Microstructured optical fiber for endoscopy

Abstract

Although the manufacture of endoscopes with conventional optical fiber is known, present a series of problems and complexities that are extremely difficult to be solved. In view of these problems, this project presents a proposal to manufacture and characterize a microstructured optical fiber for endoscopy. In addition, the equipment that will be built will also produce fibers for different applications that allows to minimize the risk of this project. Including optical fibers for: laser used in medical, laser for industrial applications, astronomy, laser marking, sensors. The microstructured fiber arose from a revolution more recent concept of optical fibers, these fibers, the cladding around the core is formed by a set of tiny air holes, which run parallel to the fiber core and throughout its length. In this case, it does not take chemical doping to form the necessary difference in refractive index between cladding and core. The air holes make this role, reducing the refractive index in the cladding. Thus, the same basic principle of total internal reflection can guide light in a solid core. However, this type of waveguide has characteristics without any parallel with his sisters (well) older, traditional optical fibers. Here can vary, unprecedented, the chromatic dispersion of the fiber, its mode area and non-linearity, which can be extremely high, or extremely low. With even more unique features and unprecedented are the microstructured fibers with core low refractive index and that guide by photonic band gap. Flexible endoscopes rely on image transfer through optical fiber bundles, are particularly important on the observations through natural openings in human organs. These instruments, also known as fiberscopes, typically focus light through a miniaturized objective or gradient-index lens (GRIN) that creates an image of an incoming coherent fiber bundle, which subsequently serves as an image guide. The results provide various approaches to explore multimode guides for imaging: a geometry has been demonstrated to light microscopy and dark field to monochromatic light and fluorescent image, where the excitation wavelength is delivered to the site by same waveguide that also collects the fluorescence signal. Even if the geometries are based on different principles, implementations allow the capture of images at high frame rates in both cases, surpassing approaches previously reported by several orders of magnitude. Furthermore, showed the controlled generation of complex light fields, such as Laguerre-Gauss modes, beams invariant propagating through a multimode fiber. This opened prospects for versions based on fiber optic techniques such as microscopy of stimulated emission depletion (STED). This will pave the way for imaging systems 'without lens' and cheap. (AU)