Holographie endoscopy through optical fibers

Abstract

Holographic endoscopy or endoholo-graphy 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 view a threedimensional, large focal depth, faithful rendition of internal organs and tissue may greatly enhance the detection of disease and abnormality. Under proper circumstances it should be possible to obtain holographic recording which can be examined microscopically. In the case of endoholo-graphic interferometry, new diagnostic techniques can emerge; e.g., the measurement of compliance of the wall of the bladder or of the arteries may provide diagnostic indicators of early stages of disease.Endoholographic image recording requires the preservation of phase information and, therefore, the need to develop a flexible multifiber structure which consists of single-mode fibers. Otherwise, endoholographic imaging can be obtained only by inserting the recording film distally as has been done, so far, in this project. Hence, the development of singlemode fiber-optic imaging bundles is of particular significance. In the case of endoholographic interferometry, the use of conventional multi-mode imaging structures is sufficient to obtain an adequate recording of the interference pattern. On the other hand, green double-pulse laser systems should significantly increase the resolution of the interferometric recordings of tissue.The use of fiber-optic 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 were recorded, one through the fiber bundle, the other in a conventional manner as a standard of reference. The fringes of both holograms were 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.Holographic endoscopy or endoholo-graphy 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 view a threedimensional, large focal depth, faithful rendition of internal organs and tissue may greatly enhance the detection of disease and abnormality. Under proper circumstances it should be possible to obtain holographic recording which can be examined microscopically. In the case of endoholo-graphic interferometry, new diagnostic techniques can emerge; e.g., the measurement of compliance of the wall of the bladder or of the arteries may provide diagnostic indicators of early stages of disease.Endoholographic image recording requires the preservation of phase information and, therefore, the need to develop a flexible multifiber structure which consists of single-mode fibers. Otherwise, endoholographic imaging can be obtained only by inserting the recording film distally as has been done, ...