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Najar U, Barolle V, Balondrade P, Fink M, Boccara C, Aubry A. Harnessing forward multiple scattering for optical imaging deep inside an opaque medium. Nat Commun 2024; 15:7349. [PMID: 39187504 PMCID: PMC11347655 DOI: 10.1038/s41467-024-51619-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Accepted: 08/14/2024] [Indexed: 08/28/2024] Open
Abstract
As light travels through a disordered medium such as biological tissues, it undergoes multiple scattering events. This phenomenon is detrimental to in-depth optical microscopy, as it causes a drastic degradation of contrast, resolution and brightness of the resulting image beyond a few scattering mean free paths. However, the information about the inner reflectivity of the sample is not lost; only scrambled. To recover this information, a matrix approach of optical imaging can be fruitful. Here, we report on a de-scanned measurement of a high-dimension reflection matrix R via low coherence interferometry. Then, we show how a set of independent focusing laws can be extracted for each medium voxel through an iterative multi-scale analysis of wave distortions contained in R. It enables an optimal and local compensation of forward multiple scattering paths and provides a three-dimensional confocal image of the sample as the latter one had become digitally transparent. The proof-of-concept experiment is performed on a human opaque cornea and an extension of the penetration depth by a factor five is demonstrated compared to the state-of-the-art.
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Affiliation(s)
- Ulysse Najar
- Institut Langevin, ESPCI Paris, PSL University, CNRS, 75005, Paris, France
| | - Victor Barolle
- Institut Langevin, ESPCI Paris, PSL University, CNRS, 75005, Paris, France
| | - Paul Balondrade
- Institut Langevin, ESPCI Paris, PSL University, CNRS, 75005, Paris, France
| | - Mathias Fink
- Institut Langevin, ESPCI Paris, PSL University, CNRS, 75005, Paris, France
| | - Claude Boccara
- Institut Langevin, ESPCI Paris, PSL University, CNRS, 75005, Paris, France
| | - Alexandre Aubry
- Institut Langevin, ESPCI Paris, PSL University, CNRS, 75005, Paris, France.
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2
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Cai Y, Thouvenin O, Grieve K, Mecê P. Influence of static and dynamic ocular aberrations on full-field optical coherence tomography for in vivo high-resolution retinal imaging. OPTICS LETTERS 2024; 49:2209-2212. [PMID: 38691681 DOI: 10.1364/ol.515749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/21/2024] [Indexed: 05/03/2024]
Abstract
Under spatially incoherent illumination, time-domain full-field optical coherence tomography (FFOCT) offers the possibility to achieve in vivo retinal imaging at cellular resolution over a wide field of view. Such performance is possible, albeit there is the presence of ocular aberrations even without the use of classical adaptive optics. While the effect of aberrations in FFOCT has been debated these past years, mostly on low-order and static aberrations, we present, for the first time to our knowledge, a method enabling a quantitative study of the effect of statistically representative static and dynamic ocular aberrations on FFOCT image metrics, such as SNR, resolution, and image similarity. While we show that ocular aberrations can decrease FFOCT SNR and resolution by up to 14 dB and fivefold, we take advantage of such quantification to discuss different possible compromises between performance gain and adaptive optics complexity and speed, to optimize both sensor-based and sensorless FFOCT high-resolution retinal imaging.
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3
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Puyo L, Pfäffle C, Spahr H, Franke J, Bublitz D, Hillmann D, Hüttmann G. Diffuse-illumination holographic optical coherence tomography. OPTICS EXPRESS 2023; 31:33500-33517. [PMID: 37859131 DOI: 10.1364/oe.498654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/11/2023] [Indexed: 10/21/2023]
Abstract
Holographic optical coherence tomography (OCT) is a powerful imaging technique, but its ability to reveal low-reflectivity features is limited. In this study, we performed holographic OCT by incoherently averaging volumes with changing diffuse illumination of numerical aperture (NA) equal to the detection NA. While the reduction of speckle from singly scattered light is only modest, we discovered that speckle from multiply scattered light can be arbitrarily reduced, resulting in substantial improvements in image quality. This technique also offers the advantage of suppressing noises arising from spatial coherence, and can be implemented with a partially spatially incoherent light source for further mitigation of multiple scattering. Finally, we show that although holographic reconstruction capabilities are increasingly lost with decreasing spatial coherence, they can be retained over an axial range sufficient to standard OCT applications.
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4
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Monfort T, Azzollini S, Ben Yacoub T, Audo I, Reichman S, Grieve K, Thouvenin O. Interface self-referenced dynamic full-field optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2023; 14:3491-3505. [PMID: 37497503 PMCID: PMC10368024 DOI: 10.1364/boe.488663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 06/02/2023] [Accepted: 06/07/2023] [Indexed: 07/28/2023]
Abstract
Dynamic full-field optical coherence tomography (D-FFOCT) has recently emerged as an invaluable live label-free and non-invasive imaging modality able to image subcellular biological structures and their metabolic activity within complex 3D samples. However, D-FFOCT suffers from fringe artefacts when imaging near reflective surfaces and is highly sensitive to vibrations. Here, we present interface Self-Referenced (iSR) D-FFOCT, an alternative configuration to D-FFOCT that takes advantage of the presence of the sample coverslip in between the sample and the objective by using it as a defocused reference arm, thus avoiding the aforementioned artefacts. We demonstrate the ability of iSR D-FFOCT to image 2D fibroblast cell cultures, which are among the flattest mammalian cells.
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Affiliation(s)
- Tual Monfort
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
- CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, 28 rue de Charenton, F-75012 Paris, France
| | - Salvatore Azzollini
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
| | - Tasnim Ben Yacoub
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
| | - Sacha Reichman
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
| | - Kate Grieve
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France
- CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, 28 rue de Charenton, F-75012 Paris, France
| | - Olivier Thouvenin
- Institut Langevin, ESPCI Paris, Université PSL, CNRS, 75005 Paris, France
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5
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Zhu Y, Zhou Y, Guo Z. Fractal-based aberration-corrected full-field OCT. BIOMEDICAL OPTICS EXPRESS 2023; 14:3775-3797. [PMID: 37497484 PMCID: PMC10368032 DOI: 10.1364/boe.485090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 06/15/2023] [Accepted: 06/15/2023] [Indexed: 07/28/2023]
Abstract
The Kolmogorov turbulence model has been validated as a quantitative 3D light scattering model of the inhomogeneous refraction index of biological tissue using full-field OCT (FF-OCT). A fractal-based computational compensation approach was proposed for correcting of depth-resolved aberrations with volumetric FF-OCT. First, the power-spectral density spectrum of the index inhomogeneities was measured by radial Fourier transformation of volumetric data. The spectrum's shape indicates the spatial correlation function and can be quantified as the fractal dimension of tissue. The defocusing correction matrix was built by applying fractal-based analysis as an image quality metric. For comparison, tissue-induced in-depth aberration models were built by phase compensation. After digital aberration correction of FF-OCT images, it enables extracting the temporal contrast indicating the sample dynamics in onion in mitosis and ex vivo mouse heart during delayed neuronal death. The proposed fractal-based contrast augmented images show subcellular resolution recording of dynamic scatters of the growing-up onion cell wall and some micro activities. In addition, low-frequency chamber and high-frequency cardiac muscle fibers from ex vivo mouse heart tissue. Therefore, the depth-resolved changes in fractal parameters may be regarded as a quantitative indicator of defocus aberration compensation. Also the enhanced temporal contrast in FF-OCT has the potential to be a label-free, non-invasive, and three-dimensional imaging tool to investigate sub-cellular activities in metabolism studies.
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Affiliation(s)
- Yue Zhu
- Department of Optical Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei, Nanjing, 210094, China
| | - Yuan Zhou
- Department of Vascular Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310020, China
| | - Zhenyan Guo
- Department of Optical Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei, Nanjing, 210094, China
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Tomita K, Makita S, Fukutake N, Morishita R, Abd El-Sadek I, Mukherjee P, Lichtenegger A, Tamaoki J, Bian L, Kobayashi M, Mori T, Matsusaka S, Yasuno Y. Theoretical model for en face optical coherence tomography imaging and its application to volumetric differential contrast imaging. BIOMEDICAL OPTICS EXPRESS 2023; 14:3100-3124. [PMID: 37497522 PMCID: PMC10368023 DOI: 10.1364/boe.491510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/19/2023] [Accepted: 05/19/2023] [Indexed: 07/28/2023]
Abstract
A new formulation of the lateral imaging process of point-scanning optical coherence tomography (OCT) and a new differential contrast method designed by using this formulation are presented. The formulation is based on a mathematical sample model called the dispersed scatterer model (DSM), in which the sample is represented as a material with a spatially slowly varying refractive index and randomly distributed scatterers embedded in the material. It is shown that the formulation represents a meaningful OCT image and speckle as two independent mathematical quantities. The new differential contrast method is based on complex signal processing of OCT images, and the physical and numerical imaging processes of this method are jointly formulated using the same theoretical strategy as in the case of OCT. The formula shows that the method provides a spatially differential image of the sample structure. This differential imaging method is validated by measuring in vivo and in vitro samples.
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Affiliation(s)
- Kiriko Tomita
- Computational Optics Group, University of Tsukuba, Japan
| | - Shuichi Makita
- Computational Optics Group, University of Tsukuba, Japan
| | | | - Rion Morishita
- Computational Optics Group, University of Tsukuba, Japan
| | - Ibrahim Abd El-Sadek
- Computational Optics Group, University of Tsukuba, Japan
- Department of Physics, Faculty of Science, Damietta University, Damietta, Egypt
| | | | - Antonia Lichtenegger
- Computational Optics Group, University of Tsukuba, Japan
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria
| | - Junya Tamaoki
- Department of Molecular and Developmental Biology, Institute of Medicine, University of Tsukuba, Japan
| | - Lixuan Bian
- Department of Molecular and Developmental Biology, Institute of Medicine, University of Tsukuba, Japan
| | - Makoto Kobayashi
- Department of Molecular and Developmental Biology, Institute of Medicine, University of Tsukuba, Japan
| | - Tomoko Mori
- Clinical Research and Regional Innovation, Faculty of Medicine, University of Tsukuba, Japan
| | - Satoshi Matsusaka
- Clinical Research and Regional Innovation, Faculty of Medicine, University of Tsukuba, Japan
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Zhang J, Mazlin V, Fei K, Boccara AC, Yuan J, Xiao P. Time-domain full-field optical coherence tomography (TD-FF-OCT) in ophthalmic imaging. Ther Adv Chronic Dis 2023; 14:20406223231170146. [PMID: 37152350 PMCID: PMC10161339 DOI: 10.1177/20406223231170146] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Accepted: 03/29/2023] [Indexed: 05/09/2023] Open
Abstract
Ocular imaging plays an irreplaceable role in the evaluation of eye diseases. Developing cellular-resolution ophthalmic imaging technique for more accurate and effective diagnosis and pathogenesis analysis of ocular diseases is a hot topic in the cross-cutting areas of ophthalmology and imaging. Currently, ocular imaging with traditional optical coherence tomography (OCT) is limited in lateral resolution and thus can hardly resolve cellular structures. Conventional OCT technology obtains ultra-high resolution at the expense of a certain imaging range and cannot achieve full field of view imaging. In the early years, Time-domain full-field OCT (TD-FF-OCT) has been mainly used for ex vivo ophthalmic tissue studies, limited by the low speed and low full-well capacity of existing two-dimensional (2D) cameras. The recent improvements in system design opened new imaging possibilities for in vivo applications thanks to its distinctive optical properties of TD-FF-OCT such as a spatial resolution almost insensitive to aberrations, and the possibility to control the curvature of the optical slice. This review also attempts to look at the future directions of TD-FF-OCT evolution, for example, the potential transfer of the functional-imaging dynamic TD-FF-OCT from the ex vivo into in vivo use and its expected benefit in basic and clinical ophthalmic research. Through non-invasive, wide-field, and cellular-resolution imaging, TD-FF-OCT has great potential to be the next-generation imaging modality to improve our understanding of human eye physiology and pathology.
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Affiliation(s)
- Jinze Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Viacheslav Mazlin
- ESPCI Paris, PSL University, CNRS, Langevin Institute, Paris, France
| | - Keyi Fei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | | | - Jin Yuan
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Jinsui Road 7, Guangzhou 510060, Guangdong, China
| | - Peng Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Jinsui Road 7, Guangzhou 510060, Guangdong, China
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8
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Cai Y, Grieve K, Mecê P. Characterization and Analysis of Retinal Axial Motion at High Spatiotemporal Resolution and Its Implication for Real-Time Correction in Human Retinal Imaging. Front Med (Lausanne) 2022; 9:868217. [PMID: 35903318 PMCID: PMC9320321 DOI: 10.3389/fmed.2022.868217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 06/20/2022] [Indexed: 11/25/2022] Open
Abstract
High-resolution ophthalmic imaging devices including spectral-domain and full-field optical coherence tomography (SDOCT and FFOCT) are adversely affected by the presence of continuous involuntary retinal axial motion. Here, we thoroughly quantify and characterize retinal axial motion with both high temporal resolution (200,000 A-scans/s) and high axial resolution (4.5 μm), recorded over a typical data acquisition duration of 3 s with an SDOCT device over 14 subjects. We demonstrate that although breath-holding can help decrease large-and-slow drifts, it increases small-and-fast fluctuations, which is not ideal when motion compensation is desired. Finally, by simulating the action of an axial motion stabilization control loop, we show that a loop rate of 1.2 kHz is ideal to achieve 100% robust clinical in-vivo retinal imaging.
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Affiliation(s)
- Yao Cai
- Institut Langevin, ESPCI Paris, CNRS, PSL University, Paris, France
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Kate Grieve
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
- CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, Paris, France
| | - Pedro Mecê
- Institut Langevin, ESPCI Paris, CNRS, PSL University, Paris, France
- DOTA, ONERA, Université Paris Saclay, Palaiseau, France
- *Correspondence: Pedro Mecê
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9
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Wang L, Fu R, Xu C, Xu M. Methods and applications of full-field optical coherence tomography: a review. JOURNAL OF BIOMEDICAL OPTICS 2022; 27:JBO-220007VR. [PMID: 35596250 PMCID: PMC9122094 DOI: 10.1117/1.jbo.27.5.050901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 04/28/2022] [Indexed: 05/24/2023]
Abstract
SIGNIFICANCE Full-field optical coherence tomography (FF-OCT) enables en face views of scattering samples at a given depth with subcellular resolution, similar to biopsy without the need of sample slicing or other complex preparation. This noninvasive, high-resolution, three-dimensional (3D) imaging method has the potential to become a powerful tool in biomedical research, clinical applications, and other microscopic detection. AIM Our review provides an overview of the disruptive innovations and key technologies to further improve FF-OCT performance, promoting FF-OCT technology in biomedical and other application scenarios. APPROACH A comprehensive review of state-of-the-art accomplishments in OCT has been performed. Methods to improve performance of FF-OCT systems are reviewed, including advanced phase-shift approaches for imaging speed improvement, methods of denoising, artifact reduction, and aberration correction for imaging quality optimization, innovations for imaging flux expansion (field-of-view enlargement and imaging-depth-limit extension), new implementations for multimodality systems, and deep learning enhanced FF-OCT for information mining, etc. Finally, we summarize the application status and prospects of FF-OCT in the fields of biomedicine, materials science, security, and identification. RESULTS The most worth-expecting FF-OCT innovations include combining the technique of spatial modulation of optical field and computational optical imaging technology to obtain greater penetration depth, as well as exploiting endogenous contrast for functional imaging, e.g., dynamic FF-OCT, which enables noninvasive visualization of tissue dynamic properties or intracellular motility. Different dynamic imaging algorithms are compared using the same OCT data of the colorectal cancer organoid, which helps to understand the disadvantages and advantages of each. In addition, deep learning enhanced FF-OCT provides more valuable characteristic information, which is of great significance for auxiliary diagnosis and organoid detection. CONCLUSIONS FF-OCT has not been completely exploited and has substantial growth potential. By elaborating the key technologies, performance optimization methods, and application status of FF-OCT, we expect to accelerate the development of FF-OCT in both academic and industry fields. This renewed perspective on FF-OCT may also serve as a road map for future development of invasive 3D super-resolution imaging techniques to solve the problems of microscopic visualization detection.
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Affiliation(s)
- Ling Wang
- Hangzhou DianZi University, School of Automation, Hangzhou, China
- Key Laboratory of Medical Information and 3D Biological of Zhejiang Province, Hangzhou, China
| | - Rongzhen Fu
- Hangzhou DianZi University, School of Automation, Hangzhou, China
| | - Chen Xu
- Hangzhou DianZi University, School of Automation, Hangzhou, China
| | - Mingen Xu
- Hangzhou DianZi University, School of Automation, Hangzhou, China
- Key Laboratory of Medical Information and 3D Biological of Zhejiang Province, Hangzhou, China
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10
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Münter M, Pieper M, Kohlfaerber T, Bodenstorfer E, Ahrens M, Winter C, Huber R, König P, Hüttmann G, Schulz-Hildebrandt H. Microscopic optical coherence tomography (mOCT) at 600 kHz for 4D volumetric imaging and dynamic contrast. BIOMEDICAL OPTICS EXPRESS 2021; 12:6024-6039. [PMID: 34745719 PMCID: PMC8547980 DOI: 10.1364/boe.425001] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 08/03/2021] [Accepted: 08/06/2021] [Indexed: 05/11/2023]
Abstract
Volumetric imaging of dynamic processes with microscopic resolution holds a huge potential in biomedical research and clinical diagnosis. Using supercontinuum light sources and high numerical aperture (NA) objectives, optical coherence tomography (OCT) achieves microscopic resolution and is well suited for imaging cellular and subcellular structures of biological tissues. Currently, the imaging speed of microscopic OCT (mOCT) is limited by the line-scan rate of the spectrometer camera and ranges from 30 to 250 kHz. This is not fast enough for volumetric imaging of dynamic processes in vivo and limits endoscopic application. Using a novel CMOS camera, we demonstrate fast 3-dimensional OCT imaging with 600,000 A-scans/s at 1.8 µm axial and 1.1 µm lateral resolution. The improved speed is used for imaging of ciliary motion and particle transport in ex vivo mouse trachea. Furthermore, we demonstrate dynamic contrast OCT by evaluating the recorded volumes rather than en face planes or B-scans. High-speed volumetric mOCT will enable the correction of global tissue motion and is a prerequisite for applying dynamic contrast mOCT in vivo. With further increase in imaging speed and integration in flexible endoscopes, volumetric mOCT may be used to complement or partly replace biopsies.
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Affiliation(s)
- Michael Münter
- University of Lübeck,
Institute of Biomedical Optics,
Peter-Monnik-Weg 4, 23562 Lübeck, Germany
- Medizinisches Laserzentrum
Lübeck GmbH, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| | - Mario Pieper
- University of
Lübeck, Institute of Anatomy, Ratzeburger Allee 160,
23562 Lübeck, Germany
- Airway Research Center North
Member of the German Center for Lung Research, DZL,
22927 Großhansdorf, Germany
| | - Tabea Kohlfaerber
- Medizinisches Laserzentrum
Lübeck GmbH, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| | - Ernst Bodenstorfer
- Austrian Institute of
Technology GmbH, Giefinggasse 4, 1210 Vienna, Austria
| | - Martin Ahrens
- University of Lübeck,
Institute of Biomedical Optics,
Peter-Monnik-Weg 4, 23562 Lübeck, Germany
- Airway Research Center North
Member of the German Center for Lung Research, DZL,
22927 Großhansdorf, Germany
| | | | - Robert Huber
- University of Lübeck,
Institute of Biomedical Optics,
Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| | - Peter König
- University of
Lübeck, Institute of Anatomy, Ratzeburger Allee 160,
23562 Lübeck, Germany
- Airway Research Center North
Member of the German Center for Lung Research, DZL,
22927 Großhansdorf, Germany
| | - Gereon Hüttmann
- University of Lübeck,
Institute of Biomedical Optics,
Peter-Monnik-Weg 4, 23562 Lübeck, Germany
- Medizinisches Laserzentrum
Lübeck GmbH, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
- Airway Research Center North
Member of the German Center for Lung Research, DZL,
22927 Großhansdorf, Germany
| | - Hinnerk Schulz-Hildebrandt
- University of Lübeck,
Institute of Biomedical Optics,
Peter-Monnik-Weg 4, 23562 Lübeck, Germany
- Medizinisches Laserzentrum
Lübeck GmbH, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
- Airway Research Center North
Member of the German Center for Lung Research, DZL,
22927 Großhansdorf, Germany
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