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Dissertations / Theses on the topic 'Surface science; Optics'
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1
Yang, Zhi. "Reconstructing and registering 3D surface from single intensity image." Thesis, State University of New York at Buffalo, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3726026.
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<p> Reconstructing 3D surface from of an intensity image is a fundamental problem in the computer-vision community. Humans have a remarkable ability to perceive shape of an object when looking at a 2D intensity image, but enabling computers to do so is still a very challenging task. Advances in this area can help us solve problem of building panoramic 3D view by registering multiple surfaces. It has many useful applications such as medical surgery using CT/MRI scans, restoring ancient artifacts using single image, path/arm guiding algorithms for robots, etc. Most existing methods in this area belong to the category of Shape from Shading. Such methods have shown limited success recovering simple shapes, such as a vase. However, due to inherent ambiguity associated with relating intensity to depth, existing methods have not been able to demonstrate similar success for complex surfaces. Improved methods use additional information, such as stereo images like Structure from Motion, or multiple light sources like Photometric Stereo. Such methods have two broad issues. Firstly, inherent problem from Lambertian reflectance model is not solved and therefore, secondly, they could not provide insights regarding the human ability to perceive depth from 2D images. </p><p> In this thesis, we are trying to solve the problem by exploiting relationship between surface gradient and corresponding intensity value at the exact position. The relationship is formulated as a novel illumination model and the model is at the core of our research. Using the illumination model, surface reconstruction problem is posed as a task of integrating step-wise absolute value of difference of depth (think of gradient). To solve the inherent ambiguity (even human being could not decide), we tackle the relative signs by using reference depth as a prior knowledge. Then the formula is simplified and approximated for handing different materials and lighting conditions. </p><p> Based on the reconstructed surfaces, we can also handle the problem of building a panoramic 3D surface with intensity images of same object from different views. The core step here is surface registration. We developed methods that use Riemannian Geometry and Machine Learning techniques for rigid or non-rigid surface registration.</p>
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Timson, Andrew John. "Second harmonic generation of molecules located at the air/water interface." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326716.
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Shaw, Joseph Alan 1962. "Laser-glint measurements of sea-surface roughness." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/290653.
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Optical glint patterns convey information about the roughness of the surface on which they are formed. This dissertation describes two new optical instruments that relate the variations of specular laser reflections (laser glints) from the sea surface in angular, temporal, and wavenumber space to the surface roughness. Measurements from these instruments are interpreted with the objective of improving the capabilities of remote-sensing instruments that view the ocean surface. Particular attention is paid to cm waves, which are resonant structures for microwave sensors and the most significant component of optical roughness. The scanning-laser glint meter counts laser glints in 1° angular bins over a ± 75° nadir-angle range. The video laser-glint imager is a CCD video camera that images glints from an array of diode lasers. Both instruments were deployed on the research platform FLIP in the Pacific Ocean near the Oregon coast for three weeks during September 1995. Normalized histograms of angular glint counts are interpreted as the probability density function (PDF) of sea-surface slope, a Gram-Charlier expansion of which facilitates studying the variation with wind speed and atmospheric stability of moments through order four. The PDF appears approximately Gaussian, but is skewed toward downwind slopes in the along-wind axis due to asymmetric wind waves. No skewness exists in the cross-wind axis. Slope PDFs also have positive peakedness, increasing the probability of very small and large slopes relative to a Gaussian. Surface roughness is shown to depend strongly on atmospheric stability, which is proportional to the air-water temperature difference. Both the mean-square slope and the peakedness increase with negative stability (water warmer than air) relative to the neutral-stability case (water and air temperatures equal). Increased surface roughness, due to increases in wind speed or negative stability, causes glint-count fractal dimensions to increase, glint-image power spectra to flatten, and glint-image autocorrelations to appear more wrinkled. Glint-image spectra are dominated by glint-size effects, which are related to surface curvature. New ways of modeling the interaction of electromagnetic waves with the ocean surface are suggested by the new fractal and spectral characterizations of surface roughness that are introduced here.
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Hahn, Walter Gordon. "Optical measurement of surface profiles of silicon dioxide films on silicon substrates and carbon coatings on magnetic disks." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185909.
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Current models for recovering the surface profile from optical measurements are inadequate for characterizing surfaces with optically dissimilar regions. This limitation in the model is evidenced in optical measurements of silicon dioxide films on silicon substrates, and carbon films on magnetic recording disk substrates. A new model that accounts for phase changes due to reflection at material boundaries is proposed, which involves measurements at several wavelengths in order to resolve these phase changes. Results of implementation of the new model are presented for silicon dioxide and carbon films.
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Thiesing, Benjamin P. "High temperature measurements of surface changes in metal alloys using digital holography." Thesis, Northern Arizona University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1537812.
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<p> Digital Holography (DH) is an emerging tool for use in the structural investigation of temperature dependent material processes. DH is able to reveal deformations and topological details at ultrahigh sensitivity (a few tens of nanometers) for particular details such as point-like objects and interfacial structures, allowing for the investigation of a range of processes. However, while DH is able to provide high precision data, the height measurement range is limited by the probe wavelength. Therefore a 'synthetic' wavelength created from the superposition of two or more individual wavelengths is often required in order to increase the measurement range to a suitable value dependent upon the object dimensions. </p><p> The use of multiple wavelengths attached to one system thus allows for surface height measurements over a relatively long range. In addition as the complex wave-front of each wavelength can be captured simultaneously in one digital image, real-time performance is achievable. In this thesis a number of materials processes were investigated at differing temperatures. The structural changes associated with the martensite to austenite phase transformation were measured using dual-wavelength digital holography during thermal cycling of nickel-aluminum-platinum (NiAlPt) and single-crystal Fe-15Cr-15Ni alloys. Real-time in-situ measurements reveal the formation of striations within the NiPtAl alloy at ∼70°C, and the FeCrNi alloy at ∼520°C. The results demonstrate that digital holography is an effective technique for acquiring non-contact, high precision information of the 3D surface evolution of alloys at high temperatures.</p>
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Averett, Shawn C. "Advancements in the Understanding of Nonlinear Optics and Their Use in Material Analysis." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6507.
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Adhesion, heterogeneous catalysis, electrochemistry, and many other important processes and properties are driven by interactions at surfaces and interfaces. Vibrational sum frequency generation spectroscopy (VSFG) is an increasingly popular analytical technique because it can provide information about the nature and physical orientation of functional groups at these surfaces and interfaces. Analysis of VSFG data can be complicated by the presence of SFG signal that is not associated with a resonant vibration. This nonresonant sum frequency generation (NR-SFG) signal can interfere with the resonant signal and influence the detected spectrum. Methods have been developed to remove NR-SFG signal; however, these methods tend to be complicated and expensive. In fact many SFG practitioners do not have the ability to remove NR-SFG signal components, and systems designed to remove NR-SFG signal contributions may not be able to do so for some materials. We have worked to help develop a better understanding of NR-SFG. As part of this work, a better understanding of the temporal and phase behavior of NR-SFG signal has been developed, based on the behavior of NR-SFG signal from Si(111) wafers. This work calls into question some assumptions underlying nonresonant suppression methods based on time-domain detection. A new method for nondestructively testing (NDT) materials has been developed that uses nonresonant second harmonic generation, the degenerate form of SFG. This new NDT technology has the potential to detect several forms of material damage, such as aluminum sensitization, and plastic deformation of materials, which are largely invisible to current NDT technologies. Methods for extracting functional group orientation from VSFG data that contains NR-SFG contributions are also demonstrated and used to investigate how the surface of high density polyethylene changes in response to mechanical deformation. This work shows that the inability to remove NR-SFG contributions from VSFG spectra does not mean that these instruments cannot be used to make important discoveries. It simply means that NR-SFG contributions must be properly understood and accounted for during experimental design, and kept in mind during the analysis of VSFG spectra.
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Khan, Mughees Mahmood. "Fabrication and testing of nano-optical structures for advanced photonics and quantum information processing applications." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1165.
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McCall, Matthew Christopher. "Looking at the Surface of the Mind: Descartes on Visual Sensory Perception." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1503315104748657.
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Hessenius, Chris. "Novel Cavities and Functionality in High-Power High-Brightness Semiconductor Vertical External Cavity Surface Emitting Lasers." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301667.
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Ever since the first laser demonstration in 1960, applications for laser systems have increased to include diverse fields such as: national defense, biology and medicine, entertainment, imaging, and communications. In order to serve the growing demand, a wide range of laser types including solid-state, semiconductor, gas, and dye lasers have been developed. For most applications it is critical to have lasers with both high optical power and excellent beam quality. This has traditionally been difficult to simultaneously achieve in semiconductor lasers. In the mid 1990's, the advent of an optically pumped semiconductor vertical-external-cavity surface-emitting laser (VECSEL) led to the demonstration of high (multi-watt) output power with near diffraction limited (TEM00) beam quality. Since that time VECSELs covering large wavelength regions have been developed. It is the objective of this dissertation to investigate and explore novel cavity designs which can lead to increased functionality in high power, high brightness VECSELs. Optically pumped VECSELs have previously demonstrated their potential for high power, high brightness operation. In addition, the "open" cavity design of this type of laser makes intracavity nonlinear frequency conversion, linewidth narrowing, and spectral tuning very efficient. By altering the external cavity design it is possible to add additional functionality to this already flexible design. In this dissertation, the history, theory, design, and fabrication are first presented as VECSEL performance relies heavily on the design and fabrication of the chip. Basic cavities such as the linear cavity and v-shaped cavity will be discussed, including the role they play in wavelength tuning, transverse mode profile, and mode stability. The development of a VECSEL for use as a sodium guide star laser is presented including the theory and simulation of intracavity frequency generation in a modified v-cavity. The results show agreement with theory and the measurement of the sodium D1 and D2 lines are demonstrated. A discussion of gain coupled VECSELs in which a single pump area accommodates two laser cavities is demonstrated and a description of mode competition and the importance of spontaneous emission in determining the lasing condition is discussed. Finally the T-cavity configuration is presented. This configuration allows for the spatial overlap of two VECSEL cavities operating with orthogonal polarizations. Independent tuning of each cavity is presented as well as the quality of the beam overlap and demonstration of Type II intracavity sum frequency generation. Future applications to this configuration are discussed in the generation of high power, high brightness lasers operating from the UV to far-infrared and even terahertz regimes.
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Karna, Sanjay K. "Enhancement of Light Emission from Metal Nanoparticles Embedded Graphene Oxide." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc849637/.
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A fully oxidized state of graphene behaves as a pure insulating while a pristine graphene behaves as a pure conducting. The in-between oxide state in graphene which is the controlled state of oxide behaves as a semiconducting. This is the key condition for tuning optical band gap for the better light emitting property. The controlling method of oxide in graphene structure is known as reduction which is the mixed state of sp2 and sp3 hybrid state in graphene structure. sp2 hybridized domains correspond to pure carbon-carbon bond i.e. pristine graphene while sp3 hybridized domains correspond to the oxide bond with carbon i.e. defect in graphene structure. This is the uniqueness of the graphene-base material. Graphene is a gapless material i.e. having no bandgap energy and this property prevents it from switching device applications and also from the optoelectronic devices applications. The main challenge for this material is to tune as a semiconducting which can open the optical characteristics and emit light of desired color. There may be several possibilities for the modification of graphene-base material that can tune a band gap. One way is to find semiconducting property by doping the defects into pristine graphene structure. Other way is oxides functional groups in graphene structure behaves as defects. The physical properties of graphene depend on the amount of oxides present in graphene structure. So if there are more oxides in graphene structure then this material behaves as a insulating. By any means if it can be reduced then oxides amount to achieve specific proportion of sp2 and sp3 that can emit light of desired color. Further, after achieving light emission from graphene base material, there is more possibility for the study of non-linear optical property. In this work, plasmonic effect in graphene oxide has been focused. Mainly there are two kinds of plasmon effects have been studied, one is long range (surface) and short range (localized) plasmon. For long range plasmon gold thin film was deposited on partially reduced graphene oxide and for short range plasmon silver nanoparticles have used. Results show that there are 10-fold enhancement in light emission from partial graphene oxide coated with gold thin film while 4-fold enhancement from reduced graphene oxide solution with silver nanoparticles. Chemical method and photocatalytic method have been employed for the reduction of graphene oxide for the study of surface plasmon and localized plasmon. For the characterization UV-Vis spectrometer for absorption, spectrofluorophotometer for fluorescent emission, Raman spectrometer for material characterization, photoluminescence and time resolved photoluminescence have been utilized. Silver and gold nanoparticles are spherical of average size of 80 nm and 40 nm have been used as plasmons.
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Wang, Lirong. "DESIGN, MODELING AND TESTING OF OPTICAL SURFACES IN ILLUMINATION OPTICS." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195097.
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This dissertation investigates design, modeling and testing methods of optical surfaces in illumination optics.The main focus of this dissertation is to investigate the faceted non-imaging specular light reflector that is often used to generate a uniform, incoherent illuminance distribution. General design methodologies of faceted light reflectors are overviewed. Several design examples of faceted light reflectors including a novel LED flashlight, a novel microscope illuminator and a 20-m segmented paraboloidal solar collector are discussed and analyzed.An accurate source model is important for illumination system design. In this dissertation, an analytic short-arc source modeling method is developed and integrated in the illumination design software ZEMAX.In addition to the design and modeling work, this dissertation explores a flexible, low-cost and robust Software Configurable Optical Test System (SCOTS) for testing specular free-form surfaces that are often used in illumination systems. The application of this testing system in measuring a 3-m segmented paraboloidal solar reflector is investigated. Preliminary SCOTS test results for an F/0.2 concave automotive headlight reflector are introduced. In addition to testing the surfaces of illumination optics using SCOTS, the applications of SCOTS in the measurement of large, high precision optics are also explored and briefly discussed.
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Karna, Sanjay K. "Enhancement of Light Emission from Metal Nanoparticles Embedded Graphene Oxide." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849637/.
Full textAbstract:
A fully oxidized state of graphene behaves as a pure insulating while a pristine graphene behaves as a pure conducting. The in-between oxide state in graphene which is the controlled state of oxide behaves as a semiconducting. This is the key condition for tuning optical band gap for the better light emitting property. The controlling method of oxide in graphene structure is known as reduction which is the mixed state of sp2 and sp3 hybrid state in graphene structure. sp2 hybridized domains correspond to pure carbon-carbon bond i.e. pristine graphene while sp3 hybridized domains correspond to the oxide bond with carbon i.e. defect in graphene structure. This is the uniqueness of the graphene-base material. Graphene is a gapless material i.e. having no bandgap energy and this property prevents it from switching device applications and also from the optoelectronic devices applications. The main challenge for this material is to tune as a semiconducting which can open the optical characteristics and emit light of desired color. There may be several possibilities for the modification of graphene-base material that can tune a band gap. One way is to find semiconducting property by doping the defects into pristine graphene structure. Other way is oxides functional groups in graphene structure behaves as defects. The physical properties of graphene depend on the amount of oxides present in graphene structure. So if there are more oxides in graphene structure then this material behaves as a insulating. By any means if it can be reduced then oxides amount to achieve specific proportion of sp2 and sp3 that can emit light of desired color. Further, after achieving light emission from graphene base material, there is more possibility for the study of non-linear optical property. In this work, plasmonic effect in graphene oxide has been focused. Mainly there are two kinds of plasmon effects have been studied, one is long range (surface) and short range (localized) plasmon. For long range plasmon gold thin film was deposited on partially reduced graphene oxide and for short range plasmon silver nanoparticles have used. Results show that there are 10-fold enhancement in light emission from partial graphene oxide coated with gold thin film while 4-fold enhancement from reduced graphene oxide solution with silver nanoparticles. Chemical method and photocatalytic method have been employed for the reduction of graphene oxide for the study of surface plasmon and localized plasmon. For the characterization UV-Vis spectrometer for absorption, spectrofluorophotometer for fluorescent emission, Raman spectrometer for material characterization, photoluminescence and time resolved photoluminescence have been utilized. Silver and gold nanoparticles are spherical of average size of 80 nm and 40 nm have been used as plasmons.
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Olitzky, Joshua D. "Time and Frequency Resolved Pump Probe Spectroscopy and Growth of Near Surface Quantum Confined Semiconductors Coupled to Metallic Nanostructures." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/595980.
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Metallic nano-structures provide for new and exciting domains to investigate light-matter interactions. The coupling of these metallic nano-structures to semiconductor emitters allows for the observation of cavity QED effects including Purcell enhancement and Vacuum Rabi splitting. The focus of this dissertation will be to present an introduction and background to semiconductor optics, and metallic metamaterial systems. This will be followed by the presentation of the spectroscopy systems designed and constructed during my tenure as graduate student and the experimental data obtained with these systems. Some of the results have been published, while some of the presented material is still actively being pursued for publication. More specifically, the dissertation will cover the research at hand, experimental techniques, and results.
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Barrios, Carlos A. "Modified Scanning Probes for the Analysis of Polymer Surfaces." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1249315424.
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Middendorf, John Raymond. "Novel Devices and Components for THz Systems." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1400252710.
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Hong, Stanley Seokjong 1977. "Surface acoustic wave optical modulation." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86715.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.<br>Includes bibliographical references (leaves 50-54).<br>by Stanley Seokjong Hong.<br>M.Eng.
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Huang, Run. "High Precision Optical Surface Metrology using Deflectometry." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/581252.
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Software Configurable Optical Test System (SCOTS) developed at University of Arizona is a highly efficient optical metrology technique based on the principle of deflectometry, which can achieve comparable accuracy with interferometry but with low-cost hardware. In a SCOTS test, an LCD display is used to generate structured light pattern to illuminate the test optics and the reflected light is captured by a digital camera. The surface slope of test optics is determined by triangulation of the display pixels, test optics, and the camera. The surface shape is obtained by the integration of the slopes. Comparing to interferometry, which has long served as an accurate non-contact optical metrology technology, SCOTS overcomes the limitation of dynamic range and sensitivity to environment. It is able to achieve high dynamic range slope measurement without requiring null optics. In this dissertation, the sensitivity and performance of the test system have been analyzed comprehensively. Sophisticated calibrations of system components have been investigated and implemented in different metrology projects to push this technology to a higher accuracy including low-order terms. A compact on-axis SCOTS system lowered the testing geometry sensitivity in the metrology of 1-meter highly aspheric secondary mirror of Large Binocular Telescope. Sub-nm accuracy was achieved in testing a high precision elliptical X-ray mirror by using reference calibration. A well-calibrated SCOTS was successfully constructed and is, at the time of writing this dissertation, being used to provide surface metrology feedback for the fabrication of the primary mirror of Daniel K. Inouye Solar Telescope which is a 4-meter off-axis parabola with more than 8 mm aspherical departure.
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Hall, Heidi Leising. "Purkinje images for optical assessment of lenticular surfaces." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/289763.
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The optical properties of Fresnel reflections from the human ocular surfaces, called Purkinje reflections, are examined. Extensive modeling of the behavior of the reflection of sources from the front of the cornea and the front of the crystalline lens with real rays in lens design software is presented. The modeling looks at the effects of various conic constant values on the ocular surfaces and rotation of the eye in particular. First and third Purkinje images were collected from 14 subjects for varying fixation positions to compare with modeling. The results showed a decrease in third Purkinje image height as the eye rotated from gazing at a point near the light sources to a point near the optical axis of the imaging camera. This matched the predictions from modeling and indicates that fixation position is an important factor in the accuracy and repeatability of comparison phakometry results. Schematic eye models were set up for each subject and the anterior lens radius of curvature and conic constant were optimized to match the collected Purkinje image height data. The mean conic constant estimate from optimization was -3.82 with a standard deviation of 1.51. The schematic eye models did not include crystalline lens tilt or individual corneal conic constant values, each of which is estimated to contribute an uncertainty of ± 0.5 in the anterior lens conic constant value. This is the first use of Purkinje images to assess anterior lens conic constant values.
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Chang, Wai-Kit. "Porous silicon surface passivation and optical properties." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41426.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996.<br>"June 1996."<br>Includes bibliographical references (leaves 84-85).<br>by Wai-Kit Chang.<br>S.M.
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Wang, Haining. "Novel optical properties of metal nanostructures based on surface plasmons." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5720.
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Surface plasmons have been attracted extensive interests in recent decades due to the novel properties in nanometer sized dimensions. My work focused on the novel optical properties of metal nanostructures based on surface plasmons using theoretical simulation methods. In the first part, we investigated metal nanofilms and nanorods and demonstrated that extremely low scattering efficiency, high absorption efficiency and propagation with long distance could be obtained by different metal nanostructures. With a perforated silver film, we demonstrated that an extremely low scattering cross section with an efficiency of less than 1% can be achieved at tunable wavelengths with tunable widths. The resonance wavelength, width, and intensity are influenced by the shape, size and arrangement pattern of the holes, as well as the distance separating the holes along the polarization direction. The extremely low scattering could be used to obtain high absorption efficiency of a two-layer silver nanofilm. Using the discrete dipole approximation method, we achieved enhanced absorption efficiencies, which are close to 100%, at tunable wavelengths in a two-layer silver thin film. The film is composed of a 100 nm thick perforated layer facing the incident light and a 100 nm thick solid layer. Resonance wavelengths are determined by the distances between perforated holes in the first layer as well as the separation between two layers. The resonance wavelengths shift to red with increasing separation distance between two layers or the periodic distance of the hole arrays. Geometries of conical frustum shaped holes in the first layer are critical for the improved absorption efficiencies. When the hole bottom diameter equals the periodic distance and the upper diameter is about one-third of the bottom diameter, close to unit absorption efficiency can be obtained. We examined the electromagnetic wave propagation along a hollow silver nanorod with subwavelength dimensions. The calculations show that light may propagate along the hollow nanorod with growing intensities. The influences of the shape, dimension, and length of the rod on the resonance wavelength and the enhanced local electric field, |E|2, along the rod were investigated. In the second part, a generalized electrodynamics model is proposed to describe the enhancement and quenching of fluorescence signal of a dye molecule placed near a metal nanoparticle (NP). Both the size of the Au NPs and quantum yield of the dye molecule are crucial in determining the emission intensity of the molecule. Changing the size of the metal NP will alter the ratio of the scattering and absorption efficiencies of the metal NP and consequently result in different enhancement or quenching effect to the dye molecule. A dye molecule with a reduced quantum yield indicates that the non-radiative channel is dominant in the decay of the excited dye molecules and the amplification of the radiative decay rate will be easier. In general, the emission intensity will be quenched when the size of metal NP is small and the quantum yield of dye molecule is about unity. A significant enhancement factor will be obtained when the quantum yield of the molecule is small and the particle size is large. When the quantum yield of the dye molecule is less than 10-5, the model is simplified to the surface enhanced Raman scattering equation.<br>Ph.D.<br>Doctorate<br>Chemistry<br>Sciences<br>Chemistry
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Gunnarsson, Sarius Niklas. "Surface Technology for Optical and Electrical Connectors." Doctoral thesis, Linköpings universitet, Tunnfilmsfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-63626.
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This thesis treats surface engineering with the purpose of improved quality of optical and electricalconnectors with a focus on electroplated and magnetron sputtered materials. In electroforming of tools formanufacturing optical connectors, the influence of ultrasonic agitation on intrinsic stresses and fillingproperties of electroplated Ni has been studied. It is established that the ultrasonic agitation at the substratesurface during deposition impacts the intrinsic stresses making it possible to increase deposition rate viacurrent density, with stress-free or low-stress levels in the Ni layers. Reduced variations of the intrinsicstress over the surface with the current density is a further important result. Filling of grooves byelectroplating of Ni using ultrasonic agitation is demonstrated. This is due to increasing mass transport ofspecies into the grooves compared to conventional pumped agitation. The enhanced filling propertiesmakes it possible to electroplate Ni in the bottom of high-aspect-ratio grooves. In order to industriallyimplement new nanocomposite coatings on electronic connectors, studies have been performed regardingthe thermal diffusion barrier properties against Cu for Ti-Si-C and Ti-Si-C-Ag nanocomposites, depositeddirectly onto Cu substrates or with sputtered Ni, Ti or electroplated Ni as an intermediate coating. Theapplication of an electroplated Ni diffusion barrier coating, hinders Cu from reaching the surface of thenanocomposites. Also, Ti-Si-C-Ag nanocomposite deposited on magnetron sputtered Ni or Ti on Cusubstrates hinder Cu from diffusing to the surface after annealing. The contact resistance of Ag-Pdtopcoated Ti-Si-C-Ag-Pd and Ti-Si-C-Ag nanocomposite coatings in contact with hard gold is shown tocompete with hard gold in contact with itself, as electrical contact coatings at contact forces around 5 N.Ag-Pd topcoated Ti-Si-C-Ag-Pd in contact with hard gold is shown to have approximately the same contactresistance as hard gold in contact with hard gold at contact forces around 0.1 N, which here is in the 10 mΩrange, while Ti-Si-C-Ag nanocomposite coatings in contact with hard gold has a contact resistance that isup to 10 times higher. The overall contribution of this thesis can be summarised as a deeper knowledge andunderstanding of techniques and coatings, that help reduce cost and increase reliability of electronics.
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Vernold, Cynthia Louise 1965. "A non-paraxial scattering theory for specifying and analyzing fabrication errors in optical surfaces." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/288930.
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There are three fundamental mechanisms in optical systems that contribute to image degradation: aperture diffraction, geometrical aberrations caused by residual design errors, and scattering effects due to optical fabrication errors. Diffraction effects, as well as optical design errors and fabrication errors that are laterally large in nature (generally referred to as figure errors), are accurately modeled using conventional ray trace analysis codes. However, these ray-trace codes fall short of providing a complete picture of image degradation; they routinely ignore fabrication-induced errors with spatial periods that are too small to be considered figure errors. These errors are typically referred to as mid-spatial-frequency (ripple) and high-spatial-frequency (micro-roughness) surface errors. These overlooked, but relevant, fabrication-induced errors affect image quality in different ways. Mid-spatial-frequency errors produce small-angle scatter that tends to widen the diffraction-limited image core (i.e. for a system with a circular exit pupil, this is the central lobe of the Airy pattern), and in doing so, reduces the optical resolution of a system. High-spatial-frequency errors tend to scatter energy out of the image core into a wide-angle halo, causing a reduction in image contrast. Micro-roughness and ripple are inherent aspects of the less conventional, small-tool-based optical fabrication approaches. It is especially important in these cases to specify these errors accurately during the design phase of a project, and deterministically monitor and control them during the fabrication phase of a project. Surprisingly, most current approaches to this issue employ some guessing and "gut feel" based on past experience, because accurate theories and analysis tools are not readily available. This dissertation takes the first step towards solving this problem by describing a Fourier-based approach for classifying and quantifying surface errors that can be present in a fabricated optical surface. Classical scalar diffraction theories and scatter theories are reviewed and their strengths, weaknesses and misuses are discussed. Then, this dissertation focuses on the development of more accurate surface scatter theories. Modified surface scatter theories are presented that do not exhibit the small angle or smooth surface limitations that are inherent in other theories. These improvements are especially critical for surfaces considered rough with respect to the test wavelength or for systems where large scatter and/or incidence angles are present. Predictions from these modified theories are then compared to and shown to be in excellent agreement with experimental measurements.
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Sullivan, John Joseph. "Non-Null Interferometer for Testing of Aspheric Surfaces." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/594367.
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The use of aspheric surfaces in optical designs can allow for improved performance with fewer optical elements. Their use has become common place due to advancements in optical manufacturing technologies. Standard interferometric testing of aspheric surfaces makes use of part specific null optics in order to match the test wavefront to the aspheric surface under test. Non-null interferometric testing offers the possibility to test a range of aspheric surfaces with a single interferometer design without the need for part specific null optics. However, non-null tests can generate interferograms with very high fringe frequencies that must be resolved and unwrapped, wavefronts with large slopes that must be imaged without vignetting, and induced aberrations which must be separated from the surface errors of the part. The main goal of this project was the construction of a non-null interferometer capable of testing the aspheric tooling used in the manufacturing of soft contact lenses. Sub-Nyquist interferometry was used to allow for large wavefront departures which generate high fringe frequency interferograms to be both captured and unwrapped. The sparse array sensor at the heart of the Sub-Nyquist technique sets limits on both the range of the parts to be tested and the design of the interferometer. Characterization of the interferometer was achieved through the reverse optimization and reverse ray tracing of a model of the interferometer and was aided by multiple measurements of the test part at shifted positions. The system was found to be capable of measuring parts with aspheric departure of over 60λ from the best fit sphere, which with introduced part shifts, generated over 300λ of OPD at the detector. The OPD introduced by the parts was measured to an accuracy of at least 0.76λ peak to valley and 0.12λ rms.
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Morris, Stephen J. "The investigation of solid surfaces using optical probes : reflectance anisotropy spectroscopy." Thesis, Cardiff University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294151.
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Johnson, James Ballard. "Characterization of Optical Surface Grinding using Bound and Loose Abrasives." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/203478.
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Large optical systems fabrication is a demanding task due to the tight requirements and big scales. To make mirrors up to 8.4m in diameter necessitates technological development in materials, tooling, and metrology. These advancements are designed to not only produce optics on a near-unheard of scale, but to improve fabrication methods with each piece.For an optical surface to be properly polished, the amount of material removed during polishing must be greater than the volume of damage left behind by the grinding process. Mixed-mode grinding, which combines bound abrasives with a compliant binder material, is a valuable tool at this stage as it creates less damage while maintaining a fast and uniform cutting rate than traditional loose abrasive grinding.These materials are challenging for large optical surfaces due to the honeycomb structures used to lightweight the mirrors. Development is done to adapt the abrasive to handle the very low pressures and speeds required to avoid imprinting structure on the optical surface.We take a comprehensive approach in measuring mixed-mode behavior using 3M Trizact™. Prior works on bound abrasives have focused on specific properties: removal rates, subsurface damage, etc. None have yet to look at the entire scope of the material and its benefits. These properties will be analyzed along with different behaviors regarding surface scattering, Twyman effect bending moments, glazing, manufacturing expenses, and failure mechanisms. This comprehensive understanding of the abrasive allows manufacturers to create better grinding schedules and reduce overall expenses in fabrication.Trizact shows up to a three times faster removal rate while producing 30\% less subsurface damage than loose abrasives of similar size. Additionally, the surface has scatters less light which can be adapted through changes in processing to create a specular reflection for optical surface metrology.Based on our findings, this type of abrasive integrates into current optical fabrication processes as a pre-polishing material. Here, the transition to these abrasives becomes cost effective by rapidly eliminating damage created during the generating of the surface and reducing the amount of polishing required.
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Timus, Oguzhan. "Free space optic communication for Navy surface ship platforms." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FTimus.pdf.
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Maldonado, Alejandro V. "High Resolution Optical Surface Metrology with the Slope Measuring Portable Optical Test System." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/337294.
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New optical designs strive to achieve extreme performance, and continually increase the complexity of prescribed optical shapes, which often require wide dynamic range and high resolution. SCOTS, or the Software Configurable Optical Test System, can measure a wide range of optical surfaces with high sensitivity using surface slope. This dissertation introduces a high resolution version of SCOTS called SPOTS, or the Slope measuring Portable Optical Test System. SPOTS improves the metrology of surface features on the order of sub-millimeter to decimeter spatial scales and nanometer to micrometer level height scales. Currently there is no optical surface metrology instrument with the same utility. SCOTS uses a computer controlled display (such as an LCD monitor) and camera to measure surface slopes over the entire surface of a mirror. SPOTS differs in that an additional lens is placed near the surface under test. A small prototype system is discussed in general, providing the support for the design of future SPOTS devices. Then the SCOTS instrument transfer function is addressed, which defines the way the system filters surface heights. Lastly, the calibration and performance of larger SPOTS device is analyzed with example measurements of the 8.4-m diameter aspheric Large Synoptic Survey Telescope's (LSST) primary mirror. In general optical systems have a transfer function, which filters data. In the case of optical imaging systems the instrument transfer function (ITF) follows the modulation transfer function (MTF), which causes a reduction of contrast as a function of increasing spatial frequency due to diffraction. In SCOTS, ITF is shown to decrease the measured height of surface features as their spatial frequency increases, and thus the SCOTS and SPOTS ITF is proportional to their camera system's MTF. Theory and simulations are supported by a SCOTS measurement of a test piece with a set of lithographically written sinusoidal surface topographies. In addition, an example of a simple inverse filtering technique is provided. The success of a small SPOTS proof of concept instrument paved the way for a new larger prototype system, which is intended to measure subaperture regions on large optical mirrors. On large optics, the prototype SPOTS is light weight and it rests on the surface being tested. One advantage of this SPOTS is stability over time in maintaining its calibration. Thus the optician can simply place SPOTS on the mirror, perform a simple alignment, collect measurement data, then pick the system up and repeat at a new location. The entire process takes approximately 5 to 10 minutes, of which 3 minutes is spent collecting data. SPOTS' simplicity of design, light weight, robustness, wide dynamic range, and high sensitivity make it a useful tool for optical shop use during the fabrication and testing process of large and small optics.
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Barman, Sarah Ann. "Measurement of profiled surfaces using polarising optical interferometry." Thesis, King's College London (University of London), 1996. http://eprints.kingston.ac.uk/8943/.
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Abanulo, Jude C. "Integrated optical surface plasmon resonance for electrochemically addressed layers." Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/42383/.
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This thesis reports on the development of the first integrated optical surface plasmon resonance sensor that combines an optical and electrochemical interrogating technique in sensing electrochemically addressed layers over a gold film. This device brings together the advantages of the analytical technique of surface plasmon resonance and of cyclic voltammetry on a single chip that exhibits portability, miniaturisation capability and compatibility with optical fibre. The integrated optical chip allows the potential introduction of a large number of sensing pads on a single chip thus allowing the acquisition of precise information about a test compound while simultaneously monitoring different test compounds in the same sensing area. The integrated optical surface plasmon resonance (IOSPR) devices fabricated were applied in the study of the oxidation of gold and the removal of the oxide layer in real time. The optical response to the oxidation process was similar to those reported in the literature using ellipsometry and or reflectance spectroscopy. Here the IOSPR device performed better, giving transmittance changes of 60 % in response to the formation of an oxide film. The introduction of a monolayer of copper onto the gold surface of the device via the underpotential deposition process was monitored for the first time using the surface plasmon technique. Here the response and performance of the device was compared with other reported studies in the literature, which combined an optical and electrochemical technique for similar analysis. The IOSPR device performed better with 10 % change in transmittance in comparison to a change of 1 % reported for reflectance measurements. Comparisons were also made with those predicted by a numerical waveguide model. The feasibility of potential applications in biological analysis was demonstrated by applying the device in analysing the adsorption and desorption of thiol and phospholipid layers onto the sensing surface of the device.
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Heideman, Kyle C. "Surface Metrology of Contact Lenses in Saline Solution." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/337379.
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Measurement of the quality and performance of soft contact lenses is not new and is continually evolving as manufacturing methods develop and more complicated contact lenses become available. Qualification of soft contact lenses has not been a simple task since they are fundamentally difficult to measure. The shape of the lens is extremely sensitive to how the lens is supported and the material properties can change quickly with time. These lenses have been measured in several different ways, the most successful being non-contact optical methods that measure the lens while it is immersed in saline solution. All of these tests measure the lens in transmission and do not directly measure the surface structure of the lens. The reason for this is that the Fresnel reflectivity of the surface of a contact lens in saline solution is about 0.07%. Surface measurements have been performed in air, but not in saline. The lens needs to be measured in solution so that it can maintain its true shape. An interferometer is proposed, constructed, verified, and demonstrated to measure the aspheric low reflectivity surfaces of a contact lens while they are immersed in saline solution. The problem is extremely difficult and requires delicate balance between stray light mitigation, color correction, and polarization management. The resulting system implements reverse raytracing algorithms to correct for retrace errors so that highly aspheric, toric, and distorted contact lens surfaces can be measured. The interferometer is capable of measuring both surfaces from the same side of the contact lens as well as the lens thickness. These measurements along with the index of refraction of the lens material are enough build a complete 3D model of the lens. A simulated transmission test of the 3D model has been shown to match the real transmission test of the same lens to within 32nm RMS or 1/20th of a wave at the test wavelength.
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Mccafferty, Sean. "Analysis and application of opto-mechanics to the etiology of sub-optimal outcomes in laser corrective eye surgery and design methodology of deformable surface accommodating intraocular lenses." Thesis, The University of Arizona, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1589573.
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<p> <b>Overview:</b> Optical concepts as they relate to the ophthalmologic correction of vision in corneal laser vision correction and intraocular lens design was examined. </p><p> <b>Purpose:</b> The interaction between the excimer laser and residual corneal tissue in laser vision correction produces unwanted side effects. Understanding the origin of these artifacts can lead to better procedures. Furthermore, accommodating intraocular lenses offer a potential for eliminating presbyopia. Understanding the properties of a new accommodating intraocular lens incorporating a deformable interface may lead to advances in cataract surgery. </p><p> <b>Introduction:</b> Corneal surface irregularities following laser refractive procedures are commonly seen. They regularly result in a patient’s decreased best corrected visual acuity and decreased contrast sensitivity. These changes are only seen in biologic tissue and the etiology has been elusive. A thermal response has been theorized and was investigated in this research. In addition, intraocular lenses using a mechanically deforming interface to change their power in order to duplicate natural accommodation have been developed. The deforming interface(s) induce optical aberrations due to irregular deformations. Design efforts have centered on minimizing these deformations. Both of the ophthalmic applications have been analyzed using finite element analysis (FEA) to understand their inherent optical properties. </p><p> <b>Methods:</b> FEA modeling of thermal theory has been applied to verify that excimer laser induced collagen contraction creates corneal surface irregularities and central islands. A mathematical model which indicates the viability of the theory was developed. The modeling results were compared to post ablation changes in eyes utilizing an excimer (ArF 193 nm), as well as non-ablative thermal heating in eyes with a CO<sub>2</sub> laser. </p><p> Addition modeling was performed on an Intraocular lens prototype measuring of actuation force, lens power, interface contour, optical transfer function, and visual Strehl ratio. Prototype verified mathematical models were utilized to optimize optical and mechanical design parameters to maximize the image quality and minimize the required force. </p><p> Results: The predictive model shows significant irregular central buckling formation and irregular folding. The amount of collagen contraction necessary to cause significant surface changes is very small (0.3%). Uniform scanning excimer laser ablation to corneal stroma produces a significant central steepening and peripheral flattening in the central 3mm diameter. Isolated thermal load from uniform CO<sub>2</sub> laser irradiation without ablation also produces central corneal steepening and paracentral flattening in the central 3mm diameter. </p><p> The iterative mathematical modeling based upon the intraocular lens prototype yielded maximized optical and mechanical performance through varied input mechanical and optical parameters to produce a maximized visual Strehl ratio and a minimized force requirement. </p><p> <b>Conclusions:</b> The thermal load created by laser irradiation creates a characteristic spectrum of morphologic changes on the porcine corneal stromal surface which correlates to the temperature rise and is not seen inorganic, isotropic material. The highly similar surface changes seen with both lasers are likely indicative of temperature induced transverse collagen fibril contraction and stress re-distribution. Refractive procedures which produce significant thermal load should be cognizant of these morphological changes. </p><p> The optimized intraocular lens operates within the physiologic constraints of the human eye including the force available for full accommodative amplitude using the eye’s natural focusing feedback, while maintaining image quality in the space available. Optimized optical and mechanical performance parameters were delineated as those which minimize both asphericity and actuation pressure. The methodology combines a multidisciplinary basic science approach from biomechanics, optical science, and ophthalmology to optimize an intraocular lens design suitable for preliminary trials.</p>
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Efford, Nicholas David. "Characterisation of the optical properties and surface roughnesses of atmosphereless planetary regoliths through photometric analysis." Thesis, Lancaster University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306581.
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Hwang, Gyuweon. "Surface trap passivation and characterization of lead sulfide quantum dots for optical and electrical applications." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98741.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 113-119).<br>Quantum dots (QDs) are semiconductor nanocrystals having a size comparable to or smaller than its exciton Bohr radius. The small size of QDs leads to the quantum confinement effects in their electronic structures. Their unique optical properties, including a tunable emission from UV to IR, make QDs attractive in optoelectronic applications. However, further improvements in device performance are required to make them competitive. One well-known factor that presently limits the performance of QD thin film devices is sub-band-gap states, also referred to as trap states. For instance, trap states impair optical properties and device performance by providing alternative pathways for exciton quenching and carrier recombination. Chemical modification of QDs has been commonly used for passivating trap states and thereby improving QD devices. However, the influence of chemical modifications of ligands, QD surfaces, or synthetic routes on electrical properties of QD thin films is not sufficiently characterized. Suppressing the trap states in QD thin films is a key to improve the performance of QDbased optoelectronics. This requires fundamental understanding of trap state source, which is lacking in these materials. In this thesis, I pursue to find a systematic method to control density of trap states by exploring different characterization techniques to investigate trap states in QD thin films. These attempts provide insight to develop a rationale for fabricating better performing QD devices. This thesis focuses on the trap states in IR emitting lead sulfide (PbS) QD thin films, which have great potential for application in photovoltaics, light emitting diodes (LEDs), photodetectors, and bio-imaging. Previously, QD thin films are treated with different ligands to passivate trap states and thereby improve the device performance. Through my work, I pursued to unveil the electrical characteristics and chemical origin of trap states, and develop a strategy to suppress the trap states. First, I hypothesize that surface dangling bonds are a major source of trap states. An inorganic shell layer comprised of cadmium sulfide (CdS) is introduced to PbS QDs to passivate the surface states. Addition of CdS shell layers on PbS QDs yields an enhanced stability and quantum yield (QY), which indicates decreased trap-assisted exciton quenching. These PbS/CdS core/shell QDs have a potential for deep-tissue bio-imaging in shortwavelength IR windows of 1550-1900 nm. However, the shell layer acts as a transport barrier for carriers and results in a significant decrease in conductivity. This hinders the incorporation of the core/shell QDs in electrical applications. An improved reaction condition enables the synthesis of PbS/CdS QDs having a monolayer-thick CdS shell layer. These QDs exhibit QY and stability comparable to thick-shell PbS/CdS QDs. Incorporation of these thin-shell QDs improves external quantum efficiency of IR QD-LEDs by 80 times compared to PbS core-only QDs. In the second phase of my work, I explore capacitance-based measurement techniques for better understanding of the electrical properties of PbS QD thin films. For in-depth analysis, capacitance-based techniques are introduced, which give complementary information to current-based measurements that are widely used for the characterization of QD devices. Nyquist plots are used to determine the dielectric constant of QD films and impedance analyzing models to be used for further analysis. Mott-Schottky measurements are implemented to measure carrier concentration and mobility to compare PbS core-only and PbS/CdS core/shell QD thin films. Drive-level capacitance profiling is employed to characterize the density and energy level of trap states when QD films are oxidized. Lastly, I investigate the chemical origin of trap states and use this knowledge to suppress the trap states of PbS QD thin films. Photoluminescence spectroscopy and X-ray photoelectron spectroscopy show that standard ligand exchange procedures for device fabrication lead to the formation of sub-bandgap emission features and under-charged Pb atoms. Our experimental results are corroborated by density functional theory simulation, which shows that the presence of Pb atoms with a lower charge in QDs contributes to sub-bandgap states. The trap states generated after ligand exchange were significantly reduced by oxidation of under-charged Pb atoms using 1,4-benzoquinone. The density of trap states measured electrically with drive-level capacitance profiling shows that this reduces the electrical trap density by a factor of 40. In this thesis, I characterized trap states and showed that by suppressing the trap states we can modify the electrical properties of QD thin films, which influence the performance of QD devices directly. This work is a starting point to fully analyze the trap states in QD thin devices and thereby provides insight to design a rationale for fabricating better performing QD devices.<br>by Gyuweon Hwang.<br>Ph. D.
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Torrance, David. "Influence of the Local Dielectric Environment and its Spatial Symmetry on Metal Nanoparticle Surface Plasmon Resonances." Honors in the Major Thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1195.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.<br>Bachelors<br>Sciences<br>Physics
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Cocilovo, Byron. "Applications of Textured Surfaces for Light Harvesting." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/612813.
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Surface textures add another dimension to optical design. They can be used to redirect light, isolate spectral bands, and enhance optical fields. They effectively take up no space, so can be applied to any optical surface–from intermediary elements to substrates. Here I present three applications of textured surfaces for light harvesting. The first project places scattering textures inside a film that can be applied to windows to scatter infrared light towards solar cells at the edges. The collected energy is then used to power tinting films. The second project uses modular diffractive structures to increase the absorption in solar cells. Lastly, structured silver surfaces are used to enhance plasmonics fields and increase two-photon excitation fluorescence.
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Kumar, Prashant. "Design and development of an optical chip interferometer for high precision on-line surface measurement." Thesis, University of Huddersfield, 2015. http://eprints.hud.ac.uk/id/eprint/27007/.
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Advances in manufacturing and with the demand of achieving faster throughput at a lower cost in any industrial setting have put forward the need for embedded metrology. Embedded metrology is the provision of metrology on the manufacturing platform, enabling measurement without the removal of the workpiece. Providing closer integration of metrology upon the manufacturing platform will improve material processing and reliability of manufacture for high added value products in ultra-high-precision engineering. Currently, almost all available metrology instrumentation is either too bulky, slow, destructive in terms of damaging the surfaces with a contacting stylus or is carried out off-line. One technology that holds promise for improving the current state-of-the-art in the online measurement of surfaces is hybrid photonic integration. This technique provides for the integration of individual optoelectronic components onto silicon daughter boards which are then incorporated on a silica motherboard containing waveguides to produce a complete photonic circuit. This thesis presents first of its kind a novel chip interferometer sensor based on hybrid integration technology for online surface and dimensional metrology applications. The complete metrology sensor system is structured into two parts; hybrid photonic chip and optical probe. The hybrid photonic chip interferometer is based on a silica-on-silicon etched integrated-optic motherboard containing waveguide structures and evanescent couplers. Upon the motherboard, electro-optic components such as photodiodes and a semiconductor gain block are mounted and bonded to provide the required functionality. Optical probe is a separate entity attached to the integrated optic module which serves as optical stylus for surface scanning in two measurement modes a) A single-point for measuring distance and thus form/surface topography through movement of the device or workpiece, b) Profiling (lateral scanning where assessment of 2D surface parameters may be determined in a single shot. Wavelength scanning and phase shifting inteferometry implemented for the retrival of phase information eventually providing the surface height measurement. The signal analysis methodology for the two measurement modes is described as well as a theoretical and experimental appraisal of the metrology capabilities in terms of range and resolution. The incremetal development of various hybrid photonic modules such as wavelength encoder unit, signal detection unit etc. of the chip interferometer are presented. Initial measurement results from various componets of metrology sensor and the surface measurement results in two measurement modes validate the applicability of the described sensor system as a potential metrology tool for online surface measurement applications.
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Armand, Damien. "Application de la spectroscopie térahertz à la détection de substances sensibles." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00721831.
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Pour répondre aux questions que pose la faisabilité d'un dispositif de détection d'explosifsà l'aide de la technologie de spectroscopie térahertz, cette thèse a exploré troisaxes. Le premier a consisté à établir une base de données des signatures spectrales (indiceet absorption) d'une large gamme de matériaux d'intérêt pour ce type d'applications,à partir des données expérimentales que nous avons mesurées par spectroscopie dans ledomaine temporel. Nous avons identifié les matériaux montrant une signature spectralesignificative et nous avons aussi étudié l'effet des matériaux de dissimulation.Dans la seconde partie de ce travail, nous avons conçu et construit un banc de spectroscopieultra-large bande destiné à une meilleure identification spectrale des substances. Nousavons identifié les limites techniques de ce type de banc et donné les pistes pour atteindreles performances désirées.Ensuite, nous avons développé et validé un banc de spectroscopie en réflexion, de typegoniométrique, afin de détecter des signaux térahertz diffusés par des matériaux hétérogènes.Finalement, nous avons étudié les plasmons de surface dans le domaine térahertz, en vuede la détection de très faibles quantités de matière.
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Ghaedi, Leila. "AN AUTOMATED DENTAL CARIES DETECTION AND SCORING SYSTEM FOR OPTIC IMAGES OF TOOTH OCCLUSAL SURFACE." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3548.
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Dental caries are one of the most prevalent chronic diseases. Worldwide 60 to 90 percent of school children and nearly 100 percent of adults experienced dental caries. The management of dental caries demands detection of carious lesions at early stages. The research of designing diagnostic tools in caries has been at peak for the last decade. This research aims to design an automated system to detect and score dental caries according to the International Caries Detection and Assessment System (ICDAS) guidelines using the optical images of the occlusal tooth surface. There have been numerous works that address the problem of caries detection by using new imaging technologies or advanced measurements. However, no such study has been done to detect and score caries with the use of optical images of the tooth surface. The aim of this dissertation is to develop image processing and machine learning algorithms to address the problem of detection and scoring the caries by the use of optical image of the tooth surface.
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Yoshioka, Hiroki 1967. "Applications of transport theory in optical remote sensing of land surfaces." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284824.
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A particle/radiative transport theory widely used in nuclear engineering was applied to investigate photon transport in layers of land surfaces which consist of vegetation and soil for application to optical remote sensing. A numerical simulation code has been developed for three dimensional vegetation canopies to compute reflected radiation by the canopy-soil systems. The code solves a discretized form of the linear Boltzmann transport equation using an Adaptive Weighted Diamond-Differencing and source iteration method. Sample problems demonstrate variations of reflectance spectra of vegetation canopies as a function of soil brightness and leaf area index, and also indicate a pattern of spectral variations induced by the soil brightness changes. Special attention has been paid to the variation patterns of canopy reflectances, known as vegetation isolines. Mathematical expressions of vegetation isolines, called vegetation isoline equations, are derived in terms of canopy optical properties and two parameters that characterize soil optical properties called soil line parameters. Behavior of vegetation isolines is analyzed using the derived equations as a function of leaf area index and fractional area covered by green-vegetation. The analyses show certain trends of the behavior of vegetation isolines. The vegetation isoline equations are then applied to investigate the performance of two-band vegetation indices and to estimate the effects of the soil line parameters. It is concluded that the vegetation isoline equations are useful for investigating patterns of canopy reflectance variations and the effects of these patterns on vegetation indices.
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Su, Tianquan. "Asphercial Metrology for Non-Specular Surfaces with the Scanning Long-Wave Optical Test System." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/347221.
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Aspherical optics are increasingly used these days. The application of aspherical surfaces on large, astronomical telescope mirrors brings challenge to the fabrication. Since the surface radius of curvature varies across the surface, the grinding/polishing tool needs to change its shape when working on different parts of the surface, making surface error more easily embedded into the surface. Therefore, a tighter test-fab loop is needed to guide the fabrication process. To maximize the accuracy during the grinding of the surface and to minimize the working time in the polishing stage, a better metrology device that can measure rough surface is needed to guide the grinding process. Scanning long-wave optical test system (SLOTS) is designed to meet this demand by providing accurate, fast, large dynamic range, and high spatial resolution measurements on rough optical surfaces (surface rms roughness<1.7 µm).SLOTS is a slope measuring deflectometry system that works like a reversed wire test. It measures the reflection of the infrared light off the test surface, and calculates the local slope of the test surface. The surface sag/height is obtained through integration. During the test, a heated metal ribbon radiates long-wave infrared light that is reflected by the test surface. A thermal imaging camera records the reflected light. The ribbon is scanned in two orthogonal directions. From the variation of the irradiance recorded by the camera, slope maps of the test surface can be retrieved in the two orthogonal directions. SLOTS is a combination of tradition slope measurement and modern technology, processing advantages from both parts. It measures surface slope, so there is no need for null optics. It uses an uncooled thermal imaging camera that is made with high resolution and high sensitivity. The linear stage used to scan the hot ribbon has long travel, small resolution, and high accuracy. Both the camera and stage enable SLOTS a large dynamic range and high sensitivity. SLOTS has successfully guided the grinding process of the primary mirror of Daniel K. Inouye Solar Telescope. This mirror is a 4-meter diameter off-axis parabola (OAP). Its largest aspherical departure is 8 mm. SLOTS is able to measure it without any null optics. Under the guidance of SLOTS, the surface shape was controlled to be 1 µm rms within designed shape (with astigmatism removed) at 0.7 µm rms surface roughness (12 µm loose abrasive grits).
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Lemaster, Richard L. "Development of an Optical Profilometer and the Related Advanced Signal Processing Methods for Monitoring Surface Quality of Wood Machining Applications." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-09282004-152158/.
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The research described here provides the technology and theory to quantify surface quality for a variety of wood and wood-based products. This technology provides a means of monitoring trends in surface quality which can be used to discriminate between Agood@ products and Abad@ products (the methods described in this research are not intended to provide ?grading? of individual workpieces) as well as provide information to the machine operator as to the source of poor quality machined surfaces. The analysis can be done either on-line at industrial speeds or off-line as a periodic quality control tool. Although the surface quality can be quantifiably measured, the determination of the best feature from the surface profile (root mean square, peak amplitude, average wavelength, frequency content, Joint Time and Frequency Analysis (JTFA) and Wavelet Analysis results, etc.) for the quantification of surface Adefects@ is highly dependent on the application. This research consisted of three broad areas: (1) determination of an optimal hardware configuration for both laboratory and industrial surface scans of wood products, (2) determination of the optimal set of surface descriptors as well as the development of advanced signal processing techniques such as the wavelet transform to accurately describe the quality of a surface as well as provide information to the machine operator on the cause of the loss of surface quality, and (3) development of a software interface to distill the advanced signal processing techniques into a readily obtainable and readable format for the machine operator as well as provide assistance for process decisions.
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Lukowski, Michal Lukasz, and Michal Lukasz Lukowski. "Novel Cavities in Vertical External Cavity Surface Emitting Lasers for Emission In Broad Spectral Region by Means Of Nonlinear Frequency Conversion." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621770.
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Optically pumped semiconductor vertical external cavity surface emitting lasers (VECSEL) were first demonstrated in the mid 1990's. Due to the unique design properties of extended cavity lasers VECSELs have been able to provide tunable, high-output powers while maintaining excellent beam quality. These features offer a wide range of possible applications in areas such as medicine, spectroscopy, defense, imaging, communications and entertainment. Nowadays, newly developed VECSELs, cover the spectral regions from red (600 nm) to around 5 µm. By taking the advantage of the open cavity design, the emission can be further expanded to UV or THz regions by the means of intracavity nonlinear frequency generation. The objective of this dissertation is to investigate and extend the capabilities of high-power VECSELs by utilizing novel nonlinear conversion techniques. Optically pumped VECSELs based on GaAs semiconductor heterostructures have been demonstrated to provide exceptionally high output powers covering the 900 to 1200 nm spectral region with diffraction limited beam quality. The free space cavity design allows for access to the high intracavity circulating powers where high efficiency nonlinear frequency conversions and wavelength tuning can be obtained. As an introduction, this dissertation consists of a brief history of the development of VECSELs as well as wafer design, chip fabrication and resonator cavity design for optimal frequency conversion. Specifically, the different types of laser cavities such as: linear cavity, V-shaped cavity and patented T-shaped cavity are described, since their optimization is crucial for transverse mode quality, stability, tunability and efficient frequency conversion. All types of nonlinear conversions such as second harmonic, sum frequency and difference frequency generation are discussed in extensive detail. The theoretical simulation and the development of the high-power, tunable blue and green VECSEL by the means of type I second harmonic generation in a V- cavity is presented. Tens of watts of output power for both blue and green wavelengths prove the viability for VECSELs to replace the other types of lasers currently used for applications in laser light shows, for Ti:Sapphire pumping, and for medical applications such as laser skin resurfacing. The novel, recently patented, two-chip T-cavity configuration allowing for spatial overlap of two, separate VECSEL cavities is described in detail. This type of setup is further used to demonstrate type II sum frequency generation to green with multi-watt output, and the full potential of the T-cavity is utilized by achieving type II difference frequency generation to the mid-IR spectral region. The tunable output around 5.4 µm with over 10 mW power is showcased. In the same manner the first attempts to generate THz radiation are discussed. Finally, a slightly modified T-cavity VECSEL is used to reach the UV spectral regions thanks to type I fourth harmonic generation. Over 100 mW at around 265 nm is obtained in a setup which utilizes no stabilization techniques. The dissertation demonstrates the flexibility of the VECSEL in achieving broad spectral coverage and thus its potential for a wide range of applications.
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Jacquet, Joel. "Évolution des diodes lasers pour les télécommunications optiques : Lasers accordables, Lasers à émission par la surface, Lasers bas coûts." Habilitation à diriger des recherches, Université Montpellier II - Sciences et Techniques du Languedoc, 2004. http://tel.archives-ouvertes.fr/tel-00922621.
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Les travaux présentés ci-après reprennent mes activités depuis le début de ma thèse en 1986. Ils ont été entièrement réalisés dans le centre de recherche d'Alcatel à Marcoussis dans le but de concevoir, réaliser et tester des composants optoélectroniques à semi-conducteurs pour des applications en télécommunications optiques. Ces composants sont à base de Phosphure d'Indium (InP) et sont destinés à émettre ou détecter de la lumière à des longueurs d'ondes proches de 1300 ou 1550 nm suivant l'application. J'ai pu bénéficier de toute l'infrastructure nécessaire au développement et à l'aboutissement des projets couvrant aussi bien les moyens technologiques (épitaxie et structuration des matériaux) que les moyens de caractérisation jusqu'aux expérimentations système grâce à l'utilisation de plate-formes de test disponibles à Alcatel. Les résultats présentés ici sont par conséquent le fruit d'un travail d'équipe ; je m'attacherai en fin de chaque paragraphe à préciser ma contribution personnelle aux résultats.
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Zhao, Zhuang. "Laser à semiconducteur à 1.55 um a emission par la surface en cavité étendue en régime de blocage de modes." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00750763.
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Dans un premier temps, nous avons optimisé des structures laser VECSEL dans le but de maximiser la puissance émise par une gestion thermique adéquate. Les structures conçues et fabriquées contiennent une zone active à base d'InP pour l'émission à 1.55 µm. Un miroir hybride métal- semiconducteur à base d'un miroir de Bragg GaAs/AlAs est intégré à la zone active. La structure semiconductrice est intégrée avec différents substrats hôtes de bonne conductivité thermique sur la base de simulations numériques, et les performances des dispositifs fabriqués sont évaluées expérimentalement sous pompage optique Les VECSELs intégrés sur substrat diamant CVD présentent les puissances de sortie les plus élevées, et sont de bons candidats pour l'émission de puissance (> 500 mW) à 1.55 µm et pour les expériences de blocage de modes. D'un autre côté nous montrons que l'intégration d'un substrat de cuivre par voie électrochimique représente une approche flexible et faible-coût, pour atteindre une puissance de sortie de plusieurs dizaines de mW jusqu'à ~ 200 mW.Dans un second temps, nous avons développé des SESAMs à 1.55 µm. La région active est formée de puits quantiques InGaAsN/GaAs, couplés par effet tunnel à des plans GaAsN à recombinaison rapide. Des temps caractéristiques de recouvrement de l'absorption de quelques picosecondes à la dizaine de picoseconde sont ainsi mesurés.La résonance de la microcavité SESAM est ajustée de manière contrôlée grâce à des couches de phase spécifques épitaxiées en surface de la structure. La gravure sélective couche par couche des couches de phase permet d'accorder la profondeur de modulation et la dispersion de vitesse de groupe (GDD) de la structure SESAM.Finalement nous avons assemblé les structures SESAM et VECSEL dans une cavité à quatre miroirs pour obtenir un fonctionnement laser en régime de blocage de modes passif. Nous observons que la durée de l'impulsion de blocage de modes peut être réduite de plusieurs picosecondes (~ 10 ps), jusqu'à moins de la picoseconde (0.9 ps) en accordant la GDD de la structurre SESAM.
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Montgomery, Matthew. "Magnetically Deflectable MEMS Actuators for Optical Sensing Applications." Master's thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6226.
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In this work, new small deflection magnetic actuators have been proposed, designed, and tested for applications in Surface Enhanced Raman Scattering optical sensors. Despite the fact that SERS sensors have been shown to increase Raman over ten orders of magnitude for molecular detection, several technological challenges have prevented the design of practical sensors, such as making SERS sensors that can efficiently detect a wide variety of molecules. Since the optimum signal-to-noise in SERS occurs at different excitation wavelengths for different molecules, individual metal nanostructures need to be designed and fabricated for each independent chemical species. One possible solution to this problem is to tune the plasmon resonance frequency of the metal nanoparticles to eliminate the need for individually optimized particles. In order to achieve a tunable local dielectric environment, and thus allow for control over the resonance frequency of metal nanoparticles, a new SERS sensor geometry is proposed and a large deflection magnetic actuator is fabricated and tested as a starting point for the design of a small deflection magnetic actuator. Using the newly developed SERS geometry and the optimized fabrication processing techniques, two small deflection magnetic actuator beam structures were designed, fabricated, and tested. These devices utilizes an off-chip electromagnet source able to produce a magnetic force of approximately 14 ?N on the on-chip nickel film generating deflections up to 139 nm for the straight beam device and 164 nm for the curved beam device. In the process of characterizing the newly developed small deflection magnetic actuator, an integrated magnetic actuator with electrostatic restoration geometry was conceived. This device was designed to meet the specifications of the small deflection magnetic actuator as well as eliminate the need of an off-chip magnetic source and fully integrate the process atop the metal nanoparticle arrays. Using adhesive iron based magnetic strips as the magnetic drive source, circular NiFe beams with 1, 2, 3, and 4 mm diameters were designed and simulated. Calculations predicted maximum achievable actuation of up to 2.5 ?m. Processing steps were laid out for a set of integrated devices as a possible predecessor to the newly designed small deflection magnetic actuator.<br>M.S.E.E.<br>Masters<br>Electrical Engineering and Computer Science<br>Engineering and Computer Science
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Shreve, Matthew Adam. "Automatic Macro- and Micro-Facial Expression Spotting and Applications." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4770.
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Automatically determining the temporal characteristics of facial expressions has extensive application domains such as human-machine interfaces for emotion recognition, face identification, as well as medical analysis. However, many papers in the literature have not addressed the step of determining when such expressions occur. This dissertation is focused on the problem of automatically segmenting macro- and micro-expressions frames (or retrieving the expression intervals) in video sequences, without the need for training a model on a specific subset of such expressions. The proposed method exploits the non-rigid facial motion that occurs during facial expressions by modeling the strain observed during the elastic deformation of facial skin tissue. The method is capable of spotting both macro expressions which are typically associated with emotions such as happiness, sadness, anger, disgust, and surprise, and rapid micro- expressions which are typically, but not always, associated with semi-suppressed macro-expressions. Additionally, we have used this method to automatically retrieve strain maps generated from peak expressions for human identification. This dissertation also contributes a novel 3-D surface strain estimation algorithm using commodity 3-D sensors aligned with an HD camera. We demonstrate the feasibility of the method, as well as the improvements gained when using 3-D, by providing empirical and quantitative comparisons between 2-D and 3-D strain estimations.
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Derom, Stéphane. "Plasmonic cavities and optical nanosources." Phd thesis, Université de Bourgogne, 2013. http://tel.archives-ouvertes.fr/tel-01005260.
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Optical microcavities exhibit high resonance quality, so that, they are of key interest for the design of low-threshold lasers or for achieving strong coupling regime. But, such systems support modes whose the volume remain diffraction limited.In this manuscript, we are interested in their plasmonic counterparts because they support confined modes at the sub-wavelength scale. First, we study an in-plane plasmonic cavity which is the transposition of 1D optical cavity to surface wave. We characterize the cavity by measuring the fluorescence lifetime of dye molecules deposited inside.Then, we are interested in 3-dimension mode confinement achieved by spherical metal nanoparticles. We discuss on the definition of the mode volume used in cavity quantum electrodynamic and based on the calculation of energy confinement around the particle. We also simulate the fluorescence enhancement of rare-earth ions embedded inside core-shell plasmonic particles. Finally, we disturb the photodynamic emission of a single-photon source by puttingthe extremity of a plasmonic tip nearby the emitter
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Nakazawa, Takeshi. "THREE-DIMENSIONAL NON-CONTACT SURFACE PROFILERS FOR SEMICONDUCTOR IC PACKAGE INSPECTION." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/205472.
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The subject of this dissertation is the development of three-dimensional (3D) surface profilers for semiconductor back-end inspection. The value of this study is: 1) to provide a new phase-to-height relationship for Fourier Transform Profilometry (FTP) that is universal as it allows alternate FTP system architectures for a micrometer scale object measurement, and 2) to provide a new method for full field substrate warpage and ball grid array (BGA) coplanarity inspection using machine vision. The desire to increase electronic device performance has resulted in denser and smaller IC packaging. As the dimensions of the devices decrease, the requirements for substrate flatness and surface quality become critical in avoiding device failure. For a high yield production, there is an increasing demand in the requirement for the dimensional verification of height, which requires 3D inspection. Based on the current demands from the semiconductor industry, this dissertation addresses the development of fast in-line surface profilers for large volume IC package inspection. Specifically, this dissertation studies two noncontact surface profilers. The first profiler is based on FTP for measuring the IC package front surface, the silicon die and the epoxy underfill profile. The second profiler is based on stereovision and it is intended for inspecting the BGA coplanarity and the substrate warpage. A geometrical shape based matching algorithm is also developed for finding point correspondences between IC package images. The FTP profiler provides a 1 σRMS error of about 4 μm for an IC package sample in an area of 14 mm x 6.5 mm with a 0.13 second data acquisition time. For evaluating the performance of the stereovision system, the linearity between our system and a confocal microscope is studied by measuring a particular IC sample with an area of 38 mm x 28.5 mm. The correlation coefficient is 0.965 and the 2σdifference in the two methods is 26.9 μm for the warpage measurement. For BGA coplanarity inspection the correlation coefficient is 0.952 and the 2difference is 31.2 μm. Data acquisition takes about 0.2 seconds for full field measurements.
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Picart, Pascal. "Contribution au contrôle de surfaces planes et sphériques de précision nanométrique." Phd thesis, Université Paris Sud - Paris XI, 1995. http://pastel.archives-ouvertes.fr/pastel-00716214.
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Le sujet de ce mémoire est l'étude d'un interféromètre de Fizeau a décalage de phase pour la mesure de surfaces planes et sphériques a des précisions nanométriques. Nous avons recensé et étudié les sources de limitation et recherche les conditions ou les solutions rendant leur contribution inférieure a un millième de longueur d'onde en valeur crête à crête (la longueur d'onde est égale a 632,8 nanomètres). Six sources potentielles d'erreurs ont été examinées: la source laser, la détection, l'élément qui crée le déphasage, le diffuseur mobile du système d'imagerie, les aberrations géométriques des composants optiques et la nature même des interférences. Nous avons optimise la configuration interférométrique. De nouveaux algorithmes ont été développes. Ils sont basés sur des méthodes des moindres carres non linéaires. Ces algorithmes sont auto calibrés mais demandent beaucoup de temps de calcul. Pour obtenir des resultats rapidement, nous avons complete nos techniques de depouillement par une méthode basée sur une correction a posteriori de la formule de carre. La validation a montré les performances de l'instrument. Avec les méthodes basées sur les moindres carrés, les mesures de bruit ont montre que les fluctuations aléatoires sont de l'ordre de 0,21 nanomètres rms ; les erreurs systématiques ont une contribution inférieure a 1,8 nanomètres crête à crête. La cale piézo-électrique qui réalise le déphasage, et le bruit de la détection, sont en fait les principales sources de limitation. La correction des défauts de positionnement de la cale piézo-électrique a été essayée sur l'algorithme de carre et sa post correction ; les résultats indiquent une exactitude meilleure que 1 nanomètre crête à crête. L'interféromètre de Fizeau a décalage de phase a été applique a l'étalonnage absolu de surfaces planes. Une méthode basée sur des combinaisons de translations et de rotations d'une des surfaces par rapport a l'autre, a été présentée. Cette méthode a été utilisée pour la mesure d'une surface plane en silice.
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Wall, Richard Andrew. "Multi-Modality Endoscopic Imaging for the Detection of Colorectal Cancer." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301761.
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Optical coherence tomography (OCT) is an imaging method that is considered the optical analog to ultrasound, using the technique of optical interferometry to construct two-dimensional depth-resolved images of tissue microstructure. With a resolution on the order of 10 μm and a penetration depth of 1-2 mm in highly scattering tissue, fiber optics-coupled OCT is an ideal modality for the inspection of the mouse colon with its miniaturization capabilities. In the present study, the complementary modalities laser-induced fluorescence (LIF), which offers information on the biochemical makeup of the tissue, and surface magnifying chromoendoscopy, which offers high contrast surface visualization, are combined with OCT in endoscopic imaging systems for the greater specificity and sensitivity in the differentiation between normal and neoplastic tissue, and for the visualization of biomarkers which are indicative of early events in colorectal carcinogenesis. Oblique incidence reflectometry (OIR) also offers advantages, allowing the calculation of bulk tissue optical properties for use as a diagnostic tool. The study was broken up into three specific sections. First, a dual-modality OCTLIF imaging system was designed, capable of focusing light over 325-1300 nm using a reflective distal optics design. A dual-modality fluorescence-based SMC-OCT system was then designed and constructed, capable of resolving the stained mucosal crypt structure of the in vivo mouse colon. The SMC-OCT instrument's OIR capabilities were then modeled, as a modified version of the probe was used measure tissue scattering and absorption coefficients.