Expand The Fiber-type Oct Imaging System And Doppler Functional Imaging

Optical coherence tomography (OCT) is a recently developed high resolution biomedical imaging method, allowing for noninvasive visualizing of internal tissue structure and physiology. It is a new technology based on low coherence tomography, combining with the advantage of Confocal microscope and Heterodyne detection. OCT functions as a type of 'optical biopsy' to provide cross-sectional images of tissue structure on the micron scale. It is a promising imaging technology because it can provide images of tissue in vivo and in real time, without the need for excision and processing of specimens. OCT has been developed not only for morphological imaging, but also for functional imaging, such as spectroscopic imaging of tissue properties, Doppler blood flow measurement and quantification of blood oxygenation or tissue birefringence. By combining Doppler velocimetry with optical sectioning capability of OCT, we developed one branch of functional OCT (F-OCT) termed optical Doppler tomography (ODT).A review of the several methods used to build optical delay lines and interferometer for Optical Coherence Tomography has been done. Their advantages and disadvantages have analyzed. In this dissertation, we report a newly developed single-mode fiber-designed OCT system based on Michelson interferometer and optical heterodyne detection using a broadband near-infrared light source. With this developed system we can pick up elastic light backscattered from the tissue, and reconstruct 2D and 3D OCT image. Simultaneity, the post-detection digital approach obtains the analytic signal from the real discrete interference signal, and the phase information fetched from the complex signal containing both amplitude and phase is used to reconstruct the ODT image. Fiber-based OCT system is compact, flexible, and convenient to be combined with fiber catheter, endoscope and other imaging equipments to expand its observing scope and application fields.This thesis includes five parts. The first chapter introduces the development and the characteristics of some biomedical imaging technologies. The second and third chapter introduces some knowledge about Optical Coherence Tomography and Optical Doppler Tomography. The chapter four discusses the method of developing single-mode fiber-designed OCT system and ODT system, and the OCT system dispersion, the influence of dispersion mismatch on the resolution, and the dispersion property of RSOD is analysed concretely. We propose and demonstrate a method of dispersion compensation by controlling the dispersion of RSOD is effective, and the resolution will not lower. And a method of obtain the velocity information inside the tissue by using digital Hilbert transformation in the ODT system is introduced. At last, in the Chapter five some typical tissue images obtained by OCT and ODT system with high quality are shown.