1. Johannes F. de Boer

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    1. Mentioned In 103 Articles

    2. In vivo optical microscopy of peripheral nerve myelination with polarization sensitive-optical coherence tomography

      In vivo optical microscopy of peripheral nerve myelination with polarization sensitive-optical coherence tomography
      Assessing nerve integrity and myelination after injury is necessary to provide insight for treatment strategies aimed at restoring neuromuscular function. Currently, this is largely done with electrical analysis, which lacks direct quantitative information. In vivo optical imaging with sufficient imaging depth and resolution could be used to assess the nerve microarchitecture. In this study, we examine the use of polarization sensitive-optical coherence tomography (PS-OCT) to quantitatively assess the sciatic nerve ...
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    3. Polarization sensitive optical frequency domain imaging system for endobronchial imaging

      Polarization sensitive optical frequency domain imaging system for endobronchial imaging
      A polarization sensitive endoscopic optical frequency domain imaging (PS-OFDI) system with a motorized distal scanning catheter is demonstrated. It employs a passive polarization delay unit to multiplex two orthogonal probing polarization states in depth, and a polarization diverse detection unit to detect interference signal in two orthogonal polarization channels. Per depth location four electro-magnetic field components are measured that can be represented in a complex 2x2 field matrix. A Jones ...
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    4. Correlation of localized glaucomatous visual field defects and spectral domain optical coherence tomography retinal nerve fiber layer thinning using a modified structure-function map for OCT

      Correlation of localized glaucomatous visual field defects and spectral domain optical coherence tomography retinal nerve fiber layer thinning using a modified structure-function map for OCT
      Purpose To study the correlation between glaucomatous visual field (VF) defects assessed by standard automated perimetry (SAP) and peripapillary retinal nerve fiber layer (RNFL) thinning measured by spectral domain optical coherence tomography (OCT) using a modified OCT-based peripapillary RNFL structurefunction map. Patients and methods Perimetric glaucoma patients and age-matched normal control subjects were recruited from a university hospital clinic. All eyes underwent testing with the Spectralis spectral domain OCT and ...
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    5. Direct Blood Flow Measurements in a Free RPE-Choroid Graft with Phase-Resolved Doppler OCT

      Direct Blood Flow Measurements in a Free RPE-Choroid Graft with Phase-Resolved Doppler OCT
      Purpose: We directly demonstrated the revascularization in a free retinal pigment epithelium (RPE)-choroid graft with direct blood flow detection by experimental phase-resolved Doppler optical coherence tomography (PRD-OCT). Methods: Seven patients with age-related macular degeneration underwent an RPE-choroid graft translocation in a prospective institutional cohort study. Spectral domain optical coherence tomography (SD-OCT) was used to measure the revascularization stage. With PRD-OCT the presence of flow was imaged postoperatively. Results: The ...
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    6. Fiber-based polarization-sensitive OCT of the human retina with correction of system polarization distortions

      Fiber-based polarization-sensitive OCT of the human retina with correction of system polarization distortions
      In polarization-sensitive optical coherence tomography (PS-OCT) the use of single-mode fibers causes unpredictable polarization distortions which can result in increased noise levels and erroneous changes in calculated polarization parameters. In the current paper this problem is addressed by a new Jones matrix analysis method that measures and corrects system polarization distortions as a function of wavenumber by spectral analysis of the sample surface polarization state and deeper located birefringent tissue ...
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    7. Systems, methods and computer-readable medium for determining depth-resolved physical and/or optical properties of scattering media by analyzing measured data over a range of depths

      Systems, methods and computer-readable medium for determining depth-resolved physical and/or optical properties of scattering media by analyzing measured data over a range of depths
      In depth-resolved imaging of scattering media, incident light interacts with tissue in a complex way before the signal reaches the detector: Light interacts with media between the light source and a specific depth, then scatters at that depth and the backscattered light again interacts with media on its way to the detector. The resulting depth-resolved signal therefore likely does not directly represent a physical or optical property of the media ...
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    8. Feature Of The Week 7/21/13: VU University Amsterdam Demonstrates Focus-Extension by Depth-Encoded Synthetic Aperture in Optical Coherence Tomography

      Feature Of The Week 7/21/13: VU University Amsterdam Demonstrates Focus-Extension by Depth-Encoded Synthetic Aperture in Optical Coherence Tomography
      Optical coherence tomography (OCT) is an interferometric technique that provides cross-sectional images of biological tissue. It has become an essential tool for clinical diagnosis and disease monitoring in ophthalmology and it shows great potential in other clinical areas such as dermatology, cardiology and gastroenterology. The axial resolution in OCT is provided by the coherence gate and is invariant over the full image depth. The lateral resolution is determined by the ...
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    9. CBORT 2013 OCT Symposium July 29th at Harvard Medical School Cambridge MA, USA

      CBORT 2013 OCT Symposium July 29th at Harvard Medical School Cambridge MA, USA
      OCT2013 the first international symposium hosted by the Center for Biomedical OCT Research and Translation at Harvard Medical School and Massachusetts General Hospital, will focus on the latest and greatest technical capabilities of OCT, provide an overview of the commercially available OCT systems, discuss advancements in numerous clinical application areas, and introduce emerging preclinical optical imaging techniques. The unique emphasis of technology and clinical utility presented in the symposium will ...
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    10. Focus-extension by depth-encoded synthetic aperture in Optical Coherence Tomography

      Focus-extension by depth-encoded synthetic aperture in Optical Coherence Tomography
      We present a novel method to extend the depth-of-focus of Optical Coherence Tomography (OCT). OCT is an interferometric imaging technique that provides depth-resolved scattering information. The axial resolution in OCT is provided by the coherence gate and is invariant over the full image depth. The lateral resolution is determined by the beam parameters such as wavelength and numerical aperture. The Rayleigh range determines the depth range over which the lateral ...
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    11. Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans

      Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans
      In conventional phase-resolved OCT blood flow is detected from phase changes between successive A-scans. Especially in high-speed OCT systems this results in a short evaluation time interval. This method is therefore often unable to visualize complete vascular networks since low flow velocities cause insufficient phase changes. This problem was solved by comparing B-scans instead of successive A-scans to enlarge the time interval. In this paper a detailed phase-noise analysis of ...
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    12. Fully-funded biomedical optics PhD student position: Quantitative in-vivo characterization of optical properties of ocular tissue for diagnosis and monitoring of chorioretinal diseases

      Fully-funded biomedical optics PhD student position: Quantitative in-vivo characterization of optical properties of ocular tissue for diagnosis and monitoring of chorioretinal diseases
      Project description Current clinical ophthalmic practice focuses on assessing the (chorio)retinal condition based on various imaging techniques that are incapable of quantitatively determining the state of the retina. In this project, we will develop techniques to quantitatively assess various optical properties of the retina and its separate layers, thereby providing information about the health status of the retina. These properties are the attenuation coefficient, polarization properties and the spectral ...
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    13. 31-45 of 103 « 1 2 3 4 5 6 7 »
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  2. About Johannes F. de Boer

    Johannes F. de Boer

    Johannes F. de Boer is a professor in the Department of Physics at Vrije Universiteit, Amsterdam The Netherlands.  His research interests: The long-term goal of the research is to develop minimally invasive optical imaging and microscopy technologies for 3-dimensional structural and functional mapping of biological tissues and specimens. A main thrust of my research is in the area of Optical Coherence Tomography (OCT). OCT creates in-vivo cross-sectional images approaching the cellular level in a non-invasive or minimally invasive way. OCT can potentially provide “optical biopsies” for real time in-vivo diagnosis, and since tissue does not need to be excised, allows functional biopsies of living tissue. My group has pioneered Polarization Sensitive OCT (PS-OCT). Over the past years we have played a leading role in the development of Spectral Domain OCT (SD/FD-OCT and OFDI) that is a hundred to a thousand times more sensitive than current state of the art OCT. The increase of light detection efficiency by 2 to 3 orders of magnitude allows In-vivo video rate imaging of biological structures with better signal to noise and enhanced depth resolution. The increase in speed represents a paradigm shift from point sampling to 3-dimensional screening of large tissue volumes. We were the first to demonstrate video rate OCT and ultra-high resolution imaging of the human retina. The superior phase stability of the new technology results in sensitivity enhancements to functional OCT, such as Doppler velocimetry and polarization and phase sensitivity. This allows video rate mapping of functionality such as flow velocity profiles in retinal arteries and characterization of structural properties such as retinal nerve fiber layer birefringence. We are developing comprehensive 3-D retinal mapping of structure, flow velocity and retinal nerve fiber layer birefringence for a better understanding of a variety of diseases in ophthalmology, in particular glaucoma. In addition, the current research projects include human studies in the area of otolaryngology and skin and small animal imaging. A second and rapidly expanding research area is optical coherence phase contrast microscopy. Phase contrast techniques give motion resolution on the order of 1-2 nm, permitting non-contact optical detection of action potentials in nerve tissue. Combined with the depth discrimination of OCT, this provides the ability to isolate phase changes to within the coherence length of the light source, i.e., 2-3 micron. The combination of structural and phase sensitive microscopy with sub-wavelength resolution allows 3-D phase contrast imaging of cell dynamics.