Dr. François Ramaz Profile

Dr. François Ramaz

at Institut Langevin

SPIE Involvement:

Author

Publications (19)

Proceedings Article | 12 March 2024 Poster + Paper

Fourier transform acousto-optic imaging: toward real-time imaging of thick biological media

François Figliolia, Qin Liu, Sylvie Janicot, Gaëlle Lucas-Leclin, Jean-Pierre Huignard, François Ramaz, Jean-Michel Tualle, Maïmouna Bocoum

Proceedings Volume 12842, 1284217 (2024) https://doi.org/10.1117/12.3003141

KEYWORDS: Adaptive optics, Acoustooptics, Cameras, Photons, Biological imaging, Laser scattering, Scattering media, Real time imaging, Laser sources, Fourier transforms

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Proceedings Article | 1 March 2019 Paper

Solid-state characterization of CdTe:Sn as a medium for adaptive interferometry

Konstantin Shcherbin, Serguey Odoulov, Dean Evans, François Ramaz, Bernard Briat

Proceedings Volume 10934, 109341H (2019) https://doi.org/10.1117/12.2514823

KEYWORDS: Crystals, Interferometers, Absorption, Semiconductors, Phase modulation, Interferometry, Two wave mixing, Photorefraction

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Proceedings Article | 24 May 2018 Presentation

Ultranarrow spectral filter for acousto-optic imaging for medical applications (Conference Presentation)

Caroline Venet, Maïmouna Bocoum, Thierry Chanelière, François Ramaz, Anne Louchet-Chauvet

Proceedings Volume 10677, 106771N (2018) https://doi.org/10.1117/12.2303511

KEYWORDS: Acousto-optics, Optical filters, Medical imaging, Crystals, Ultrasonography, Tissues, Modulation, Hole burning spectroscopy, Real time imaging, Liver

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Nowadays imaging the early liver metastases has to be improved in order to have an easier setup than MRI or to be more discriminant than ultrasound between healthy and diseased tissues. Acousto-optic imaging could solve these issues by coupling itself with ultrasound modality: the additional optical contrast would suppress the indetermination on the health of the biological tissue. Acousto-optic imaging is a multi-wave technique which localizes light in very scattering media thanks to an acoustic wave: the acousto-optic effect creates frequency-shifted light, carrying local information about the insonified volume. The central challenge of acousto-optic imaging is the detection of the frequency-shifted light, because there are only very few modulated photons and they create a speckle pattern. We choose to explore the detection by spectral filtering using the spectral hole burning process in rare earth doped crystal [1]. Spectral hole burning consists in creating a sub-MHz-wide transparency window in the wide absorption spectrum of a rare earth doped crystal: the crystal becomes transparent at the wavelength of the spectral hole and thus can filter the modulated light. This filtering technique is intrinsically immune to speckle decorrelation and therefore well adapted to in vivo imaging. We use a YAG crystal doped with thulium ions under a magnetic field which increases the lifetime of the spectral hole from 10ms to longer than a minute. We have undertaken a spectroscopic study to optimize the hole preparation sequence. The long lifetime simplifies the optimization of fast imaging sequences, making real-time acousto-optic imaging reachable. We will present the first acousto-optic images achieved with a long-lived spectral filter in Tm:YAG, in a scattering medium. [1] Li, Y., Zhang, H., Kim, C., Wagner, K. H., Hemmer, P., & Wang, L. V. (2008). Pulsed ultrasound-modulated optical tomography using spectral-hole burning as a narrowband spectral filter. Applied physics letters, 93(1), 011111.

Proceedings Article | 15 March 2018 Presentation

Acousto-optic imaging using plane waves (Conference Presentation)

Maïmouna Bocoum, Jean-Baptiste Laudereau, Alexander Grabar, Caroline Venet, Jean-Luc Gennisson, Clément Dupuy, Mickaël Tanter, François Ramaz

Proceedings Volume 10494, 104941Q (2018) https://doi.org/10.1117/12.2288327

KEYWORDS: Ultrasonography, Acousto-optics, Photons, Image restoration, Acoustics, Tomography, Multimodal imaging, Reconstruction algorithms, Ultrafast imaging, Radon

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Proceedings Article | 15 March 2018 Presentation

Ultra-thin spectral filter for acousto-optic imaging for medical applications (Conference Presentation)

Caroline Venet, Maïmouna Bocoum, Jean-Baptiste Laudereau, Thierry Chanelière, François Ramaz, Anne Louchet-Chauvet

Proceedings Volume 10494, 104941S (2018) https://doi.org/10.1117/12.2285841

KEYWORDS: Acousto-optics, Optical filters, Ultrasonography, Light scattering, Medical imaging, Hole burning spectroscopy, Spectroscopy, Tissues, Scattering, Crystals

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Proceedings Article | 13 March 2015 Paper

Acousto-optic imaging with a smart-pixels sensor

K. Barjean, K. Contreras, J.-B. Laudereau, E. Tinet, D. Ettori, F. Ramaz, J.-M. Tualle

Proceedings Volume 9403, 940308 (2015) https://doi.org/10.1117/12.2183112

KEYWORDS: Sensors, CMOS sensors, Acousto-optics, Signal to noise ratio, Speckle pattern, Acoustics, Photons, Transducers, Signal detection, Biomedical optics

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Proceedings Article | 8 March 2014 Paper

Monolithic device for on-chip fast optical phase conjugation integrating an image sensor and a spatial light modulator

Timothé LaForest, Arnaud Verdant, Antoine Dupret, Sylvain Gigan, François Ramaz, Gilles Tessier, Émilie Benoit à la Guillaume

Proceedings Volume 8989, 89890N (2014) https://doi.org/10.1117/12.2039675

KEYWORDS: Liquid crystals, Phase conjugation, Electrodes, Aluminum, Photodiodes, Image processing, Image sensors, Liquid crystal on silicon, Biomedical optics, Cameras

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Proceedings Article | 4 March 2014 Paper

Co-integration of a smart CMOS image sensor and a spatial light modulator for real-time optical phase modulation

Timothé Laforest, Arnaud Verdant, Antoine Dupret, Sylvain Gigan, François Ramaz, Gilles Tessier

Proceedings Volume 9022, 90220N (2014) https://doi.org/10.1117/12.2039867

KEYWORDS: Liquid crystals, Phase conjugation, Sensors, Electrodes, Photodiodes, CMOS sensors, Signal detection, Spatial light modulators, Cameras, Holography

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Proceedings Article | 18 February 2011 Paper

Photorefractive acousto optic imaging in the therapeutic window

Salma Farahi, Germano Montemezzani, Alexander Grabar, Jean-Pierre Huignard, François Ramaz

Proceedings Volume 7899, 789918 (2011) https://doi.org/10.1117/12.871217

KEYWORDS: Photons, Crystals, Ultrasonography, Adaptive optics, Acousto-optics, Light scattering, Tissue optics, Holography, Tissues, Scattering

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Proceedings Article | 12 February 2011 Paper

High-resolution large dynamic range spectral filtering at 800 nm using Tm:YAG crystals

Anne Louchet-Chauvet, Romain Lauro, Philippe Goldner, Francois Ramaz, Thierry Chanelière, Jean-Louis Le Gouët

Proceedings Volume 7948, 794805 (2011) https://doi.org/10.1117/12.874009

KEYWORDS: Optical filters, Crystals, Absorption, Telecommunications, Bragg cells, Ions, Transparency, Spectral resolution, Photonic crystals, Photonics

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Proceedings Article | 6 March 2006 Paper

Sub-millisecond in situ measurement of the photorefractive response in a self adaptive wavefront holography setup developed for acousto-optic imaging

M. Lesaffre, F. Jean, A. Bordes, F. Ramaz, E. Bossy, A. Boccara, M. Gross, P. Delaye, G. Roosen

Proceedings Volume 6086, 608612 (2006) https://doi.org/10.1117/12.641669

KEYWORDS: Crystals, Acousto-optics, Speckle, Laser crystals, Tissues, Ultrasonics, Modulation, Holography, Photons, Amplitude modulation

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Proceedings Article | 6 March 2006 Paper

Experimental investigation of time-reversal of photo-acoustic waves

Emmanuel Bossy, Gabriel Montaldo, Michael Tanter, Benoit Forget, François Ramaz, Mathias Fink, Claude Boccara

Proceedings Volume 6086, 60860X (2006) https://doi.org/10.1117/12.646132

KEYWORDS: Ultrasonography, Ultrasonics, Transducers, Acoustics, Optical spheres, Point spread functions, Electronics, Nd:YAG lasers, Tissue optics, Q switched lasers

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Proceedings Article | 1 September 2005 Paper

Acousto-optic imaging with a digital holography scheme: new scheme to obtain axial resolution

Pedro Santos, Michael Atlan, Benoit Forget, Francois Ramaz, A. Claude Boccara, Michel Gross

Proceedings Volume 5864, 586401 (2005) https://doi.org/10.1117/12.633192

KEYWORDS: Adaptive optics, Modulation, Acousto-optics, Digital holography, Image resolution, CCD cameras, Interference (communication), Tomography, Ultrasonography, Speckle

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Proceedings Article | 25 April 2005 Paper

Photorefractive acousto-optical imaging for thick biological tissues

Francois Ramaz, Benoit Forget, Michael Atlan, A. Claude Boccara, Michel Gross, Philippe Delaye, Gerald Roosen

Proceedings Volume 5697, (2005) https://doi.org/10.1117/12.590090

KEYWORDS: Crystals, Acousto-optics, Modulation, Phase modulation, Signal to noise ratio, Amplitude modulation, Sensors, Speckle, Photons, Acoustics

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Proceedings Article | 25 April 2005 Paper

Pulsed acousto-optic imaging with a digital holography scheme

Michael Atlan, Benoit Forget, Francois Ramaz, A. Claude Boccara, Michel Gross

Proceedings Volume 5697, (2005) https://doi.org/10.1117/12.590070

KEYWORDS: Acousto-optics, Acoustics, Photons, Digital holography, Speckle, Ultrasonography, Sensors, Tomography, Heterodyning, Signal detection

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Proceedings Article | 14 October 2003 Paper

Evidence of a millimeter size virtual light source for acousto-optical tomography in scattering media using a chirp modulation of the ultrasound

Michael Atlan, Francois Ramaz, Benoit Forget, Albert-Claude Boccara

Proceedings Volume 5143, (2003) https://doi.org/10.1117/12.499958

KEYWORDS: Modulation, Tomography, Light, Acoustics, Light sources, Scattering media, Speckle, Light scattering, Ultrasonography, Optical properties

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Proceedings Article | 1 July 2003 Paper

High-contrast FFT acousto-optical tomography of biological tissues with a frequency-chirped modulation of the ultrasound

Benoit Forget, Michael Atlan, Juliette Selb, Lionel Pottier, Francois Ramaz, Albert Boccara

Proceedings Volume 4960, (2003) https://doi.org/10.1117/12.477642

KEYWORDS: Modulation, Acousto-optics, Tissues, Ultrasonography, Spatial resolution, Adaptive optics, Tissue optics, CCD cameras, Ultrasonics, Biomedical optics

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