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 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 Development and Application of Optical Coherence Tomography OCT written by Michael Pircher and published by MDPI. This book was released on 2018-03-23 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Development and Application of Optical Coherence Tomography (OCT)" that was published in Applied Sciences

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 Optical Coherence Tomography written by Wolfgang Drexler and published by Springer Science & Business Media. This book was released on 2008-12-10 with total page 1346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is the optical analog of ultrasound imaging and is emerging as a powerful imaging technique that enables non-invasive, in vivo, high resolution, cross-sectional imaging in biological tissue. This book introduces OCT technology and applications not only from an optical and technological viewpoint, but also from biomedical and clinical perspectives. The chapters are written by leading research groups, in a style comprehensible to a broad audience.

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 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 Progress Towards Detecting Neural Activity in Optical Coherence Tomography Using Phase written by Jasmine Kavan Shah and published by . This book was released on 2017 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography (OCT) is non-invasive, real time optical imaging method based on low coherence interferometry with high resolution. It is capable of imaging microstructure by measuring the light backscattered from the sample. Under the AGI grant, I have built a Swept Source OCT (SS-OCT) / phase resolved OCT to detect the nanometer(nm) scale changes in the cell membrane that occur during membrane depolarization and Ion influx. This type of small changes can be seen using phase. Intensity is robust but is less sensitive to the small-scale changes whereas phase is highly sensitive. The noise level for phase difference quantification depends on the lateral motion, triggering of the wavelength mismatch and signal to noise ratio (SNR). To detect the nm scale changes phase noise should be minimum. The phase noise is inversely proportional to SNR. The SNR of the system should be maximum. The SS-OCT has swept source with sweep rate 100 kHz and it is not phase stable. It needs post processing algorithm to match the triggering wavelength to stabilize the phase. I wrote the code in GPU to reduce the computation time for post processing algorithm. Due to a few setbacks related to moving the system to a collaborating lab, the biological portion of my thesis work, trying to find the neural activity in the walking leg nerve of the Lobster using phase, was done with a spectral domain OCT (SD-OCT). To see any action potential change in the nerve I realigned the SD-OCT system with center wavelength to increase the SNR of the system and the sample arm with the nerve chamber (3D printed) to stimulate the nerve at one end and take the OCT image at the other end to see the action potential.

Download or read book Optical Coherence Tomography written by Rui Bernardes and published by Springer Science & Business Media. This book was released on 2012-05-08 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography represents the ultimate noninvasive ocular imaging technique although being in the field for over two-decades. This book encompasses both medical and technical developments and recent achievements. Here, the authors cover the field of application from the anterior to the posterior ocular segments (Part I) and present a comprehensive review on the development of OCT. Important developments towards clinical applications are covered in Part II, ranging from the adaptive optics to the integration on a slit-lamp, and passing through new structural and functional information extraction from OCT data. The book is intended to be informative, coherent and comprehensive for both the medical and technical communities and aims at easing the communication between the two fields and bridging the gap between the two scientific communities.

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 System Development for Bioimaging Applications written by 俞罗琴 and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 Source Development and Dispersion Measurements in Optical Coherence Tomography written by Bastian Bräuer and published by . This book was released on 2017 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: OPTICAL coherence tomography (OCT) is a non-invasive imaging modality, which provides mm-deep cross sectional and volumetric images in real-time at micrometer resolution. Additional to its promising imaging capabilities it can provide label-free detection of flow in semi-transparent and translucent samples. OCT has gained great popularity in recent years due to enhanced laser and imaging technologies, offering unprecedented long range imaging at high speed. These technologies, however, are restricted to laboratories having lithography capabilities to manufacturer laser gain chips. Laboratories without the capability to manufacture laser gain chips still depend on the implementation of OCT systems having either long imaging range at slow speeds or high speed with decreased imaging range. Imaging range in swept source OCT (SS-OCT), one of the OCT configurations, is coupled with the coherence length of the laser. This thesis describes novel laser design configurations to close the gap between the imaging range and the A-scan speed of the laser while maintaining a cost effective approach for the design. The configuration used in the laser development is a modified laser cavity, based on the well known Littman-Metcalf design cavity. Lasers in the range of 1 m to 1.7 m were built and tested. These lasers were subsequently used for label-free detection and characterisation of tissue types in ocular media. Current tissue detection for optical imaging modalities are mostly based on staining of the sample. Label-free detection can be accomplished through material specific coefficients such as Young's modulus (E) or the dispersion coefficient ( 2). In this dissertation label-free detection of biological and non-biological materials was accomplished by using the differential walk-off, induced by the refractive index difference of two wavelength regions travelling through a medium. The differential walk-off can be experimentally measured and used to calculate the dispersion coefficient 2, which is specific to different materials. The novelty in this technique is the use of dispersion for detection which is normally a non-favourable effect in optical imaging modalities, due to its degrading nature in image quality.

Download or read book Optical Coherence Tomography written by Rui Bernardes and published by Springer. This book was released on 2012-05-16 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography represents the ultimate noninvasive ocular imaging technique although being in the field for over two-decades. This book encompasses both medical and technical developments and recent achievements. Here, the authors cover the field of application from the anterior to the posterior ocular segments (Part I) and present a comprehensive review on the development of OCT. Important developments towards clinical applications are covered in Part II, ranging from the adaptive optics to the integration on a slit-lamp, and passing through new structural and functional information extraction from OCT data. The book is intended to be informative, coherent and comprehensive for both the medical and technical communities and aims at easing the communication between the two fields and bridging the gap between the two scientific communities.

Download or read book Development of Advanced Label Free Optical Bioimaging Technologies written by JINGJIANG. XU and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Development of Advanced Label-free Optical Bioimaging Technologies" by Jingjiang, Xu, 许景江, 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: Today label-free bioimaging has been leading to widespread and fast-growing applications, which demands for a more efficient way to keep up such momentum. To this end, the research in this thesis will study the techniques of efficiency improvement for advanced label-free bioimaging, including the time efficiency, cost efficiency and information efficiency. Optical coherence tomography (OCT) is one of the most valuable label-free bioimaging modalities to provide noninvasive cross-sectional assessment of biological tissue. In many occasions, these applications demand for three dimensional (3D) imaging at video-rate in order to perform real-time diagnoses, which can be overcome by MHz-OCT. Here we demonstrate inertia-free all-optical ultrahigh-speed swept-source optical coherence tomography (OCT) based on amplified optical time-stretch (AOT). More importantly, the key significance of AOT-OCT is its broadband amplification stage, which greatly enhances the detection sensitivity compared with the prior attempts to employ optical time-stretch to OCT. We report an AOT-OCT system which is operated at an A-scan rate of multi-megahertz with high sensitivity (>80 dB) and perform time-stretch-based OCT of biological tissue in vivo. Moreover, using a more stable and coherent mode-locked fiber laser, we can achieve better performance without the compromise of averaging for supercontinuum-generation-based AOT-OCT system. It represents a major step forward in utilizing AOT as an alternative for achieving practical time-efficient OCT imaging at multi-MHz speed. For the further development of this ultrahigh-speed OCT, we present a theoretical analysis of the AOT-OCT system. The spectral resolution, coherence length and sensitivity of AOT-OCT system have been discussed in detail. By theoretical model of the noise sources based on Raman amplifier, we also quantify how the input signal, amplifier gain, A-scan rate affect the sensitivity of AOT-OCT imaging. These simulation results are expected to be valuable for optimizing the design of AOT-OCT. We also investigate in cost-effective implementation to realize efficient optical time-stretch process based on dispersive fiber. We explore and demonstrate the feasibility of using the standard telecommunication single-mode fibers as few-mode fibers (FMFs) for optical time-stretch confocal microscopy in the 1m range. It can provide sufficiently high dispersion-to-loss ratios for practical time-stretch imaging at 1 m, without the needs for high-cost specialty 1 m single mode fiber. In addition, Coherent anti-Stokes Raman scattering (CARS) microscopy is another attractive efficient tool for label-free biochemical-specific imaging, which can bypass laborious steps of preparing and staining in routine standard histopathology. Here we further explore ultrabroadband hyperspectral multiplex (HM-CARS) to perform chemoselective histological imaging with efficient information in fingerprint region. In order to unravel the congested CARS spectra, we employ phase-retrieval algorithm based on Kramers-Kronig (KK) transform and principal component analysis (PCA) to display the key cellular structures with components distribution. All these research efforts are aiming at improving the efficiency, from theory to implementation, for label-free bioimaging technology such as OCT and CARS. These schemes demonstrate great potential to realize powerful label-free bioimaging