Download or read book High Speed Swept Source Optical Coherence Tomography Handheld Instrument at 1310nm for Point of care Imaging written by Patrick Wai-Kit Yiu and published by . This book was released on 2018 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is a novel biomedical imaging technique that functions as a type of "optical biopsy" by using low coherence interferometry to non-invasively generate high resolution cross-sectional images of tissue in real time. OCT has become a standard diagnostic tool in ophthalmology and investigators have demonstrated OCT in a variety of biomedical applications including cardiology, gastroenterology, dermatology, and urology. Recent research advances in swept source lasers have enabled swept source OCT (SS-OCT) to achieve imaging speeds 5-50x faster than commercially available spectral domain OCT (SD-OCT) systems. This thesis describes the design of a handheld SS-OCT instrument for portable-real-time imaging in situ at the point of care. Traditional OCT devices require bulky table-mounted systems, but the handheld device has the potential to be used as an advanced point-of-care diagnostic instrument in primary care settings or intraoperatively. The combination of the wide scanning angle in the handheld and the high imaging speed of SS-OCT could allow for screening of pathology with a single volumetric data set spanning the areas of interest on the patient. The compact, easy-to-use form factor could enable the adoption of SS-OCT in settings like primary care clinics or the surgical theater where space is limited. Emergent applications can include intraoperative assessment of kidney transplant viability, as many donor kidneys suffer ischemic insult while awaiting transplant and there is a critical clinical need for a reliable, real-time assay to evaluate donor kidney viability and predict post-transplant outcome.

Download or read book High Speed Handheld Instrument for Ophthalmic Optical Coherence Tomography written by Chen David Lu and published by . This book was released on 2013 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is a non-contact, high resolution biomedical imaging technique that uses low coherence interferometry to generate cross-sectional images of tissue. OCT has become a standard tool in ophthalmology for imaging the retina to detect or monitor pathologies. Recent research advances in swept source lasers have allowed swept source OCT (SS-OCT) to have 5-50x faster imaging speeds when compared to SD-OCT commercial systems. This thesis describes the design of a handheld SS-OCT instrument to screen for retinal diseases. Many retinal diseases are asymptomatic in their early stages and remain undetected until they advance to cause irreversible vision loss. Early detection and treatment of these diseases can prevent permanent damage to the retina. While OCT has been proven effective at diagnosing retinal pathology, most commercial systems are bulky and table mounted, limiting their screening capabilities. The compact and easy to use handheld device can be used to quickly screen patients outside of the ophthalmology clinic in primary care, pediatrics applications, or in the field in developing countries. A custom motion registration algorithm corrects for the additional operator motion in the images. The wide scanning angle combined with the high imaging speeds used in SS-OCT allows screening of pathology with a single volumetric data set spanning the areas of interest on the retina.

Download or read book High speed Phase stable Swept Source Optical Coherence Tomography written by Yuye Ling and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We thus came up with an idea of applying the compressive sensing (CS) to reduce the data size. Currently, we have demonstrated some preliminary results with using CS on reference k-clock channel compression. In the future, we will apply the same theory to compress the sample channel data, especially or time lapse OCT imaging.

Download or read book SWEPT SOURCE OPTICAL COHERENCE written by Luoqin Yu and published by Open Dissertation Press. This book was released on 2017-01-26 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Swept Source Optical Coherence Tomography System Development for Bioimaging Applications" by Luoqin, Yu, 俞罗琴, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Optical coherence tomography (OCT) is an imaging modality with strengths in high-resolution, label-free, and noninvasive, which strategically fills the gap between ultrasound and microscopy and is superior for some biomedical applications. Swept source OCT (SS-OCT) improves system simplicity and sensitivity compared to previous versions of time domain OCT (TD-OCT) because of a static reference mirror and has faster imaging speed compared to spectral domain OCT (SD-OCT) because of a single photodetector and the availability of high-repetition-rate broadband lasers. Furthermore, functional spectroscopic OCT (SOCT) analyzes materials according to their specific optical properties at different wavelengths. Thus, by utilizing an ultra-wide band OCT and analyzing the sub-band images, it provides us a spectroscopic way to recognize materials. These kinds of newly developed OCT systems are quite promising in clinical bioimaging applications. One of the most commonly used swept sources in SS-OCT systems is the Fourier domain mode-locked (FDML) laser. It has a narrow instantaneous linewidth that improves imaging range, a broad sweeping range that renders high resolution, fast building up time that enables fast scanning, and a proper output power. However, traditional FDML lasers have limited sweeping range because of a limited amplification window of the gain medium that is usually unable to achieve an ultra-wide wavelength range. It hinders its way in spectroscopic imaging applications. Nevertheless, multi-band illumination can break through the bandwidth limitation of single-band SOCT. Consequently, developing swept sources with various output wavelength ranges is of high interest. The FDML lasers with output at 1.0 m range are most suitable in water-rich tissues where water dispersion and absorption are minimized. Thus, 1.0 m FDML laser cavities are firstly proposed with different amplification schemes to compare their performances. Dual-and tri-band SS-OCT systems for SOCT application are further investigated for contrast enhancement and differentiation of materials, such as lipid and porcine artery. Not only the output wavelength ranges of swept sources are of big concern, the swept speed is another bottleneck yet to be surpassed, especially for endoscopic applications. As the mechanical inertia of FDML lasers will limit the fundamental A-scan rate to hundreds of kilohertz, an ultrafast mode-locked laser together with inertia-free optical time-stretch mechanism is a promising alternative for SS-OCT endoscopic application. It has long imaging range and allows an A-scan rate up to more than ten megahertz. We further demonstrated this kind of amplified optical time-stretch (AOT) OCT with extensional application by endoscopic imaging. In summary, the goal of this thesis is to develop and extend SS-OCT systems in different aspects for various bioimaging applications. The SS-OCT systems with different advantages are proposed for spectroscopic and endoscopic imaging. Subjects: Imaging systems in medicine Optical coherence tomography

Download or read book Optical Coherence Tomography and Its Non medical Applications written by Michael Wang and published by BoD – Books on Demand. This book was released on 2020-05-27 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is a promising non-invasive non-contact 3D imaging technique that can be used to evaluate and inspect material surfaces, multilayer polymer films, fiber coils, and coatings. OCT can be used for the examination of cultural heritage objects and 3D imaging of microstructures. With subsurface 3D fingerprint imaging capability, OCT could be a valuable tool for enhancing security in biometric applications. OCT can also be used for the evaluation of fastener flushness for improving aerodynamic performance of high-speed aircraft. More and more OCT non-medical applications are emerging. In this book, we present some recent advancements in OCT technology and non-medical applications.

Download or read book Atlas of Swept Source Optical Coherence Tomography written by Zofia Michalewska and published by Springer. This book was released on 2017-03-21 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This atlas presents an overview of Swept Source Optical Coherence Tomography (OCT) and its implications on diagnostics of vitreous, retina and choroid. As the sensitivity of OCT imaging devices has increased, updated technologies have become available for engineers, scientists and medical specialists to adopt, and recent developments have led to the creation of a new generation of devices. The aim of this resource is to explain this new technology and its advantages over previous imaging devices and to illustrate how it may be used in to define eye diseases, aid in their treatment and facilitate treatment options.

Download or read book Full Field Swept Source Optical Coherence Tomography written by James Fergusson and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography (OCT) is a non-invasive volumetric imaging technique that offers micron scale resolution over several millimetres of depth penetration in tissue. The aim of the project was to develop Full Field Swept Source OCT (FFSSOCT), charting the specifications of the system throughout and drawing comparisons with available Fourier domain OCT (FDOCT) systems. A super luminescent diode (SLD) light source was tuned to different optical frequencies using an acousto-optical tunable filter. The successive optical frequencies were distributed across the sample in parallel and the sequential interference spectra were recorded with a high speed digital camera. Using a 5mW optical source at 850nm, 70dB sensitivity was ultimately achieved in a single five second acquisition, improving the original performance by 5dB and increasing acquisition and processing time significantly. Ex vivo retinal images of rat and tree shrew were recorded with multiple layers visible. All software was custom written in Labview, improving the user interface and processing time over the existing Matlab code. To enhance the performance of the system, the camera was subsequently upgraded from 15 to 45% quantum efficiency and from 250k to 1.3M pixels. The light source was also upgraded to 20mW. The software was improved with spectral processing and dispersion compensation. 85dB sensitivity was ultimately achieved. Further ex vivo retinal images were taken, showing comparative image quality to those of the same retinal samples recorded with FDOCT. Further attempts to increase the system performance were limited by internal reflections and interfering surfaces within the FFSSOCT design leading to saturation of the digital camera. In vivo imaging was attempted using software based phase jitter compensation. Improvement could be seen with simple reflecting structures.

Download or read book Swept Source Optical Coherence Tomography written by Kelvin Y. C. Teo and published by World Scientific Publishing Company. This book was released on 2018-04-16 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is written for retinal specialists and clinicians with a special interest in retinal diseases. It presents a collection of images and brief annotations of the microstructures of both the normal and diseased eye captured on swept source optical coherence tomography. The swept-source OCT is a relatively new form of imaging and is able to capture structures and details which previous generations of OCT machines cannot. This type of imaging represents the forefront in ocular imaging. This second edition includes a new chapter on optic nerve conditions and more cases on eye conditions that were imaged with the SS-OCT. It also showcases the use of swept-source OCT for OCT angiography.

Download or read book MEMS VCSEL Swept source Optical Coherence Tomography for Multi MHz Endoscopic Structural and Angiographic Imaging written by Jason Zhang (S.M.) and published by . This book was released on 2021 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Swept-source optical coherence tomography (SS-OCT) enables volumetric imaging of subsurface structure, but applications requiring wide fields of view, rapid imaging, and higher resolutions have been challenging because of the need for multi-MHz A-scan rates. Until now, achieving multi-MHz A-scan rates has been limited to Fourier-domain mode-locked lasers or stretched-pulse lasers. We describe a microelectromechanical-system, vertical-cavity surface-emitting laser (MEMS-VCSEL) for SS-OCT at A-scan rates of 2.4 and 3.0 MHz using a dual-channel acquisition system. Dual-channel operation enables simultaneous acquisition of Mach-Zehnder interferometer (MZI) fringes for sweep-to-sweep calibration and resampling, overcoming inherent optical clock limitations in state-of-the-art digitizers. We demonstrate structural OCT and OCT angiography (OCTA) imaging of the swine gastrointestinal tract using a suite of endoscopic devices, including a 3.2 mm diameter micromotor catheter, a 12 mm diameter tethered capsule, and a 12 mm diameter wide-field OCTA probe. MEMS-VCSELs promise to enable ultrahigh-speed SS-OCT with a scalable, low cost, and manufacturable technology, suitable for a diverse range of imaging applications.

Download or read book Optical Coherence Tomography written by Mark E. Brezinski and published by Elsevier. This book was released on 2006-08-25 with total page 645 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography gives a broad treatment of the subject which will include 1)the optics, science, and physics needed to understand the technology 2) a description of applications with a critical look at how the technology will successfully address actual clinical need, and 3) a discussion of delivery of OCT to the patient, FDA approval and comparisons with available competing technologies. The required mathematical rigor will be present where needed but be presented in such a way that it will not prevent non-scientists and non-engineers from gaining a basic understanding of OCT and the applications as well as the issues of bringing the technology to the market. - Optical Coherence Tomography is a new medical high-resolution imaging technology which offers distinct advantages over current medical imaging technologies and is attracting a large number of researchers. - Provides non-scientists and non-engineers basic understanding of Optical Coherence Tomography applications and issues.

Download or read book Ultrahigh Speed Optical Coherence Tomography for Ophthalmic Imaging Applications written by Jonathan Jaoshin Liu and published by . This book was released on 2014 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is a non-contact, non-invasive, micron-scale optical imaging technology that has become a standard clinical tool in ophthalmology. Fourier domain OCT detection methods have enabled higher sensitivity and imaging speeds compared to previous generation timedomain OCT. Spectral / Fourier domain OCT (SD-OCT) detects the interference spectrum using a broadband light source and spectrometer. Swept-source / Fourier domain OCT (SS-OCT) detects the interference spectrum over time using a wavelength-swept laser. Current standard commercial ophthalmic clinical systems based on SD-OCT technology have imaging speeds of 20,000 - 40,000 axial scans per second and axial resolutions of 5 - 7 ptm. In this thesis, ultrahigh speed OCT for ophthalmic imaging applications are presented. SD-OCT systems using high speed CMOS camera technology can achieve imaging speeds over 70,000 axial scans per second. Axial resolutions better than 3 ptm can be achieved with multiplexed broadband superluminescent diodes. A novel registration motion-correction algorithm for volumetric OCT datasets reducing motion artifacts and improving signal quality is investigated. Ultrahigh speed, ultrahigh resolution SD-OCT ophthalmic imaging applications including small animal retinal imaging and clinical imaging of age-related macular degeneration (AMD) are illustrated. SS-OCT systems using short cavity wavelength-swept laser light sources can achieve imaging speeds over 100,000 axial scans per second with 6 pm axial resolution for small animal and clinical imaging. The high sensitivity of SS-OCT enables enhanced vitreous imaging, visualizing features in the vitreous and vitreoretinal interface. Finally, a new vertical cavity surface-emitting (VCSEL) technology based wavelength-swept laser light source SS-OCT system with tunable speed and wavelength range as well as long coherence length enabling ultrahigh speed and ultralong range OCT imaging applications is demonstrated. In addition to comprehensive structural imaging, the emergence of functional OCT imaging of retinal blood flow using ultrahigh speed OCT may also improve the understanding of ocular disease pathogenesis. Therefore, ultrahigh speed OCT is a promising tool for the diagnosis and management of diseases in ophthalmology.

Download or read book Full Range Swept Source Optical Coherence Tomography with Ultra Small Fiber Probes for Biomedical Imaging written by Youxin Mao and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Full Range Swept-Source Optical Coherence Tomography with Ultra Small Fiber Probes for Biomedical Imaging.

Download or read book Sensors and Structured Beams in Optical Coherence Tomography written by Eun Song Kim and published by . This book was released on 2017 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is an emerging medical imaging technique that provides images of various tissue structures at micrometer scale resolution. A swept source laser which emits time-varying wavelengths light at a high-speed was developed that greatly improves OCT processing speed and image resolution. This dissertation presents system developments for swept source based OCT. I have designed and demonstrated three different OCT systems that can be used for diagnostic applications. First, I present a common-path OCT system with a cleaved optical fiber as a probe. The system is built as a tactile sensor for implementation in surgical robots. A tactile sensor, often referred to as a force sensor, is a device that is sensitive to applied force or pressure. Since the system has a high sensitivity to pressure and a compact size, the sensor is compatible with the surgical robots field which require fine force control. This new sensor may aid in diagnosing diseased tissue or cells by measuring their Young' s modulus. Secondly, an Angular/Longitudinal Doppler OCT system (ALD-OCT) was constructed to sense the rotation of an object. Previous work has shown, it is feasible to detect a linearly moving object by Doppler OCT. However, ALD-OCT, OCT utilizes a helical phase shape beam that, has been studied due to its distinct characteristics. An application of using a vortex beam is sensing a rotating object by measuring the angular Doppler shift from the beam reflected off the object. ALD-OCT can utilize depth resolved analysis and be implemented to detect helical shaped particles or the vorticity of blood flows under the skin or in the retina noninvasively. Lastly, we propose several designs of optical probes for a swept source OCT system. The designs of the GRIN lens bundle probes were presented to demonstrate angled illumination and detection techniques in OCT systems. The beam profiles of the output beams from the probes were analyzed theoretically using ABCD ray matrices. We present a method to measure the beam profile of a sweeping wavelength laser source, which can be applied to measure any optical probes connected to the swept source laser.

Download or read book Development and Application of Multifunctional Optical Coherence Tomography written by Zhongwei Zhi and published by . This book was released on 2014 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microcirculation refers to the functions of capillaries and the neighboring lymphatic vessels. It plays a vital role in the pathophysiology of disorders in many clinical areas including cardiology, dermatology, neurology and ophthalmology, and so forth. It is crucial to develop imaging technologies that can provide both qualitative and quantitative information as to how microcirculation responds to certain injury and/or disease, and its treatment. Optical coherence tomography (OCT) is a non-invasive optical imaging technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine. Current state-of-the-art OCT systems operate in the Fourier domain, using either a broadband light source with a spectrometer, known as spectral domain OCT (SDOCT), or a rapidly tunable laser, known as swept source OCT (SSOCT). The current Fourier domain OCT systems have dramatically improvement in sensitivity, resolution and speed compared to time domain OCT. In addition to the improvement in the OCT system hardware, different methods for functional measurements of tissue beds have been developed and demonstrated. This includes but not limited to, i) Phase-resolved Doppler OCT for quantifying the blood flow, ii) OCT angiography for visualization of microvasculature, iii) Polarization sensitive OCT for measuring the intrinsic optical property/ birefringence of tissue, iv) spectroscopic OCT for measuring blood oxygenation, etc. Functional OCT can provide important clinical information that is not available in the typical intensity based structural OCT images. Among these functional OCT modalities, Doppler OCT and OCT angiography attract great interests as they show high capability for in vivo study of microvascular pathology. By analyzing the Doppler effect of a flowing particle on light frequency, Doppler OCT allows the quantification of the blood flow speed and blood flow rate. The most popular approach for Doppler OCT is achieved through analysis of the phase term in complex OCT signal which termed as Phase-resolved Doppler OCT. However, as limited by the phase noise and motion, Phase-resolved Doppler OCT can only be applied for relative large blood vessels, such as arterioles and venules. On the other hand, in order to visualize the microcirculation network, a number of strategies to enable better contrast of microvasculature components, which we termed OCT angiography, have been introduced during recent years. As a variation of Fourier domain OCT, optical microangiography (OMAG) is one of earliest proposed OCT angiography technique which is capable of generating 3D images of dynamic blood perfusion distribution within microcirculatory tissue beds. The OMAG algorithm works by separating the static and moving elements by high pass filtering on complex valued interferometric data after Fourier transform. Based on the conventional OMAG algorithm, we further developed ultra-high sensitive OMAG (UHS-OMAG) by switching the high-pass filtering from fast scan direction (adjacent A-lines within one B-frame) to slow scan direction (adjacent B-frames), which has a dramatically improved performance for capillary network imaging and analysis. Apart from the microvascular study with current available functional OCT for, visualization of the lymphatic system (lymph nodes and lymphatic vessels) plays a significant role in assessing patients with various malignancies and lymphedema. However, there is a lack of label-free and noninvasive method for lymphangiography. Hence, a cutting edge research to investigate the capability of OCT as a tool for non-invasive and label-free lymphangiography would be highly desired. The objective of my thesis is to develop a multiple-functional SDOCT system to image the microcirculation and quantify the several important parameters of microcirculation within microcirculatory tissue beds, and further apply it for pre-clinical research applications. The multifunctional OCT system provides modalities including structural OCT, OCT angiography, Doppler OCT and Optical lymphangiography, for multi-parametric study of tissue microstructure, blood vessel morphology, blood flow and lymphatic vessel all together. The thesis mainly focus on two parts: first, development of multi-functional OCT/optical microangiography (OMAG) system and methods for volumetric imaging of microvasculature and quantitative measurement of blood flow, and its application for pathological research in ophthalmology on rodent eye models; second, development of ultra-high resolution OCT system and algorithm for simultaneous label free imaging of blood and lymphatic vessel, and its application in wound healing study on mouse ear flap model. Objectives of my research are achieved through the following specific aims: Aim 1: Improve the sensitivity of OMAG for microvasculature imaging; perform volumetric and quantitative imaging of vasculature with combined OMAG and Phase-resolved Doppler OCT for in vivo study of vascular physiology. Aim 2: Develop high speed high resolution OCT system and method for rodent eye imaging. Apply the combined OMAG and Phase-resolved Doppler OCT approach to investigate the impact of elevated intraocular pressure on retinal, choroidal and optic nerve head blood flow in rat eye model, which aids to the better understanding of the mechanism and development of glaucoma. Aim 3: Apply the developed OCT system and ultra-high sensitive OMAG algorithm for noninvasive imaging of retinal morphology and microvasculature in obese mice, which may play an important role in early diagnosis of Diabetic retinopathy. Aim 4: Developing an ultra-high resolution SDOCT system using broadband Supercontinuum light source to achieve ultra-high resolution microvasculature imaging of biological tissue. Aim 5: Develop methods for simultaneous label free optical imaging of blood and lymphatic vessel and demonstrate its capability by monitoring the blood and lymph response to wound healing on mouse ear pinna model.

Download or read book Development of Optical Coherence Tomography for Tissue Diagnostics written by Panomsak Meemon and published by . This book was released on 2010 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microvasculature can be found in almost every part of the human body, including the internal organs. Importantly, abnormal changes in microvasculature are usually related to pathological development of the tissue cells. Monitoring of changes in blood flow properties in microvasculature, therefore, provides useful diagnostic information about pathological conditions in biological tissues as exemplified in glaucoma, diabetes, age related macular degeneration, port wine stains, burn-depth, and potentially skin cancer. However, the capillary network is typically only one cell in wall thickness with 5 to 10 microns in diameter and located in the dermis region of skin. Therefore, a non-invasive flow imaging technique that is capable of depth sectioning at high resolution and high speed is demanded. Optical coherence tomography (OCT), particularly after its advancement in frequency domain OCT (FD-OCT), is a promising tool for non-invasive high speed, high resolution, and high sensitivity depth-resolved imaging of biological tissues. Over the last ten years, numerous efforts have been paid to develop OCT-based flow imaging techniques. An important effort is the development of phase-resolved Doppler OCT (PR-DOCT). Phase-resolved Doppler imaging using FD-OCT is particularly of interest because of the direct access to the phase information of the depth profile signal. Furthermore, the high speed capability of FD-OCT is promising for real time flow monitoring as well as 3D flow segmentation applications. However, several challenges need to be addressed; 1) Flow in biological samples exhibits a wide dynamic range of flow velocity caused by, for example, the variation in the flow angles, flow diameters, and functionalities. However, the improvement in imaging speed of FD-OCT comes at the expense of a reduction in sensitivity to slow flow information and hence a reduction in detectable velocity range; 2) A structural ambiguity so-called 'mirror image' in FD-OCT prohibits the use of maximum sensitivity and imaging depth range; 3) The requirement of high lateral resolution to resolve capillary vessels requires the use of an imaging optics with high numerical aperture (NA) that leads to a reduction in depth of focus (DOF) and hence the imaging depth range (i.e. less than 100 microns) unless dynamic focusing is performed. Nevertheless, intrinsic to the mechanism of FD-OCT, dynamic focusing is not possible. In this dissertation, the implementation of PR-DOCT in a high speed swept-source based FD-OCT is investigated and optimized. An acquisition scheme as well as a processing algorithm that effectively extends the detectable velocity dynamic range of the PR-DOCT is presented. The proposed technique increased the overall detectable velocity dynamic range of PR-DOCT by about five times of that achieved by the conventional method. Furthermore, a novel technique of mirror image removal called 'Dual-Detection FD-OCT' (DD-FD-OCT) is presented. One of the advantages of DD-FD-OCT to Doppler imaging is that the full-range signal is achieved without manipulation of the phase relation between consecutive axial lines. Hence the full-range DD-FD-OCT is fully applicable to phase-resolved Doppler detection without a reduction in detectable velocity dynamic range as normally encountered in other full-range techniques. In addition, PR- DOCT can utilize the maximum SNR ratio provided by the full-range capability. This capability is particularly useful for imaging of blood flow that locates deep below the sample surface, such as blood flow at deep posterior human eye and blood vessels network in the dermis region of human skin. Beside high speed and functional imaging capability, another key parameter that will open path for optical diagnostics using OCT technology is high resolution imaging (i.e. in a regime of a few microns or sub-micron). Even though the lateral resolution of OCT can be independently improved by opening the NA of the imaging optics, the high lateral resolution is maintained only over a short range as limited by the depth of focus that varies inversely and quadratically with NA. Recently developed by our group, 'Gabor-Domain Optical Coherence Microscopy' (GD-OCM) is a novel imaging technique capable for invariant resolution of about 2-3 [micrometers] over a 2 mm cubic field-of-view. This dissertation details the imaging protocol as well as the automatic data fusion method of GD-OCM developed to render an in-focus high-resolution image throughout the imaging depth of the sample in real time. For the application of absolute flow measurement as an example, the precise information about flow angle is required. GD-OCM provides more precise interpretation of the tissue structures over a large field-of-view, which is necessary for accurate mapping of the flow structure and hence is promising for diagnostic applications particularly when combined with Doppler imaging. Potentially, the ability to perform high resolution OCT imaging inside the human body is useful for many diagnostic applications, such as providing an accurate map for biopsy, guiding surgical and other treatments, monitoring the functional state and/or the post-operative recovery process of internal organs, plaque detection in arteries, and early detection of cancers in the gastrointestinal tract. Endoscopic OCT utilizes a special miniature probe in the sample arm to access tubular organs inside the human body, such as the cardiovascular system, the lung, the gastrointestinal tract, the urinary tract, and the breast duct. We present an optical design of a dynamic focus endoscopic probe that is capable of about 4 to 6 [micrometers] lateral resolution over a large working distance (i.e. up to 5 mm from the distal end of the probe). The dynamic focus capability allows integration of the endoscopic probe to GD-OCM imaging to achieve high resolution endoscopic tomograms. We envision the future of this developing technology as a solution to high resolution, minimally invasive, depth-resolved imaging of not only structure but also the microvasculature of in vivo biological tissues that will be useful for many clinical applications, such as dermatology, ophthalmology, endoscopy, and cardiology. The technology is also useful for animal study applications, such as the monitoring of an embryo's heart for the development of animal models and monitoring of changes in blood circulation in response to external stimulus in small animal brains.

Download or read book Development of Phase Stabilized Swept Source Optical Coherence Tomography for Biomedical Imaging and Sensing written by Ravi Kiran Manapuram and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Spectral Domain Optical Coherence Tomography A Practical Guide written by Dacosta Shaun and published by JP Medical Ltd. This book was released on 2011-08 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of Spectral Domain OCT is a practical guide to the investigation and diagnosis of retinal disease using the Topcon machine. Beginning with an overview of OCT, the book provides a step by step approach to image capture, analysis and interpretation. With the help of numerous case studies, OCT patterns in different types of retinal disease are presented as both 2D and 3D images. In addition, Spectral Domain OCT highlights features of the new Topcon 2000 machine with an enhanced speed of 27,000 A scans/second, improved software algorithms and extra facilities for anterior segment imaging.