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1
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Uhlířová H, Stibůrek M, Pikálek T, Gomes A, Turtaev S, Kolbábková P, Čižmár T. "There's plenty of room at the bottom": deep brain imaging with holographic endo-microscopy. NEUROPHOTONICS 2024; 11:S11504. [PMID: 38250297 PMCID: PMC10798506 DOI: 10.1117/1.nph.11.s1.s11504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 12/09/2023] [Accepted: 12/14/2023] [Indexed: 01/23/2024]
Abstract
Significance Over more than 300 years, microscopic imaging keeps providing fundamental insights into the mechanisms of living organisms. Seeing microscopic structures beyond the reach of free-space light-based microscopy, however, requires dissection of the tissue-an intervention seriously disturbing its physiological functions. The hunt for low-invasiveness tools has led a growing community of physicists and engineers into the realm of complex media photonics. One of its activities represents exploiting multimode optical fibers (MMFs) as ultra-thin endoscopic probes. Employing wavefront shaping, these tools only recently facilitated the first peeks at cells and their sub-cellular compartments at the bottom of the mouse brain with the impact of micro-scale tissue damage. Aim Here, we aim to highlight advances in MMF-based holographic endo-microscopy facilitating microscopic imaging throughout the whole depth of the mouse brain. Approach We summarize the important technical and methodological prerequisites for stabile high-resolution imaging in vivo. Results We showcase images of the microscopic building blocks of brain tissue, including neurons, neuronal processes, vessels, intracellular calcium signaling, and red blood cell velocity in individual vessels. Conclusions This perspective article helps to understand the complexity behind the technology of holographic endo-microscopy, summarizes its recent advances and challenges, and stimulates the mind of the reader for further exploitation of this tool in the neuroscience research.
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Affiliation(s)
- Hana Uhlířová
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Miroslav Stibůrek
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Tomáš Pikálek
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - André Gomes
- Leibniz Institute of Photonic Technology, Jena, Germany
| | | | - Petra Kolbábková
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
| | - Tomáš Čižmár
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czech Republic
- Leibniz Institute of Photonic Technology, Jena, Germany
- Friedrich Schiller University Jena, Institute of Applied Optics, Jena, Germany
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2
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Mezil S, Wang I, Bossy E. Imaging through a square multimode fiber by scanning focused spots with the memory effect. OPTICS LETTERS 2023; 48:4701-4704. [PMID: 37656590 DOI: 10.1364/ol.494241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/07/2023] [Indexed: 09/03/2023]
Abstract
The existence of a shift-shift memory effect in square waveguides, whereby any translation of the input field induces translations in the output field in four symmetrical directions, has been previously observed by correlation measurements. Here we demonstrate that this memory effect is also observed in real space and can be put to use for imaging purposes. First, a focus is created at the output of a square-core multimode fiber, by wavefront shaping based on feedback from a guide-star. Then, because of the memory effect, four symmetrical spots can be scanned at the fiber output by shifting the wavefront at the fiber input. We demonstrate that this property can be exploited to perform fluorescence imaging through the multimode fiber, without requiring the measurement of a transmission matrix.
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3
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Bouchet D, Caravaca-Aguirre AM, Godefroy G, Moreau P, Wang I, Bossy E. Speckle-correlation imaging through a kaleidoscopic multimode fiber. Proc Natl Acad Sci U S A 2023; 120:e2221407120. [PMID: 37343065 PMCID: PMC10293815 DOI: 10.1073/pnas.2221407120] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Accepted: 05/23/2023] [Indexed: 06/23/2023] Open
Abstract
Speckle-correlation imaging techniques are widely used for noninvasive imaging through complex scattering media. While light propagation through multimode fibers and scattering media share many analogies, reconstructing images through multimode fibers from speckle correlations remains an unsolved challenge. Here, we exploit a kaleidoscopic memory effect emerging in square-core multimode fibers and demonstrate fluorescence imaging with no prior knowledge on the fiber. Experimentally, our approach simply requires to translate random speckle patterns at the input of a square-core fiber and to measure the resulting fluorescence intensity with a bucket detector. The image of the fluorescent object is then reconstructed from the autocorrelation of the measured signal by solving an inverse problem. This strategy does not require the knowledge of the fragile deterministic relation between input and output fields, which makes it promising for the development of flexible minimally invasive endoscopes.
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Affiliation(s)
- Dorian Bouchet
- Université Grenoble Alpes, CNRS, LIPhy, 38000Grenoble, France
| | | | - Guillaume Godefroy
- Université Grenoble Alpes, CNRS, LIPhy, 38000Grenoble, France
- Université Grenoble Alpes, CEA, Leti, 38000Grenoble, France
| | - Philippe Moreau
- Université Grenoble Alpes, CNRS, LIPhy, 38000Grenoble, France
| | - Irène Wang
- Université Grenoble Alpes, CNRS, LIPhy, 38000Grenoble, France
| | - Emmanuel Bossy
- Université Grenoble Alpes, CNRS, LIPhy, 38000Grenoble, France
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4
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Němcová Š, Čáp J. Mechanically loaded GRIN lens for endoscopy. OPTICS EXPRESS 2023; 31:13096-13103. [PMID: 37157455 DOI: 10.1364/oe.485554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Endoscopic techniques are broadly used in medicine. Small diameter endoscopes are either made as fiber bundles or, beneficially, as graded index lenses. Fiber bundles can withstand a mechanical load during their use but the GRIN lens's performance can be affected by its deflection. Here, we analyze the effect of deflection on the image quality and unwanted associated effects with relation to the eye endoscope we designed and built. We also present the result of our effort to make a reliable model of a bent GRIN lens in the OpticStudio software.
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5
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Liu S, Sun Y, Liu W, Xiao F, Song H. Information distribution on regions of speckle patterns for imaging of multimode fiber. Heliyon 2023; 9:e13357. [PMID: 36816253 PMCID: PMC9932470 DOI: 10.1016/j.heliyon.2023.e13357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/20/2023] [Accepted: 01/29/2023] [Indexed: 02/04/2023] Open
Abstract
Multimode fibers (MMF) have been extensively investigated for transmitting images. The transmitting images are distorted into speckle patterns by MMFs, which can be reconstructed by neural networks. We studied the information distribution of MMF speckle patterns for image reconstruction. The speckle patterns, segmented by three methods of segmentation, as Centering (1), Quartering (2) and Surrounding (3), are reconstructed into input images by Complex Artificial Neural Network (CANN). Experimental results show that only about one third of full speckle patterns is enough to reconstruct the original images. The quality of reconstructed image is related to the cropping method with different frequency components in speckle patterns, under the same cropped size, Centering segmentation has 4% performance improvement compared to Surrounding segmentation. Optimized segmentation will improve the quality of reconstructed images.
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6
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Cifuentes A, Trägårdh J. A method for single particle tracking through a multimode fiber. OPTICS EXPRESS 2022; 30:36055-36064. [PMID: 36258542 DOI: 10.1364/oe.470111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Accepted: 08/27/2022] [Indexed: 06/16/2023]
Abstract
Multimode optical fiber (MMF) endoscopes have recently gained widespread attention as a novel tool for imaging deep within tissue using light microscopy. We here present a method for particle tracking through the MMF, which overcomes the lack of a fast enough wide-field fluorescence imaging modality for this type of endoscope, namely a discrete implementation of orbital particle tracking. We achieve biologically relevant tracking speeds (up to 1.2 μm/s) despite using a slow SLM for the wavefront shaping. We demonstrate a tracking accuracy of λ/50 for a 0.3 NA fiber and show tracking of a pinhole moving to mimic Brownian motion with diffusion rates of up to 0.3 μm2/s.
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7
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Liu Z, Wang L, Meng Y, He T, He S, Yang Y, Wang L, Tian J, Li D, Yan P, Gong M, Liu Q, Xiao Q. All-fiber high-speed image detection enabled by deep learning. Nat Commun 2022; 13:1433. [PMID: 35301332 PMCID: PMC8930987 DOI: 10.1038/s41467-022-29178-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 02/24/2022] [Indexed: 12/29/2022] Open
Abstract
Ultra-high-speed imaging serves as a foundation for modern science. While in biomedicine, optical-fiber-based endoscopy is often required for in vivo applications, the combination of high speed with the fiber endoscopy, which is vital for exploring transient biomedical phenomena, still confronts some challenges. We propose all-fiber imaging at high speeds, which is achieved based on the transformation of two-dimensional spatial information into one-dimensional temporal pulsed streams by leveraging high intermodal dispersion in a multimode fiber. Neural networks are trained to reconstruct images from the temporal waveforms. It can not only detect content-aware images with high quality, but also detect images of different kinds from the training images with slightly reduced quality. The fiber probe can detect micron-scale objects with a high frame rate (15.4 Mfps) and large frame depth (10,000). This scheme combines high speeds with high mechanical flexibility and integration and may stimulate future research exploring various phenomena in vivo.
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Affiliation(s)
- Zhoutian Liu
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Lele Wang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Yuan Meng
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Tiantian He
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Sifeng He
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Yousi Yang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Liuyue Wang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Jiading Tian
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China
| | - Dan Li
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China.,Key Laboratory of Photonic Control Technology, Ministry of Education, Tsinghua University, Beijing, 100084, China
| | - Ping Yan
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China.,Key Laboratory of Photonic Control Technology, Ministry of Education, Tsinghua University, Beijing, 100084, China
| | - Mali Gong
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China.,Key Laboratory of Photonic Control Technology, Ministry of Education, Tsinghua University, Beijing, 100084, China
| | - Qiang Liu
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China.,Key Laboratory of Photonic Control Technology, Ministry of Education, Tsinghua University, Beijing, 100084, China
| | - Qirong Xiao
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, 100084, China. .,Key Laboratory of Photonic Control Technology, Ministry of Education, Tsinghua University, Beijing, 100084, China.
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8
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Stellinga D, Phillips DB, Mekhail SP, Selyem A, Turtaev S, Čižmár T, Padgett MJ. Time-of-flight 3D imaging through multimode optical fibers. Science 2021; 374:1395-1399. [PMID: 34882470 DOI: 10.1126/science.abl3771] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Daan Stellinga
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - David B Phillips
- School of Physics and Astronomy, University of Exeter, Exeter EX4 4QL, UK
| | | | - Adam Selyem
- Fraunhofer Centre for Applied Photonics, Glasgow G1 1RD, UK
| | - Sergey Turtaev
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
| | - Tomáš Čižmár
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany.,Institute of Scientific Instruments of the CAS, Královopolská 147, 612 64 Brno, Czech Republic
| | - Miles J Padgett
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
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9
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Tučková T, Šiler M, Boonzajer Flaes DE, Jákl P, Turtaev S, Krátký S, Heintzmann R, Uhlířová H, Čižmár T. Computational image enhancement of multimode fibre-based holographic endo-microscopy: harnessing the muddy modes. OPTICS EXPRESS 2021; 29:38206-38220. [PMID: 34808878 DOI: 10.1364/oe.434848] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 10/06/2021] [Indexed: 06/13/2023]
Abstract
In imaging geometries, which employ wavefront-shaping to control the light transport through a multi-mode optical fibre (MMF), this terminal hair-thin optical component acts as a minimally invasive objective lens, enabling high resolution laser-scanning fluorescence microscopy inside living tissues at depths hardly accessible by any other light-based technique. Even in the most advanced systems, the diffraction-limited foci scanning the object across the focal plane are contaminated by a stray optical signal carrying typically few tens of % of the total optical power. The stray illumination takes the shape of a randomised but reproducible speckle, and is unique for each position of the focus. We experimentally demonstrate that the performance of imaging a fluorescent object can be significantly improved, when resulting images are computationally post-processed, utilising records of intensities of all speckle-contaminated foci used in the imaging procedure. We present two algorithms based on a regularised iterative inversion and regularised direct pseudo-inversion respectively which lead to enhancement of the image contrast and resolution.
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10
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Gao W, Mo H, Wu G, Yang D, Yin L. Compressive endoscopic imaging with complementary light modulation. APPLIED OPTICS 2021; 60:8221-8225. [PMID: 34612917 DOI: 10.1364/ao.433712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/15/2021] [Indexed: 06/13/2023]
Abstract
We propose an effective endoscopic imaging method utilizing compressive sensing (CS) theory on the basis of complementary light modulation of a spatial light modulator. Both the simulated and the experimental results show that complementary compressive sensing (CCS) always needs less time to obtain better work than conventional CS with normal modulation at the same sampling rate. First, the speed of CCS is at least twice as fast as CS. Second, in comparison with CS, CCS can improve the signal-to-noise ratio of the reconstructed image by 49.7%, which indicates that this method is of great significance to endoscopic applications in terms of image fidelity and denoising performance.
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11
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Singh S, Labouesse S, Piestun R. Tunable mode control through myriad-mode fibers. JOURNAL OF LIGHTWAVE TECHNOLOGY : A JOINT IEEE/OSA PUBLICATION 2021; 39:2961-2970. [PMID: 33994658 PMCID: PMC8117977 DOI: 10.1109/jlt.2021.3057615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Multimode fibers are attractive for imaging, communication, computation, and energy delivery. Unfortunately, intermodal and polarization coupling precludes direct control of the delivered mode composition. We present a technique to tailor the mode composition at the output of a multimode fiber with thousands of modes, which we refer to as myriad-mode fiber, using its experimentally measured transmission matrix. While precise mode control has been demonstrated in typical multimode fibers with up to 210 modes, the method proposed here is particularly useful for high mode number fibers, such as when the number of modes is comparable to the number of modes of the wavefront shaping spatial light modulator. To illustrate the technique, we select different subsets of modes to create focal spots at the output of a fiber with 7140 modes. Importantly, we define efficiency and fidelity metrics to evaluate the mode control and demonstrate the relationship between efficiency, fidelity, and the spatial location of the spots across the distal fiber cross-section.
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Affiliation(s)
- Sakshi Singh
- Department of Electrical, Computer, and Energy Engineering, University of Colorado Boulder, Colorado 80309, USA
| | - Simon Labouesse
- Department of Electrical, Computer, and Energy Engineering, University of Colorado Boulder, Colorado 80309, USA
| | - Rafael Piestun
- Department of Electrical, Computer, and Energy Engineering, University of Colorado Boulder, Colorado 80309, USA
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12
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Kazarian SG. Perspectives on infrared spectroscopic imaging from cancer diagnostics to process analysis. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 251:119413. [PMID: 33461133 DOI: 10.1016/j.saa.2020.119413] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 12/28/2020] [Accepted: 12/30/2020] [Indexed: 05/20/2023]
Abstract
This perspective paper discusses the recent and potential developments in the application of infrared spectroscopic imaging, with a focus on Fourier transform infrared (FTIR) spectroscopic imaging. The current state-of-the-art has been briefly reported, that includes recent trends and advances in applications of FTIR spectroscopic imaging to biomedical systems. Here, some new opportunities for research in the biomedical field, particularly for cancer diagnostics, and also in the engineering field of process analysis; as well as challenges in FTIR spectroscopic imaging are discussed. Current and future prospects that will bring spectroscopic imaging technologies to the frontier of advanced medical diagnostics and to process analytics in engineering applications will be outlined in this opinion paper.
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Affiliation(s)
- Sergei G Kazarian
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.
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13
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Choudhury D, McNicholl DK, Repetti A, Gris-Sánchez I, Li S, Phillips DB, Whyte G, Birks TA, Wiaux Y, Thomson RR. Computational optical imaging with a photonic lantern. Nat Commun 2020; 11:5217. [PMID: 33060608 PMCID: PMC7562926 DOI: 10.1038/s41467-020-18818-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 09/10/2020] [Indexed: 11/24/2022] Open
Abstract
The thin and flexible nature of optical fibres often makes them the ideal technology to view biological processes in-vivo, but current microendoscopic approaches are limited in spatial resolution. Here, we demonstrate a route to high resolution microendoscopy using a multicore fibre (MCF) with an adiabatic multimode-to-single-mode “photonic lantern” transition formed at the distal end by tapering. We show that distinct multimode patterns of light can be projected from the output of the lantern by individually exciting the single-mode MCF cores, and that these patterns are highly stable to fibre movement. This capability is then exploited to demonstrate a form of single-pixel imaging, where a single pixel detector is used to detect the fraction of light transmitted through the object for each multimode pattern. A custom computational imaging algorithm we call SARA-COIL is used to reconstruct the object using only the pre-measured multimode patterns themselves and the detector signals. Here, the authors demonstrate a route to high resolution microendoscopy using a multicore fibre with a photonic lantern. They show that distinct multimode patterns of light can be projected from the output of the lantern by individually exciting the single-mode MCF cores, whose patterns are highly stable to fibre movement.
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Affiliation(s)
- Debaditya Choudhury
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.,EPSRC IRC Hub, MRC Centre for Inflammation Research, Queen's Medical Research Institute (QMRI), University of Edinburgh, Edinburgh, UK
| | - Duncan K McNicholl
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.,EPSRC IRC Hub, MRC Centre for Inflammation Research, Queen's Medical Research Institute (QMRI), University of Edinburgh, Edinburgh, UK
| | - Audrey Repetti
- Institute of Sensors, Signals and System, Heriot-Watt University, Edinburgh, EH14 4AS, UK.,Department of Actuarial Mathematics and Statistics, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Itandehui Gris-Sánchez
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK.,ITEAM Research Institute, Universitat Politècnica de València, 46022, Valencia, Spain
| | - Shuhui Li
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, 430074, Wuhan, Hubei, China.,School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK
| | - David B Phillips
- School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK
| | - Graeme Whyte
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Tim A Birks
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Yves Wiaux
- Institute of Sensors, Signals and System, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Robert R Thomson
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK. .,EPSRC IRC Hub, MRC Centre for Inflammation Research, Queen's Medical Research Institute (QMRI), University of Edinburgh, Edinburgh, UK.
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14
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Mezil S, Caravaca-Aguirre AM, Zhang EZ, Moreau P, Wang I, Beard PC, Bossy E. Single-shot hybrid photoacoustic-fluorescent microendoscopy through a multimode fiber with wavefront shaping. BIOMEDICAL OPTICS EXPRESS 2020; 11:5717-5727. [PMID: 33149981 PMCID: PMC7587274 DOI: 10.1364/boe.400686] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/17/2020] [Accepted: 08/23/2020] [Indexed: 05/14/2023]
Abstract
We present a minimally-invasive endoscope based on a multimode fiber that combines photoacoustic and fluorescence sensing. From the measurement of a transmission matrix during a prior calibration step, a focused spot is produced and raster-scanned over a sample at the distal tip of the fiber by use of a fast spatial light modulator. An ultra-sensitive fiber-optic ultrasound sensor for photoacoustic detection placed next to the fiber is combined with a photodetector to obtain both fluorescence and photoacoustic images with a distal imaging tip no larger than 250 µm. The high signal-to-noise ratio provided by wavefront shaping based focusing and the ultra-sensitive ultrasound sensor enables imaging with a single laser shot per pixel, demonstrating fast two-dimensional hybrid in vitro imaging of red blood cells and fluorescent beads.
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Affiliation(s)
- Sylvain Mezil
- Univ. Grenoble Alpes, CNRS, LIPhy, 38000 Grenoble, France
| | | | - Edward Z. Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
| | | | - Irène Wang
- Univ. Grenoble Alpes, CNRS, LIPhy, 38000 Grenoble, France
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, UK
| | - Emmanuel Bossy
- Univ. Grenoble Alpes, CNRS, LIPhy, 38000 Grenoble, France
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15
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Turcotte R, Sutu E, Schmidt CC, Emptage NJ, Booth MJ. Deconvolution for multimode fiber imaging: modeling of spatially variant PSF. BIOMEDICAL OPTICS EXPRESS 2020; 11:4759-4771. [PMID: 32923076 PMCID: PMC7449755 DOI: 10.1364/boe.399983] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/12/2020] [Accepted: 07/13/2020] [Indexed: 05/29/2023]
Abstract
Focusing light through a step-index multimode optical fiber (MMF) using wavefront control enables minimally-invasive endoscopy of biological tissue. The point spread function (PSF) of such an imaging system is spatially variant, and this variation limits compensation for blurring using most deconvolution algorithms as they require a uniform PSF. However, modeling the spatially variant PSF into a series of spatially invariant PSFs re-opens the possibility of deconvolution. To achieve this we developed svmPSF: an open-source Java-based framework compatible with ImageJ. The approach takes a series of point response measurements across the field-of-view (FOV) and applies principal component analysis to the measurements' co-variance matrix to generate a PSF model. By combining the svmPSF output with a modified Richardson-Lucy deconvolution algorithm, we were able to deblur and regularize fluorescence images of beads and live neurons acquired with a MMF, and thus effectively increasing the FOV.
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Affiliation(s)
- Raphaël Turcotte
- Department of Engineering Science,
University of Oxford, Parks Road, Oxford OX1 3PJ, United Kingdom
- Department of Pharmacology, University of
Oxford, Mansfield Road, Oxford OX1 3QT, United
Kingdom
| | - Eusebiu Sutu
- Department of Engineering Science,
University of Oxford, Parks Road, Oxford OX1 3PJ, United Kingdom
| | - Carla C. Schmidt
- Department of Pharmacology, University of
Oxford, Mansfield Road, Oxford OX1 3QT, United
Kingdom
| | - Nigel J. Emptage
- Department of Pharmacology, University of
Oxford, Mansfield Road, Oxford OX1 3QT, United
Kingdom
| | - Martin J. Booth
- Department of Engineering Science,
University of Oxford, Parks Road, Oxford OX1 3PJ, United Kingdom
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16
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Shabairou N, Lengenfelder B, Hohmann M, Klämpfl F, Schmidt M, Zalevsky Z. All-optical, an ultra-thin endoscopic photoacoustic sensor using multi-mode fiber. Sci Rep 2020; 10:9142. [PMID: 32499607 PMCID: PMC7272416 DOI: 10.1038/s41598-020-66076-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 05/14/2020] [Indexed: 01/05/2023] Open
Abstract
Photoacoustic endoscopy (PAE) is a method of in-vivo imaging that uses tissue absorption properties. In PAE, the main tools used to detect the acoustic signal are mechanical ultrasound transducers, which require direct contact and which are difficult to miniaturize. All-optic photoacoustic sensors can challenge this issue as they can provide contact-free sensing. Here, we demonstrate sensing of photo-acoustic signals through a multimode fiber (MMF) which can provide an ultra-thin endoscopic photoacoustic sensor. Furthermore, we show the advantage of using the optical-flow method for speckle sensing and extract the photoacoustic signal despite the mode-mixing along the MMF. Moreover, it is demonstrated for the first time that the speckle reconstruction method can be used without the need for imaging of the speckles as this enables the use of multimode fibers for the speckle method.
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Affiliation(s)
- Nadav Shabairou
- Faculty of Engineering, Bar-Ilan University, Ramat-Gan, 52900, Israel.
| | - Benjamin Lengenfelder
- Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Martin Hohmann
- Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Florian Klämpfl
- Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Michael Schmidt
- Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Konrad-Zuse-Straße 3/5, 91052, Erlangen, Germany.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
| | - Zeev Zalevsky
- Faculty of Engineering, Bar-Ilan University, Ramat-Gan, 52900, Israel.,Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Straße 6, 91052, Erlangen, Germany
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17
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Amitonova LV, de Boer JF. Endo-microscopy beyond the Abbe and Nyquist limits. LIGHT, SCIENCE & APPLICATIONS 2020; 9:81. [PMID: 32411366 PMCID: PMC7206071 DOI: 10.1038/s41377-020-0308-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 04/01/2020] [Accepted: 04/03/2020] [Indexed: 05/23/2023]
Abstract
For several centuries, far-field optical microscopy has remained a key instrument in many scientific disciplines, including physical, chemical, and biomedical research. Nonetheless, far-field imaging has many limitations: the spatial resolution is controlled by the diffraction of light, and the imaging speed follows the Nyquist-Shannon sampling theorem. The recent development of super-resolution techniques has pushed the limits of spatial resolution. However, these methods typically require complicated setups and long acquisition times and are still not applicable to deep-tissue bioimaging. Here, we report imaging through an ultra-thin fibre probe with a spatial resolution beyond the Abbe limit and a temporal resolution beyond the Nyquist limit simultaneously in a simple and compact setup. We use the random nature of mode coupling in a multimode fibre, the sparsity constraint and compressive sensing reconstruction. The new approach of super-resolution endo-microscopy does not use any specific properties of the fluorescent label, such as depletion or stochastic activation of the molecular fluorescent state, and therefore can be used for label-free imaging. We demonstrate a spatial resolution more than 2 times better than the diffraction limit and an imaging speed 20 times faster than the Nyquist limit. The proposed approach can significantly expand the realm of the application of nanoscopy for bioimaging.
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Affiliation(s)
- Lyubov V. Amitonova
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
- Advanced Research Center for Nanolithography (ARCNL), Science Park 106, 1098 XG Amsterdam, The Netherlands
| | - Johannes F. de Boer
- LaserLaB, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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18
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Pikálek T, Trägårdh J, Simpson S, Čižmár T. Wavelength dependent characterization of a multimode fibre endoscope. OPTICS EXPRESS 2019; 27:28239-28253. [PMID: 31684580 DOI: 10.1364/oe.27.028239] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/01/2019] [Indexed: 06/10/2023]
Abstract
Multimode fibres have recently shown promise as miniature endoscopic probes. When used for non-linear microscopy, the bandwidth of the imaging system limits the ability to focus light from broadband pulsed lasers as well as the possibility of wavelength tuning during the imaging. We demonstrate that the bandwidth is limited by the dispersion of the off-axis hologram displayed on the SLM, which can be corrected for, and by the limited bandwidth of the fibre itself. The selection of the fibre is therefore crucial for these experiments. In addition, we show that a standard prism pulse compressor is sufficient for material dispersion compensation for multi-photon imaging with a fibre endoscope.
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19
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Gordon GSD, Joseph J, Sawyer T, Macfaden AJ, Williams C, Wilkinson TD, Bohndiek SE. Full-field quantitative phase and polarisation-resolved imaging through an optical fibre bundle. OPTICS EXPRESS 2019; 27:23929-23947. [PMID: 31510290 PMCID: PMC6825613 DOI: 10.1364/oe.27.023929] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 07/11/2019] [Accepted: 07/11/2019] [Indexed: 05/06/2023]
Abstract
Flexible optical fibres, used in conventional medical endoscopy and industrial inspection, scramble phase and polarisation information, restricting users to amplitude-only imaging. Here, we exploit the near-diagonality of the multi-core fibre (MCF) transmission matrix in a parallelised fibre characterisation architecture, enabling accurate imaging of quantitative phase (error <0.3 rad) and polarisation-resolved (errors <10%) properties. We first demonstrate accurate recovery of optical amplitude and phase in two polarisations through the MCF by measuring and inverting the transmission matrix, and then present a robust Bayesian inference approach to resolving 5 polarimetric properties of samples. Our method produces high-resolution (9.0±2.6μm amplitude, phase; 36.0±10.4μm polarimetric) full-field images at working distances up to 1mm over a field-of-view up to 750×750μm 2 using an MCF with potential for flexible operation. We demonstrate the potential of using quantitative phase for computational image focusing and polarisation-resolved properties in imaging birefringence.
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Affiliation(s)
- George S. D. Gordon
- Now at: Department of Electrical and Electronic Engineering, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK
- Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, CB3 0FA, UK
| | - James Joseph
- Department of Physics, Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
| | - Travis Sawyer
- Department of Physics, Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Alexander J. Macfaden
- Now at: Department of Electrical and Electronic Engineering, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Calum Williams
- Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, CB3 0FA, UK
- Department of Physics, Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Timothy D. Wilkinson
- Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge, CB3 0FA, UK
| | - Sarah E. Bohndiek
- Department of Physics, Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
- Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Robinson Way, Cambridge, CB2 0RE, UK
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20
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McGoran JJ, McAlindon ME, Iyer PG, Seibel EJ, Haidry R, Lovat LB, Sami SS. Miniature gastrointestinal endoscopy: Now and the future. World J Gastroenterol 2019; 25:4051-4060. [PMID: 31435163 PMCID: PMC6700702 DOI: 10.3748/wjg.v25.i30.4051] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/22/2019] [Accepted: 07/03/2019] [Indexed: 02/06/2023] Open
Abstract
Since its original application, gastrointestinal (GI) endoscopy has undergone many innovative transformations aimed at expanding the scope, safety, accuracy, acceptability and cost-effectiveness of this area of clinical practice. One method of achieving this has been to reduce the caliber of endoscopic devices. We propose the collective term “Miniature GI Endoscopy”. In this Opinion Review, the innovations in this field are explored and discussed. The progress and clinical use of the three main areas of miniature GI endoscopy (ultrathin endoscopy, wireless endoscopy and scanning fiber endoscopy) are described. The opportunities presented by these technologies are set out in a clinical context, as are their current limitations. Many of the positive aspects of miniature endoscopy are clear, in that smaller devices provide access to potentially all of the alimentary canal, while conferring high patient acceptability. This must be balanced with the costs of new technologies and recognition of device specific challenges. Perspectives on future application are also considered and the efforts being made to bring new innovations to a clinical platform are outlined. Current devices demonstrate that miniature GI endoscopy has a valuable place in investigation of symptoms, therapeutic intervention and screening. Newer technologies give promise that the potential for enhancing the investigation and management of GI complaints is significant.
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Affiliation(s)
- John J McGoran
- Digestive Diseases Centre, Leicester Royal Infirmary, Leicester LE1 5WW, United Kingdom
| | - Mark E McAlindon
- Department of Gastroenterology, Royal Hallamshire Hospital, Sheffield S10 2JF, United Kingdom
| | - Prasad G Iyer
- Division of Gastroenterology and Hepatology, Mayo Clinic Rochester, MN 55905, United States
| | - Eric J Seibel
- Department of Mechanical Engineering, University of Washington, 4000 Mason St, Seattle, WA 98195, United States
| | - Rehan Haidry
- Division of Surgery and Interventional Science, University College London, London WC1E 6BT, United Kingdom
| | - Laurence B Lovat
- Division of Surgery and Interventional Science, University College London, London WC1E 6BT, United Kingdom
| | - Sarmed S Sami
- Division of Surgery and Interventional Science, University College London, London WC1E 6BT, United Kingdom
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21
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Su X, Yuan T, Wang Z, Song K, Li R, Yuan C, Kong B. Two-Dimensional Light Scattering Anisotropy Cytometry for Label-Free Classification of Ovarian Cancer Cells via Machine Learning. Cytometry A 2019; 97:24-30. [PMID: 31313517 DOI: 10.1002/cyto.a.23865] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 06/14/2019] [Accepted: 07/01/2019] [Indexed: 12/24/2022]
Abstract
We develop a single-mode fiber-based cytometer for the obtaining of two-dimensional (2D) light scattering patterns from static single cells. Anisotropy of the 2D light scattering patterns of single cells from ovarian cancer and normal cell lines is investigated by histograms of oriented gradients (HOG) method. By analyzing the HOG descriptors with support vector machine, an accuracy rate of 92.84% is achieved for the automatic classification of these two kinds of label-free cells. The 2D light scattering anisotropy cytometry combined with machine learning may provide a label-free, automatic method for screening of ovarian cancer cells, and other types of cells. © 2019 International Society for Advancement of Cytometry.
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Affiliation(s)
- Xuantao Su
- Institute of Biomedical Engineering, School of Control Science and Engineering, Shandong University, Jinan, Shandong, 250061, China
| | - Tao Yuan
- Institute of Biomedical Engineering, School of Control Science and Engineering, Shandong University, Jinan, Shandong, 250061, China
| | - Zhiwen Wang
- Institute of Biomedical Engineering, School of Control Science and Engineering, Shandong University, Jinan, Shandong, 250061, China
| | - Kun Song
- Department of Obstetrics and Gynecology, Qilu Hospital, Shandong University, Jinan, 250012, China.,Gynecology Oncology Key Laboratory, Qilu Hospital, Shandong University, Jinan, 250012, China
| | - Rongrong Li
- Department of Obstetrics and Gynecology, Qilu Hospital, Shandong University, Jinan, 250012, China
| | - Cunzhong Yuan
- Department of Obstetrics and Gynecology, Qilu Hospital, Shandong University, Jinan, 250012, China
| | - Beihua Kong
- Department of Obstetrics and Gynecology, Qilu Hospital, Shandong University, Jinan, 250012, China
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22
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Lan M, Guan D, Gao L, Li J, Yu S, Wu G. Robust compressive multimode fiber imaging against bending with enhanced depth of field. OPTICS EXPRESS 2019; 27:12957-12962. [PMID: 31052828 DOI: 10.1364/oe.27.012957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/12/2019] [Indexed: 06/09/2023]
Abstract
Imaging through single multimode fiber prevails its counterpart using single mode fiber bundle on spatial resolution limit and minimum radius. Current multimode fiber imaging suffers from fussy calibration, which can be reduced by recent developed compressive sensing scheme [ [L. V. Amitonova, Opt. Lett. 43, 5427 (2018)]. Experiments demonstrate improvement on depth of field by more than three orders of magnitude, together with robustness against macro fiber bending, which is vital to endoscopic applications.
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23
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Warren-Smith SC, Dowler A, Ebendorff-Heidepriem H. Soft-glass imaging microstructured optical fibers. OPTICS EXPRESS 2018; 26:33604-33612. [PMID: 30650793 DOI: 10.1364/oe.26.033604] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 11/18/2018] [Indexed: 06/09/2023]
Abstract
We demonstrate the fabrication of multi-core (imaging) microstructured optical fiber via soft-glass preform extrusion through a 3D printed titanium die. The combination of extrusion through 3D printed dies and structured element (capillary) stacking allows for unprecedented control of the optical fiber geometry. We have exploited this to demonstrate a 100 pixel rectangular array imaging microstructured fiber. Due to the high refractive index of the glass used (n = 1.62), such a fiber can theoretically have a pixel pitch as small as 1.8 µm. This opens opportunities for ultra-small, high-resolution imaging fibers fabricated from diverse glass types.
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24
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Sato M, Eto K, Masuta J, Nishidate I. Depolarization characteristics of spatial modes in imaging probe using short multimode fiber. APPLIED OPTICS 2018; 57:10083-10091. [PMID: 30645212 DOI: 10.1364/ao.57.010083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 10/29/2018] [Indexed: 06/09/2023]
Abstract
Optical coherence tomography is one of the standard imaging modalities at present, widely used in the medical and biological fields to obtain three-dimensional (3D) images with high spatial resolution. However, the depth up to which the 3D images can be directly obtained is limited to within 3 mm. Therefore, the suitability of many kinds of catheters and needles has been considered for minimally invasive imaging. We have examined the utility of a short multimode fiber (SMMF) using graded index optical fibers for minimal invasive imaging of deeper areas, up to 6-8 mm. The diameter and length of the SMMF are 125 μm and 6-8 mm, respectively. In the core of the SMMF, scattering and multirefraction occur due to small variations in the refractive index to generate deformations and depolarization of images. In order to investigate the depolarization characteristics, the images reflected at the facet of the SMMF were measured by changing the angle of the polarizer, using an LED as the light source. The reflection image almost corresponds to that obtained with combined linearly polarized modes with the ratio of LP01∶LP11∶LP21 equal to 1∶0.2∶0.7. Comparing the measured results with simulations in the simple model, the depolarization ratio was estimated at 0.7 in the core. The degrees of polarization were measured to be 0.15 around the center and increased to 0.90 at the periphery.
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25
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Verbeeck J, Béché A, Müller-Caspary K, Guzzinati G, Luong MA, Den Hertog M. Demonstration of a 2 × 2 programmable phase plate for electrons. Ultramicroscopy 2018; 190:58-65. [DOI: 10.1016/j.ultramic.2018.03.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 03/16/2018] [Accepted: 03/24/2018] [Indexed: 02/03/2023]
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26
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Boonzajer Flaes DE, Stopka J, Turtaev S, de Boer JF, Tyc T, Čižmár T. Robustness of Light-Transport Processes to Bending Deformations in Graded-Index Multimode Waveguides. PHYSICAL REVIEW LETTERS 2018; 120:233901. [PMID: 29932680 DOI: 10.1103/physrevlett.120.233901] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Indexed: 05/14/2023]
Abstract
Light transport through a multimode optical waveguide undergoes changes when subjected to bending deformations. We show that optical waveguides with a perfectly parabolic refractive index profile are almost immune to bending, conserving the structure of propagation-invariant modes. Moreover, we show that changes to the transmission matrix of parabolic-index fibers due to bending can be expressed with only two free parameters, regardless of how complex a particular deformation is. We provide detailed analysis of experimentally measured transmission matrices of a commercially available graded-index fiber as well as a gradient-index rod lens featuring a very faithful parabolic refractive index profile. Although parabolic-index fibers with a sufficiently precise refractive index profile are not within our reach, we show that imaging performance with standard commercially available graded-index fibers is significantly less influenced by bending deformations than step-index types under the same conditions. Our work thus predicts that the availability of ultraprecise parabolic-index fibers will make endoscopic applications with flexible probes feasible and free from extremely elaborate computational challenges.
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Affiliation(s)
- Dirk E Boonzajer Flaes
- LaserLaB Amsterdam, Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Jan Stopka
- Institute of Scientific Instruments of CAS, Královopolská 147, 612 64 Brno, Czech Republic
- Department of Theoretical Physics and Astrophysics, Masaryk University, Kotlářská 2, 61137 Brno, Czechia
| | - Sergey Turtaev
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
- School of Science and Engineering, University of Dundee, Ewing building, Nethergate, DD1 4HN Dundee, Scotland, United Kingdom
| | - Johannes F de Boer
- LaserLaB Amsterdam, Department of Physics and Astronomy, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Tomáš Tyc
- Institute of Scientific Instruments of CAS, Královopolská 147, 612 64 Brno, Czech Republic
- Department of Theoretical Physics and Astrophysics, Masaryk University, Kotlářská 2, 61137 Brno, Czechia
| | - Tomáš Čižmár
- Institute of Scientific Instruments of CAS, Královopolská 147, 612 64 Brno, Czech Republic
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
- School of Science and Engineering, University of Dundee, Ewing building, Nethergate, DD1 4HN Dundee, Scotland, United Kingdom
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27
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Vasquez-Lopez SA, Turcotte R, Koren V, Plöschner M, Padamsey Z, Booth MJ, Čižmár T, Emptage NJ. Subcellular spatial resolution achieved for deep-brain imaging in vivo using a minimally invasive multimode fiber. LIGHT, SCIENCE & APPLICATIONS 2018; 7:110. [PMID: 30588295 PMCID: PMC6298975 DOI: 10.1038/s41377-018-0111-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 12/03/2018] [Accepted: 12/03/2018] [Indexed: 05/21/2023]
Abstract
Achieving intravital optical imaging with diffraction-limited spatial resolution of deep-brain structures represents an important step toward the goal of understanding the mammalian central nervous system1-4. Advances in wavefront-shaping methods and computational power have recently allowed for a novel approach to high-resolution imaging, utilizing deterministic light propagation through optically complex media and, of particular importance for this work, multimode optical fibers (MMFs)5-7. We report a compact and highly optimized approach for minimally invasive in vivo brain imaging applications. The volume of tissue lesion was reduced by more than 100-fold, while preserving diffraction-limited imaging performance utilizing wavefront control of light propagation through a single 50-μm-core MMF. Here, we demonstrated high-resolution fluorescence imaging of subcellular neuronal structures, dendrites and synaptic specializations, in deep-brain regions of living mice, as well as monitored stimulus-driven functional Ca2+ responses. These results represent a major breakthrough in the compromise between high-resolution imaging and tissue damage, heralding new possibilities for deep-brain imaging in vivo.
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Affiliation(s)
| | - Raphaël Turcotte
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT UK
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ UK
| | - Vadim Koren
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT UK
| | - Martin Plöschner
- School of Engineering, Physics and Mathematics, College of Art, Science & Engineering, University of Dundee, Nethergate, Dundee, DD1 4HN Scotland UK
| | - Zahid Padamsey
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT UK
| | - Martin J. Booth
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ UK
| | - Tomáš Čižmár
- School of Engineering, Physics and Mathematics, College of Art, Science & Engineering, University of Dundee, Nethergate, Dundee, DD1 4HN Scotland UK
- Institute of Scientific Instruments of the CAS, Královopolská 147, 612 64 Brno, Czech Republic
| | - Nigel J. Emptage
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT UK
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28
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Gusachenko I, Nylk J, Tello JA, Dholakia K. Multimode fibre based imaging for optically cleared samples. BIOMEDICAL OPTICS EXPRESS 2017; 8:5179-5190. [PMID: 29188112 PMCID: PMC5695962 DOI: 10.1364/boe.8.005179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/12/2017] [Accepted: 10/13/2017] [Indexed: 05/27/2023]
Abstract
Optical clearing is emerging as a popular approach particularly for studies in neuroscience. However the use of corrosive clearing solutions typically requires sophisticated objectives or extreme care with optical components chosen for single- or multi-photon imaging. In contrast to the use of complex, custom-made microscope objectives, we show that the use of a corrected multimode fibre (MMF) offers a route that is resistant to corrosion, can be used in clearing media, is not constrained by the refractive index of the immersion medium and offers flexible working distances. Using a corrected MMF, we demonstrate fluorescence imaging of beads and stained neuroblastoma cells through optically cleared mouse brain tissue, as well as imaging in an extreme oxidative environment to show the versatility of our approach. Additionally, we perform Raman imaging of polystyrene beads in clearing media to demonstrate that this approach may be used for vibrational spectroscopy of optically cleared samples.
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Affiliation(s)
- Ivan Gusachenko
- SUPA, School of Physics and Astronomy, University of St. Andrews, Fife, KY16 9SS,
UK
| | - Jonathan Nylk
- SUPA, School of Physics and Astronomy, University of St. Andrews, Fife, KY16 9SS,
UK
| | - Javier A. Tello
- School of Medicine, University of St. Andrews, Fife, KY16 9TF,
UK
| | - Kishan Dholakia
- SUPA, School of Physics and Astronomy, University of St. Andrews, Fife, KY16 9SS,
UK
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29
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Singh AK, Pedrini G, Takeda M, Osten W. Scatter-plate microscope for lensless microscopy with diffraction limited resolution. Sci Rep 2017; 7:10687. [PMID: 28878361 PMCID: PMC5587816 DOI: 10.1038/s41598-017-10767-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/14/2017] [Indexed: 11/22/2022] Open
Abstract
Scattering media have always been looked upon as an obstacle in imaging. Various methods, ranging from holography to phase compensation as well as to correlation techniques, have been proposed to cope with this obstacle. We, on the other hand, have a different understanding about the role of the diffusing media. In this paper we propose and demonstrate a ‘scatter-plate microscope’ that utilizes the diffusing property of the random medium for imaging micro structures with diffraction-limited resolution. The ubiquitous property of the speckle patterns permits to exploit the scattering medium as an ultra-thin lensless microscope objective with a variable focal length and a large working distance. The method provides a light, flexible and cost effective imaging device as an alternative to conventional microscope objectives. In principle, the technique is also applicable to lensless imaging in UV and X-ray microscopy. Experiments were performed with visible light to demonstrate the microscopic imaging of USAF resolution test target and a biological sample with varying numerical aperture (NA) and magnifications.
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Affiliation(s)
- Alok Kumar Singh
- Institut für Technische Optik and Stuttgart Research Center of Photonic Engineering (SCoPE), University of Stuttgart, Pfaffenwaldring 9, 70569, Stuttgart, Germany.
| | - Giancarlo Pedrini
- Institut für Technische Optik and Stuttgart Research Center of Photonic Engineering (SCoPE), University of Stuttgart, Pfaffenwaldring 9, 70569, Stuttgart, Germany
| | - Mitsuo Takeda
- Institut für Technische Optik and Stuttgart Research Center of Photonic Engineering (SCoPE), University of Stuttgart, Pfaffenwaldring 9, 70569, Stuttgart, Germany.,Center for Optical Research and Education (CORE), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi, 321-8585, Japan
| | - Wolfgang Osten
- Institut für Technische Optik and Stuttgart Research Center of Photonic Engineering (SCoPE), University of Stuttgart, Pfaffenwaldring 9, 70569, Stuttgart, Germany
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30
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Phillips DB, Sun MJ, Taylor JM, Edgar MP, Barnett SM, Gibson GM, Padgett MJ. Adaptive foveated single-pixel imaging with dynamic supersampling. SCIENCE ADVANCES 2017; 3:e1601782. [PMID: 28439538 PMCID: PMC5400451 DOI: 10.1126/sciadv.1601782] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 02/19/2017] [Indexed: 05/09/2023]
Abstract
In contrast to conventional multipixel cameras, single-pixel cameras capture images using a single detector that measures the correlations between the scene and a set of patterns. However, these systems typically exhibit low frame rates, because to fully sample a scene in this way requires at least the same number of correlation measurements as the number of pixels in the reconstructed image. To mitigate this, a range of compressive sensing techniques have been developed which use a priori knowledge to reconstruct images from an undersampled measurement set. Here, we take a different approach and adopt a strategy inspired by the foveated vision found in the animal kingdom-a framework that exploits the spatiotemporal redundancy of many dynamic scenes. In our system, a high-resolution foveal region tracks motion within the scene, yet unlike a simple zoom, every frame delivers new spatial information from across the entire field of view. This strategy rapidly records the detail of quickly changing features in the scene while simultaneously accumulating detail of more slowly evolving regions over several consecutive frames. This architecture provides video streams in which both the resolution and exposure time spatially vary and adapt dynamically in response to the evolution of the scene. The degree of local frame rate enhancement is scene-dependent, but here, we demonstrate a factor of 4, thereby helping to mitigate one of the main drawbacks of single-pixel imaging techniques. The methods described here complement existing compressive sensing approaches and may be applied to enhance computational imagers that rely on sequential correlation measurements.
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Affiliation(s)
- David B. Phillips
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
- Corresponding author. (D.B.P.); (M.-J.S.)
| | - Ming-Jie Sun
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
- Department of Opto-Electronic Engineering, Beihang University, Beijing 100191, China
- Corresponding author. (D.B.P.); (M.-J.S.)
| | - Jonathan M. Taylor
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - Matthew P. Edgar
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - Stephen M. Barnett
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - Graham M. Gibson
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - Miles J. Padgett
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
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31
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Abstract
Multimode fibers can guide thousands of modes capable of delivering spatial information. Unfortunately, mode dispersion and coupling have so far prevented their use in endoscopic applications. To address this long-lasting challenge, we present a robust scanning fluorescence endoscope. A spatial light modulator shapes the input excitation wavefront to focus light on the distal tip of the fiber and to rapidly scan the focus over the region of interest. A detector array collects the fluorescence emission propagated back from the sample to the proximal tip of the fiber. We demonstrate that proper selection of the multimode fiber is critical for a robust calibration and for high signal-to-background ratio performance. We compare different types of multimode fibers and experimentally show that a focus created through a graded-index fiber can withstand a few millimeters of fiber distal tip translation. The resulting scanning endoscopic microscope images fluorescent samples over a field of view of 80µm with a resolution of 2µm.
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32
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Liu Z, Wright LG, Christodoulides DN, Wise FW. Kerr self-cleaning of femtosecond-pulsed beams in graded-index multimode fiber. OPTICS LETTERS 2016; 41:3675-8. [PMID: 27519060 DOI: 10.1364/ol.41.003675] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We observe a nonlinear spatial self-cleaning process for femtosecond pulses in graded-index (GRIN) multimode fiber (MMF). Pulses with ∼80 fs duration at 1030 nm are launched into GRIN MMF with 62.5 μm core. The near-field beam profile at the output end of the fiber evolves from a speckled pattern to a centered, bell-shaped transverse structure with increasing pulse energy. The experimental observations agree well with numerical simulations, which show that the Kerr nonlinearity underlies the process. This self-cleaning process may find applications in ultrafast pulse generation and beam-combining.
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33
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Descloux A, Amitonova LV, Pinkse PWH. Aberrations of the point spread function of a multimode fiber due to partial mode excitation. OPTICS EXPRESS 2016; 24:18501-12. [PMID: 27505814 DOI: 10.1364/oe.24.018501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We investigate the point spread function of a multimode fiber. The distortion of the focal spot created on the fiber output facet is studied for a variety of the parameters. We develop a theoretical model of wavefront shaping through a multimode fiber and use it to confirm our experimental results and analyze the nature of the focal distortions. We show that aberration-free imaging with a large field of view can be achieved by using an appropriate number of segments on the spatial light modulator during the wavefront-shaping procedure. The results describe aberration limits for imaging with multimode fibers as in, e.g., microendoscopy.
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34
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Czarske JW, Haufe D, Koukourakis N, Büttner L. Transmission of independent signals through a multimode fiber using digital optical phase conjugation. OPTICS EXPRESS 2016; 24:15128-15136. [PMID: 27410664 DOI: 10.1364/oe.24.015128] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Multimode fibers are attractive for a variety of applications such as communication engineering and biophotonics. However, a major hurdle for the optical transmission through multimode fibers is the inherent mode mixing. Although an image transmission was successfully accomplished using wavefront shaping, the image information was not transmitted individually for each of the independent pixels. We demonstrate a transmission of independent signals using individually shaped wavefronts employing a single segmented spatial light modulator for optical phase conjugation regarding each light signal. Our findings pave the way towards transferring independent signals through strongly scattering media.
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35
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Phillips DB, He R, Chen Q, Gibson GM, Padgett MJ. Non-diffractive computational ghost imaging. OPTICS EXPRESS 2016; 24:14172-14182. [PMID: 27410575 DOI: 10.1364/oe.24.014172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Computational ghost imaging (CGI) enables an image to be recorded using a single-pixel detector. The image can be reconstructed from correlations between the scene and a series of known projected intensity patterns. In this work we investigate the performance of CGI using pseudo non-diffracting (ND) speckle patterns. We demonstrate an extended depth-of-field that is ∼ 2-3 times greater than that achievable with conventional speckle, when only computing each intensity pattern to a single depth. In addition, the average speckle grain size of ND speckle is reduced by a factor of ∼ 1.5 relative to conventional speckle, which enhances the lateral Rayleigh-limit resolving power of our reconstructed images. However, the point-spread function (PSF) of our imaging system takes the form of a Bessel beam, which manifests itself as long-range correlations between speckle grains in the projected patterns. We discuss the trade-off between enhancement of the depth-of-field and the lateral resolution when using ND speckle, at the expense of a reduction in image contrast. Our work demonstrates that the tailoring of lateral and axial correlations in projected intensity patterns permits PSF engineering in CGI.
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36
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Shin J, Bosworth BT, Foster MA. Single-pixel imaging using compressed sensing and wavelength-dependent scattering. OPTICS LETTERS 2016; 41:886-9. [PMID: 26974071 DOI: 10.1364/ol.41.000886] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We demonstrate two-dimensional imaging using illumination via a single-mode fiber with a multiply scattering tip and compressed sensing acquisition. We illuminate objects with randomly structured, but deterministic, speckle patterns produced by a coherent light source propagating through a TiO2-coated fiber tip. The coating thickness is optimized to produce speckle patterns that are highly sensitive to laser wavelength, yet repeatable. Images of the object are reconstructed from the characterized wavelength dependence of the speckle patterns and the wavelength dependence of the total light collected from the object using a single photodetector. Our imaging device is mechanically scan-free and insensitive to bending of the fiber, making it suitable for micro-endoscopy.
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37
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Amitonova LV, Descloux A, Petschulat J, Frosz MH, Ahmed G, Babic F, Jiang X, Mosk AP, Russell PSJ, Pinkse PWH. High-resolution wavefront shaping with a photonic crystal fiber for multimode fiber imaging. OPTICS LETTERS 2016; 41:497-500. [PMID: 26907407 DOI: 10.1364/ol.41.000497] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We demonstrate that a high-numerical-aperture photonic crystal fiber allows lensless focusing at an unparalleled resolution by complex wavefront shaping. This paves the way toward high-resolution imaging exceeding the capabilities of imaging with multi-core single-mode optical fibers. We analyze the beam waist and power in the focal spot on the fiber output using different types of fibers and different wavefront shaping approaches. We show that the complex wavefront shaping technique, together with a properly designed multimode photonic crystal fiber, enables us to create a tightly focused spot on the desired position on the fiber output facet with a subwavelength beam waist.
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38
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Mekhail SP, Arbuthnott G, Chormaic SN. Advances in Fibre Microendoscopy for Neuronal Imaging. ACTA ACUST UNITED AC 2016. [DOI: 10.1515/odps-2016-0003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractTraditionally, models for neural dynamics in the brain have been formed through research conducted on slices, with electrodes, or by lesions to functional areas. Recent developments in functional dyes and optogenetics has made brain research more accessible through the use of light. However, this improved accessibility does not necessarily apply to deep regions of the brain which are surrounded by scattering tissue. In this article we give an overview of some of the latest methods in development for neural measurement and imaging.We specifically address methods designed to overcome the problem of imaging invivo for regions far beyond the mean free path of photons in brain tissue. These methodswould permit previously restricted neural research.
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39
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Laporte GPJ, Stasio N, Moser C, Psaltis D. Enhanced resolution in a multimode fiber imaging system. OPTICS EXPRESS 2015; 23:27484-27493. [PMID: 26480408 DOI: 10.1364/oe.23.027484] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Multimode fibers have recently been demonstrated to be a promising candidate for ultrathin and high resolution endoscopy. However, this method does not offer depth discrimination for fluorescence imaging and the numerical aperture of the fiber limits its resolution. In this paper we demonstrate optical sectioning and enhanced resolution using saturated excitation and temporal modulation. Using a continuous wave laser excitation, we demonstrate improved resolution in all three dimensions and increased image contrast by rejecting out of focus light.
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40
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Gu RY, Mahalati RN, Kahn JM. Design of flexible multi-mode fiber endoscope. OPTICS EXPRESS 2015; 23:26905-18. [PMID: 26480352 DOI: 10.1364/oe.23.026905] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Multi-mode fiber (MMF) endoscopes are extremely thin and have higher spatial resolution than conventional endoscopes; however, all current MMF endoscope designs require either that the MMF remain rigid during insertion and imaging or that the orientation of the MMF be known. This limits their possible medical applications. We describe an MMF endoscope design that allows the MMF to be arbitrarily bent as it is maneuvered to the target site prior to imaging. This is achieved by the addition of a partial reflector to the distal end of the MMF, which allows measurement of the mode coupling in the MMF using the reflected light arriving at the proximal end of the MMF. This measurement can be performed while the distal end of the endoscope is not directly accessible, as when the endoscope is being maneuvered. We simulate imaging through such a flexible MMF endoscope, where the MMF is step-index with 1588 spatial modes, and obtain an image even after the mode coupling matrix of the MMF is altered randomly, corresponding to an unknown bending of the MMF.
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41
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Gordon GSD, Joseph J, Bohndiek SE, Wilkinson TD. Single-pixel phase-corrected fiber bundle endomicroscopy with lensless focussing capability. JOURNAL OF LIGHTWAVE TECHNOLOGY : A JOINT IEEE/OSA PUBLICATION 2015; 33:3419-3425. [PMID: 27279676 PMCID: PMC4894463 DOI: 10.1109/jlt.2015.2436816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this paper a novel single-pixel method for coherent imaging through an endoscopic fiber bundle is presented. The use of a single-pixel detector allows greater sensitivity over a wider range of wavelengths, which could have significant applications in endoscopic fluorescence microscopy. First, the principle of lensless focussing at the distal end of a coherent fiber bundle is simulated to examine the impact of pixelation at microscopic scales. Next, an experimental optical correlator system using spatial light modulators (SLMs) is presented. A simple contrast imaging method of characterizing and compensating phase aberrations introduced by fiber bundles is described. Experimental results are then presented showing that our phase compensation method enables characterization of the optical phase profile of individual fiberlets. After applying this correction, early results demonstrating the ability of the system to electronically adjust the focal plane at the distal end of the fiber bundle are presented. The structural similarity index (SSIM) between the simulated image and the experimental focus-adjusted image increases noticeably when the phase correction is applied and the retrieved image is visually recognizable. Strategies to improve image quality are discussed.
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Affiliation(s)
- George S D Gordon
- Electrical Engineering Division, University of Cambridge, CB3 0FA, Cambridge, U.K.
| | - James Joseph
- Department of Physics and Cancer Research UK Cambridge Institute, University of Cambridge and CRUK-EPSRC Cancer Imaging Centre in Cambridge and Manchester
| | - Sarah E Bohndiek
- Department of Physics and Cancer Research UK Cambridge Institute, University of Cambridge and CRUK-EPSRC Cancer Imaging Centre in Cambridge and Manchester
| | - Timothy D Wilkinson
- Electrical Engineering Division, University of Cambridge, CB3 0FA, Cambridge, U.K
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42
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Amitonova LV, Mosk AP, Pinkse PWH. Rotational memory effect of a multimode fiber. OPTICS EXPRESS 2015; 23:20569-75. [PMID: 26367909 DOI: 10.1364/oe.23.020569] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We demonstrate the rotational memory effect in a multimode fiber. Rotating the incident wavefront around the fiber core axis leads to a rotation of the resulting pattern of the fiber output without significant changes in the resulting speckle pattern. The rotational memory effect can be exploited for non-invasive imaging or ultrafast high-resolution scanning through a multimode fiber. Our experiments demonstrate this effect over a full range of angles in two experimental configurations.
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43
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Plöschner M, Čižmár T. Compact multimode fiber beam-shaping system based on GPU accelerated digital holography. OPTICS LETTERS 2015; 40:197-200. [PMID: 25679843 DOI: 10.1364/ol.40.000197] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Real-time, on-demand, beam shaping at the end of the multimode fiber has recently been made possible by exploiting the computational power of rapidly evolving graphics processing unit (GPU) technology [Opt. Express 22, 2933 (2014)]. However, the current state-of-the-art system requires the presence of an acousto-optic deflector (AOD) to produce images at the end of the fiber without interference effects between neighboring output points. Here, we present a system free from the AOD complexity where we achieve the removal of the undesired interference effects computationally using GPU implemented Gerchberg-Saxton and Yang-Gu algorithms. The GPU implementation is two orders of magnitude faster than the CPU implementation which allows video-rate image control at the distal end of the fiber virtually free of interference effects.
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44
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Barankov R, Mertz J. High-throughput imaging of self-luminous objects through a single optical fibre. Nat Commun 2014; 5:5581. [PMID: 25410902 DOI: 10.1038/ncomms6581] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 10/16/2014] [Indexed: 11/09/2022] Open
Abstract
Imaging through a single optical fibre offers attractive possibilities in many applications such as micro-endoscopy or remote sensing. However, the direct transmission of an image through an optical fibre is difficult because spatial information is scrambled upon propagation. We demonstrate an image transmission strategy where spatial information is first converted to spectral information. Our strategy is based on a principle of spread-spectrum encoding, borrowed from wireless communications, wherein object pixels are converted into distinct spectral codes that span the full bandwidth of the object spectrum. Image recovery is performed by numerical inversion of the detected spectrum at the fibre output. We provide a simple demonstration of spread-spectrum encoding using Fabry-Perot etalons. Our technique enables the two-dimensional imaging of self-luminous (that is, incoherent) objects with high throughput in principle independent of pixel number. Moreover, it is insensitive to fibre bending, contains no moving parts and opens the possibility of extreme miniaturization.
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Affiliation(s)
- Roman Barankov
- Department of Biomedical Engineering, Boston University, 44 Cummington Street, Boston, Massachusetts 02215, USA
| | - Jerome Mertz
- Department of Biomedical Engineering, Boston University, 44 Cummington Street, Boston, Massachusetts 02215, USA
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45
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Lu P, Shipton M, Wang A, Xu Y. Adaptive control of waveguide modes using a directional coupler. OPTICS EXPRESS 2014; 22:20000-20007. [PMID: 25321209 DOI: 10.1364/oe.22.020000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using adaptive optics (AO) and a directional coupler, we demonstrate adaptive control of linearly polarized (LP) modes in a two mode fiber. The AO feedback is provided by the coupling ratio of the directional coupler, and does not depend on the spatial profiles of optical field distributions. As a proof of concept demonstration, this work confirms the feasibility of using AO and all fiber devices to control the waveguide modes in a multimode network in a quasi-distributed manner.
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46
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Gu RY, Mahalati RN, Kahn JM. Noise-reduction algorithms for optimization-based imaging through multi-mode fiber. OPTICS EXPRESS 2014; 22:15118-32. [PMID: 24977605 DOI: 10.1364/oe.22.015118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Three modifications are shown to improve resolution and reduce noise amplification in endoscopic imaging through multi-mode fiber using optimization-based reconstruction (OBR). First, random sampling patterns are replaced by sampling patterns designed to have more nearly equal singular values. Second, the OBR algorithm uses a point-spread function based on the estimated spatial frequency spectrum of the object. Third, the OBR algorithm gives less weight to modes having smaller singular values. In simulations for a step-index fiber supporting 522 spatial modes, the modifications yield a 20% reduction in image error (l(2) norm) in the noiseless case, and a further 33% reduction in image error at a 22-dB shot noise-limited SNR as compared to the original method using random sampling patterns and OBR.
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47
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Kim D, Moon J, Kim M, Yang TD, Kim J, Chung E, Choi W. Toward a miniature endomicroscope: pixelation-free and diffraction-limited imaging through a fiber bundle. OPTICS LETTERS 2014; 39:1921-4. [PMID: 24686639 DOI: 10.1364/ol.39.001921] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
A fiber bundle is widely used for endoscopic imaging due to its direct image delivery capability. However, there exists an inevitable pixelation artifact, which limits spatial resolution to the diameter of individual fibers. In this Letter, we present a method that can eliminate this artifact and achieve diffraction-limited spatial resolution. We exploited the binary control of a digital micromirror device to measure a transmission matrix of a fiber bundle and to subsequently control mode mixing among individual fibers. In doing so, we achieved a 22 kHz scanning rate of a diffraction-limited focused spot and obtained fluorescence endoscope imaging (58 μm × 58 μm) with near video-rate (10.3 Hz) acquisition. Our study lays a foundation for developing an ultrathin and high-resolution microendoscope.
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48
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Lu P, Shipton M, Wang A, Soker S, Xu Y. Adaptive control of waveguide modes in a two-mode-fiber. OPTICS EXPRESS 2014; 22:2955-2964. [PMID: 24663587 PMCID: PMC3927635 DOI: 10.1364/oe.22.002955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 01/23/2014] [Accepted: 01/24/2014] [Indexed: 06/03/2023]
Abstract
We experimentally demonstrate an adaptive-optics-based approach that allows selective excitation of waveguide modes and their mixtures in a two-mode fiber (TMF). A phase-only spatial light modulator is used for wavefront control, using feedback signals provided by the correlation between the experimentally measured field distribution and the desired mode profiles. Experimental results show the optical field within the TMF can be shaped to be pure linearly polarized (LP) modes or their combinations. Analysis shows selective mode excitation can be achieved using only 5 × 5 independent phase blocks. With proper feedback signals, this method should enable one to precisely control the optical field within any multimode fiber or other types of waveguides in real time.
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Affiliation(s)
- Peng Lu
- Center for Photonics Technology, Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061,
USA
| | - Matthew Shipton
- Center for Photonics Technology, Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061,
USA
| | - Anbo Wang
- Center for Photonics Technology, Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061,
USA
| | - Shay Soker
- Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157,
USA
| | - Yong Xu
- Center for Photonics Technology, Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061,
USA
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49
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Plöschner M, Straka B, Dholakia K, Čižmár T. GPU accelerated toolbox for real-time beam-shaping in multimode fibres. OPTICS EXPRESS 2014; 22:2933-47. [PMID: 24663585 DOI: 10.1364/oe.22.002933] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We present a GPU accelerated toolbox for shaping the light propagation through multimode fibre using a spatial light modulator (SLM). The light is modulated before being coupled to the proximal end of the fibre in order to achieve arbitrary light patterns at the distal end of the fibre. First, the toolbox optimises the acquisition time of the transformation matrix of the fibre by synchronous operation of CCD and SLM. Second, it uses the acquired transformation matrix retained within the GPU memory to design, in real-time, the desired holographic mask for on-the-fly modulation of the output light field. We demonstrate the functionality of the toolbox by acquiring the transformation matrix at the maximum refresh rate of the SLM - 204 Hz, and using it to display an on-demand oriented cube, at the distal end of the fibre. The user-controlled orientation of the cube and the corresponding holographic mask are obtained in 20 ms intervals. Deleterious interference effects between the neighbouring points are eliminated by incorporating an acousto-optic deflector (AOD) into the system. We remark that the usage of the toolbox is not limited to multimode fibres and can be readily used to acquire transformation matrix and implement beam-shaping in any other linear optical system.
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50
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Bianchi S, Rajamanickam VP, Ferrara L, Di Fabrizio E, Liberale C, Di Leonardo R. Focusing and imaging with increased numerical apertures through multimode fibers with micro-fabricated optics. OPTICS LETTERS 2013; 38:4935-4938. [PMID: 24281476 DOI: 10.1364/ol.38.004935] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The use of individual multimode optical fibers in endoscopy applications has the potential to provide highly miniaturized and noninvasive probes for microscopy and optical micromanipulation. A few different strategies have been proposed recently, but they all suffer from intrinsically low resolution related to the low numerical aperture of multimode fibers. Here, we show that two-photon polymerization allows for direct fabrication of micro-optics components on the fiber end, resulting in an increase of the numerical aperture to a value that is close to 1. Coupling light into the fiber through a spatial light modulator, we were able to optically scan a submicrometer spot (300 nm FWHM) over an extended region, facing the opposite fiber end. Fluorescence imaging with improved resolution is also demonstrated.
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