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Dissertationen zum Thema „Infrared“
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1
Anacona, J. R. "Far infrared and mid infrared laser spectroscopy of free radicals." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304717.
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2
Thurairajah, Brentha. "Thermal infrared imaging of the atmosphere : the infrared cloud imager." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/thurairajah/ThurairajahB04.pdf.
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3
Shelton, David. "TUNABLE INFRARED METAMATERIALS." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3925.
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Metamaterials are engineered periodic composites that have unique refractive-index characteristics not available in natural materials. They have been demonstrated over a large portion of the electromagnetic spectrum, from visible to radiofrequency. For applications in the infrared, the structure of metamaterials is generally defined using electron-beam lithography. At these frequencies, the loss and dispersion of any metal included in the composite are of particular significance. In this regard, we investigate deviations from the Drude model due to the anomalous skin effect. For comparison with theoretical predictions, the optical properties of several different metals are measured, both at room temperature and at 4 K. We extend this analysis to the coupling between plasmon and phonon modes in a metamaterial, demonstrating that very thin oxide layers residing at the metal-substrate interface will significantly affect the spectral location of the overall resonance. Oxide-thickness-dependent trends are then explored in some detail. Potential applications of this general area of study include surface-enhanced infrared spectroscopy for chemical sensing, and development of narrowband notch filters in the very long wavelength infrared. We then consider various possibilities for development of tunable infrared metamaterials. These would have wide applicability in dynamically variable reflectance surfaces and in beam steering. We consider several methods that have been previously shown to produce tunable metamaterials in the radio frequency band, and explore the challenges that occur when such techniques are attempted at infrared frequencies. A significant advance in tunable-infrared-metamaterial technology is then demonstrated with the use of thermochromic vanadium dioxide thin films. Highlights include the first demonstration of a tunable reflectarray in the infrared for active modulation of reflected phase, the first demonstration of a tunable resonance frequency in the thermal infrared band, and the largest resonance-frequency shift recorded to date in any part of the infrared. Finally, future work is proposed that holds the promise of wideband frequency tuning and electronically-controllable metamaterials.<br>Ph.D.<br>Department of Mechanical, Materials and Aerospace Engineering;<br>Engineering and Computer Science<br>Materials Science & Engr PhD
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Forde, Darren Andrew. "Infrared finite amplitudes." Thesis, Durham University, 2004. http://etheses.dur.ac.uk/3047/.
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Soft and collinear singularities, known collectively as infrared singularities here, plague the calculation of scattering amplitudes in gauge theories with massless particles such as QCD. The aim of this thesis is to describe methods of deriving amplitudes that are infrared finite and therefore do not suffer from this problem. We begin with an overview of scattering theory which includes a detailed discussion of the source of infrared singularities and outlines approaches that can be used to avoid them. Taking one of these approaches, namely that of dressed states, we give a detailed description of how such states can be constructed. We then proceed to give an explicit example calculation of the total cross section of the process e+e(^-) →2 jets at NLO. In this example we construct dressed amplitudes and demonstrate their lack of infrared singularities and then go on to show that the total cross section is the same as that calculated using standard field theory techniques. We then move on and attempt to improve the efficiency of calculations using dressed states amplitudes. We describe some of the problems of the method, specifically the large numbers of diagrams produced and the multiple different delta functions present in each amplitude. In attempting to fix these issues we demonstrate the difficulties of producing covariant amplitudes from this formalism. Finally we propose the use of the asymptotic interaction representation as a solution to these difficulties and outline a method of producing covariant infrared finite scattering amplitudes using this.
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Bristow, N. "Infrared laser chemistry." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353552.
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Pearson, Martin. "Synchrotron infrared microspectroscopy." Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324753.
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Harmon, Robin Thomas. "The infrared sky." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303052.
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8
Lee, Colin K. "Infrared face recognition." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FLee%5FColin.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, June 2004.<br>Thesis advisor(s): Monique P. Fargues, Gamani Karunasiri. Includes bibliographical references (p. 135-136). Also available online.
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Vines, Peter. "Infrared detection and spectral imaging using low strain quantum mdot infrared photodetectors." Thesis, University of Sheffield, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.544176.
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10
Fairbarn, Kenneth G. Jr. "VISIBLENEAR INFRARED (VNIR) AND SHORTWAVE INFRARED (SWIR) SPECTRAL VARIABILITY OF URBAN MATERIALS." Monterey, California. Naval Postgraduate School, 2013. http://hdl.handle.net/10945/32816.
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The advent of relatively high spatial resolution hyperspectral imagery (HSI) provides a different perspective of the urban environment than lower spatial resolution hyperspectral data and either multispectral or panchromatic images. The objective of this thesis was to build and analyze a spectral library of urban materials and to understand how spectral variability affects the ability of classification algorithms to identify and discriminate various materials. The scope of the project was limited to non-vegetative impervious materials located on the Naval Postgraduate School campus. An airborne hyperspectral image, acquired September 30th 2011 was used for image-derived endmembers and a portable spectroradiometer was used to collect field spectra. Visual analysis of spectra was performed to assess intra- and inter-class variability and to identify spectral features and their causes. The spectral angle mapper (SAM) algorithm was used on the HSI data as a method to quantify intra-class spectral variability using a standard spectral angle. Classification maps were created with both SAM and mixture tuned matched filtering (MTMF) algorithms to determine how intra- and inter-class spectral variability affect the algorithms ability to classify urban materials. The spatially complex nature of the urban environment negatively affected the performance of the SAM algorithm, but the ability to increase the spectral angle to account for materials with high spectral variability allowed improved inter-class discrimination. The MTMF algorithm was better suited for intra-class discrimination of materials.
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Etteh, Nkaepe Esoetok Ikpong. "Dark current models in mid- and far-infrared quantum well infrared photodetectors." Thesis, University of Leeds, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400264.
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12
Lenggenhager, René. "CMOS thermoelectric infrared sensors /." [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10744.
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13
Valiante, Elisabetta. "High-redshift infrared galaxies." Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-91747.
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Yoshioka, Koichi. "Infrared Fixed Point Physics." 京都大学 (Kyoto University), 2000. http://hdl.handle.net/2433/181116.
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Hollingworth, Andrew Roy. "Semiconductor optoelectronic infrared spectroscopy." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/842674/.
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We use spectroscopy to study infrared optoelectronic inter and intraband semiconductor carrier dynamics. The overall aim of this thesis was to study both III-V and Pb chalcogenide material systems in order to show their future potential use in infrared emitters. The effects of bandstructure engineering have been studied in the output characteristics of mid-IR III-V laser diodes to show which processes (defects, radiative, Auger and phonon) dominate and whether non-radiative processes can be suppressed. A new three-beam pump probe experiment was used to investigate interband recombination directly in passive materials. Experiments on PbSe and theory for non-parabolic near-mirror bands and non-degenerate statistics were in good agreement. Comparisons with HgCdTe showed a reduction in the Auger coefficient of 1-2 orders of magnitude in the PbSe. Using Landau confinement to model spatial confinement in quantum dots (QDs) "phonon bottlenecking" was studied. The results obtained from pump probe and cyclotron resonance saturation measurements showed a clear suppression in the cooling of carriers when Landau level separation was not resonant with LO phonon energy. When a bulk laser diode was placed in a magnetic field to produce a quasi quantum wire device the resulting enhanced differential gain and reduced Auger recombination lowered Ith by 30%. This result showed many peaks in the light output which occurred when the LO phonon energy was a multiple of the Landau level separation. This showed for the first time evidence of the phonon bottleneck in a working laser device. A new technique called time resolved optically detected cyclotron resonance, was used as a precursor to finding the earner dynamics within a spatially confined quantum dot. By moving to the case of a spatial QD using an optically detected intraband resonance it was possible to measure the energy separation interband levels and conduction and valence sublevels within the dot simultaneously. Furthermore this technique has been shown that the inhomogeneous broadening of the photoluminescence spectrum is not purely affected by just size and composition. We suggest that other processes such as state occupancy, In roughing, and exciton binding energies may account for the extra energy.
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Moreau, David. "Infrared stimulation of neurons." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0050/document.
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L’exposition aux radiations laser infrarouge peut être utilisée afin de dépolariser des neurones et stimuler l’activité neuronale. Le mécanisme sous-jacent d’une telle stimulation est supposé résulter d’une interaction photothermique. En effet, l’absorption de la radiation infrarouge par le tissu biologique cible, et l’eau qu’il contient, induit une augmentation de température de manière localisée, qui soit influencerait directement les propriétés membranaires de la cellule soit agirait par le biais de l’activation de canaux ioniques thermo-sensibles. Dans la plupart des cas, l’activité électrique des neurones est mesurée électriquement à l’aide de microélectrodes, mais elle peut également être sondée par le biais de la microscopie de fluorescence faisant intervenir des indicateurs calciques. Dans ce travail, l’impact de l’exposition à la radiation infrarouge sur les signaux calciques de neurones a été étudié dans le but d’éclaircir et de préciser le mécanisme résultant de l’interaction photothermique. Des neurones HT22, issus d’hippocampe de souris, et des cellules U87, issues d’un glioblastome humain, ont été utilisés en tant qu’exemples de cellules électriquement excitables et non excitables respectivement. Afin de mesurer la température et les signaux calciques au niveau cellulaire, les fluorophores Rhodamine B et Fluo-4 ont été employés. Le montage, par conséquent tout optique, pour étudier l’influence de l’exposition infrarouge sur l’activité neurale est donc présenté, ainsi que la démarche scientifique menant à l’identification de l’implication de l’activité de la phospholipase C dans le mécanisme étudié. La possibilité de stimuler l’activité neurale in vivo, dans le cerveau d’une souris, avec une mesure simultanée des signaux calciques, est également démontrée à l’aide de souris transgéniques exprimant le GCaMP6S<br>Infrared laser light radiation may be used to depolarize neurons and to stimulate neural activity. The underlying mechanism of such stimulation is believed to happen due to a photothermal interaction. The absorption of the infrared radiation by the targeted biological tissue inducing a local temperature increase which either directly influence membrane properties or act via temperature sensitive ion channels. Action potentials are typically measured electrically in neurons with microelectrodes, but they can also be observed using fluorescence microscopy techniques that use synthetic or genetically encoded calcium indicators. In this work, we studied the impact of infrared laser light on neuronal calcium signals to address the mechanism of these thermal effects. HT22 mouse hippocampal neurons and U87 human glioblastoma cells were used loaded with the fluorescent calcium dye Fluo-4 and with the temperature sensitive fluorophore Rhodamine B to measure calcium signals and temperature changes at the cellular level. Here we present our all-optical strategy for studying the influence of infrared laser light on neural activity, and the scientific approach leading to conclusion of the involvement of Phospholipase C activity during infrared neural stimulation. The ability of infrared exposure to trigger neural activity in mice brain in vivo is also investigated with the use of GCaMP6s transgenic mice
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Nichol, A. C. "Infrared spectroscopy of solids." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308601.
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Summerfield, Stephen. "Near infrared fluorescence spectroscopy." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/10601.
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Fluorimetry in the very near infrared region ca. 600-1000nm is a new approach to photochemical analysis. The advantages include greatly reduced background fluorescence signals from important sample matrices (such as blood serum), reduced scattering, and reduced probability of sample decomposition. Also, the availability of low cost, efficient, stable and robust optical components (e.g. laser diodes and light emitting diodes), solid state detectors (e.g. single silicon photodiodes and diode arrays) and fibre optics, allows the construction of an inexpensive fluorimeter. In the near infrared region, there are some very bright fluorophores that can be adapted for use as fluorescent probes, labels for immunoassay, and as ion-pair agents. The advantageous performance of most types of fluorimetric analysis now undertaken In the ultraviolet and visible region of the spectrum may therefore be extended into the longer wavelength region. Excellent limits of detection are attainable, and some near infrared fluorophores show invaluable fluorescence probe properties, such as Nile Red. The most useful of the dye groups investigated were the phenoxazines and thiazines. Reactive derivatives of these dyes show great potential as fluorescent labels for Immunoassay. These dyes have also been used as probes due to their solvatochromism and sensitivity to pH.
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Jackman, J. "Pre-emptive infrared countermeasures." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/6935.
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The aim of this PhD is to investigate pre-emptive flare release compared to reactive flare release and their efficacy as a countermeasure device in the protection of fast jet and transport aircraft against the MANPAD threat. Implicit in this is to study the optimum release time of the flare decoy. Consequently, this also raises the question of whether flares of reduced payload size can be as effective as standard flares when released at this optimum time. To achieve these aims the initial step is to develop models for the different types of Man-Portable Air-Defence (MANPAD) systems and the IR seekers they utilise. This also requires the simulation of the full pre-launch process, namely the acquisition of the target to obtain lock-on then the application of lead and super elevation to give a more realistic model of the firing sequence. Two target models are also developed, a fast jet (AMX-A1) and a transport aircraft (C130), with realistic positions and ejection characteristics for the countermeasure (CM) dispensers. The next stage includes a counter-countermeasure (CCM) capability in the IR seekers. The first is a track angle bias with values optimised for the two aircraft models. Second is the development of a two-colour seeker with signal processors designed for both a spinscan and a conscan system. Using all MANPAD models flares are released at intervals throughout the engagements to find the optimum firing time and the simulations repeated for flares with reduced peak intensity and burn time. The results show that flare release around the time of missile launch is effective against most threats, even the more advanced MANPADs with CCMs. Also, that for reduced performance flares maintaining the burn time is perhaps more important than the peak intensity.
20
Foulkes, Peter William. "Towards infrared image understanding." Thesis, University of Oxford, 1991. http://ora.ox.ac.uk/objects/uuid:5c4a198e-cd7b-4d40-a391-44afe05b43b9.
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An extensive literature survey has revealed that the majority of previous work in infrared image processing has ignored the processes leading to the formation of infrared images. Processing has normally either been restricted to simple lowlevel image enhancement convolutions or has consisted of algorithms copied from computer vision without regard for the inherent differences between infrared and visible images. In this thesis, we address the problem of infrared image formation and derive an irradiance equation for simple infrared scenes. We consider the complications caused by mutual illumination of one or more bodies and indicate how the infrared irradiance equation can also be specified for more complex scenes. The infrared irradiance equation we derive is solved in closed form for some simple geometries for both Lambertian and non-Lambertian surfaces. An infrared imager has been built and is described. Images taken with the imager of a variety of scene geometries show that the experimental results compare favourably with the theoretically derived equations, indicating the validity of the theoretical analysis. We describe how a knowledge of the formation of infrared images can be used to predict the image irradiance pattern of a particular object. We also show how, with a knowledge of the radiance properties and surface geometry of the object, it is possible to detect instances of that object in a scene. Examples are given of successful object detection based on an understanding of the image irradiance. We present a brief history of infrared imagers and a description of the principles on which modern infrared imagers are based. In addition to the survey of the literature published on infrared image processing, a brief summary of some techniques from the computer vision literature and their suitability to infrared image processing is given. A selection of vision techniques are applied to both infrared and visible images to verify conclusions reached in the thesis.
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Morley-Fletcher, Mark. "Covariant infrared finite amplitudes." Thesis, Durham University, 2005. http://etheses.dur.ac.uk/2718/.
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The calculation of observables in gauge theories with massless particles such as QCD - by traditional methods is significantly complicated by the presence of soft and collinear singularities, collectively termed infrared divergences, in the scattering amplitudes. The aim of this thesis is to investigate calculational methods which produce finite results at the amplitude level. We discuss the origin of the infrared divergences and outline some previous approaches to constructing finite amplitudes. After reviewing the traditional method for performing calculations we see how incorrect assumptions result in the presence of infrared divergences and what steps must be taken in order to produce infrared finite results. We then investigate how these ideas could be applied to the calculation of specific amplitudes. We see that there are problems involved in applying this exact approach, but that it suggests the adoption of a workable, more pragmatic alternative. We use this method in an explicit example calculation of the contributing cross sections for the process e+e (^_)> jets at O(as). We demonstrate that we recover the same result as that obtained with standard field theory techniques. We then briefly discuss how this approach might be adapted to suit more complex calculations and, eventually, a completely numerical approach.
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Ibbett, R. N. "Infrared diffuse reflectance spectroscopy." Thesis, University of East Anglia, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382895.
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Moore, B. D. "Time-resolved infrared spectroscopy." Thesis, University of Nottingham, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332449.
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Fox, Shaw Grant. "Infrared spectroscopy of surfaces." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254609.
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Thorley, Antony M. "Infrared characterisation of semiconductors." Thesis, University of St Andrews, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278212.
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Bello, K. A. "Near-infrared absorbing dyes." Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375504.
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Denham, Michael Charles. "Calibration in infrared spectroscopy." Thesis, University of Liverpool, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316562.
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Forbes, Duncan Alan. "Galaxies in the infrared." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240127.
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Davis, Ian Howard. "Far-infrared laser spectroscopy." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306442.
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Beckett, Martin Gregory. "High resolution infrared imaging." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388828.
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Spyromilio, Jason. "Infrared spectroscopy of supernovae." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47669.
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Han, Zhaohong Ph D. Massachusetts Institute of Technology. "Integrated infrared sensor platform." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108962.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 113-117).<br>Infrared spectrum, especially mid-infrared range (2.512tm) covers the absorption peaks of many important chemicals including carbon monoxide, methane and water vapor. By analyzing the absorption spectrum of achemical, one can measure the concentration of the chemicals as well as distinguish the chemical species. The purpose of this work is to build a Si CMOS compatible integrated mid-infrared (MIR) platform for sensing. In this work, we evaluated the three major components (materials and devices) comprising an integrated mid-infrared (MIR) sensing platform: the light source, the waveguide sensor and the detector. To build an integrated MIR light source, we evaluated three approaches. 1) Germanium light source, which is the representative of the CMOS compatible semiconductor light source. By applying tensile strain as well as increasing doping and injection level, Ge is tuned to pseudo-direct or direct bandgap structure and the emission wavelength extends to MIR range. 2) Er-doped GaLaS (GLS) platform which is the representative of the rare earth doped material system. A new laser structure is designed for this system with a threshold power of 7.6 ptW and a slope efficiency of 10.26%. 3) Frequency comb generation which is a new area using nonlinearity to generate new frequencies. Thick Si3N4 material for comb structures are designed, fabricated and tested. In the waveguide sensor section, a waveguide structure based on chalcogenide glass (ChG) is built and tested. The sensing limit for methane reaches 2.5 vol. %. Besides, a ChG based small-footprint plasmonic optical switch is designed to work as an optical router for integrated spectrometer applications with a small (167 nm long) footprint. In the last part, a MIR PbTe based integrated detector has been successfully demonstrated for the first time. A further improvement in the material property and device structure yields a responsivity is about 1.4 A/W in the MIR regime.<br>by Zhaohong Han.<br>Ph. D.
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Gemmell, Nathan Robert. "Infrared single photon sensing." Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/2981.
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Servoss, Thomas G. "Infrared symbolic scene comparator /." Online version of thesis, 1993. http://hdl.handle.net/1850/11725.
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Young, Alexander James, Casse Brian J. La, Patrick M. Kain, Setareh Madhoush, and Peter J. Pflibsen. "Uncooled Thermal Infrared Camera." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/145107.
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Padhye, Anuja Arun. "Novel continuous-wave infrared parametric sources and noise analysis of infrared upconversion detectors." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669321.
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The ability to manipulate frequency of light, through parametric frequency conversion sources based on X(2) nonlinear materials, offers an effective route to spectral regions unapproachable by conventional lasers. Most importantly, three-wave mixing processes provide tunable coherent radiation over a broad spectral range. Among the most important tunable devices, narrow linewidth continuous-wave (cw) infrared (IR) optical parametric oscillators (OPOs) are indispensable excitation sources for many applications in molecular spectroscopy and precision metrology. In order to exploit such applications, the development of cw OPOs deploying different wavelength tuning schemes and novel nonlinear materials is highly dezirable, as presented in this thesis. We demonstrated a rapidly tunable cw OPO based on fan-out grating design periodically-poled KTiOPO4 (PPKTP) crystal at room temperature. This approach allows continuous wavelength tuning by avoiding increased thermal fluctuations at higher operating crystal temperatures. The 532 nm-pumped, output-coupled singly-resonant oscillator (OC-SRO) provides widely tunable near-IR radiation across 741-922 nm and 1258-1884 nm, with total output power of 1.65 W. The use of output coupling for the resonating wave reduces thermal loading and enables 30% enhancement in the OPO extraction efficiency over the pure SRO configuration. Towards the goal of developing a next-generation cw source >4 µm using a new found quasi-phase-matched semiconductor material, orientation-patterned gallium phosphide (OP-GaP), we demonstrated the first realization of a tunable cw mid-IR source based on OP-GaP by exploiting single-pass difference-frequency-generation (DFG) between a Tm-fiber laser at 2010 nm and a home-built OPO based on MgO-doped periodically-poled LiNbO3 (MgO:PPLN) crystal. The DFG source generates up to 43 mW of output power, with >30 mW across 96% of the tuning range 4608-4694 nm, in high beam quality. As the tunable mid-IR sources are making great strides, the availabilityof fast and sensitive mid-IR detectors become equally important. However, the conventional mid-IR detectors demand cryogenic systems for low-noise operation which sets a major drawback as these devices are often bulky and expensive. In this context, the nonlinear frequency upconversion technique has emerged as a promising alternative to the direct detection of mid-IR radiation at room temperature. An upconversion detector (UCD) can be further optimized by identifying and suppressing its noise sources. In order to do so, we experimentally and theoretically investigated noise properties of 1064 nm-pumped single-pass UCD designed for signal detection in telecom and mid-IR range using MgO:PPLN crystals. We studied the dependence of newly discovered SHG (532 nm)-induced spontaneous parametric downconversion (SHG-SPDC) noise intensity on the pump power and crystal temperature, and compared it with the well-known UCD noise source upconverted spontaneous parametric downconversion (USPDC). The measurements deduce that SHG-SPDC must be given a careful consideration since it can act as a dominant noise source under certain operating conditions. However, SHG-SPDC can be avoided by choosing a proper combination of MgO:PPLN grating period,operating temperature, and bandpass filter.<br>La capacidad de manipular la frecuencia de la luz, a través de sintonizables fuentes de conversión de frecuencia paramétrica basadas en materiales no lineales del tipo ¿(2), ofrece un acceso eficaz a las regiones espectrales inaccesible por los láseres convencionales. Entre los dispositivos sintonizables más importantes, los osciladores ópticos paramétricos (OPOs) de onda continua (cw) en el infrarrojo (IR) con ancho de banda estrecho, son fuentes esenciales para muchas aplicaciones en espectroscopia molecular y metrología de precisión. Con el fin de explotar tales aplicaciones, es muy deseable el desarrollo de OPOs de cw mediante diferentes esquemas de sintonización de longitud de onda y nuevos materiales no lineales, como se presentan en esta tesis. Mostramos aquí un OPO de cw rápidamente sintonizable basado en un cristal periodically-poled KTiOPO4 con diseño de red fan-out a temperatura ambiente. Este enfoque permite una sintonización continua de la longitud de onda evitando el aumento de las fluctuaciones térmicas a temperaturas de funcionamiento más altas de los cristales. El OPO resonante con acoplador de salida bombeado a longitud de onda de 532 nm, proporciona radiación sintonizable en el infrarrojo cercano (near-IR) a través de 741-922 nm y 1258-1884nm, con una potencia de salida máxima de 1.65 W. El uso del acoplador de salida para la onda resonante reduce la carga térmica y permite una mejora del 30% en la eficiencia de extracción del OPO sobre la configuración SRO pura. Con el objetivo de desarrollar la nueva generación de fuentes de onda continua con longitud de onda >4 µm utilizando la técnica de quasi-phase-matching con materiales semiconductores, presentamos la primera demostración de una fuente de onda continua sintonizable en el infrarrojo medio (mid-IR) utilizando el patrón de orientación de fosfuro de galio (OP-GaP) y generación de frecuencia diferencia (DFG) entre láser de fibra Tm a longitud de onda de 2010 nm y otro OPO hecho en el laboratorio basado en un cristal MgO-doped periodically-poled LiNbO3 (MgO:PPLN). La fuente DFG genera hasta 43 mW de potencia de salida, con >30 mW a través de un 96% del rango de sintonización 4608-4694 nm, con una alta calidad de haz. A medida que las fuentes de emisión en el mid-IR sintonizables mejoren sus prestaciones, la disponibilidad de detectores de mid-IR rápidos y sensibles se vuelve igualmente importante. Sin embargo, los detectores de mid-IR convencionales requieren sistemas criogénicos para operar con poco ruido, lo que presenta un gran inconveniente ya que estos dispositivos suelen ser voluminosos y caros. En este contexto, la técnica no lineal de conversión ascendente de frecuencia ha surgido como una alternativa prometedora a la detección directa de la radiación de mid-IR a temperatura ambiente. Un detector de conversión ascendente (UCD) se puede optimizar aún más dentificando y suprimiendo sus fuentes de ruido. Para hacerlo, investigamos teórica y experimentalmente las propiedades de ruido de un UCD de un solo paso bombeado a 1064 nm diseñado para la detección de señales en telecomunicaciones y rango mid-IR, utilizando cristales MgO:PPLN. Descubrimos una nueva fuente de ruido llamada ruido espontáneo paramétrico de conversión descendente inducido por generación de segundo harmónico SHG (SHG-SPDC). Estudiamos, también, la dependencia de la intensidad de este ruido (SHG-SPDC) con la potencia de bombeo y la temperatura del cristal. Finalmente, también comparamos su intensidad con el conocido ruido generado por el detector UCD, llamado ruido de conversión ascendente por conversión paramétrica descendente espontánea (USPDC). Los resultados obtenidos nos dicen que se debe considerar cuidadosamente el SHG-SPDC, ya que puede actuar como una fuente de ruido dominante en ciertas condiciones de operación. Sin embargo, el SHG-SPDC se puede evitar al elegir una combinación adecuada de MgO:PPLN, el período de red la temperatura de operación y el filtro de tipo pasa banda.
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Dehlin, Jonas, and Joakim Löf. "Dynamic Infrared Simulation : A Feasibility Study of a Physically Based Infrared Simulation Model." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7993.
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<p>The increased usage of infrared sensors by pilots has created a growing demand for simulated environments based on infrared radiation. This has led to an increased need for Saab to refine their existing model for simulating real-time infrared imagery, resulting in the carrying through of this thesis. Saab develops the Gripen aircraft, and they provide training simulators where pilots can train in a realistic environment. The new model is required to be based on the real-world behavior of infrared radiation, and furthermore, unlike Saab's existing model, have dynamically changeable attributes.</p><p>This thesis seeks to develop a simulation model compliant with the requirements presented by Saab, and to develop the implementation of a test environment demonstrating the features and capabilities of the proposed model. All through the development of the model, the pilot training value has been kept in mind.</p><p>The first part of the thesis consists of a literature study to build a theoretical base for the rest of the work. This is followed by the development of the simulation model itself and a subsequent implementation thereof. The simulation model and the test implementation are evaluated as the final step conducted within the framework of this thesis.</p><p>The main conclusions of this thesis first of all includes that the proposed simulation model does in fact have its foundation in physics. It is further concluded that certain attributes of the model, such as time of day, are dynamically changeable as requested. Furthermore, the test implementation is considered to have been feasibly integrated with the current simulation environment.</p><p>A plan concluding how to proceed has also been developed. The plan suggests future work with the proposed simulation model, since the evaluation shows that it performs well in comparison to the existing model as well as other products on the market.</p>
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Hammer, Daniel Xavier. "Infrared detection in Melanophila acuminata." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3032972.
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Hamdan, Abdullah. "Infrared spectroscopy of methane dimer." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978829921.
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Wruck, Eric Michael. "Applying near-infrared spectroscopy (nirs)." Texas A&M University, 2005. http://hdl.handle.net/1969.1/2386.
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Over recent decades, much has been learned about the perceptual capacity that
enables infants to recognize and understand language. However, not until very recently
have the neural mechanisms that are the substance of language learning been
investigated. A recently developed optical imaging technique called near-infrared
spectroscopy (NIRS) shows promise for being an acceptable alternative to invasive
imaging techniques. NIRS measures correlates of neural activity by assessing
hemoglobin concentration changes in the infant brain. The research presented here
investigates neural activation in the left temporal and occipital cortex regions during
exposure to speech and visual stimuli. As hypothesized, hemodynamic reaction was
observed in both areas. Results indicate a significant activation in response to speech in
the left temporal region, and an intriguing difference between uni- and bi-modally
presented speech stimuli. These results have interesting implications for future multimodal
studies of infant speech perception.
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Paiam, Mohammad Reza. "In-theatre infrared audio broadcasting." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6695.
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Several factors have to be analyzed before designing an appropriate communication system for in-theatre IR multi-channel audio broadcasting. The infrared channel characteristics for the in-theatre propagation environment are examined and a suitable IR transmission configuration is suggested. The free-space IR transmission has a simple channel model which simplifies the analysis. The CD digital audio technology which provides advanced digital signal processing techniques at a relatively low cost is a strong candidate for use in the system. However, the channel coding used in the CD system (known as EFM) has a high redundancy which results in a performance degradation. A more suitable channel coding scheme (which is a version of 8B10B channel modulation) is designed and simple implementations for the corresponding coder and decoder are given. The receiver design for an indoor non-directional IR communication system requires an approach different from that commonly employed in optical fibre communications. A signal-to-noise ratio analysis is carried out and a simple strategy for the receiver design is proposed. A link power budget calculation is performed to find the required transmitted optical power. Also, it is shown analog FM requires much higher transmitted optical power to provide the performance achieved by the CD-based digital audio system in the in-theatre IR audio broadcasting. Finally, a simulation is carried out to investigate the effects of the multipath dispersion on the performance of the system.
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McFarlan, Andrew J. "Infrared studies of silica surfaces." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7852.
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The silanol distributions on "as received" aerosil and precipitated silica have been studied (1) by using time-resolved infrared spectroscopy in order to follow a reaction with AlMe$\sb3$, TiCl$\sb4$, or BCl$\sb3$, (2) by spectroscopically comparing the accessibility of probe molecules having different steric dimensions, that react with surface silanols (SiOH) either by chemisorption or H/D exchange, and (3) by gravimetrically measuring surface silanol densities using vacuum microbalance techniques. The results have been used to compare and characterize these non-porous silicas of similar surface area. Initially, H-bonded silanols are relatively more reactive than isolated silanols in the order of reagents, BCl$\sb3$ $>$ TiCl$\sb4$ $>$ AlMe$\sb3$. In the fully hydroxylated "as received" state, the number of silanol groups on either silica which react with various hydrogen sequestering (HS) agents decreases as the size of the agent increases (ZnMe$\sb2$, BCl$\sb3$, TiCl$\sb4$, AlMe$\sb3$ and Me$\sb3$SiNHSiMe$\sb3$ (HMDS) in increasing size). The number of silanols that undergo H/D exchange also decreases as the size of the probe molecule increases (D$\sb2$O, ND$\sb3$, and deuterated methanol, i-propanol and t-butanol). The reaction between HMDS and H-bonded silanols occurs preferentially with the terminal silanols of a chain, and we propose that these silanols occupy sites which are inherently more accessible to this bulky reactant. By following the evolution of the SiOH bands on both silicas in all three spectral regions for 450, 600, and 800$\sp\circ$C activation, we have assigned bands to two types of isolated silanols. The type I silanols are preferentially eliminated between 450 and 800$\sp\circ$C activation and are more abundant on precipitated silica than on aerosil. Type II silanols (isolated single silanols) dominate the surface of highly activated aerosil or precipitated silica. The vibrational spectra are reported for the physically adsorbed complexes, SiOH...X (X = CO, N$\sb2$, and CH$\sb4$) and the nature of their specific interaction with surface SiOH is discussed. Mechanisms are proposed for the room-temperature reaction between SiOH and TMP to produce DMP, and the SiOH catalyzed isomerization of TMP to DMMP. (Abstract shortened by UMI.)
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Kerr, Thomas Hugh. "Infrared spectroscopy of interstellar grains." Thesis, University of Central Lancashire, 1994. http://clok.uclan.ac.uk/21040/.
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Spectra are presented of interstellar 1120 and CO ices in three molecular douds. The high signal—to—noise in many of these enabled high quality comparisons to be made with laboratory data, constraining mantle constituents and thermal history. CGS 4 spectra of H 2 0 ices in the p Oph cloud were best fitted with two—component laboratory spectra of non—processed and thermally processed 1120 ices. Variations in the depth of the 3.4 jim excess absorption between lines of sight implied that heating weakens this feature. No features due to C11 30H ices were detected, but a feature at 3.47 pm was observed towards two objects, recently attributed to diamond—like carbon. Solid CO features in p Oph were similarly obtained and compared to laboratory features. They were found to be consistent with pure or nearly pure CO and generally possessed weak or undetectable long—wavelength shoulders implying rigorous segregation between 1120 and CO in the mantles. The CO features were not consistent with CO in 02, implying segregation between these two components, or a lack of 02. Gas phase CO was also observed in some lines of sight and shown not to be spatially coincident with solid CO. Solid CO was observed in the Taurus cloud towards four background field stars and one embedded object. The feature towards Elias 16 was similar to those observed in p Oph, although other spectra were consistent with CO in CO 2 , but the quality of three of these was disputed. The effect of UV on the grains was considered, and assuming cloud uniformity, was found to have an effect only at the outer edges or close to YSOs. Age estimates of the cloud using observational data and theoretical models were found to disagree. A brief study was made of CO ices in the Serpens cloud within which it was concluded that solid CO is a widespread component, although its host matrix may differ between lines of sight within the cloud, implying subtle differences in regional chemistry. Infrared spectroscopy of interstellar grains has enabled many grain components to be identified and their importance in the ISM to be understood. An analysis of cold molecular cloud mantles has been presented in this thesis, and should provide a basis for future study, especially with the launch of ISO in the near future.
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Pakravan, Mohammad Reza. "Indoor infrared wireless communication channels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0016/NQ57061.pdf.
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Rochat, Michel. "Far-infrared quantum cascade lasers." Online version, 2002. http://bibpurl.oclc.org/web/24095.
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McFarland, Elizabeth Gramling. "Infrared absorption characteristics of fabrics." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/10185.
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Ozugur, Timucin. "Advanced infrared local area networks." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/13542.
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Bone, Stewart A. "Analytical applications of infrared spectroscopy." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385929.
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Ewen, Graham Bruce Lachlan. "Infrared limb observations of cloud." Thesis, University of Oxford, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427868.
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Zyambo, Emmanuel Baleke. "High-speed wireless infrared communications." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275377.
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