers are placed on the vertices of an equilateral triangle. The various (differential, total and averaged total) cross sections and the poles of the scattering matrix are given. These results are analyzed in part by considering the effects which arise from the geometry of the system, and in part by comparison with the results (cross sections and poles) for a system with an identical arrangement of three hard (perfectly conducting) disks and with a system of one dielectric disk. This analysis helps rule out structure that arise from the chaos, which is very likely to exist, in the classical (geometric) limit of the three (or more) dielectric disk system. In the future after I study the geometric (classical) and physics (semiclassical) regimes of this system, I plan to reanalyse the exact wave solution in an attempt to discover the traces of the chaos present in the system. Time dependent Hartree-Fock theory (TDHF), with improved formulation and improved computer capabilities, is used to repeat the calculations of charge capture for the He²⁺ on He collision. The results of these calculations allow us to discuss the effects of various numerical truncations and to establish with certainty the viability and the accuracy of TDHF in its application to ion-atom collisions. Initially, we had hoped to find chaos in the TDHF problem, as it is nonlinear. However, due to the complexity and computational difficulties present in the TDHF problem, a simpler scattering system of light scattering from dielectric disk arrays was chosen for study.

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Kim, Kibum. "Monte Carlo simulation and experimental analysis of dense medium light scattering, with applications to corneal light scattering." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001172.

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Dahlgren, Eric D. "Small angle light scattering analysis of tissue." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0111102-171921.

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Algarni, Saad A. "Development and Application of an Area Recorded Generalized Optical Scattering Technique." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-dissertations/426.

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"A novel approach to a light scattering experiment that employs a lounge image capture assay has been developed for both static and dynamic measurement on a wide variety of samples. In this work, the 'Development and Application of an Area Recorded Generalized Optical Scattering Technique', abbreviate as ARGOS, an approach is based on the placement of a translucent screen where the scattered light, now converted to a diffuse light, is imaged as a function of time. The placement and size of the screen determines the range of scattering wave-vectors, while the time between images determines the fastest dynamic resolvable . The overall experimental stability determines the slowest dynamic resolvable and so can be made arbitrarily long. The scattering intensity is measured by a camera whose dynamic range (number of bits per pixel), resolution, and speed determines the sensitivity and accuracy of intensity of the scattered light. The system allows for an extremely well-defined scattering experiment geometry, where images may be manipulated to extract structure (i.e. average I(q)over t) and dynamics (average I(q,t) over q) for a wide range of samples(liquids and solids). A number of innovation were developed. Instead of a beam stop to block the high intensity thru-beam, a thru-beam attenuator was developed such that the exact center of the scattering geometry is determined for each image acquired. A variety of image processing algorithms were also developed to correct for dead pixels, camera response, and intensity normalization. Of particular use was the development of the root-mean-square difference(RSD) image to probe dynamic. Here, the first image is taken as the time-zero reference image and subtracted from all succeeding images where averaged over a speci ed q and plotted as a function of time revealing the build up image changes due to dynamics. The technique was validated for both static and dynamic measurements with a set ofdilute suspended latex spheres in water (sizes ranging from 0.01 to 2micro m). The static light scattering result in terms of particle radius and dimension closely matched the expected values. The dynamic light scattering results could only several the end of the dynamics of these suspended latex spheres due to Brownian motion because of the speed limitation of the camera. However, sedimentation dynamics that are much slower, were early observed. The ARGOS technique was then applied to two biological systems, the evolution of a dilute suspension of E. Coli bacteria through the life-cycle and the evolution of the same suspended bacteria but infected with the MS2 bacteria-phage virus. High temporal resolution data were obtained of the bacteria life-cycle which werecorrelated with size, structure, and dynamics that revealed potentially new insights on behavior not well understood in the literature . The MS2 infected bacteria revealed the effect of the bacteria-phage on every character of the E. Coli life-cycle. The successful development and implementation of ARGOS here has also revealed avenues to greatly improve the performance."

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Padmabandu, Gamaralalage Gunasiri. "Scattering of light from two parallel dielectric cylinders at normal incidence: An experimental determination." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184728.

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The entire sixteen element scattering matrix for two parallel dielectric fibers over an angular range of θ = 5°-170° as measured from the forward θ = 0 direction has been experimentally measured using the polarization modulation technique. Experimental results were in good agreement with theory for light scattering from two parallel fibers. Measurements were made for both endside and broadside illuminations at normal incidence for fibers at various separations from 2 μm to 70 μm. Laser wavelengths used were 632.8 nm and 441.2 nm, and fiber radii were 0.400±0.002 μm, 0.370±0.002 μm, 0.428±0.002 μm, and 0.406±0.002 μm. Special care was taken to measure the fiber radii, fiber separation, and to establish the parallelism between the two fibers. Electrostatic attraction between the fibers prevented the investigation for separation below 2 μm. A vibration detection device based on two-fiber light scattering has also been suggested.

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Abromson, David 1961. "SMALL PARTICLE PERTURBATION OF A LASER RING CAVITY'S DECAY LIFETIME." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275525.

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Pauk, Vladyslav [Verfasser]. "Light-by-light scattering and muon’s anomalous magnetic moment / Vladyslav Pauk." Mainz : Universitätsbibliothek Mainz, 2014. http://d-nb.info/1055858679/34.

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Au, Yat-Yin. "Light scattering studies of metallic magnetic microstructures." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1141842225.

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Liu, Suo. "Minimizing distortions in dynamic light scattering experiments." Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489892.

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Several methods are discussed and applied for minimizing distortions m dynamic light scattering (DLS). Multiple scattering, a very common phenomenon in DLS experiments, is discussed. Distortions caused by multiple scattering and its influence on correlation data are analyzed in detail. Five different methods are applied in simulations of suppression of multiple scattering in DLS experiments. The effect of foreign large particles, such as larger particles left by previous experiments, fast sinking dust in the sample suspension or agglomerations of the sample particles, are discussed and analyzed. Two 'dust' removal methods are discussed and applied on anticontamination simulations and real experimental data. Investigations are carried out considering samples flowing with velocities and also distortions coming from stray light. An area difference method is introduced in detecting a sample's velocity and stray light. From the results of simulations and real experiment data, the conclusion can be made that the methods discussed in this thesis perform well in minimizing the distortions in DLS experiment.

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Everitt, Jed. "Gegenbauer analysis of light scattering from spheres." Thesis, University of Hertfordshire, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302277.

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Zhang, Xiaodong. "Light scattering by microbubbles in the ocean." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0009/MQ49476.pdf.

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Johansson, Niklas. "Measuring and modelling light scattering in paper." Doctoral thesis, Mittuniversitetet, Avdelningen för naturvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-24986.

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

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29

Li, Chunhua. "Ultrasound modulated light detection in scattering media." Thesis, University of Nottingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439854.

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Watt, Morag. "Inelastic light scattering in low dimensional semiconductors." Thesis, University of Glasgow, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364643.

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Sefton, M. S. "Dynamic light scattering from thermotropic liquid crystals." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370981.

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Obradovic, Bojan. "Light scattering and luminescence of InGanN epilayers." Thesis, University of Essex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343546.

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MacCallum, Iain. "Measurement and modelling of phytoplankton light scattering." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248311.

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Bustard, Helen Kathryn. "Investigations into light scattering by human hair." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46692.

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Chamberlin, Richard Addison. "Light scattering studies on lecithin micellar solution." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13859.

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Šćepanović, Obrad R. 1980. "Light scattering spectroscopy clinical imaging device implementation." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87887.

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Heinson, Yuli Wang. "Light scattering studies of irregularly shaped particles." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32517.

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Doctor of Philosophy
Physics
Christopher M. Sorensen
We present light scattering studies of irregularly shaped particles which significantly affect the climate. We built and calibrated our apparatus which was able to measure all six independent scattering matrix elements. Our apparatus detects light from 0.32° to 157° simultaneously. We studied all six scattering matrix elements of irregularly shaped Arizona Road Dust which behave differently than those of spheres. We strongly focused on the most important scattering matrix element – the phase function, scattered intensity vs. the scattering angle, which we applied Q-space analysis to. Q-space analysis involves plotting the scattering intensity vs. the magnitude of the scattering wave vector q or qR with R the radius of a particle, on a double logarithmic scale. We measured and studied the phase functions of Al₂O₃ abrasives; compared the scattering from the abrasives with the scattering of spheres. To generalize the study, we collected a large amount of experimental and theoretical data from our group and others and applied Q-space analysis. They all displayed a common scattering pattern. The power law exponents showed a quasi-universal functionality with the internal coupling parameter ρ'. In situ studies of the soot fractal aggregates produced from a burner were also conducted. A power law exponent -1.85 is seen to imply the aggregates have fractal dimension of D[subscript f]=1.85. The overall work presented shows Q-space analysis uncovers patterns common to all particles: a q-independent forward scattering regime is followed by a Guinier regime, a power law regime, and sometimes an enhanced back scattering regime. The description of the patterns applies to spheres as well, except the power law regime has more than a single power law. These simple patterns give a unified description for all particle shapes. Moreover, the power law exponents have a quasi-universal functionality with ρ' for non-fractal aggregates. The absolute value of the exponents start from 4 when ρ' is small. As ρ' increases, the exponents decrease until the trend levels off at ρ'≳10 where the exponents reach a constant 1.75±0.25. All the non-fractal particles fall on the same trend regardless of the detail of their structure.

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Kim, Min-Joong. "Light scattering from characterised random rough surfaces." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47513.

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Au, Yat-Yin. "Light scattering studies of metallic magneti microstructures." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1141842225.

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Konthasinghe, Kumarasiri. "Resonant Light Scattering from Semiconductor Quantum Dots." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6527.

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In this work, resonant laser spectroscopy has been utilized in two major projects --resonance fluorescence measurements in solid-state quantum-confined nanostructures and laser-induced fluorescence measurements in gases. The first project focuses on studying resonant light-matter interactions in semiconductor quantum dots "artificial atoms" with potential applications in quantum information science. Of primary interest is the understanding of fundamental processes and how they are affected by the solid-state matrix. Unlike atoms, quantum dots are susceptible to a variety of environmental influences such as phonon scattering and spectral diffusion. These interactions alter the desired properties of the scattered light and hinder uses in certain single photon source applications. One application of current interest is the use of quantum dots in “quantum repeaters” for which two-photon interference is key. Motivated by such an application we have explored the limits imposed by environmental effects on two quantum dots in the same sample, the scattered light from which is being interfered. We find that both one-photon and two-photon interference, although substantial, are affected in a variety of ways, in particular by spectral diffusion. These observations are discussed and compared with a theoretical model. We further investigated correlations in pulsed resonance fluorescence, and found significant unexpected spectral and temporal deviations from those studied under continuous wave excitation. Under these conditions, the scattered light exhibits Rabi oscillations and photon anti-bunching, while maintaining a rich spectrum containing many spectral features. These observations are discussed and compared with a theoretical model. In the second project, the focus is on the investigation of the possibility of detecting N2+ ions in air using laser induced fluorescence, with potential applications in detection of fissile materials at a distance. A photon-counting analysis reveals that the fluorescence decay rate rapidly increases with increasing N2 pressure and thus limits the detection at elevated pressures, in particular at atmospheric pressure. We show that time-gated detection can be used to isolate N2+ fluorescence from delayed N2 emission. Based on the spontaneous Raman signal from N2 simultaneously observed with N2+ fluorescence, we could estimate a limit of detection in air of order 108-1010 cm3.

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Wang, Tong. "Light Scattering Study on Single Wall Carbon Nanotube (SWNT) Dispersions." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5200.

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Carbon nanotubes, and particularly single wall carbon nanotubes (SWNTs) have attracted much attention for their unique structure, as well as for their excellent mechanical, electrical and thermal properties. Most properties of carbon nanotubs are closely related with its anisotropic structure and geometry factor. Characterization of carbon nanotube length is critical for understanding their behavior in solutions as well as in polymer composites. Microscopy, particularly atomic force microscopy, has been used for their length measurement. Microscopy, though straightforward, is quite laborious, particularly for statistically meaningful sampling. Light scattering can be used to measure particle dimensions. In this study, light scattering has been used to study polyvinyl pyrrolidone (PVP) wrapped SWNTs surfactant assisted aqueous dispersion and SWNT dispersion in oleum. To determine the length of SWNTs, Stokes - Mueller formalism was used, which is a universal model for particles with any size and shape. The Mueller matrix for an ensemble of long, thin cylinders proposed by McClain et al. was used in this study. This Mueller matrix includes the information of size (length and radius) and optical constants (refractive index and extinction coefficient) of cylinders. In this matrix, extinction coefficient, radius and length of SWNTs are unknown. By normalizing scattering intensity I(theta) (theta from 30 to 155 degree) to that at 30degree , the effects of radius and extinction coefficient were cancelled out. Thus, the effect of SWNT length on scattering intensity could be studied independently. A series of curves of normalized scattering intensity of SWNTs (I(theta) /I(30degree)) with varied length as a function of wave vector were predicted. A curve of normalized scattering intensity of SWNT as a function of wave vector was also obtained experimentally. By comparing experimental and predicted curves, average SWNT length in the dispersion has been determined. Scattering intensity at a given angle initially increases with concentration, and then reaches a critical concentration(C*), above which the scattering intensity decreases. This phenomenon has been attributed to the competition between scattering and absorption of light by the presence of SWNT. By using Beer-Lambert law, this phenomenon has been used to determine the molar absorption coefficient of SWNTs.

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Kwon, Oh-Sun. "Quasi-elastic scattering of ultracold neutrons /." View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3186907.

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Li, Jian-Yang. "Light scattering properties of asteroids and cometary nuclei." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/2466.

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Thesis (PhD) -- University of Maryland, College Park, 2005
Thesis research directed by: Astronomy. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Nillius, Peter. "Image Analysis using the Physics of Light Scattering." Doctoral thesis, KTH, Numerical Analysis and Computer Science, NADA, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3780.

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Any generic computer vision algorithm must be able to copewith the variations in appearance of objects due to differentillumination conditions. While these variations in the shadingof a surface may seem a nuisance, they in fact containinformation about the world. This thesis tries to provide anunderstanding what information can be extracted from theshading in a single image and how to achieve this. One of thechallenges lies in finding accurate models for the wide varietyof conditions that can occur.

Frequency space representations are powerful tools foranalyzing shading theoretically. Surfaces act as low-passfilters on the illumination making the reflected lightband-limited. Hence, it can be represented by a finite numberof components in the Fourier domain, despite having arbitraryillumination. This thesis derives a basis for shading byrepresenting the illumination in spherical harmonics and theBRDF in a basis for isotropic reflectance. By analyzing thecontributing variance of this basis it is shown how to createfinite dimensional representations for any surface withisotropic reflectance.

The finite representation is used to analytically derive aprincipal component analysis (PCA) basis of the set of imagesdue to the variations in the illumination and BRDF. The PCA isperformed model-based so that the variations in the images aredescribed by the variations in the illumination and the BRDF.This has a number of advantages. The PCA can be performed overa wide variety of conditions, more than would be practicallypossible if the images were captured or rendered. Also, thereis an explicit mapping between the principal components and theillumination and BRDF so that the PCA basis can be used as aphysical model.

By combining a database of captured illumination and adatabase of captured BRDFs a general basis for shading iscreated. This basis is used to investigate materialclassification from a single image with known geometry butarbitrary unknown illumination. An image is classified byestimating the coecients in this basis and comparing them to adatabase. Experiments on synthetic data show that materialclassification from reflectance properties is hard. There aremis-classifications and the materials seem to cluster intogroups. The materials are grouped using a greedy algorithm.Experiments on real images show promising results.

Keywords:computer vision, shading, illumination,reflectance, image irradiance, frequency space representations,spherical harmonics, analytic PCA, model-based PCA, materialclassification, illumination estimation

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Dahlgren, Ronnie. "Monte Carlo Simulation of Light Scattering in Paper." Thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-97857.

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Paper is a very complex optical material. Analytical models explaining some of the optical properties of mpaper exist, but they often rely on bold simplifications. Monte Carlo simulation models are less constrained and allow for a greater degree of complexity. Grace is a three-dimensional light scattering simulation tool for paper, previously implemented in Matlab. During this project, the basesheet model was implemented in C++. This model simulates a layer containing a network of wood fibers and filler material. The new implementation makes simulations much faster. In addition, some new features and enhancements were developed. Wavelength dependency of parameters and fluorescence were implemented and tested. A problem with Grace was that there was no simple way to calculate the grammage of the simulated paper. A method to analytically determine grammage was developed so that the user has complete control over the grammage of the fiber network. Modifications were made to improve light scattering at the pore boundaries. A new feature was also added to study how the fibers’ and fillers’ geometry affects the light scattering at the paper surface.

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Bélanger, Christian. "The examination of polymer blends by light scattering /." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61983.

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Schumacher, Gerhard A. (Gerhard Arthur). "Light scattering studies on electrostatically stabilized colloidal particles." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74537.

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The effect of electrical double layers on the diffusion of spherical colloidal particles was studied using photon correlation spectroscopy (PCS). The diffusion constant was found to equal that of a neutral particle at low and high electrolyte concentration and was reduced by several percent when the electrical double layer is comparable to the particle radius, in agreement with the general theory for charged particles.
PCS studies of bimodal colloidal dispersions included the experimental verification of the bimodal homodyne autocorrelation function and the introduction of quasi-heterodyne detection.
The effect of electrical double layers on the diffusion of rod shaped colloidal particles was studied with PCS, using tobacco mosaic virus particles as probes. The results are qualitatively similar to those for spherical particles, with the minimum occurring when the double layer is comparable to the radius of an equivalent sphere.
The intensity of the light scattered from latex particles in an evanescent wave was measured as a function of the penetration depth of the evanescent wave. The results were found to be consistent with those predicted from DLVO theory.

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Van, Heiningen Jan. "Ultra-small angle light scattering : apparatus design optimization." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84092.

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Ultra-small angle light scattering (USALS) is a technique used to probe large average spatial and temporal structure of soft condensed matter complementary to microscopy. Limited information is available on the design and features of a multi-speckle CCD-based USALS apparatus. The optics of such a setup are described followed by an optimization scheme involving ray tracing that can be used to choose the optimum lenses by taking into account the finite spot size due to lens aberrations, diffraction, and the CCD pixel size. Results of calculations of the optimization scheme are presented for a static light scattering (SLS) setup followed by a few experimental tests of our current apparatus.

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Fairbanks, M. "Neutron and light scattering studies of molten salts." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233457.

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Asbury, Vicky. "Light scattering by Helix aspera ganglia in vitro." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615607.

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Dissertations / Theses on the topic 'Light scattering'

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