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Dissertations / Theses on the topic 'Optical imaging'
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Vettenburg, Tom. "Optimal design of hybrid optical digital imaging systems." Thesis, Heriot-Watt University, 2010. http://hdl.handle.net/10399/2438.
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Several types of pupil modulation have been reported to decrease the aberration variance of the modulation-transfer-function (MTF) in aberration-tolerant hybrid optical-digital imaging systems. It is common to enforce restorability constraints on the MTF, requiring trade of aberration-tolerance and noise-gain. In this thesis, instead of optimising specific MTF characteristics, the expected imaging-error of the joint design is minimised directly. This method is used to compare commonly used phase-modulation functions. The analysis shows how optimal imaging performance is obtained using moderate phasemodulation, and more importantly, it shows the relative merits of different functions. It is shown that the technique is readily integrable with off-the-shelf optical design software, which is demonstrated with the optimisation of a wide-angle reflective system with significant off-axis aberrations. The imaging error can also be minimised for amplitudeonly masks. It is shown that phase aberrations in an imaging system can be mitigated using binary amplitude masks. This offers a low-cost, transmission-mode alternative to phase correction as used in active and adaptive optics. More efficient masks can be obtained by the optimisation of the imaging fidelity.
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Bronk, Karen Srour. "Imaging based sensor arrays /." Thesis, Connect to Dissertations & Theses @ Tufts University, 1996.
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Thesis (Ph.D.)--Tufts University, 1996.Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Elazhary, Tamer Mohamed Tawfik Ahmed Mohamed. "Generalized Pupil Aberrations Of Optical Imaging Systems." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/347096.
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In this dissertation fully general conditions are presented to correct linear and quadratic field dependent aberrations that do not use any symmetry. They accurately predict the change in imaging aberrations in the presence of lower order field dependent aberrations. The definitions of the image, object, and coordinate system are completely arbitrary. These conditions are derived using a differential operator on the scalar wavefront function. The relationships are verified using ray trace simulations of a number of systems with varying degrees of complexity. The math is shown to be extendable to provide full expansion of the scalar aberration function about field. These conditions are used to guide the design of imaging systems starting with only paraxial surface patches, then growing freeform surfaces that maintain the analytic conditions satisfied for each point in the pupil. Two methods are proposed for the design of axisymmetric and plane symmetric optical imaging systems. Design examples are presented as a proof of the concept.
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Wilson, Richard Walter. "Synthesis imaging in optical astronomy." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281906.
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Mazurenko, Anton. "Optical imaging of Rydberg atoms." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78519.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 109-111).
We present an experiment exploring electromagnetically induced transparency (EIT) in Rydberg atoms in order to observe optical nonlinearities at the single photon level. ⁸⁷Rb atoms are trapped and cooled using a magneto-optical trap (MOT) and a far off resonance dipole trap (FORT). Once the system is prepared, a ladder EIT scheme with Rydberg atoms is used to map the photon field onto the ensemble. The powerful dipole interaction between Rydberg atoms allows the system to exhibit many-body quantum mechanical effects. We also describe an imaging method to observe the Rydberg blockade. Last of all, we present a preliminary measurement of EIT in a Rydberg system. In this measurement, the transmission shows sensitivity to the applied photon flux, and exhibits temporal correlations in the photons exiting the EIT medium.
by Anton Mazurenko.
S.B.
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Wu, Jigang Yang Changhuei Yang Changhuei. "Coherence domain optical imaging techniques /." Diss., Pasadena, Calif. : Caltech, 2009. http://resolver.caltech.edu/CaltechETD:etd-12112008-102138.
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Adie, Steven G. "Enhancement of contrast in optical coherence tomography : new modes, methods and technology." University of Western Australia. School of Electrical, Electronic and Computer Engineering, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0127.
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This thesis is concerned with exploiting the native optical coherence tomography (OCT) contrast mechanism in new ways and with a new contrast mechanism, in both cases to enhance the information content of the tomographic image. Through experiments in microsphere solutions, we show that static speckle contains information about local particle density when the effective number of scatterers in the OCT resolution volume is less than about five. This potentially provides contrast enhancement in OCT images based on local scatterer density, and we discuss the experimental conditions suited to utilising this in biological tissue. We also describe the corrupting effects of multiple scattering, a ubiquitous phenomenon in OCT, on the information content of the static speckle. Consequently, we detail the development of polarisation-based metrics for characterising multiple scattering in OCT images of solid biological tissues. We exploit a detection scheme used for polarisation-sensitive contrast for a new purpose. We present experiments demonstrating the behaviour of these metrics in liquid phantoms, and in biological tissues, ranging from homogeneous non-birefringent to highly heterogeneous and birefringent samples. We discuss the conditions under which these metrics could be used to characterise the relative contribution of single and multiple scattering and, thus, aid in the study of penetration depth limits in OCT. We present a study of a new contrast mechanism - dynamic elastography which seeks to determine the dynamic mechanical properties of tissues. We present a framework for describing the OCT signal in samples undergoing vibrations, and perform experiments at vibration frequencies in the order of tens to hundreds of Hertz, to confirm the theory, and demonstrate the modes of measurement possible with this technique. These modes of measurement, including acoustic amplitude-sweep and frequency-sweep, could provide new information about the local mechanical properties of a sample. We describe a technological advancement enabling, in principle, measurements of local tissue refractive index contrast much deeper within a sample, than is possible with conventional OCT imaging. The design is based on measurement of the optical path length through tissue filling a fixed-width channel situated at the tip of a needle. The needle design and calibration is presented, as well as measurements of scattering phantoms and various biological tissues. This design potentially enables the use of refractive index-based contrast enhancement in the guidance of breast biopsy procedures.
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Luo, Yuan. "Novel Biomedical Imaging Systems." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/193907.
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The overall purpose of the dissertation is to design and develop novel optical imaging systems that require minimal or no mechanical scanning to reduce the acquisition time for extracting image data from biological tissue samples. Two imaging modalities have been focused upon: a parallel optical coherence tomography (POCT) system and a volume holographic imaging system (VHIS). Optical coherence tomography (OCT) is a coherent imaging technique, which shows great promise in biomedical applications. A POCT system is a novel technology that replaces mechanically transverse scanning in the lateral direction with electronic scanning. This will reduce the time required to acquire image data. In this system an array with multiple reduced diameter (15μm) single mode fibers (SMFs) is required to obtain an image in the transverse direction. Each fiber in the array is configured in an interferometer and is used to image one pixel in the transverse direction. A VHIS is based on volume holographic gratings acting as Bragg filters in conjunction with conventional optical imaging components to form a spatial-spectral imaging system. The high angular selectivity of the VHIS can be used to obtain two-dimensional image information from objects without the need for mechanical scanning. In addition, the high wavelength selectivity of the VHIS can provide spectral information of a specific area of the object that is being observed. Multiple sections of the object are projected using multiplexed holographic gratings in the same volume of the Phenanthrenquinone- (PQ-) doped Poly (methyl methacrylate) (PMMA) recording material.
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Kosmeier, Sebastian. "Optical eigenmodes for illumination & imaging." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3369.
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This thesis exploits so called “Optical Eigenmodes” (OEi) in the focal plane of an optical system. The concept of OEi is introduced and the OEi operator approach is outlined, for which quadratic measures of the light field are expressed as real eigenvalues of an Hermitian operator. As an example, the latter is employed to locally minimise the width of a focal spot. The limitations of implementing these spots with state of the art spatial beam shaping technique are explored and a selected spot with a by 40 % decreased core width is used to confocally scan an in focus pair of holes, delivering a two-point resolution enhanced by a factor of 1.3. As a second application, OEi are utilised for fullfield imaging. Therefore they are projected onto an object and for each mode a complex coupling coefficient describing the light-sample interaction is determined. The superposition of the OEi weighted with these coefficients delivers an image of the object. Compared to a point-by-point scan of the sample with the same number of probes, i.e. scanning points, the OEi image features higher spatial resolution and localisation of object features, rendering OEi imaging a compressive imaging modality. With respect to a raster scan a compression by a factor four is achieved. Compared to ghost imaging as another fullfield imaging method, 2-3 orders of magnitude less probes are required to obtain similar images. The application of OEi for imaging in transmission as well as for fluorescence and (surface enhanced) Raman spectroscopy is demonstrated. Finally, the applicability of the OEi concept for the coherent control of nanostructures is shown. For this, OEi are generated with respect to elements on a nanostructure, such as nanoantennas or nanopads. The OEi can be superimposed in order to generate an illumination of choice, for example to address one or multiple nanoelements with a defined intensity. It is shown that, compared to addressing such elements just with a focussed beam, the OEi concept reduces illumination crosstalk in addressing individual nanoelements by up to 70 %. Furthermore, a fullfield aberration correction is inherent to experimentally determined OEi, hence enabling addressing of nanoelements through turbid media.
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Steinert, Steffen [Verfasser]. "Widefield Magneto-Optical Imaging / Steffen Steinert." München : Verlag Dr. Hut, 2013. http://d-nb.info/1033041556/34.
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Hewlett, Simon J. "Imaging strategies in scanning optical microscopy." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302904.
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Hanna, Philip M. "Expectation-Maximization Optical Tomosynthetic Volume Imaging." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1213216116.
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Ma, Pei. "OPTICAL IMAGING OF EMBRYONIC CARDIAC CONDUCTION." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1464714110.
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Zaidi, Syed Anwar Hyder. "Optical Redox Imaging of Metabolic Activity." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1484672916027993.
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Kerviche, Ronan, and Ronan Kerviche. "Scalable Computational Optical Imaging System Designs." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/624555.
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Computational imaging and sensing leverages the joint-design of optics, detectors and processing to overcome the performance bottlenecks inherent to the traditional imaging paradigm. This novel imaging and sensing design paradigm essentially allows new trade-offs between the optics, detector and processing components of an imaging system and enables broader operational regimes beyond the reach of conventional imaging architectures, which are constrained by well-known Rayleigh, Strehl and Nyquist rules amongst others.
In this dissertation, we focus on scalability aspects of these novel computational imaging architectures, their design and implementation, which have far-reaching impacts on the potential and feasibility of realizing task-specific performance gains relative to traditional imager designs. For the extended depth of field (EDoF) computational imager design, which employs a customized phase mask to achieve defocus immunity, we propose a joint-optimization framework to simultaneously optimize the parameters of the optical phase mask and the processing algorithm, with the system design goal of minimizing the noise and artifacts in the final processed image. Using an experimental prototype, we demonstrate that our optimized system design achieves higher fidelity output compared to other static designs from the literature, such as the Cubic and Trefoil phase masks.
While traditional imagers rely on an isomorphic mapping between the scene and the optical measurements to form images, they do not exploit the inherent compressibility of natural images and thus are subject to Nyquist sampling. Compressive sensing exploits the inherent redundancy of natural images, basis of image compression algorithms like JPEG/JPEG2000, to make linear projection measurements with far fewer samples than Nyquist for the image forming task. Here, we present a block wise compressive imaging architecture which is scalable to high space-bandwidth products (i.e. large FOV and high resolution applications) and employs a parallelizable and non-iterative piecewise linear reconstruction algorithm capable of operating in real-time. Our compressive imager based on this scalable architecture design is not limited to the imaging task and can also be used for automatic target recognition (ATR) without an intermediate image reconstruction. To maximize the detection and classification performance of this compressive ATR sensor, we have developed a scalable statistical model of natural scenes, which enables the optimization of the compressive sensor projections with the Cauchy-Schwarz mutual information metric. We demonstrate the superior performance of this compressive ATR system using simulation and experiment.
Finally, we investigate the fundamental resolution limit of imaging via the canonical incoherent quasi-monochromatic two point-sources separation problem. We extend recent results in the literature demonstrating, with Fisher information and estimator mean square error analysis, that a passive optical mode-sorting architecture with only two measurements can outperform traditional intensity-based imagers employing an ideal focal plane array in the sub-Rayleigh range, thus overcoming the Rayleigh resolution limit.
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Chaix, Cécile. "AdaptiSPECT: a Preclinical Imaging System." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/594908.
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This dissertation addresses the design, development, calibration and performance evaluation of a pre-clinical imaging system called AdaptiSPECT. Single-Photon Emission Computed Tomography (SPECT) systems are powerful tools for multiple applications in small-animal research, ranging from drug discovery to fundamental biology. Traditionally, pinhole SPECT systems are designed with fixed imaging characteristics in terms of sensitivity, resolution and size of the field of view, that are dictated by the hardware configuration of the system. The SPECT system described in this dissertation can change its hardware configuration in response to the subject data it is acquiring in order to improve the imaging performance. We employed 16 modular gamma-ray detectors, each of which consists of a NaI:Tl scintillation crystal, a fused silica lightguide, and an array of 9 PMTs. The camera is designed to work with maximum-likelihood position estimation methods. These detectors are arranged into 2 rings of 8 detectors around an adjustable pinhole aperture. The aperture itself comprises three cylinders of different diameters, each with pinholes of different diameters. The three aperture cylinders are stacked together along the imager axis, and selection of the appropriate ring of pinholes is carried out by translating the entire aperture assembly. In addition, some sections of the aperture are fitted with shutters to open or close additional pinholes that increase sensitivity. We reviewed the method used to calibrate AdaptiSPECT, and proposed a new interpolation scheme specific to adaptive SPECT imaging systems where the detectors can move to multiple locations, that yields system matrices for any configuration employed during adaptive imaging. We evaluated the performances of AdaptiSPECT for various configurations. The magnification of the system ranges from 1.2 to 11.1. The corresponding resolution ranges from 3.2 mm to 0.6 mm, and the corresponding transaxial field-of-view ranges from 84 mm to 10 mm. The sensitivity of the system varies from 220 cps/MBq to 340 cps/MBq for various configurations. Imaging of a mouse injected with a bone radiotracer revealed the finer structures that can be acquired at higher magnifications, and illustrated the ability to conveniently image with a variety of magnifications during the same study. In summary, we have brought the concept of an adaptive SPECT imaging system as it was originally described by Barrett et al. in 2008 to life. We have engineered a system that can switch configurations with speed, precision, and repeatability suitable to carry out adaptive imaging studies on small animals, thus opening the door to a new research and medical imaging paradigm in which the imager hardware is adjusted on the fly to maximize task-performance for a specific patient, not, as currently, an ensemble of patients.
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Liu, Xiaojing. "Optical Coherence Photoacoustic Microscopy (OC-PAM) for Multimodal Imaging." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/3189.
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Optical coherence tomography (OCT) and Photoacoustic microscopy (PAM) are two noninvasive, high-resolution, three-dimensional, biomedical imaging modalities based on different contrast mechanisms. OCT detects the light backscattered from a biological sample either in the time or spectral domain using an interferometer to form an image. PAM is sensitive to optical absorption by detecting the light-induced acoustic waves to form an image. Due to their complementary contrast mechanisms, OCT and PAM are suitable for being combined to achieve multimodal imaging.
In this dissertation, an optical coherence photoacoustic microscopy (OC-PAM) system was developed for in vivo multimodal retinal imaging with a pulsed broadband NIR light source. To test the capabilities of the system on multimodal ophthalmic imaging, the retina of pigmented rats was imaged. The OCT images showed the retinal structures with quality similar to conventional OCT, while the PAM images revealed the distribution of melanin in the retina since the NIR PAM signals are generated mainly from melanin in the posterior segment of the eye.
By using the pulsed broadband light source, the OCT image quality highly depends on the pulse-to-pulse stability of the light source without averaging. In addition, laser safety is always a concern for in vivo applications, especially for eye imaging with a pulsed light source. Therefore, a continuous wave (CW) light source is desired for OC-PAM applications. An OC-PAM system using an intensity-modulated CW superluminescent diode was then developed. The system was tested for multimodal imaging the vasculature of a mouse ear in vivo by using Gold Nanorods (GNRs) as contrast agent for PAM, as well as excised porcine eyes ex vivo.
Since the quantitative information of the optical properties extracted from the proposed NIR OC-PAM system is potentially able to provide a unique technique to evaluate the existence of melanin and lipofuscin specifically, a phantom study has been conducted and the relationship between image intensity of OCT and PAM was interpreted to represent the relationship between the optical scattering property and optical absorption property. It will be strong evidence for practical application of the proposed NIR OC-PAM system.
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Shibata, Kosuke. "High-sensitivity in situ imaging of atoms in an optical lattice with narrow optical transitions." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/185216.
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Luo, Haitao. "Snapshot Imaging Polarimeters Using Spatial Modulation." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/193905.
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The recent demonstration of a novel snapshot imaging polarimeter using the fringe modulation technique shows a promise in building a compact and moving-parts-free device. As just demonstrated in principle, this technique has not been adequately studied. In the effort of advancing this technique, we build a complete theory framework that can address the key issues regarding the polarization aberrations caused by using the functional elements. With this model, we can have the necessary knowledge in designing, analyzing and optimizing the systems. Also, we propose a broader technique that uses arbitrary modulation instead of sinusoidal fringes, which can give us more engineering freedom and can be the solution of achromatizing the system. In the hardware aspect, several important progresses are made. We extend the polarimeter technique from visible to middle wavelength infrared by using the yttrium vanadate crystals. Also, we incorporate a Savart Plate polarimter into a fundus camera to measure the human eye's retinal retardance, useful information for glaucoma diagnosis. Thirdly, a world-smallest imaging polarimeter is proposed and demonstrated, which may open many applications in security, remote sensing and bioscience.
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Tingstad, James Scott 1962. "Design of an advanced I.R. catadioptric optical system." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276689.
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This thesis explains and develops the design of a compact 3-5μm catadioptric optical imaging system. This system is intended for use with a two-dimensional array detector that replaces the need for the scan mirrors of a traditional FLIR system. This design also illustrates the complete optical design process. From the basic system requirements, to a complete design with consideration to such items as assembly and alignment, cost, and maintaining focus for a change in the environmental temperature.
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Clements, Ethan Robert. "CHARACTERIZATION OF OPTICAL LATTICES USING PUMP-PROBESPECTROSCOPY AND FLUORESCENCE IMAGING." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1470323164.
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Li, Jia, and 李佳. "Computational imaging technologies for optical lithography extension." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206757.
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With the development and production of integrated circuits at the 22nm node, optical lithography faces increasing challenges to keep up with the specifications on its performance along various metrics, such as pattern fidelity and process window. The past few years saw the emergence of source mask optimization (SMO) as an important technique in computational lithography, which allows lithographers to rise to the challenges by exploiting a larger design space on both mask and illumination configuration, and integrates with methods such as inverse imaging. Yet, many methods that are used to tackle SMO problem arising in the inverse imaging involve heavy computation and slow convergence, making the technique unappealing for full-chip simulations or large circuits. Therefore, the purpose of this research is to take advantage of computational imaging technologies to solve source and mask design problems, extending the lifetime of optical lithography.
The computational burden results in part from identical optimization over the whole mask pattern, consequently, we propose a weighted SMO scheme which applies different degrees of correction in the corresponding regions so that the optimal solutions are reached with fewer iterations. Additionally, undesirably long time is also attributed to the algorithm adopted to solve SMO problem. A fast algorithm based on augmented Lagrangian methods is therefore developed, which use the quasi-Newton method to accelerate convergence, thereby shortening the overall execution time. However, as semiconductor lithography is pushed to even smaller dimensions, mask topography effects have to be taken into account for a more accurate solution of SMO. At this stage, intensive computation is spent mainly in rigorous 3D mask modeling and simulations. To address this issue, we devise an optimization framework incorporating pupil aberrations into SMO procedure, which is performed based on the thin mask model so as to ensure a faster speed.
We apply the above approaches to various mask geometries with different critical dimensions. Compared to conventional SMO, simulation results show that the proposed methods lead to better pattern fidelity and larger process window, especially in rigorous calculations. This demonstrates that the source and mask design generated through our algorithms are more practical. More importantly, the improved performance is not at the cost of speed. Instead, our methods take the least time to achieve it. This allows the advantages of computational imaging technologies to be worth exploring for further applications in optical lithography.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
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Seeger, Mauritius. "3-D imaging using optical coherence radar." Thesis, University of Kent, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263698.
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Hee, Michael Richard. "Biological imaging with low coherence optical interferometry." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12928.
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Brand, Ulrich. "Optical data processing in high-NA imaging." Thesis, King's College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393167.
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Běhounek, Tomáš. "Imaging Reflectometry Measuring Thin Films Optical Properties." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-233857.
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V této práci je prezentována inovativní metoda zvaná \textit{Zobrazovací Reflektometrie}, která je založena na principu spektroskopické reflektometrie a je určena pro vyhodnocování optických vlastností tenkých vrstev .\ Spektrum odrazivosti je získáno z map intenzit zaznamenaných CCD kamerou. Každý záznam odpovídá předem nastavené vlnové délce a spektrum odrazivosti může být určeno ve zvoleném bodu nebo ve vybrané oblasti.\ Teoretický model odrazivosti se fituje na naměřená data pomocí Levenberg~-~Marquardtova algoritmu, jehož výsledky jsou optické vlastnosti vrstvy, jejich přesnost, a určení spolehlivosti dosažených výsledků pomocí analýzy citlivosti změn počátečních nastavení optimalizačního algoritmu.
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Nurgiyatna, Nurgiyatna. "Tomography imaging based on plastic optical fibre." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/tomography-imaging-based-on-plastic-optical-fibre(481b898a-b1dc-49ae-aa3f-3555a982bb75).html.
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Plastic optical fibres (POF) can be made sensitive to various parameters. Therefore, a successful implementation of tomographic imaging based on POF sensors will open the way to develop imagers for various parameters utilising this inexpensive sensor material. The work reported in this thesis is aiming to implement real time tomographic imaging based on the POF sensor. As the system uses light (photons) guided along the sensor to capture the information and deliver a signal at the periphery of the sensor, this technique is referred to as Photonic Guided Path Tomography (PGPT). As an initial stage of the work, we perform systematic testing of the sensitivity of POF transmission to bending. The results confirm that grooving can enhance this sensitivity of the POF sensor. They also provide an empirical proof of the anticipated changes in transmission loss by positive and negative bending for grooved POF (opening and closing of grooves respectively). We show that small positive bending increases the power loss, while for negative bending the power loss experiences a minimum, corresponding to the best achievable waveguiding recovery because of the closing of grooves. Beyond certain deformation, the sensitivity of the POF sensor is dominated by losses in the un-grooved regions. A bending test for the mechanical integrity of grooved POFs shows that repetitive bending to a small radius results in a quick deterioration depending on the depth of the groove. However for bending radii more than 20mm and groove depths up to 0.3mm, the lifetime of the POF sensor is still acceptable for many targeted sensor application.While it is clear that the grooved POF is more sensitive to small bending compared to the un-grooved POF, the latter offers uncompromised mechanical integrity and is more desirable when the highest possible sensitivity is not a priority. Therefore, in the final stage of the work, both grooved and un-grooved POF are considered as candidates for developing the tomographic imaging modality. Further detail is considered in view of the targeted deliverable, a real PGPT system for footstep imaging, based on POF sensors. This has been successfully achieved by designing, integrating and testing two different PGPT systems: one based on grooved POF with sensor head size of 0.9m x 0.9m incorporating a multiplexed photodetector and another based on un-grooved POF with sensor head size of 2m x 1m, incorporating independent POF sensors. Both are capable of performing the real time imaging task as well as storing the numerical data for alternative processing. The image reconstruction is by applying a median-filtered Landweber method to solve the inverse tomography problem. The frame rate achieved is 2Hz and 1Hz with spatial resolution estimated as 10cm and 3cm for the first and second system respectively
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Lee, Seoungjun. "Super-resolution optical imaging using microsphere nanoscopy." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/superresolution-optical-imaging-using-microsphere-nanoscopy(c3b36c86-11b5-4c77-9a69-b966585b0509).html.
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Standard optical microscopes cannot resolve images below 200 nm within the visible wavelengths due to optical diffraction limit. This Thesis reports an investigation into super-resolution imaging beyond the optical diffraction limit by microsphere optical nano-scopy (MONS) and submerged microsphere optical nano-scopy (SMON). The effect of microsphere size, material and the liquid type as well as light illumination conditions and focal plane positions on imaging resolution and magnification have been studied for imaging both biological (viruses and cells) and non-biological (Blu-ray disk patterns and nano-pores of anodised aluminium oxide) samples. In particular, sub-surface imaging of nano-structures (data-recorded Blu-ray) that cannot even be seen by a scanning electron microscope (SEM) has been demonstrated using the SMON technique. Adenoviruses of 75 nm in size have been observed with white light optical microscopy for the first time. High refractive index microsphere materials such as BaTiO3 (refractive index n = 1.9) and TiO2-BaO-ZnO (refractive index n = 2.2) were investigated for the first time for the imaging. The super-resolution imaging of sub-diffraction-limited objects is strongly influenced by the relationship between the far-field propagating wave and the near-field evanescent waves. The diffraction limit free evanescent waves are the key to achieving super-resolution imaging. This work shows that the MONS and SMON techniques can generate super-resolution through converting evanescent waves into propagating wave. The optical interactions with the microspheres were simulated using special software (DSIMie) and finite different in time domain numerical analysis software (CST Microwave Studio). The optical field structures are observed in the near-field of a microsphere. The photonic nanojets waist and the distance between single dielectric microsphere and maximum intensity position were calculated. The theoretical modelling was calculated for comparisons with experimental measurements in order to develop and discover super-resolution potential.
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Lin, Haibo Yu Ping. "Speckle mechanism in holographic optical coherence imaging." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6184.
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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 15, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Ping Yu. Vita. Includes bibliographical references.
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PIAZZA, SIMONLUCA. "Advanced optical systems for imaging and fabrication." Doctoral thesis, Università degli studi di Genova, 2018. http://hdl.handle.net/11567/932054.
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Yang, Zhenyu. "Smartphone-based Optical Sensing." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1461863029.
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Behrooz, Ali. "Multiplexed fluorescence diffuse optical tomography." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50401.
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Fluorescence tomography (FT) is an emerging non-invasive in vivo molecular imaging modality that aims at quantification and three-dimensional (3D) localization of fluorescent tagged inclusions, such as cancer lesions and drug molecules, buried deep in human and animal subjects. Depth-resolved 3D reconstruction of fluorescent inclusions distributed over the volume of optically turbid biological tissue using the diffuse fluorescent photons detected on the skin poses a highly ill-conditioned problem, as depth information must be extracted from boundary data. Due to this ill-posed nature of FT reconstructions, noise and errors in the data can severely impair the accuracy of the 3D reconstructions. Consequently, improvements in the signal-to-noise ratio (SNR) of the data significantly enhance the quality of the FT reconstructions. Furthermore, enhancing the SNR of the FT data can greatly contribute to the speed of FT scans. The pivotal factor in the SNR of the FT data is the power of the radiation illuminating the subject and exciting the administered fluorescent agents. In existing single-point illumination FT systems, the illumination power level is limited by the skin maximum radiation exposure levels. In this research, a multiplexed architecture governed by the Hadamard transform was conceptualized, developed, and experimentally implemented for orders-of-magnitude enhancement of the SNR and the robustness of FT reconstructions. The multiplexed FT system allows for Hadamard-coded multi-point illumination of the subject while maintaining the maximal information content of the FT data. The significant improvements offered by the multiplexed FT system were validated by numerical and experimental studies carried out using a custom-built multiplexed FT system developed exclusively in this work. The studies indicate that Hadamard multiplexing offers significantly enhanced robustness in reconstructing deep fluorescent inclusions from low-SNR FT data.
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LaCasse, Charles. "Modulated Imaging Polarimetry." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/247279.
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In this work, image processing algorithms are presented for an advanced sensor classification known collectively as imaging modulated polarimetry. The image processing algorithms presented are novel in that they use frequency domain based approaches, in comparison to the data domain based approaches that all previous algorithms have employed. Under the conditions on the data and imaging device derived in this work, the frequency domain based demodulation algorithms will optimally reduced reconstruction artifacts in a least squared sense. This work provides a framework for objectively comparing polarimeters that modulate in different domains (i.e. time vs. space), referred to as the spectral density response function. The spectral density response function is created as an analog to the modulation transfer function (or the more general transfer function for temporal devices) employed in the design of conventional imaging devices. The framework considers the total bandwidth of the object to be measured, and then can consider estimation artifacts that arise in both time and space due to the measurement modality that has been chosen. Using the framework for objectively comparing different modulated polarimeters (known as the spectral density response function), a method of developing a Wiener filter for multi-signal demodulation is developed, referred to as the polarimetric Wiener filter. This filter is then shown to be optimal for one extensive test case. This document provides one extensive example of implementing the algorithms and spectral density response calculations on a real system, known as the MSPI polarimeter. The MSPI polarimeter has been published extensively elsewhere, so only a basic system description here is used as necessary to describe how the methods presented here can be implemented on this system.
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Xu, Weiming. "Offset Optical Coherence Tomography." Miami University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=miami1626870603439104.
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Carlini, A. R. "Imaging modes of confocal scanning microscopy." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233485.
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Xu, Wei. "Analog Signal Processing for Optical Coherence Imaging Systems." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195225.
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Optical coherence tomography (OCT) and optical coherence microscopy (OCM) are non-invasive optical coherence imaging techniques, which enable micron-scale resolution, depth resolved imaging capability. Both OCT and OCM are based on Michelson interferometer theory. They are widely used in ophthalmology, gastroenterology and dermatology, because of their high resolution, safety and low cost. OCT creates cross sectional images whereas OCM obtains en face images. In this dissertation, the design and development of three increasingly complicated analog signal processing (ASP) solutions for optical coherence imaging are presented.The first ASP solution was implemented for a time domain OCT system with a Rapid Scanning Optical Delay line (RSOD)-based optical signal modulation and logarithmic amplifier (Log amp) based demodulation. This OCT system can acquire up to 1600 A-scans per second. The measured dynamic range is 106dB at 200A-scan per second. This OCT signal processing electronics includes an off-the-shelf filter box with a Log amp circuit implemented on a PCB board.The second ASP solution was developed for an OCM system with synchronized modulation and demodulation and compensation for interferometer phase drift. This OCM acquired micron-scale resolution, high dynamic range images at acquisition speeds up to 45,000 pixels/second. This OCM ASP solution is fully custom designed on a perforated circuit board.The third ASP solution was implemented on a single 2.2 mm x 2.2 mm complementary metal oxide semiconductor (CMOS) chip. This design is expandable to a multiple channel OCT system. A single on-chip CMOS photodetector and ASP channel was used for coherent demodulation in a time domain OCT system. Cross-sectional images were acquired with a dynamic range of 76dB (limited by photodetector responsivity). When incorporated with a bump-bonded InGaAs photodiode with higher responsivity, the expected dynamic range is close to 100dB.
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Norris, Evan. "Ptychography for Nonlinear Optical Microscopy." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42648.
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In this thesis I will introduce a novel nonlinear optical microscopy method to address some of the shortcomings in the current nonlinear optical microscopy literature and offer a supplement to traditional fluorescent microscopy for label free optical biomedical imaging. In order to demonstrate this method I describe a method for the generation of a numerical sample of collagen fibrils, produce a set of numerical diffraction measurements. I introduce a novel Ptychography model for the simultaneous reconstruction of the components of the nonlinear optical susceptibility tensor and demonstrate the results of this model using numerically generated measurements from a numerical collagen sample. I additionally use the recovered information from Ptychography to retrieve new information about the structure of a sample.
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Schroeter, Matthias. "Enlightening the brain : optical imaging in cognitive neuroscience /." Leipzig ; München : MPI for Human Cognitive and Brain Sciences, 2006. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014995433&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Schuetz, Christopher Arnim. "Optical techniques for millimeter-wave detection and imaging." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 179 p, 2007. http://proquest.umi.com/pqdweb?did=1397913011&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Haniff, Christopher Allim. "High-resolution imaging with ground-based optical telescopes." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238537.
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D'Esposito, Angela Maria. "Development of three-dimensional, ex vivo optical imaging." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1566767/.
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The ability to analyse tissue in 3-D at the mesoscopic scale (resolution: 2-50 μm) has proven essential in the study of whole specimens and individual organs. Techniques such as ex vivo magnetic resonance imaging (MRI) and X-ray computed tomography (CT) have been successful in a number of applications. Although MRI has been used to image embryo development and gene expression in 3-D, its resolution is not sufficient to discriminate between the small structures in embryos and individual organs. Furthermore, since neither MRI nor X-ray CT are optical imaging techniques, none of them is able to make use of common staining techniques. 3-D images can be generated with confocal microscopy by focusing a laser beam to a point within the sample and collecting the fluorescent light coming from that specific plane, eliminating therefore out-of-focus light. However, the main drawback of this microscopy technique is the limited depth penetration of light (~1 mm). Tomographic techniques such as optical projection tomography (OPT) and light sheet fluorescence microscopy (also known as single plane illumination microscopy, SPIM) are novel methods that fulfil a requirement for imaging of specimens which are too large for confocal imaging and too small for conventional MRI. To allow sufficient depth penetration, these approaches require specimens to be rendered transparent via a process known as optical clearing, which can be achieved using a number of techniques. The aim of the work presented in this thesis was to develop methods for threedimensional, ex vivo optical imaging. This required, in first instance, sample preparation to clear (render transparent) biological tissue. In this project several optical clearing techniques have been tested in order to find the optimal method per each kind of tissue, focusing on tumour tissue. Indeed, depending on its structure and composition (e.g. amount of lipids or pigments within the tissue) every tissue clears at a different degree. Though there is currently no literature reporting quantification of the degree of optical clearing. Hence a novel, spectroscopic technique for measuring the light attenuation in optically cleared samples is described in this thesis and evaluated on mouse brain. 5 Optical clearing was applied to the study of cancer. The main cancer model investigated in this report is colorectal carcinoma. Fluorescently labelled proteins were used to analyse the vascular network of colorectal xenograft tumours and to prove the effect of vascular disrupting agents on the vascular tumour network. Furthermore, optical clearing and fluorescent compounds were used for ex vivo analysis of perfusion of a human colorectal liver metastasis model.
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Gil, Darío 1975. "Maskless nanolithography and imaging with diffractive optical arrays." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/18066.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 221-228).
Semiconductor lithography is at a crossroads. With mask set costs in excess of one million dollars, long mask turn-around times, and tools that are characterized by their inflexibility and skyrocketing costs, there is a need for a new paradigm in lithography. The work presented in this thesis, Zone-Plate-Array Lithography (ZPAL), bypasses some of the most pressing problems of current lithography equipment by developing a maskless lithography tool that will be scalable, flexible and cost-effective. It is the departure from a century-old tradition of refractive optics, in combination with the use of advanced micromechanics and fast computing, that enables ZPAL to open up a new application space in lithography. This thesis addresses in detail all levels of the ZPAL system, from the micromechanics, to the diffractive optics, to the control system. Special emphasis is placed on the design, fabrication and characterization of high-numerical-aperture diffractive optical elements for lithography and imaging. The results achieved provide conclusive evidence that diffractive optics in general, and zone plates in particular, are capable of state-of-the-art lithography.
by Darío Gil.
Ph.D.
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Licitra, Rossella. "Galaxy cluster detection with optical and infrared imaging." Paris 7, 2014. http://www.theses.fr/2014PA077149.
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En tant que structures gravitationnellement liées les plus massives, les amas de galaxies permettent de poser des contraintes fortes sur les structures à grande échelle prédites par le modèle cosmologique standard. Ils permettent aussi de comprendre l'influence de l'environnement sur l'évolution des galaxies. Pour mener ce type d'étude et obtenir des résultats robustes, il est impératif de construire des catalogues d'amas complets et purs. Dans le présent manuscrit, je décris l'algorithme de détection d'amas que j'ai développé lors de ma thèse de doctorat -Red GOLD ainsi que les résultats que j'ai obtenus en l'appliquant aux relevés multi-longueur d'onde. Mon algorithme est fondé sur la détection de surdensités de galaxies et la caractérisation de leur séquence rouge : il détecte les surdensités de galaxies rouges par rapport à la distribution moyenne des galaxies. Je sélectionne les galaxies rouges à l'aide des couleurs prédites par les modèles de population stellaire, en imposant des coupes en couleur en fonction du redshift. Parmi ces galaxies, j'identifie celles ayant un type spectral correspondant à des galaxies de type précoce. J'ai appliqué Red-GOLD à des données dans le visible venant de deux relevés diférents, le Next Generation Virgo Cluster Survey (NGVS) et le Canada-France-Hawaii Telescope Lensing Survey (CFHTLS) et j'ai détecté des candidats amas jusqu'à z~1. J'ai estimé les performances de mon algorithme en l'appliquant aux catalogues de galaxies simulées issus des simulations Millenium. Mon catalogue d'amas est complet à ~ 80 % jusqu'à z=1 et pur à 81%Being galaxy clusters the most massive bound structures in the Universe, they represent a powerful tool to probe the large-scale structure predicted by the standard cosmological model, and to understand how environmental effects affect galaxy evolution. To conduct these studies and obtain reliable results, it is important to build complete and pure cluster catalogs. The use of these catalogs for cosmology requires accurate estimates of cluster mass. In this work, I describe the cluster detection algorithm that I developed during my PhD thesis : Red-GOLD, and the results that I obtained by applying i to current multi-wavelength surveys. My algorithm is based on the detection of galaxy overdensities and the characterisation of their red-sequence. The algorithm finds red galaxy overdensities with respect to the mean background. I select red galaxies using color predictions given by stellar population synthesis models and impose color limits as a function of redshift. Among those galaxies, I discern the early-type galaxies from their spectral type. I then identify cluster members using accurate photometric redshifts, and estimate the cluster candidate richness. I applied Red-GOLD to optical data coming from two different surveys, the Next Generatiôn Virgo Cluster Survey (NGVS) and the Canada-France-Hawaii Telescope Lensing Survey (CFHTLS) and detected galaxy cluster candidates up to redshift z=1. I assessed the performances of my algorithm by applying it to simulated galaxy catalogs from the Millennium simulations. My cluster catalogue is complete at the 80% up to redshift z=1 and pure at 81%
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Jenkins, Michael W. "Imaging the Embryonic Heart with Optical Coherence Tomography." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1207340565.
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Liu, Yehe. "System and Process Optimization for Biomedical Optical Imaging." Case Western Reserve University School of Graduate Studies / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=case162556700760192.
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Foreman, Matthew Roy. "Informational limits in optical polarimetry and vectorial imaging." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5748.
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Light has provided the means to learn and gather information about the physical world throughout history. In a world where science moves to smaller scales and more specialised problems however, the boundaries of current technology are continually challenged, motivating the search for more sophisticated systems providing greater information content, sensitivity and increased dimensionality. Utilising the vectorial nature of light presents a promising avenue by which to meet these growing requirements. Polarisation can, for example, be used to transmit information, or alternatively, changes in polarisation induced by an object allow study of previously neglected material properties, such as birefringence and diattenuation. Central to this thesis is thus the characterisation and exploitation of the opportunities afforded by the electromagnetic (i.e. vectorial) nature of light. To this end the work follows three running themes: quantification of polarisation information; formulation of simple propagation tools for electromagnetic waves; and development of specific polarisation based optical systems. Characterising the informational limits inherent to polarisation based systems reduces to considering the uncertainty present in any observations. Uncertainty can, for example, arise from stochastic variation in the polarisation state being measured, or from random noise perturbations upon detection. Both factors are considered and quantified here. Development of vectorial optical systems does, however, pose significant difficulties in modelling, due to mathematical complexity and computational requirements. A number of new tools are hence developed, as prove applicable to a wide variety of applications. Examples are naturally given. To illustrate the potential of polarisation based systems, specific current topics are discussed; namely the growing demand for data storage, and single molecule studies. It will be shown that polarisation, can not only be used to multiplex information in data pits on optical media, but also to allow full 3D study of single molecules. Factors pertinent to such studies are studied in detail.
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Koh, Kevin Rongsheng. "Multimodal multispectral optical endoscopic imaging for biomedical applications." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/6330.
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Optical imaging is an emerging field of clinical diagnostics that can address the growing medical need for early cancer detection and diagnosis. Various human cancers are amenable to better prognosis and patient survival if found and treated during early disease onset. Besides providing wide-field, macroscopic diagnostic information similar to existing clinical imaging techniques, optical imaging modalities have the added advantage of microscopic, high resolution cellular-level imaging from in vivo tissues in real time. This comprehensive imaging approach to cancer detection and the possibility of performing an ‘optical biopsy’ without tissue removal has led to growing interest in the field with numerous techniques under investigation. Three optical techniques are discussed in this thesis, namely multispectral fluorescence imaging (MFI), hyperspectral reflectance imaging (HRI) and fluorescence confocal endomicroscopy (FCE). MFI and HRI are novel endoscopic imaging-based extensions of single point detection techniques, such as laser induced fluorescence spectroscopy and diffuse reflectance spectroscopy. This results in the acquisition of spectral data in an intuitive imaging format that allows for quantitative evaluation of tissue disease states. We demonstrate MFI and HRI on fluorophores, tissue phantoms and ex vivo tissues and present the results as an RGB colour image for more intuitive assessment. This follows dimensionality reduction of the acquired spectral data with a fixed-reference isomap diagnostic algorithm to extract only the most meaningful data parameters. FCE is a probe-based point imaging technique offering confocal detection in vivo with almost histology-grade images. We perform FCE imaging on chemotherapy-treated in vitro human ovarian cancer cells, ex vivo human cancer tissues and photosensitiser-treated in vivo murine tumours to show the enhanced detection capabilities of the technique. Finally, the three modalities are applied in combination to demonstrate an optical viewfinder approach as a possible minimally-invasive imaging method for early cancer detection and diagnosis.
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Lessard, Guillaume Quake Stephen R. "Apertureless near-field optical microscopy for fluorescence imaging /." Diss., Pasadena, Calif. : California Institute of Technology, 2003. http://resolver.caltech.edu/CaltechETD:etd-05302003-145931.
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Lin, Yuxiang. "DEVELOPMENT AND ANALYSIS OF OPTICAL PH IMAGING TECHNIQUES." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/193846.
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The pH of tumors and surrounding tissues is a key biophysical property of the tumor microenvironment that affects how a tumor survives and how it invades the surrounding space of normal tissue. Research into tumorigenesis and tumor treatment is greatly dependent on accurate, precise, and reproducible measurements. Optical imaging is generally regarded as the best choice for non-invasive and high spatial resolution measurements. Ratiometric fluorescence imaging and fluorescence lifetime imaging microscopy (FLIM) are two primary ways for measuring tumor pH.pH measurements in a window chamber animal model using a ratiometric fluorescence imaging technique is demonstrated in this dissertation. The experimental setup, imaging protocols, and results are presented. A significantly varying bias was consistently observed in the measured pH. A comprehensive analysis on the possible error sources accounting for this bias is carried out. The result of analysis reveals that accuracy of ratiometric method is most likely limited by biological and physiological factors.FLIM is a promising alternative because the fluorescence lifetime is insensitive to the biological and physiological factors. Photon noise is the predominant error source of FLIM. The Fisher information matrix and the Cramér-Rao lower bound are used to calculate the lowest possible variance of estimated lifetime for time-domain (TD) FLIM. A statistical analysis of frequency-domain (FD) FLIM using homodyne lock-in detection is also performed and the probability density function of the estimated lifetime is derived. The results allow the derivation of the optimum experimental parameters, which yields the lowest variance of the estimated lifetime in a given period of imaging time. The analyses of both TD and FD-FLIM agree with results of corresponding Monte Carlo simulations.
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Hummert, Stephanie Maria. "Magneto-Optical Imaging of Superconducting MgB2 Thin Films." W&M ScholarWorks, 2007. https://scholarworks.wm.edu/etd/1539626854.
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