1. Articles in category: Student Theses

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    1. Techniques in Optical Coherence and Resonance for Sensing (Thesis)

      Techniques in Optical Coherence and Resonance for Sensing (Thesis)

      Optical sensors are ubiquitous for their precision and non-contact acquisition, and have enjoyed widespread use in applications such as biosensing, environmental monitoring, and security. Despite their sensitivity, many of these sensors rely on costly laboratory instrumentation, and are not adaptable to the ever-growing volume of consumer detectors and optics that are readily available, making their application limited to benchtop analytics. This work leverages plasmonic resonances and optical coherence phenomena to make modifications upon traditional sensing formats that improve their sensitivity when deployed in off-the-shelf optical systems. In particular, we demonstrate that label-free plasmonic sensors can be combined with electrochemical impedance ...

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    2. Improving optical coherence tomography theories and techniques for advanced performance and reduced cost (Thesis)

      Improving optical coherence tomography theories and techniques for advanced performance and reduced cost (Thesis)

      Optical coherence tomography (OCT) has been developed as a high-resolution three-dimensional imaging technique for clinical diagnosis. This thesis proposes several theoretical discoveries and technical improvements to the current OCT systems aiming to drastically reduce system costs while achieving the state-of-the-art performance. Polarization-sensitive OCT (PS-OCT) is a functional extension of conventional OCT which offers the depth-resolved birefringence imaging capability. To resolve local retardation in tissue samples, the current PS-OCT system employs two multiplexed polarization states to illuminate the sample under investigation and detects the backscattered light with two detection channels. We observed that the polarization state of light after round-trip propagation ...

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    3. Optical Coherence Photoacoustic Microscopy (OC-PAM) for Multimodal Imaging (Thesis)

      Optical Coherence Photoacoustic Microscopy (OC-PAM) for Multimodal Imaging (Thesis)

      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 ...

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    4. Parapapillary Atrophy : prevalence and distribution of alpha, beta and gamma parapapillary atrophy identified by the means of spectral domain optical coherence tomography (SD-OCT) (Thesis)

      Parapapillary Atrophy : prevalence and distribution of alpha, beta and gamma parapapillary atrophy identified by the means of spectral domain optical coherence tomography (SD-OCT) (Thesis)

      Purpose: The purpose of this study was to estimate the prevalence and distribution of alpha, beta and gamma parapapillary atrophy in diabetic adults over the age of 40 years, as identified by the means of spectral domain optical coherence tomography (SD-OCT). Methods: All subjects underwent anamnesis, subjective binocular refraction and imaging with SD-OCT in both eyes. The obtained OCT sections provided 24 degree sections for assessment of the parapapillary retina, which were analysed for the presence of alpha, beta and gamma parapapillary atrophy. Results: 135 eyes of 70 subjects, with mean age of 61.33 years (range: 43-81, SD: 9 ...

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    5. DEEP LEARNING OPTIMIZATION FOR OPTICAL COHERENCE TOMOGRAPHY MEDICAL IMAGE ANALYSIS (Thesis)

      DEEP LEARNING OPTIMIZATION FOR OPTICAL COHERENCE TOMOGRAPHY MEDICAL IMAGE ANALYSIS (Thesis)

      Optical Coherence Tomography (OCT) is an interferometric imaging modality that can visualize biological microstructure via cross-sectional images. OCT can construct 3D image data and produce a concise summary of the scanned objects. Because of the non-invasiveness and swift diagnostic procedure, OCT becomes a high potential technology for the real-time surgery guidance. Machine learning algorithms have been widely applied and investigated for automatic medical image analysis. This research proposes two deep learning models for OCT human tissue image classification. Based on the inception module structure, a deep dilated depthwise separable convolution neural network (DDSCN) model is proposed to combine the strength ...

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    6. Quantitative Phase Imaging of Biological Samples using Optical Coherence Tomography (Thesis)

      Quantitative Phase Imaging of Biological Samples using Optical Coherence Tomography (Thesis)

      Advancement in the diagnostic techniques is required for early detection of the disease which will avoid the many risks to patients. This thesis research work describes a novel imaging technique for quantitative phase imaging of the biological samples. We developed a full-field optical spatial coherence microscopy (FF-OSCM) system based on monochromatic laser. The system is characterized in terms of axial resolution, lateral resolution, phase sensitivity and phase stability. The developed system exploits the property of spatial coherence and its performance is comparable to the conventional optical coherence microscopy based on temporal coherence. The system is used for the quantification of ...

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    7. The multi-spectral signal properties of multiple reference optical coherence tomography (Thesis)

      The multi-spectral signal properties of multiple reference optical coherence tomography (Thesis)

      Efforts to reduce the size and costs of optical coherence tomography systems (OCT) for consumer applications, in general, focus on Fourier-domain OCT, due to its potential to be integrated on an optical chip, implementing the interferometer and the spectrometer together as a compact system. An alternative and near-term solution is multiple reference OCT. This technique utilizes a partial mirror in the reference arm to enhance the axial imaging depth of traditional time-domain OCT. The motivation of this thesis is to investigate the performance and sensitivity characteristics of multiple reference OCT in comparison to time-domain OCT. Due to the partial mirror ...

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    8. Dual modality optical coherence tomography : Technology development and biomedical applications (Thesis)

      Dual modality optical coherence tomography : Technology development and biomedical applications (Thesis)

      Optical coherence tomography (OCT) is a cross-sectional imaging modality that is widely used in clinical ophthalmology and interventional cardiology. It is highly promising for in situ characterization of tumor tissues. OCT has high spatial resolution and high imaging speed to assist clinical decision making in real-time. OCT can be used in both structural imaging and mechanical characterization. Malignant tumor tissue alters morphology. Additionally, structural OCT imaging has limited tissue differentiation capability because of the complex and noisy nature of the OCT signal. Moreover, the contrast of structural OCT signal derived from tissue’s light scattering properties has little chemical specificity ...

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    9. Computational Methods to Quantify Human Lens Shape and Optical Properties Using Laser Ray Tracing and Optical Coherence Tomography (Thesis)

      Computational Methods to Quantify Human Lens Shape and Optical Properties Using Laser Ray Tracing and Optical Coherence Tomography (Thesis)

      Vision is worsening on a global scale. Myopia, a visual condition where distant objects appear blurry, is increasing in prevalence at an alarming rate. This condition typically starts during childhood and progressively worsens, potentially leading to more severe visual conditions if left unchecked. Currently, the best treatment method to slow myopic progression is heavily debated as the etiology of myopia is not fully understood. The development of effective long-term solutions require a better understanding of how vision changes with age. The cornea and lens, the length of the human eye, and the surrounding ocular media dictate visual quality. Extensive studies ...

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    10. A Novel Use of Optical Coherence Tomography for the Assessment of Ocular Torsion (Thesis)

      A Novel Use of Optical Coherence Tomography for the Assessment of Ocular Torsion (Thesis)

      Abnormal ocular torsion is most frequently the result paresis of the fourth cranial nerve. The presence of torsion can be a barrier to fusion, in which case, surgical intervention is required for a patient to have single vision. Clinically, ocular torsion can be measured either subjectively or objectively, the latter traditionally using the relationship between the fovea and the optic disc. However, previous literature has shown inconsistencies between torsion a patient’s perceived subjective torsion, and the amount of anatomical fundus torsion. Therefore, the aim of the current study was to investigate the relationship of subjective and objective ocular torsion ...

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    11. SPECTRAL CALIBRATION FOR SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY BASED ON B-SCAN DOPPLER SHIFT WITH IN SITU. TISSUE IMAGES (Thesis)

      SPECTRAL CALIBRATION FOR SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY BASED ON B-SCAN DOPPLER SHIFT WITH IN SITU. TISSUE IMAGES (Thesis)

      We propose a simple method of linearizing spectral interference fringes of spectral domain optical coherence tomography (SDOCT) based on B-scan Doppler frequency shift (DFS), which can be obtained by offsetting the laser beam from the pivot of a scanning mirror. We show that DFS is proportional to wavenumber. A DFS curve can be then extracted from either a single mirror image or multiple tissue images. By examining the convergence of the nonlinear coefficients of the DFS curve fitted with a polynomial equation, in situ. tissue images themselves can be used to linearize the wavenumber without requiring mirror images or additional ...

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    12. Application of optical coherence tomography for improved in-situ flaw detection in nylon 12 selective laser sintering (Thesis)

      Application of optical coherence tomography for improved in-situ flaw detection in nylon 12 selective laser sintering (Thesis)

      Despite significant advances made since the inception of selective laser sintering (SLS), many of the same problems identified by early researchers including high part porosity, inadequate surface finish, and part strength uncertainty persist today. Because of these challenges, quality validation and improved process control continue to be identified as critical areas of improvement in industry roadmaps. To address these issues, an optical coherence tomography (OCT) sensor is investigated for feasibility of use in in-situ flaw detection in SLS. Benchtop OCT imaging of nylon in solid, liquid, and resolidified phases revealed subsurface imaging through liquid and resolidified nylon material was possible ...

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    13. Co-alignment of detectors in dual-channel spectrometers by optical coherence tomography (Thesis)

      Co-alignment of detectors in dual-channel spectrometers by optical coherence tomography (Thesis)

      This work presents a method for detectors co-alignment in dual-channel spectrometer using optical coherence tomography. The method is proposed for the ELOIS (Enhanced Light Offner Imaging Spectrometer) developed by the AMOS company (Advance Mechanical and Optical Systems). This company designs and builds optical components and instruments related to the space industry and one of their current project is the ELOIS instrument. A crucial aspect in the development of the instrument is the correct alignment of the focal plane assembly components. During this phase, the two detectors of the spectrometer need to be correctly co-aligned with each other in the six ...

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    14. Quantification of Ciliary Muscle Function through Morphological Analysis of Optical Coherence Tomography Images (Thesis)

      Quantification of Ciliary Muscle Function through Morphological Analysis of Optical Coherence Tomography Images (Thesis)

      s we grow older, we lose our ability to accommodate, or focus from far to near, in a condition called presbyopia. Presbyopia is an issue in our everyday life, complicating routine tasks such as using smartphones or reading street signs while driving. To develop effective therapies to treat presbyopia, we need to understand the changes in the eye that occur with age. We need to be able to observe the eye in vivo as accommodation occurs. The present dissertation focuses on the part of the eye responsible for starting the mechanics of accommodation, the ciliary muscle. Imaging of the muscle ...

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    15. Application of Multi-Tonal Complex with Optical Coherence Tomography Imaging System for Vibrometric Analysis of Inner-Ear Structures (Thesis)

      Application of Multi-Tonal Complex with Optical Coherence Tomography Imaging System for Vibrometric Analysis of Inner-Ear Structures (Thesis)

      Currently, research is being conducted on single tone sound transduction within the auditory portion of the inner ear, the cochlea [1]. The study of cochlear mechanics in large rodents has provided important insight into cochlear function [1]. Additionally, multi-tone stimuli can provide a new perspective in vibrometric analyses that could be used in audiometry as a measure of hearing loss for patients in terms of both magnitude and their unique frequency envelope. Therefore, the proposed study was aimed to test the recent implementation of multitone calibration into an existing python program, PyVib2, which was used during Optical Coherence Tomography (OCT ...

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    16. Fiber-optic probe and bulk-optics Spectral Domain Optical Coherence tomography systems for in vivo cochlear mechanics measurements (Thesis)

      Fiber-optic probe and bulk-optics Spectral Domain Optical Coherence tomography systems for in vivo cochlear mechanics measurements (Thesis)

      Acquiring the motions of the inner ear sensory tissues provides insight to how the cochlea works. For this purpose, Spectral Domain Optical Coherence Tomography (SDOCT) is an ideal tool as it has a penetration depth of several millimeters. SDOCT can not only image inside the cochlear partition, but also measure the sample structures’ simultaneous displacements. We customized a commercial Spectral Domain Optical Coherence Tomography system for such functions and detailed the software and hardware steps so this powerful system could be more accessible to auditory researchers. The cochlea is surrounded by bones and tissues, and damage to it would make ...

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    17. Title Automated Plaque Characterization of Intravascular Optical Coherence Tomography (IVOCT) Images Using 3D Cryo-image/Histology Validation (Thesis)

      Title Automated Plaque Characterization of Intravascular Optical Coherence Tomography (IVOCT) Images Using 3D Cryo-image/Histology Validation (Thesis)

      Intravascular optical coherence tomography (IVOCT) is a high-resolution (10-20 µm), high-contrast, catheter-based imaging technology that can identify major coronary plaques types (fibrous, lipid, and calcium). However, with >500 images generated in a single 2.5 second scan, automation is needed to facilitate live-time clinical use and off-line assessment of drug therapeutics. Therefore, we developed machine learning approaches for automated plaque characterization using cryo-imaging/histology for validation. However, we confronted a challenge in that IVOCT images are obtained perpendicular to the imaging catheter, while cryo-image volumes display the true 3D vessel geometry at a higher sampling rate. Our solution was to ...

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    18. Development of High-Speed Optical Coherence Tomography for Time-Lapse Nondestructive Characterization of Samples (Thesis)

      Development of High-Speed Optical Coherence Tomography for Time-Lapse Nondestructive Characterization of Samples (Thesis)

      Yongyang Huang received his B.S. degree in Physics at Peking University in July 2013. Since September 2013, he has been a Ph.D student in the Department of Electrical & Computer Engineering (ECE) in Lehigh University. His research area is focused on optical coherence tomography (OCT) and its applications in biomedical imaging.

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    19. Biomedical optical techniques for intracochlear cellular imaging (Thesis)

      Biomedical optical techniques for intracochlear cellular imaging (Thesis)

      Imaging the inner ear microanatomy is of great importance for the assessment of the state of the cells responsible for sound detection. Hearing disorders are mainly due to a malfunction of the cochlea, the bone containing the cells inside the inner ear. Under this situation, using suitable imaging techniques would be extremely helpful in detecting disease and diagnosing pathologies of the inner ear. However, cochlear small size and encasement in bone provide challenging obstacles, preventing visualization of intracochlear microanatomy using standard clinical imaging modalities. In this thesis, we explore optical techniques to image inner ear cells and we report an ...

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    20. Early Phase Disease Modification Trials with Selisistat and Optical Coherence Tomography as a Biomarker in Huntington’s Disease (Thesis)

      Early Phase Disease Modification Trials with Selisistat and Optical Coherence Tomography as a Biomarker in Huntington’s Disease (Thesis)

      Huntington’s disease (HD) is a monogenic neurodegenerative disorder with no known cure. Selisistat is a novel, highly potent Sirt1 inhibitor with supportive pre-clinical data. Facilitation of autophagy and amelioration of transcriptional dysregulation are proposed as mechanisms of action. A first in disease Phase 1B study showed safety and tolerability. The peripheral immune dysfunction in HD could be modulated by Sirtuins which have both pro and anti-inflammatory activities. However selisistat did not alter the cytokine profile in this study. Phase 2 data over a longer duration was also well tolerated however potential hepatotoxicity is a concern. Sub-analysis of clinical assessments ...

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    21. Design and development of optical reflectance spectroscopy and optical coherence tomography catheters for myocardial tissue characterization (Thesis)

      Design and development of optical reflectance spectroscopy and optical coherence tomography catheters for myocardial tissue characterization (Thesis)

      atheter ablation therapy attempts to restore sinus rhythm in arrhythmia patients by producing site-specific tissue modification along regions which cause abnormal electrical activity. This treatment, though widely used, often requires repeat procedures to observe long-term therapeutic benefits. This limitation is driven in part by challenges faced by conventional schemes in validating lesion adequacy at the time of the procedure. Optical techniques are well-suited for the interrogation and characterization of biological tissues. In particular, optical coherence tomography (OCT) relies on coherence gating of singly-scattered light to enable high-resolution structural imaging for tissue diagnostics and procedural guidance. Alternatively, optical reflectance spectroscopy (ORS ...

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    22. Characterization and modeling of the human left atrium using optical coherence tomography (Thesis)

      Characterization and modeling of the human left atrium using optical coherence tomography (Thesis)

      With current needs to better understand the interaction between atrial tissue microstructure and atrial fibrillation dynamics, micrometer scale imaging with optical coherence tomography has significant potential to provide further insight on arrhythmia mechanisms and improve treatment guidance. However, optical coherence tomography imaging of cardiac tissue in humans is largely unexplored, and the ability of optical coherence tomography to identify the structural substrate of atrial fibrillation has not yet been investigated. Therefore, the objective of this thesis was to develop an optical coherence tomography imaging atlas of the human heart, study the utility of optical coherence tomography in providing useful features ...

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    23. Evaluation of Transfer Learning for Classification of: (1) Diabetic Retinopathy by Digital Fundus Photography and (2) Diabetic Macular Edema, Choroidal Neovascularization and Drusen by Optical Coherence Tomography (Thesis)

      Evaluation of Transfer Learning for Classification of: (1) Diabetic Retinopathy by Digital Fundus Photography and (2) Diabetic Macular Edema, Choroidal Neovascularization and Drusen by Optical Coherence Tomography (Thesis)

      Deep learning has been successfully applied to a variety of image classification tasks. In the last few years, starting with the ground-breaking results of AlexNet at the ImageNet Large Scale Visual Recognition Challenge (ILSVRC), there has been tremendous and rapid growth in deep learning and its potential applications. There has been keen interest to apply deep learning in the medical domain, particularly specialties that heavily utilize imaging, such as dermatology, pathology, radiology, and ophthalmology. One issue that may hinder application of deep learning to the medical domain is the vast amount of data necessary to train deep neural networks (DNNs ...

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    24. Share your OCT Thesis on OCT News

      Share your OCT Thesis on OCT News

      OCT News is seeking links to bachelors, masters, and PhD theses in the area of "Optical Coherence Tomography". Traditionally student theses contain a great wealth of information but are rarely accessible to the OCT community. If you or someone you know wrote an OCT thesis and would like to share it with the community please submit a link or PDF using the "Contact OCT News" tab in the main menu bar or the feedback link in the footer and we will include it here: Student Theses. Thesis will only be included if the link is free of charge to users.

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