Diffuse laser illumination for Maxwellian view Doppler holography of the retina

We describe the advantages of diffuse illumination in laser holography for ophthalmology. The presence of a diffusing element introduces an angular diversity of the optical radiation and reduces its spatial coherence, which spreads out the energy distribution of the illumination beam in the focal plane of the eyepiece. The field of view of digitally computed retinal images can easily be increased as the eyepiece can be moved closer to the cornea to obtain a Maxwellian view of the retina without compromising ocular safety. Compliance with American and European safety standards for ophthalmic devices is more easily obtained by preventing the presence of a laser hot spot observed in front of the cornea in the absence of a scattering element. Diffuse laser illumination does not introduce any adverse effects on digitally computed laser Doppler images.Comment: 9 page

IISMM – Institut d’études de l’Islam et des sociétés du monde musulman

Olivier Bouquet, maître de conférences à l’Université de Nice-Sophia AntipolisAnne-Laure Dupont, maître de conférences à l’Université Paris-IV/SorbonneBenjamin Lellouch, maître de conférences à l’Université Paris-VIII/Vincennes-Saint-DenisCatherine Mayeur-Jaouen, professeur à l’INaLCOSabrina Mervin, chargée de recherche au CNRSNicolas Michel, maître de conférences à l’Université Aix-Marseille-I/ProvenceM’hamed Oualdi, Chantai Verdeil, maîtres de conférences à l’INaLCO Histoire moderne et cont..

IISMM – Institut d’études de l’Islam et des sociétés du monde musulman

Olivier Bouquet, maître de conférences à l’Université de Nice-Sophia AntipolisAnne-Laure Dupont, maître de conférences à l’Université Paris-IV/SorbonneBenjamin Lellouch, maître de conférences à l’Université Paris-VIII/Vincennes-Saint-DenisCatherine Mayeur-Jaouen, professeur à l’INaLCOSabrina Mervin, chargée de recherche au CNRSNicolas Michel, maître de conférences à l’Université Aix-Marseille-I/ProvenceM’hamed Oualdi, Chantai Verdeil, maîtres de conférences à l’INaLCO Histoire moderne et cont..

Microsystèmes Magnéto-Mécaniques (MMMS) pour le contrôle actif d'écoulements aérauliques.

203 pagesSituated at the intersection between the needs of the Aerospace industry and the possibilities of the MEMS community, the thesis dealt with the dimensioning, realization and characterization of flexible membrane microvalves producing pulsed jets for active flow control on one hand, and of integrated magnetostrictively actuated microactuators on the other hand. This work was supported by the CNRS; by both DASSAULT AVIATION and MBDA, and is part of the ADVACT European project.A preliminary study of the physics of flow control and of the industrial needs in such a domain yield the definition of precise specifications for the management of detached flows in the case of aeronautical applications. Two characterization benches were subsequently built in order to measure the properties of millimetre sized pulsed jets by high speed shadowgraph and hot wire anemometry.The microvalve, witch actuation principle is based on the pinching of a micofluidic channel by a flexible membrane was designed, fabricated and characterized. A theoretical study of the static and dynamical characteristics of the fluid-structure coupled system yield the identification of three actuation means and their characteristic bandwidth: electromagnetic actuation (0-600 Hz), assisted self-oscillation (400-1500Hz), and self-oscillation (1kHz – 2.5 KHz). The fabricated prototypes show an outlet speed superior to 100 m/s in each of these frequency ranges. A numerical simulation study was then undertaken in order to maximize the outlet speed via the optimization of the microchannel geometry. Microvalve arrays were finally packaged and installed in wind tunnel for further research on detached flows (ONERA).An innovative microsystem design consisting in a cantilever covered with a nanostructured magnetostrictive film actuated in situ by two microcoils was also investigated. Using the huge sensitivity gain obtained by the induction of a magnetic instability in the magnetostrictive film (Spin Reorientation Transition, SRT), the magnetic field produced by two microcoils placed at each tip of the cantilever was shown sufficient to induce the vibration of the mechanical part. Moreover, such a system benefits from the highly non-linear properties of the magnetostrictive films near the SRT. A microvalve concept based on this type of actuation was finally proposed and fabricated.Situé à l'intersection des besoins de l'industrie aéronautique et des possibilités offertes par les microtechnologies, le travail présenté dans ce mémoire concerne le dimensionnement, la réalisation et la caractérisation de micro-actionneurs à membrane souple permettant la fabrication de micro-jets pulsés pour le contrôle actif de décollement d'une part, et de micro-actionneurs à actionnement magnétostrictif intégré d'autre part. Ainsi, un cahier des charges précis est a d'abord été défini suite à l'analyse des phénomènes fluides liés au contrôle de décollement et à l'identification des besoins industriels dans ce domaine. Deux bancs de mesure ont ensuite été mis en place de manière à permettre la caractérisation complète des microjets pulsés, par ombroscopie ultra-rapide et anémométrie au fil chaud. Un prototype de microvalve dont le fonctionnement est fondé sur le pincement d'un canal microfluidique à l'aide d'une membrane souple a été dimensionné puis fabriqué. Une étude théorique du fonctionnement statique et dynamique du système couplé fluide-structure a permis d'identifier trois types d'actionnement et leur plage fréquentielle caractéristique : actionnement éléctromagnétique (0-600 Hz), auto-oscillation assistée (400-1500Hz) et auto-oscillation (1kHz – 2.5 KHz). Les prototypes fabriqués montrent quant à eux une vitesse de sortie supérieure à 100 m/s dans chacune de ces plages fréquentielles. L'optimisation de la géométrie des microvalves a ensuite été réalisée, ainsi qu'un premier packaging permettant la mise en place de barrettes d'actionneurs en soufflerie. Enfin, un microsystème innovant dont l'actionnement est fondé sur la vibration d'une micro-poutre recouverte d'un film magnétostrictif multicouche nanostructuré a été mis au point. Utilisant l'induction d'une instabilité magnétique de type Transition de Réorientation de Spin pour augmenter la sensibilité du système magnétique, nous avons montré qu'un couple de microbobines suffit à l'actionnement de ce type de structure mécanique, mettant ainsi en lumière de nouvelles méthodes d'actionnement tirant avantage des propriétés fortement non-linéaires des films magnétostrictifs au voisinage de la TRS

SURFACE ACOUSTIC WAVE-INDUCED MICROSTREAMING IN DROPLETS FOR THE ENHANCEMENT OF BIOSENSING PERFORMANCES

ABSTRACT A droplet-based micro-total analysis system (microTAS) based on digital microfluidics, involving surface acoustic wave (SAW) microstreaming dedicated to the enhancement of the performance of biosensors was designed and studied. We first present the characterization of the flow induced in the droplet during SAW stirring. We then present the evaluation of the biosensor performance enhancement obtained using SAW, evaluated by finite element simulation. We finally stress on the importance of the Damköher and Peclet numbers in the design of stirring-based microTAS systems

Microsystèmes Magnéto-Mécaniques (MMMS) pour le contrôle actif d'écoulements aérauliques

LILLE1-BU (590092102) / SudocVILLENEUVE D'ASCQ-ECLI (590092307) / SudocSudocFranceF

Fast block partitioning method in HEVC Intra coding for UHD video

International audienc

Quality Assessment of HDR/WCG Images Using HDR Uniform Color Spaces

High Dynamic Range (HDR) and Wide Color Gamut (WCG) screens are able to render brighter and darker pixels with more vivid colors than ever. To assess the quality of images and videos displayed on these screens, new quality assessment metrics adapted to this new content are required. Because most SDR metrics assume that the representation of images is perceptually uniform, we study the impact of three uniform color spaces developed specifically for HDR and WCG images, namely, I C t C p , J z a z b z and H D R - L a b on 12 SDR quality assessment metrics. Moreover, as the existing databases of images annotated with subjective scores are using a standard gamut, two new HDR databases using WCG are proposed. Results show that MS-SSIM and FSIM are among the most reliable metrics. This study also highlights the fact that the diffuse white of HDR images plays an important role when adapting SDR metrics for HDR content. Moreover, the adapted SDR metrics does not perform well to predict the impact of chrominance distortions

Quality Metric Aggregation for HDR/WCG Images

International audienceHigh Dynamic Range (HDR) and Wide Color Gamut (WCG) screens are able to display images with brighter and darker pixels with more vivid colors than ever. Automatically assessing the quality of these HDR/WCG images is of critical importance to evaluate the performances of image compression schemes. In recent years, full-reference metrics, such as HDR-VDP-2, PU-encoding metrics, have been designed for this purpose. However, none of these met-rics consider chromatic artifacts. In this paper, we propose our own full-reference quality metric adapted to HDR and WCG content that is sensitive to chromatic distortions. The proposed metric is based on two existing HDR quality metrics and color image features. A support vector machine regression is used to combine the aforemen-tioned features. Experimental results demonstrate the effectiveness of the proposed metric in the context of image compression