Dr. Alexandra Fragola Profile

Dr. Alexandra Fragola

at ESPCI ParisTech

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Author

Publications (14)

Proceedings Article | 13 March 2024 Presentation

Fast adaptive optics for deep imaging of biological media in light-sheet and two-photon microscopy

Fabrice Harms, Xavier Levecq, Cynthia Veilly, Mathias Mercier, Alice Guillaume-Manca, Alexandra Fragola, Laurent Bourdieu

Proceedings Volume PC12851, PC128510M (2024) https://doi.org/10.1117/12.3002671

KEYWORDS: Microscopes, Tissues, Scattering, Image segmentation, Microscopy, Wavefront sensors, Wavefronts, Adaptive optics, Two photon excitation microscopy, Biological imaging

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SPIE Journal Paper | 16 June 2023 Open Access

Enhanced neuroimaging with a calcium sensor in ex-vivo Drosophila melanogaster brains using closed-loop adaptive optics light-sheet fluorescence microscopy

Antoine Hubert, Georges Farkouh, Fabrice Harms, Cynthia Veilly, Sophia Imperato, Mathias Mercier, Vincent Loriette, François Rouyer, Alexandra Fragola

JBO, Vol. 28, Issue 06, 066501, (June 2023) https://doi.org/10.1117/12.10.1117/1.JBO.28.6.066501

KEYWORDS: Adaptive optics, Neuroimaging, Neurons, Calcium, Brain, Wavefront sensors, Sensors, Wavefronts, Wavefront aberrations, Fluorescence

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Proceedings Article | 30 May 2022 Presentation

A direct wavefront sensing device resilient to scattering for use in adaptive optics two-photon microscopy of the mouse brain

Sophia Imperato, Fabrice Harms, Cynthia Veilly, Mathias Mercier, Laurent Bourdieu, Alexandra Fragola

Proceedings Volume PC12144, PC121440X (2022) https://doi.org/10.1117/12.2621838

KEYWORDS: Tissues, Scattering, Microscopy, Luminescence, Wavefront sensors, Wavefronts, Adaptive optics, Two photon excitation microscopy, Scatter measurement, Brain

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Optical microscopy allows to perform structural and functional imaging within large volume of tissues with subcellular resolution. Non-linear microscopy allows the interrogation of neuronal activity in mammalian brains but remains limited because of scattering and optical aberrations. To overcome these issues, Adaptive Optics (AO) strategies have been implemented to retrieve the microscope imaging quality while addressing important imaging depths. A first AO strategy implemented in non-linear microscopy relies on a sensorless configuration, but is a time-consuming iterative process hardly compatible with photobleaching issues. A second approach is based on direct wavefront sensing using Shack-Hartmann wavefront sensors and has proved its efficiency on in vivo experiments. However, this method fails at large depths because of the strong scattering of the emitted fluorescence. A method for direct wavefront sensing more resilient to scattering of the fluorescence emission would therefore facilitate the use of AO in optical microscopy. This work proposes an alternative method of direct wavefront measurement, which relies on the cross-correlation of images of an extended source obtained through a microlens array. This extended-source Shack-Hartmann wavefront sensor (ESSH) requires to be coupled to an optical sectioning method. Its efficiency has been proven when coupled to Light Sheet Fluorescence Microscopy in the adult drosophila brain in weekly scattering conditions. Here, we show that it allows quantitative aberration measurements through highly scattering fixed brain slices, up to four times the scattering length of the tissue. We demonstrate that it is more resilient to scattering compared to the current centroid-based approach. Taking advantage of its geometry, this new wavefront sensor also provides scattering coefficient measurements of biological tissues. Finally, we present its implementation on a two-photon microscope within a closed–loop configuration for in depth neuroimaging in mouse brain and compare its performances in scattering media to the classical centroid approach.

Proceedings Article | 30 May 2022 Presentation

Axially-swept adaptive optics light sheet fluorescence microscopy for high resolution neuroimaging in the drosophila brain

Mathias Mercier, Sophia Imperato, Cynthia Veilly, Fabrice Harms, Alexandra Fragola

Proceedings Volume PC12144, PC121440K (2022) https://doi.org/10.1117/12.2621304

KEYWORDS: Optical imaging, Stars, Sensors, Microscopy, Wavefront sensors, Wavefronts, Adaptive optics, Objectives, Neuroimaging, Pulsed laser operation

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Proceedings Article | 7 December 2021 Paper

Adaptive optics light-sheet microscopy for functional neuroimaging

Antoine Hubert, Fabrice Harms, Sophie Imperato, Vincent Loriette, Cynthia Veilly, Xavier Levecq, Georges Farkouh, Francois Rouyer, Alexandra Fragola

Proceedings Volume 11922, 119220H (2021) https://doi.org/10.1117/12.2615699

KEYWORDS: Microscopy, Luminescence, Image resolution, Wavefront sensors, Wavefronts, Adaptive optics, Functional imaging, Neuroimaging, Neurons, Brain

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Proceedings Article | 5 March 2021 Presentation

Compact, easy-to-use adaptive optics module for light-sheet structural and functional imaging of neuronal structures

Fabrice Harms, Antoine Hubert, Pauline Treimany, Cynthia Veilly, Guillaume Dovillaire, Xavier Levecq, Vincent Loriette, Alexandra Fragola

Proceedings Volume 11652, 116520K (2021) https://doi.org/10.1117/12.2583287

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Proceedings Article | 9 March 2020 Presentation

Time-gated fluorescence imaging and sensing using long lifetime near infrared quantum dots (Conference Presentation)

Thomas Pons, Sophie Bouccara, Manon Debayle, Vincent Loriette, Nicolas Lequeux, Alexandra Fragola

Proceedings Volume 11243, 112430W (2020) https://doi.org/10.1117/12.2545627

KEYWORDS: Near infrared, Tissues, Luminescence, Photons, Diffusion, Fluorescence spectroscopy, Quantum dots, In vivo imaging, Auto-fluorescence imaging, Absorption

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Proceedings Article | 24 April 2017 Presentation

Long lifetime near-infrared-emitting quantum dots for time-gated in vivo imaging of rare circulating cells (Conference Presentation)

Alexandra Fragola, Sophie Bouccara, Sophie Pezet, Nicolas Lequeux, Vincent Loriette, Thomas Pons

Proceedings Volume 10079, 1007904 (2017) https://doi.org/10.1117/12.2252224

KEYWORDS: Near infrared, Tumors, Tissues, Luminescence, Fluorescence spectroscopy, Chemistry, Quantum dots, Toxicity, In vivo imaging, Pulsed laser operation

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SPIE Journal Paper | 11 March 2016 Open Access

Sensorless adaptive optics implementation in widefield optical sectioning microscopy inside in vivo Drosophila brain

Mélanie Pedrazzani, Vincent Loriette, Paul Tchenio, Sakina Benrezzak, Daniele Nutarelli, Alexandra Fragola

JBO, Vol. 21, Issue 03, 036006, (March 2016) https://doi.org/10.1117/12.10.1117/1.JBO.21.3.036006

KEYWORDS: Brain, Adaptive optics, Mirrors, Microscopes, Sensors, Microscopy, Neuroimaging, Monochromatic aberrations, Biomedical optics, Spatial frequencies

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Proceedings Article | 4 March 2014 Paper

Time-gated imaging of near-infrared quantum dots for in vivo cell tracking

S. Bouccara, E. Giovanelli, G. Sitbon, N. Lequeux, T. Pons, V. Loriette, A. Fragola

Proceedings Volume 8947, 89471B (2014) https://doi.org/10.1117/12.2039983

KEYWORDS: Near infrared, Tissues, Microscopy, Luminescence, Fluorescence spectroscopy, Quantum dots, In vivo imaging, Tissue optics, Signal detection, Pulsed laser operation

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SPIE Journal Paper | 6 January 2014 Open Access

Time-gated cell imaging using long lifetime near-infrared-emitting quantum dots for autofluorescence rejection

Sophie Bouccara, Alexandra Fragola, Emerson Giovanelli, Gary Sitbon, Nicolas Lequeux, Thomas Pons, Vincent Loriette

JBO, Vol. 19, Issue 05, 051208, (January 2014) https://doi.org/10.1117/12.10.1117/1.JBO.19.5.051208

KEYWORDS: Luminescence, Near infrared, Quantum dots, Zinc, Signal detection, Copper, Tissue optics, Tissues, In vivo imaging, Absorption

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Proceedings Article | 29 February 2012 Paper

Multimodal full-field optical coherence tomography on biological tissue: toward all optical digital pathology

F. Harms, E. Dalimier, P. Vermeulen, A. Fragola, A. Boccara

Proceedings Volume 8216, 821609 (2012) https://doi.org/10.1117/12.908459

KEYWORDS: Visualization, Tissues, Cameras, Optical coherence tomography, Pathology, Skin, Microscopy, Luminescence, Objectives, Tissue optics

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SPIE Journal Paper | 1 July 2011 Open Access

Adaptive optics for fluorescence wide-field microscopy using spectrally independent guide star and markers

Pierre Vermeulen, Eleonora Muro, Thomas Pons, Vincent Loriette, Alexandra Fragola

JBO, Vol. 16, Issue 07, 076019, (July 2011) https://doi.org/10.1117/12.10.1117/1.3603847

KEYWORDS: Stars, Adaptive optics, Microscopes, Microscopy, Luminescence, Cameras, Sensors, Image quality, Wavefronts, Objectives

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Proceedings Article | 14 October 2003 Paper

Fluorescence apertureless scanning near-field microscopy for high-resolution biological imaging

Alexandra Fragola, Lionel Aigouy

Proceedings Volume 5143, (2003) https://doi.org/10.1117/12.500667

KEYWORDS: Microscopes, Optical spheres, Microscopy, Luminescence, Image resolution, Atomic force microscopy, Near field scanning optical microscopy, Near field, Spatial resolution, Scanning tunneling microscopy

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Showing 5 of 14 publications

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