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101 results on '"Bouwens, Arno"'

1. Visible spectrum extended-focus optical coherence microscopy for label-free sub-cellular tomography

Author

Marchand, Paul J., Bouwens, Arno, Szlag, Daniel, Nguyen, David, Descloux, Adrien, Sison, Miguel, Coquoz, Séverine, Extermann, Jérôme, and Lasser, Theo

Subjects
Physics - Biological Physics, Physics - Optics
Abstract

We present a novel extended-focus optical coherence microscope (OCM) attaining 0.7 {\mu}m axial and 0.4 {\mu}m lateral resolution maintained over a depth of 40 {\mu}m, while preserving the advantages of Fourier domain OCM. Our method uses an ultra-broad spectrum from a super- continuum laser source. As the spectrum spans from near-infrared to visible wavelengths (240 nm in bandwidth), we call the method visOCM. The combination of such a broad spectrum with a high-NA objective creates an almost isotropic 3D submicron resolution. We analyze the imaging performance of visOCM on microbead samples and demonstrate its image quality on cell cultures and ex-vivo mouse brain tissue., Comment: 15 pages, 7 figures

Published
2017

2. Parallel photonic reservoir computing using frequency multiplexing of neurons

Author

Akrout, Akram, Bouwens, Arno, Duport, François, Vinckier, Quentin, Haelterman, Marc, and Massar, Serge

Subjects
Computer Science - Emerging Technologies, Physics - Optics
Abstract

Today's unrelenting increase in demand for information processing creates the need for novel computing concepts. Reservoir computing is such a concept that lends itself particularly well to photonic hardware implementations. Over recent years, these hardware implementations have gained maturity and now achieve state-of-the-art performance on several benchmark tasks. However, implementations so far are essentially all based on sequential data processing, leaving the inherent parallelism of photonics unexploited. Parallel implementations process all neurons simultaneously, and therefore have the potential of reducing computation time by a factor equal to the number of neurons, compared to sequential architectures. Here, we report a parallel reservoir computer that uses frequency domain multiplexing of neuron states. We illustrate its performance on standard benchmark tasks such as nonlinear channel equalization, the reproduction of a nonlinear 10th-order system, and speech recognition, obtaining error rates similar to previous optical experiments. The present experiment is thus an important step towards high speed, low footprint, all optical photonic information processing.

Published
2016

4. 3D super-resolved in vitro multiphoton microscopy by saturation of excitation

Author

Nguyen, Anh Dung, Duport, François, Bouwens, Arno, Vanholsbeeck, Frédérique, Egrise, Dominique, Van Simayes, Gaetan, Emplit, Philippe, Goldman, Serge, and Gorza, Simon-Pierre

Subjects
Physics - Medical Physics, Physics - Biological Physics
Abstract

We demonstrate a significant resolution enhancement beyond the conventional limit in multiphoton microscopy (MPM) using saturated excitation of fluorescence. Our technique achieves super-resolved imaging by temporally modulating the excitation laser-intensity and demodulating the higher harmonics from the saturated fluorescence signal. The improvement of the lateral and axial resolutions is measured on a sample of fluorescent microspheres. While the third harmonic already provides an enhanced resolution, we show that a further improvement can be obtained with an appropriate linear combination of the demodulated harmonics. Finally, we present in vitro imaging of fluorescent microspheres incorporated in HeLa cells to show that this technique performs well in biological samples.

Published
2015

6. Self-contained and modular structured illumination microscope: Supplementary Information

Author

Van den Eynde, Robin, Vandenberg, Wim, Hugelier, Siewert, Bouwens, Arno, Hofkens, Johan, Müller, Marcel, and Dedecker, Peter

Subjects
ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, ComputerApplications_COMPUTERSINOTHERSYSTEMS, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries)
Abstract

Supplementary information for our manuscript by the same title. Text with alignment and construction information. List of parts. Optical calculations summary. Microcontroller code.

Published
2021
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11. Identifying microbial species by single-molecule DNA optical mapping and resampling statistics

Author

Bouwens, Arno, primary, Deen, Jochem, additional, Vitale, Raffaele, additional, D’Huys, Laurens, additional, Goyvaerts, Vince, additional, Descloux, Adrien, additional, Borrenberghs, Doortje, additional, Grussmayer, Kristin, additional, Lukes, Tomas, additional, Camacho, Rafael, additional, Su, Jia, additional, Ruckebusch, Cyril, additional, Lasser, Theo, additional, Van De Ville, Dimitri, additional, Hofkens, Johan, additional, Radenovic, Aleksandra, additional, and Frans Janssen, Kris Pieter, additional

Published
2019
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29. Longitudinal three-dimensional visualisation of autoimmune diabetes by functional optical coherence imaging

Author

Berclaz, Corinne, primary, Schmidt-Christensen, Anja, additional, Szlag, Daniel, additional, Extermann, Jerome, additional, Hansen, Lisbeth, additional, Bouwens, Arno, additional, Villiger, Martin, additional, Goulley, Joan, additional, Schuit, Frans, additional, Grapin-Botton, Anne, additional, Lasser, Theo, additional, and Holmberg, Dan, additional

Published
2015
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30. Functional and Structural Imaging with Optical Coherence Microscopy:Principles & Applications

Author

Bouwens, Arno

Abstract

Fluorescence microscopy techniques are well established research tools and have proven their use in a large variety of biomedical applications. Microscopic molecular contrast is achieved by imaging fluorescent dyes that bind specifically to a molecule of interest and gene expression can be imaged by genetically modifying organisms to express fluorescent proteins. This versatile technique has, however, three limitations: fluorescent labels can cause toxicity or have an unwanted influence on the process under study; the photobleaching effect limits observation time; and the highest acquisition speed is restricted by the fluorophore’s brightness and by the raster scan required for 3-D imaging. For applications where direct molecular contrast is not essential, label-free imaging offers a solution to these issues and can simplify imaging experiments. In this work, we present methods to perform 3-D label-free imaging of the anatomy (structural imaging) and physiology (functional imaging) of living tissue and cells with optical coherence microscopy (OCM). OCM is founded on low-coherence interferometry and acquires 3-D images of the local light back-scattering strength from within highly scattering biological tissue. By measuring in the spectral or Fourier domain, image acquisition is multiplexed over depth and achieves high sensitivity. OCM can therefore offer an important gain in acquisition speed, under the condition that lateral resolution is maintained over the imaging depth. This is realized by extended focus OCM (xfOCM), which uses Bessel beam illumination to create a high lateral resolution over an extended depth of field. The combination of high 3-D resolution and fast acquisition is especially useful for in vivo experiments, where measurement time is limited, and when fast processes are studied. We demonstrate long-term in vivo imaging with xfOCM of amyloid plaque in a mouse model of Alzheimer’s disease (AD), without administration of extrinsic contrast agents. By implementing a 3-D image segmentation algorithm, we further show how xfOCM can be employed to perform a label-free ex vivo transversal study of the development of amyloid plaque in the mouse brain. The high acquisition speed obtained from multiplexing depth acquisition is further exploited to image cerebral blood flow. We first analyze the Doppler frequency spectrum measured by OCM when scatterers such as erythrocytes flow through the system’s focus and show how it relates to the axial and lateral flow velocity components. This then enables quantitative blood flow imaging with xfOCM, with in an unprecedented combination of 3-D resolution and acquisition speed. We apply this technique to label-free in vivo angiography and quantitative blood flow imaging in the murine brain. xfOCM achieves deep tissue penetration due to the use of a near-infrared spectrum. The study of cell cultures, however, does not require such deep penetration, but instead could benefit from higher resolution. For these applications, we introduce visible spectrum OCM (visOCM), enabling label-free and long-term imaging of living cell cultures with 3-D sub-micron resolution. visOCM allows cell morphology to be imaged in thin single layer cultures, but also in thicker three-dimensional cultures and organotypic slices, for which no label-free tomographic microscopy exists to date.

Published
2013
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36. Optical Coherence Microscopy From Tissue to Cell

Author

Lasser, Theo, primary, Bouwens, Arno, additional, Bolmont, Tristan, additional, Szlag, Daniel, additional, Berclaz, Corinne, additional, Broillet, Stephane, additional, Coquoz, Severine, additional, Marchand, Paul, additional, Sison, Miguel, additional, Extermann, Jerome, additional, and Leutenegger, Marcel, additional

Published
2014
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43. Diabetes imaging—quantitative assessment of islets of Langerhans distribution in murine pancreas using extended-focus optical coherence microscopy

Author

Berclaz, Corinne, primary, Goulley, Joan, additional, Villiger, Martin, additional, Pache, Christophe, additional, Bouwens, Arno, additional, Martin-Williams, Erica, additional, Van de Ville, Dimitri, additional, Davison, Anthony C., additional, Grapin-Botton, Anne, additional, and Lasser, Theo, additional

Published
2012
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44. Statistical parametric mapping of stimuli evoked changes in total blood flow velocity in the mouse cortex obtained with extended-focus optical coherence microscopy

Author

Marchand, Paul J., Bouwens, Arno, Bolmont, Tristan, Shamaei, Vincent K., Nguyen, David, Szlag, Daniel, Extermann, Jérôme, and Lasser, Theo

Abstract

Functional magnetic resonance (fMRI) imaging is the current gold-standard in neuroimaging. fMRI exploits local changes in blood oxygenation to map neuronal activity over the entire brain. However, its spatial resolution is currently limited to a few hundreds of microns. Here we use extended-focus optical coherence microscopy (xfOCM) to quantitatively measure changes in blood flow velocity during functional hyperaemia at high spatio-temporal resolution in the somatosensory cortex of mice. As optical coherence microscopy acquires hundreds of depth slices simultaneously, blood flow velocity measurements can be performed over several vessels in parallel. We present the proof-of-principle of an optimised statistical parametric mapping framework to analyse quantitative blood flow timetraces acquired with xfOCM using the general linear model. We demonstrate the feasibility of generating maps of cortical hemodynamic reactivity at the capillary level with optical coherence microscopy. To validate our method, we exploited 3 stimulation paradigms, covering different temporal dynamics and stimulated limbs, and demonstrated its repeatability over 2 trials, separated by a week.

Published
2017

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