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5 results on '"Alexander A. Grabar"'

1. Reconstruction of bi-dimensional images in Fourier-Transform Acousto-Optic Imaging

Author

Jean-Luc Gennisson, Alexander A. Grabar, François Ramaz, Maïmouna Bocoum, Jean-Michel Tualle, Institut Langevin - Ondes et Images (UMR7587) (IL), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), LaBoratoire d'Imagerie biOmédicale MultimodAle Paris-Saclay (BIOMAPS), Service Hospitalier Frédéric Joliot (SHFJ), Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institute of Solid State Physics and Chemistry [Uzhgorod] (ISSPC), Uzhgorod National University (UzhNU), Laboratoire de Physique des Lasers (LPL), Université Paris 13 (UP13)-Centre National de la Recherche Scientifique (CNRS)-Université Sorbonne Paris Nord, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Unité BioMaps (BIOMAPS), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université Sorbonne Paris Nord

Subjects
[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], business.industry, Image quality, Computer science, Detector, Plane wave, 02 engineering and technology, Photorefractive effect, Iterative reconstruction, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010309 optics, symbols.namesake, Optics, Fourier transform, Proof of concept, 0103 physical sciences, symbols, Spatial frequency, 0210 nano-technology, business
Abstract

We present a new, to the best of our knowledge, method to perform acousto-optic imaging based on a spatiotemporal structuration of long-duration acoustic plane waves. This approach is particularly relevant when using detectors with long integration times. We show how it is possible to reconstruct an image by measuring its two-dimensional Fourier components. A proof of concept is presented using a photorefractive detection scheme, demonstrating equal performances to direct imaging. The overall acquisition time is compatible with medical monitoring applications.

Published
2020
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2. Ultrafast acousto-optic imaging with ultrasonic plane waves

Author

Mickael Tanter, Alexander A. Grabar, Jean-Luc Gennisson, François Ramaz, Jean-Baptiste Laudereau, Institut Langevin - Ondes et Images (UMR7587) (IL), Sorbonne Université (SU)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Paris (UP)-Centre National de la Recherche Scientifique (CNRS), Institute of Solid State Physics and Chemistry [Uzhgorod] (ISSPC), and Uzhgorod National University (UzhNU)

Subjects
Acoustics, Acousto-optics, 02 engineering and technology, 01 natural sciences, Light scattering, 010309 optics, Optics, 0103 physical sciences, Ultrasound, Medical imaging, Physics, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], business.industry, Turbid media, 021001 nanoscience & nanotechnology, Holographic interferometry, Atomic and Molecular Physics, and Optics, Diffuse optical imaging, Imaging through turbid media, Holo-graphic interferometry, Ultrasonic sensor, 0210 nano-technology, business, Ultrashort pulse
Abstract

International audience; Due to multiple light scattering inside biological tissues, deep non-invasive optical medical imaging is very challenging. Acousto-optic imaging is a technique coupling ultrasound and light that allows recovering optical contrast at depths of few centimeters with a millimeter resolution. Recent advances in acousto-optic imaging are using short focused ultra-sound pulses often averaged over several hundred or thousand pulses. As the pulsing rate of commercial probes is limited to about few ultrasound cycles every 100 µs, acquiring an acousto-optic image usually takes several tens of seconds due to the high number of acoustic pulses excitation. We propose here a new acousto-optic imaging technique based on the use of ultrasound plane waves instead of focused ones that allows increasing drastically the imaging rate.

Published
2016
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3. Enhanced photorefractive properties of Bi-doped Sn2P2S6

Author

Olivier Bidault, Alexander A. Grabar, Yulian M. Vysochanskii, I. M. Stoika, Ihor V. Kedyk, Pierre Mathey, Grégory Gadret, Institute of Solid State Physics and Chemistry, Laboratoire Interdisciplinaire Carnot de Bourgogne ( LICB ), Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Institute of Solid State Physics and Chemistry [Uzhgorod] (ISSPC), Uzhgorod National University (UzhNU), Laboratoire Interdisciplinaire Carnot de Bourgogne (LICB), and Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Photorefractive materials, Nonlinear optics, Band gap, Analytical chemistry, chemistry.chemical_element, 02 engineering and technology, Dielectric, Non linear material, 01 natural sciences, Ternary compounds, Doped materials, 010309 optics, Optics, 0103 physical sciences, Tin Hypothiophosphates, Optical properties, business.industry, Doping, Two wave mixing, Statistical and Nonlinear Physics, Photorefractive effect, 021001 nanoscience & nanotechnology, Atomic and Molecular Physics, and Optics, Bismuth additions, Light intensity, Wavelength, chemistry, Energy transfer, Dielectric properties, Optical materials, 0210 nano-technology, business, Tin, Refractive index
Abstract

International audience; Enhanced photorefractive properties of tin hypothiodiphosphate (Sn2P2S6) crystals as a result of Bi doping are presented. These new crystals were obtained by the vapor-transport technique using stoichiometric Sn2P2S6 composition with an additional amount of Bi up to 0.5 mol. % in the initial compound. The bandgap edges of the obtained crystals are located at ~750 nm and shift toward the red wavelengths with increasing Bi concentration. Sn2P2S6:Bi crystals are found to exhibit larger two-beam coupling gain coefficients (up to 17 cm−1 at a wavelength of 854 nm) as compared to (i) pure Sn2P2S6 (2.5 cm−1 at 854 nm), (ii) Sn2P2S6 crystals modified by the growth conditions (14 cm−1 at 860 nm), and (iii) Te-doped Sn2P2S6 (8 cm−1 at 860 nm). At the same time, for an intensity of 1.3 W/cm2 at 854 nm, buildup times of 0.9 and 2.5 ms at grating spacings of Λ=9.8 and 1.3 μm, respectively, are found; Bi-doped Sn2P2S6 crystals are the fastest among all the presently known Sn2P2S6 crystals operating at near-infrared wavelengths.

Published
2008
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4. Tailoring of infrared photorefractive properties of Sn2P2S6 crystals by Te and Sb doping

Author

Mojca Jazbinsek, Alexander A. Grabar, Yulian M. Vysochanskii, Peter Günter, Tobias Bach, Germano Montemezzani, Coda, Virginie, Nonlinear Optics Laboratory, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Institute of Solid State Physics and Chemistry [Uzhgorod] (ISSPC), Uzhgorod National University (UzhNU), Laboratoire Matériaux Optiques, Photonique et Systèmes (LMOPS), and Université de Lorraine (UL)-CentraleSupélec

Subjects
[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], Materials science, [SPI.OPTI] Engineering Sciences [physics]/Optics / Photonic, Infrared, business.industry, Diffusion, Doping, Near-infrared spectroscopy, Analytical chemistry, Nonlinear optics, Statistical and Nonlinear Physics, 02 engineering and technology, Photorefractive effect, 021001 nanoscience & nanotechnology, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010309 optics, Wavelength, Optics, Orders of magnitude (time), 0103 physical sciences, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, 0210 nano-technology, business, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; The photorefractive properties of Sn2P2S6 crystals doped with Te and Sb in the near-infrared wavelength range up to 1064 nm are reported. The main photorefractive parameters, i.e., two-wave mixing gain, effective electro-optic coefficient, diffusion length, concentration of traps, and response time, are compared with conventional nominally pure Sn2P2S6. Te-doped Sn2P2S6 shows the fastest response with the smallest decrease of the photorefractive efficiency with increasing wavelength in the near infrared. Sb doping, on the other hand, inhibits photorefraction in the near infrared. Sn2P2S6:Te and Sn2P2S6:Sb crystals both show a high two-wave mixing gain Γ at 633 nm, and 10 and 20 cm−1. Te-doped Sn2P2S6 shows a photorefractive gain of 4.5 cm−1 at 1064 nm. Response times at 1064 nm of 20 ms have been measured for the intensity 6 W⁄cm2, which is 2 orders of magnitude shorter than in Rh-doped BaTiO3.

Published
2007
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5. Real-time Photoinduced Waveguides in Sn2P2S6 Bulk Crystals with Visible or Near Infrared Light

Author

Delphine Wolfersberger, Germano Montemezzani, R. Mosimann, Mojca Jazbinsek, Nicolas Fressengeas, Flurin Juvalta, Peter Günter, M. Gorram, Cristian Dan, Alexander A. Grabar, Van Luchene, Sébastien, Laboratoire Matériaux Optiques, Photonique et Systèmes (LMOPS), Université de Lorraine (UL)-CentraleSupélec, Institute of Solid State Physics and Chemistry [Uzhgorod] (ISSPC), Uzhgorod National University (UzhNU), and CentraleSupélec-Université de Lorraine (UL)

Subjects
[PHYS.PHYS.PHYS-OPTICS] Physics [physics]/Physics [physics]/Optics [physics.optics], [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], Near infrared light, Materials science, Infrared, business.industry, Near-infrared spectroscopy, Nonlinear optics, 02 engineering and technology, 021001 nanoscience & nanotechnology, 01 natural sciences, law.invention, 010309 optics, law, Electric field, 0103 physical sciences, Optoelectronics, 0210 nano-technology, business, Waveguide, Bulk crystal, Visible spectrum
Abstract

http://www.opticsinfobase.org//abstract.cfm?URI=PR-2007-TuB3; International audience; Light induced waveguides are demonstrated in Sn2P2S6by two alternative methods allowing a waveguide formation time of the order of 1 ms. The techniques are based on shaped visible lateral illumination and near infrared self-focusing.

Published
2007

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