Parallel transmission of images through single optical fibers

Friesem, Asher A.; Levy, Uri; Silberberg, Yaron

doi:10.1109/proc.1983.12560

Cited by 46 publications

(22 citation statements)

References 23 publications

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“…Indeed, numerous studies have already indicated that at least some aspects of the ordered behaviour (propagation constants of modes) can 'survive' over very large distances [20][21][22][23] .…”

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Seeing through chaos in multimode fibres

2015

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In a similar fashion to diffusers or other highly scattering media, multimode fibres deliver coherent light signals in the form of apparently random speckled patterns. In contrast to other optically random environments, multimode fibres feature remarkably faithful cylindrical symmetry. Our experimental studies challenge the commonly held notion that classifies multimode fibres as unpredictable optical systems. Instead, we demonstrate that commercially available multimode fibres are capable of performing as extremely precise optical components. We show that, with a sufficiently accurate theoretical model, light propagation within straight or even significantly deformed segments of multimode fibres may be predicted up to distances in excess of hundreds of millimetres. Harnessing this newly discovered predictability in imaging, we demonstrate the unparalleled power of multimode fibre-based endoscopes, which offer exceptional performance both in terms of resolution and instrument footprint. These results thus pave the way for numerous exciting applications, including high-quality imaging deep inside motile organisms.T he theoretical description of light transport processes within ideal multimode fibres (MMFs) has been developed for over half a century 1-4 . This elaborate theoretical model is, however, frequently considered inadequate to describe real-life MMFs, which are manufactured by drawing melted silica preforms. Such fibres are commonly seen as unreliable, and the inherent randomization of light propagating through them is typically attributed to undetectable deviations from the ideal fibre structure. It is a commonly held belief that this additional chaos is unpredictable and that its influence grows with the length of the fibre. Despite this, light transport through MMFs remains deterministic.The prospect of deterministic light propagation within MMFs has only recently been used through methods of digital holography and by adopting the concept of empirical measurement of the transformation matrix (TM) 5-11 . This technique, developed in studies of light propagation through highly turbid media 12-17 , has opened a new window of opportunity for MMFs to become extremely narrow and minimally invasive endoscopes, allowing sub-micrometre resolution imaging in deep regions of sensitive tissues 9,18 .However attractive, this technology suffers from several major limitations, the most critical being the lack of flexible operation. Any bending or looping of the fibre results in changes to its TM, rendering the imaging heavily impaired. All current methods exploiting MMFs for imaging require open optical access to the distal end of the fibre during the time-consuming measurement of the TM. Furthermore, this characterization must be repeated upfront for every intended configuration (deformation) and any axial distance of the focal plane behind the fibre before the system can be used for imaging 7,19 . The necessity to determine the TM empirically is therefore a major bottleneck of the technology, and it would be immense...

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Seeing through chaos in multimode fibres

2015

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“…Unfortunately, fiber bundles suffer from a limited imaging resolution and low fill factors dictated by the individual fiber's core and cladding diameters, respectively. Alternatively, the image information can be delivered by a single multimode fiber (MMF), where each transverse fiber mode transmits a different pixel element [2,3]. The inherent problem of phase randomization and mode mixing in propagation through a MMF can be compensated for by pre-measuring the complex inputoutput transmission matrix (TM) for the propagating fiber modes [3], or by phase conjugation [2,3], effectively unmixing back the propagation effects.…”

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“…Alternatively, the image information can be delivered by a single multimode fiber (MMF), where each transverse fiber mode transmits a different pixel element [2,3]. The inherent problem of phase randomization and mode mixing in propagation through a MMF can be compensated for by pre-measuring the complex inputoutput transmission matrix (TM) for the propagating fiber modes [3], or by phase conjugation [2,3], effectively unmixing back the propagation effects. Recently, impressive results have been obtained by applying the principles of these approaches using digital cameras and computer-controlled spatial light modulators (SLMs) [4][5][6][7][8][9].…”

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Scanning-free imaging through a single fiber by random spatio-spectral encoding

et al. 2015

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We present an approach for two-dimensional (2D) imaging through a single single-mode or multimode fiber without the need for scanners. A random scattering medium placed next to the distal end of the fiber is used to encode the collected light from every imaged pixel with a different random spectral signature. 2D objects illuminated by a white-light source are then imaged from a single measured spectrum at the fiber's proximal end. The technique is insensitive to fiber bending, an advantage for endoscopic applications.

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“…The transmission of spatial information through an optical fiber can be achieved in many ways [10, 11]. One example is by modal multiplexing where different spatial distributions of light are coupled to different spatial modes of a multimode fiber.…”

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“…By placing a miniature grating and lens in front of an optical fiber, directional (spatial) information can be converted into color (spectral) information, and launched into the fiber. Such a technique has been used to perform 1D imaging of transmitting or reflecting [11, 15, 16, 17] or even self-luminous [18, 19] objects, where 2D imaging is then obtained by a mechanism of physical scanning along the orthogonal axis. Alternatively, scanningless 2D imaging with no moving parts has been performed by angle-wavelength encoding [11] or fully spectral encoding using a combination of gratings [20] or a grating and a virtual image phased array (VIPA) [21, 22].…”

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