Applications Of Endoscopic Holography Through Fiber Optics

Abstract

Holographic endoscopy or endoholography combines the features of endoscopy and holography. It can be utilized in holographic imaging or interferometry inside natural cavities of the body. In imaging, the ability to record a three-dimensional, large focal depth, high resolution image of internal organs and tissue may greatly enhance the detection of disease and abnormality. With contact recording endoholography it is possible to obtain high resolution holographic recordings which can be examined microscopically. In this technique, a specially designed endoscope uses a single-mode optical fiber for illumination where Denisyuk holograms are recorded on film at the endoscope's distal end. The holograms are viewed under a stereomicroscope with high magnification, allowing for the observation of individual cells. Specific dyes are used to enhance the contrast of the tissue prior to the recording of the holographic images. In endoholographic interferometry, the use of conventional multi-fiber imaging structures is sufficient to obtain an adequate recording of interference patterns. The use of conventional fiberoptic imaging structures for holographic investigations of displacement and vibration is demonstrated. Image-plane holograms are formed at the proximal output end of an imaging multifiber. Pairs of double-pulsed holograms of dynamic events are recorded, one through the multifiber, the other in a conventional manner as a standard of reference. The fringes of both holograms are practically identical. The ability to perform measurements in holographic interferometry through optical fibers should lead to further developments in medical as well as industrial applications.