1. Articles from Mathias Fink

    1-14 of 14
    1. Probing dynamic processes in the eye at multiple spatial and temporal scales with multimodal full field OCT

      Probing dynamic processes in the eye at multiple spatial and temporal scales with multimodal full field OCT

      We describe recent technological progress in multimodal en face full-field optical coherence tomography that has allowed detection of slow and fast dynamic processes in the eye. We show that by combining static, dynamic and fluorescence contrasts we can achieve label-free high-resolution imaging of the retina and anterior eye with temporal resolution from milliseconds to several hours, allowing us to probe biological activity at subcellular scales inside 3D bulk tissue. Our setups combine high lateral resolution over a large field of view with acquisition at several hundreds of frames per second which make it a promising tool for clinical applications and ...

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    2. In vivo imaging through the entire thickness of human cornea by full-field optical coherence tomography

      In vivo imaging through the entire thickness of human cornea by full-field optical coherence tomography

      Despite obvious improvements in visualization of the in vivo cornea through the faster imaging speeds and higher axial resolutions, cellular imaging stays unresolvable task for OCT, as en face viewing with a high lateral resolution is required. The latter is possible with FFOCT, a method that relies on a camera, moderate numerical aperture (NA) objectives and an incoherent light source to provide en face images with a micrometer-level resolution. Recently, we for the first time demonstrated the ability of FFOCT to capture images from the in vivo human cornea1. In the current paper we present an extensive study of appearance ...

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    3. In vivo high resolution human corneal imaging using full-field optical coherence tomography

      In vivo high resolution human corneal imaging using full-field optical coherence tomography

      We present the first full-field optical coherence tomography (FFOCT) device capable of in vivo imaging of the human cornea. We obtained images of the epithelial structures, Bowman’s layer, sub-basal nerve plexus (SNP), anterior and posterior stromal keratocytes, stromal nerves, Descemet’s membrane and endothelial cells with visible nuclei. Images were acquired with a high lateral resolution of 1.7 µm and relatively large field-of-view of 1.26 mm x 1.26 mm – a combination, which, to the best of our knowledge, has not been possible with other in vivo human eye imaging methods. The latter together with a contactless ...

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    4. The multiple scattering limit in optical microscopy

      The multiple scattering limit in optical microscopy

      Optical microscopy offers a unique insight of biological structures with a sub-micrometer resolution and a minimum invasiveness. However, the inhomogeneities of the specimen itself can induce multiple scattering of light and optical aberrations which limit the observation to depths close to the surface. To predict quantitatively the penetration depth in microscopy, we theoretically derive the single-to-multiple scattering ratio in reflection. From this key quantity, the multiple scattering limit is deduced for various microscopic imaging techniques such as confocal microscopy, optical coherence tomography and related methods.

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    5. Cell Motility as Contrast Agent in Retinal Explant Imaging With Full-Field Optical Coherence Tomography

      Cell Motility as Contrast Agent in Retinal Explant Imaging With Full-Field Optical Coherence Tomography

      Purpose : To use cell motility as a contrast agent in retinal explants. Methods : Macaque and mouse retinal explants were imaged with high resolution full field optical coherence tomography (FFOCT) and dynamic FFOCT, coupled with fluorescence imaging. Results : Static and dynamic FFOCT create complementary contrast from different structures within a cell. When imaging in vitro samples, static FFOCT detects steep refractive index gradients to reveal stationary structures including fibers, vessels, collagen, and cell contours, while dynamic FFOCT emphasizes metabolic activity of moving structures that are mainly intracellular, thus creating or enhancing contrast in cells that were previously hidden in noise. Dynamic ...

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    6. Full-Field Optical Coherence Tomography as a Diagnosis Tool: Recent Progress with Multimodal Imaging

      Full-Field Optical Coherence Tomography as a Diagnosis Tool: Recent Progress with Multimodal Imaging

      Full-field optical coherence tomography (FF-OCT) is a variant of OCT that is able to register 2D en face views of scattering samples at a given depth. Thanks to its superior resolution, it can quickly reveal information similar to histology without the need to physically section the sample. Sensitivity and specificity levels of diagnosis performed with FF-OCT are 80% to 95% of the equivalent histological diagnosis performances and could therefore benefit from improvement. Therefore, multimodal systems have been designed to increase the diagnostic performance of FF-OCT. In this paper, we will discuss which contrasts can be measured with such multimodal systems ...

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    7. Retinal imaging with adaptive optics full-field OCT

      Retinal imaging with adaptive optics full-field OCT

      Adaptive optics full-filed OCT (FFOCT) with a transmissive liquid crystal spatial light modulator (LCSLM) as wavefront corrector is used without strict plane conjugation for low order aberrations corrections. We validated experimentally that FFOCT resolution is independent of aberrations and only reduce the signal level. A signal based sensorless algorithm was thus applied for wavefront distortion compensation. Image quality improvements by the wavefront sensorless control of the LCSLM were evaluated on in vitro samples. By replacing the FFOCT sample arm objective with an artificial eye used to train ophthalmologists, adaptive optics retinal imaging was achieved. In vivo experiments using a liquid ...

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    8. Dynamic multimodal full-field optical coherence tomography and fluorescence structured illumination microscopy

      Dynamic multimodal full-field optical coherence tomography and fluorescence structured illumination microscopy

      We report on the development of a configuration of a multimodal full-field optical coherence tomography (FF-OCT) and fluorescence microscope. Our system can simultaneously acquire FF-OCT and structured illumination microscopy images. Dynamic parallel evolution of tissue microstructures and biochemical environments can be visualized. We use high numerical aperture objectives to optimize the combination of the two modalities. We imaged the propagation of mechanical waves initiated by calcium waves in a heart wall to illustrate the interest of simultaneous recording of mechanical and biochemical information.

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    9. Diffuse shear wave imaging: toward passive elastography using low-frame rate spectral-domain optical coherence tomography

      Diffuse shear wave imaging: toward passive elastography using low-frame rate spectral-domain optical coherence tomography

      Optical coherence tomography (OCT) can map the stiffness of biological tissue by imaging mechanical perturbations (shear waves) propagating in the tissue. Most shear wave elastography (SWE) techniques rely on active shear sources to generate controlled displacements that are tracked at ultrafast imaging rates. Here, we propose a noise-correlation approach to retrieve stiffness information from the imaging of diffuse displacement fields using low-frame rate spectral-domain OCT. We demonstrated the method on tissue-mimicking phantoms and validated the results by comparison with classic ultrafast SWE. Then we investigated the in vivo feasibility on the eye of an anesthetized rat by applying noise correlation ...

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    10. Adaptive optics full-field optical coherence tomography

      Adaptive optics full-field optical coherence tomography

      We describe a simple and compact full-field optical coherence tomography (FFOCT) setup coupled to a transmissive liquid crystal spatial light modulator (LCSLM) to induce or correct aberrations. To reduce the system complexity, strict pupil conjugation was abandoned because low-order aberrations are often dominant. We experimentally confirmed a recent theoretical and experimental demonstration that the image resolution was almost insensitive to aberrations that mostly induce a reduction of the signal level. As a consequence, an image-based algorithm was applied for the optimization process by using the FFOCT image intensity as the metric. Aberration corrections were demonstrated with both an USAF resolution ...

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    11. Full-field spatially incoherent illumination interferometry: a spatial resolution almost insensitive to aberrations

      Full-field spatially incoherent illumination interferometry: a spatial resolution almost insensitive to aberrations

      We show that with spatially incoherent illumination, the point spread function (PSF) width/spatial resolution of an imaging interferometer like that used in full-field optical coherence tomography (OCT) is almost insensitive to aberrations. In these systems, aberrations mostly induce a reduction of the signal level that leads to a loss of the signal-to-noise ratio without broadening the system PSF. This is demonstrated by comparison with traditional scanning OCT and wide-field OCT with spatially coherent illuminations. Theoretical analysis and numerical calculation as well as experimental results are provided to show this specific merit of incoherent illumination in full-field OCT. To the ...

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    12. Smart optical coherence tomography for ultra-deep imaging through highly scattering media

      Smart optical coherence tomography for ultra-deep imaging through highly scattering media

      Multiple scattering of waves in disordered media is a nightmare whether it be for detection or imaging purposes. The best approach so far to get rid of multiple scattering is optical coherence tomography. It basically combines confocal microscopy and coherence time-gating to discriminate ballistic photons from a predominant multiple scattering background. Nevertheless, the imaging depth range remains limited to 1 mm at best in human soft tissues. Here we propose a matrix approach of optical imaging to push back this fundamental limit. By combining a matrix discrimination of ballistic waves and iterative time-reversal, we show both theoretically and experimentally an ...

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    13. Feature Of The Week: Feature Of The Week 1/26/14: ESPCI-ParisTech Investigates Full-Field Optical Coherence Tomograpy (FF-OCT) Shear Wave Elastography

      Feature Of The Week: Feature Of The Week 1/26/14: ESPCI-ParisTech Investigates Full-Field Optical Coherence Tomograpy (FF-OCT) Shear Wave Elastography

      Elasticity maps of tissue have proved to be particularly useful in providing complementary contrast to ultrasonic imaging, e.g., for cancer diagnosis at the millimeter scale. Optical coherence tomography (OCT) offers an endogenous contrast based on singly backscattered optical waves. Adding complementary contrast to OCT images by recording elasticity maps could also be valuable in improving OCT-based diagnosis at the microscopic scale. Static elastography has been successfully coupled with full-field OCT (FF-OCT) in order to realize both micrometer-scale sectioning and elasticity maps. Nevertheless, static elastography presents a number of drawbacks, mainly when stiffness quantification is required. Here, we describe the ...

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    14. From supersonic shear wave imaging to full-field optical coherence shear wave elastograph

      From supersonic shear wave imaging to full-field optical coherence shear wave elastograph

      Elasticity maps of tissue have proved to be particularly useful in providing complementary contrast to ultrasonic imaging, e.g., for cancer diagnosis at the millimeter scale. Optical coherence tomography (OCT) offers an endogenous contrast based on singly backscattered optical waves. Adding complementary contrast to OCT images by recording elasticity maps could also be valuable in improving OCT-based diagnosis at the microscopic scale. Static elastography has been successfully coupled with full-field OCT (FF-OCT) in order to realize both micrometer-scale sectioning and elasticity maps. Nevertheless, static elastography presents a number of drawbacks, mainly when stiffness quantification is required. Here, we describe the ...

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    1-14 of 14
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  2. Topics in the News

    1. (13 articles) ESPCI ParisTech
    2. (13 articles) Mathias Fink
    3. (13 articles) Claude Boccara
    4. (4 articles) Kate Grieve
    5. (4 articles) LLTech
    6. (3 articles) Amir Nahas
    7. (3 articles) Thu-Mai Nguyen
    8. (2 articles) University of Pittsburgh
    9. (2 articles) Mickaël Tanter
    10. (2 articles) Jean-Marie Chassot
    11. (1 articles) L V Prasad Eye Institute
    12. (1 articles) Jon Holmes
    13. (1 articles) Michelson Diagnostics
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    From supersonic shear wave imaging to full-field optical coherence shear wave elastograph Feature Of The Week: Feature Of The Week 1/26/14: ESPCI-ParisTech Investigates Full-Field Optical Coherence Tomograpy (FF-OCT) Shear Wave Elastography Smart optical coherence tomography for ultra-deep imaging through highly scattering media Full-field spatially incoherent illumination interferometry: a spatial resolution almost insensitive to aberrations Adaptive optics full-field optical coherence tomography Diffuse shear wave imaging: toward passive elastography using low-frame rate spectral-domain optical coherence tomography Dynamic multimodal full-field optical coherence tomography and fluorescence structured illumination microscopy Retinal imaging with adaptive optics full-field OCT Full-Field Optical Coherence Tomography as a Diagnosis Tool: Recent Progress with Multimodal Imaging In vivo high resolution human corneal imaging using full-field optical coherence tomography Optical coherence tomography angiography of foveal neovascularisation in proliferative diabetic retinopathy Treating port wine stain birthmarks using dynamic optical coherence tomography-guided setting