All-fiber endoscopic optical imaging devices

Optical technologies are being increasingly used to obtain high resolution images of biological materials. Over the past decade, optical coherence tomography (OCT) and Confocal Microscopy (CM) technologies have experienced tremendous growth. Their unique capability to visualize biological tissue in vivo at very high resolution, even beyond the cellular level, as well as the different possibilities for signal processing have stimulated researchers from many different disciplines. These unique imaging capabilities may offer new ways to analyze and provide new therapies for various diseases.;Optical coherence tomography (OCT) is an emerging imaging modality that is capable of providing noninvasive, subsurface optical imaging of biological tissues with micron-scale resolution. The operation of an OCT system is based on the principle of interferometry, which uses the low coherence interference between a reference and a signal beam derived from a broadband optical source. It can be used to generate slice images of three-dimensional objects at a resolution level much greater than that currently available using MRI, CT scan, or ultrasound scans. One of the goals of this dissertation is to design and test a compact all-fiber Fourier Domain Optical Coherence Tomography (FD-OCT) system based on a common-path interferometer configuration, to develop the software algorithms necessary to acquire cross-sectional biological tissue images at high refresh rates, to provide various scanning approaches for the fiber optic probes and to optimize and analyze the system sensitivity for various specific applications.;Analysis and Optimization of the Fourier Domain OCT system reference is also performed and studied. The Signal-to-Noise ratio for the system is experimentally measured. Experiments showing high resolution imaging capability with a variety of samples are demonstrated.;Confocal microscopy, another commonly used optical imaging technology, samples small volumes of bulk tissue, producing images with micrometer resolution at depths up to several hundred micrometers. Many techniques have been explored with bulk confocal microscopes to obtain reflected light images of accessible tissues. Flexible endoscopes used to record confocal images based on fiber optics have been developed before, using fiber bundles. An all-fiber single-mode confocal microscope (FCM) capable of imaging biological tissues with sub-cellular resolution was developed. In this dissertation the design, performance and biological image results of the first prototype of this imaging system, which uses a single mode fiber coupled to a GRIN lens, will be presented.