Flexible and miniaturized microscope for three dimensionnal measurements

ISBN: 978-1-4673-2875-3 INSPEC: 13250769International audienceIn three dimensional measurement systems, two properties are generally difficult to maximize simultaneously: compactness and measurement accuracy. Compactness can be obtained with miniaturized opto-electronic devices such as small cameras. However, quality (resolution, frame-rate, signal to noise ratio...) of these small devices is lower than standard sized ones. In this paper an alternative configuration is described where the opto-electronic devices are not miniaturized but optically connected to small probes through image guides. Instrumental description of this system is detailed and a measurement result is finally presented

A Compact Active Stereovision System with Dynamic Reconfiguration for Endoscopy or Colonoscopy Applications

International audienceA new concept of endoscopic device based on a compact optical probe which can capture 3D shape of objects using an active stereovision method is presented. The distinctive feature of this probe is its capability to dynamically switch between two distinct points of view. If the first measurement angle of view does not give results with sufficient quality, the system can switch to a second mode which sets distinct angle of view within less than 25 milliseconds. This feature consequently allows selecting the angle that provides the more useful 3D information and enhances the quality of the captured result. The instrumental setup of this measurement system and the reconstruction algorithms are presented in this paper. Then, the advantages of this new endoscopic probe are explained with an experimental 3D reconstruction of a coin's surface. Finally, first measurements on a phantom colon are provided. In future works, further miniaturization of the device and its integration into a real colonoscope will be implemented

Tri-dimensional optical inspection based on flexible image guide: first step toward 3D industrial endoscopy

International audience3D optical endoscopy is now a major challenge to allow the high resolution inspection of industrial equipments. The proposed instrument is based on a flexible image guide (70 000 fibres) and a Digital Micro mirror Device (DMD, 1024 x 768 "on-off" micro mirrors). The optical design is as follows: the light emitted by a 532 nm laser diode is dynamically structured by the DMD chip as a fringes pattern which is phase-shifted due to the active control of the DMD chip and projected onto an object on a circular field of 6 mm in diameter. Due to a telecentric and binocular arrangement that creates a stereoscopic angle, it is possible to get a depth of field of 2 mm along the optical axis without keystone distortions and few disturbances created by defocus and coma aberrations. Then, images are captured by a 1024 x 768 digital camera (not yet moved away by fibres) at 15 fps and directly used in the reconstruction algorithm to access the tri-dimensional shape of the unpainted object. The results are compared to incoherent white light results obtained with white painted mechanical objects. The lateral resolution is 31.3 µm and the RMS axial resolution is 10 µm for the laser-based design after speckle attenuation

Binary pattern codification strategies in an active stereoscopic system based on flexible image guides

International audienceA wide variety of three dimensional (3D) measurement systems that can extract shape information's with sub millimetric accuracy is available in the industry. However, they generally are of macroscopic size and measuring on confined areas is not feasible. To miniaturize such systems, the step proposed is the integration of flexible image guides combined with compact optical probes. This miniaturization process is tested on an active stereoscopic measurement system. In the projection channel of the system, a digital micro-mirror device (DMD) generates structured binary patterns from an incoherent white light source and injects them into a first image guide. Then, a compact optical system projects the pattern on the measurement area. The same configuration principle is applied to the acquisition channel and allows the capture of the measurement area through a second image guide and finally to a digital camera. In this miniaturized system, image guides have lower resolution than in standard imaging devices. Indeed they are equivalent of 70k pixels devices to compare to the almost 800k pixels of the DMD and camera. That implies lower axial and lateral resolutions and consequently the shape reconstruction method must be carefully chosen. In this paper, several reconstruction strategies such as tuning the projected patterns frequency and also phase-shfit versus gray code based methods were compared considering the best axial resolution criteria

Modélisation stochastique et approche fiabiliste pour la sécurité routière des poids lourds articulés

L'objectif de cet article est le développement d'une stratégie fiabiliste pour la prévention des risques de renversement et de mise en portefeuille des véhicules, de type poids lourd (tracteur et semi-remorque), en zone accidentogène. Le caractère aléatoire du triplet conducteur-véhicule-infrastructure est intégré à l'aide de variables et processus aléatoires dans un modèle dynamique spécifiquement développé. Une analyse de sensibilité globale ainsi qu'une analyse de fiabilité, par des méthode de type FORM/SORM, permettent la détection de situations à risque

Le cadre de vie des hommes du Paléolithique moyen (stades isotopiques 6 et 5) dans le site de Payre (Rompon, Ardèche) : d'une grotte à un abri sous roche effondré

The Middle Palaeolithic site of Payre is located in the south-east of France, in the Middle Rhone Valey. Since 1990, excavations have yielded a sequence dating from isotopic stages 7 to 5 (6 to 5 for the human occupation levels). The evidence points to a collapsed cave, inhabited several times by human beings ; the last occupation was in a rock shelter. The sequence and the mammal assemblages allow the site morphology during the different settlements to be reconstructed. The also give an idea of the environment chosen by the Neanderthal population for what were probably short periods of occupation.Le gisement paléolithique moyen de Payre est situé dans le sud-est de la France, dans la moyenne vallée du Rhône. Les fouilles, qui s'y déroulent depuis 1990, livrent une séquence datée des stades isotopiques 7 à 5, 6 à 5 pour les occupations humaines. Les observations à la fouille permettent de visualiser les limites d'une cavité aujourd'hui effondrée. les hommes seraient venus à plusieurs reprises dans cette cavité et auraient occupé en dernier lieu un abri sous roche. Les données du remplissage, associées à celles livrées par l'assemblage osseux, aboutissent à proposer aujourd'hui une reconstitution de la morphologie du site aux différents moments de occupations humaines et à donner une idée du cadre de vie choisi par les hommes, en particulier pour des occupations sans doute de courte durée

Comparative analysis of conjugated alkynyl chromophore-triazacyclononane ligands for sensitized emission of europium and terbium

A series of europium and terbium complexes based on a functionalized triazacyclononane carboxylate or phosphinate macrocyclic ligand is described. The influence of the anionic group, that is, carboxylate, methylphosphinate, or phenylphosphinate, on the photophysical properties was studied and rationalized on the basis of DFT calculated structures. The nature, number, and position of electron-donating or electron-withdrawing aryl substituents were varied systematically within the same phenylethynyl scaffold in order to optimize the brightness of the corresponding europium complexes and investigate their two-photon absorption properties. Finally, the europium complexes were examined in cell-imaging applications, and selected terbium complexes were studied as potential oxygen sensors

Quality Indicators for Colonoscopy Procedures: A Prospective Multicentre Method for Endoscopy Units

BACKGROUND AND AIMS: Healthcare professionals are required to conduct quality control of endoscopy procedures, and yet there is no standardised method for assessing quality. The topic of the present study was to validate the applicability of the procedure in daily practice, giving physicians the ability to define areas for continuous quality improvement. METHODS: In ten endoscopy units in France, 200 patients per centre undergoing colonoscopy were enrolled in the study. An evaluation was carried out based on a prospectively developed checklist of 10 quality-control indicators including five dependent upon and five independent of the colonoscopy procedure. RESULTS: Of the 2000 procedures, 30% were done at general hospitals, 20% at university hospitals, and 50% in private practices. The colonoscopies were carried out for a valid indication for 95.9% (range 92.5-100). Colon preparation was insufficient in 3.7% (range 1-10.5). Colonoscopies were successful in 95.3% (range 81-99). Adenoma detection rate was 0.31 (range 0.17-0.45) in successful colonoscopies. CONCLUSION: This tool for evaluating the quality of colonoscopy procedures in healthcare units is based on standard endoscopy and patient criteria. It is an easy and feasible procedure giving the ability to detect suboptimal practice and differences between endoscopy-units. It will enable individual units to assess the quality of their colonoscopy techniques

Capteurs à fibres optiques pour la mesure à haute résolution de déplacements linéaires et angulaires sur une grande étendue (application aux systèmes mécaniques de dimensions réduites)

La demande croissante de systèmes mécaniques et mécatroniques miniatures exige la miniaturisation des composants ayant une fonction d'actionnement ou de mesure dans ces systèmes. Des capteurs miniatures, privilégiant un rapport entre la limite de résolution et l'étendue de la mesure de l'ordre de 10-5 à 10-6, s'avèrent alors des éléments incontournables. Ce mémoire présente la conception et la réalisation de deux capteurs à fibres optiques pour la mesure à haute résolution de déplacements linéaires et angulaires sur de grandes étendues utilisant un même principe. Après une étude bibliographique portant sur les capteurs optiques, une modélisation géométrique de la mesure de déplacements linéaires sur une grande étendue par l'utilisation de deux sondes et d'un réseau a été réalisée. Un premier réseau optique en alliage d'aluminium a été obtenu par Usinage Haute Précision. Puis, grâce à la micro fabrication du silicium, un second réseau a été réalisé dans le but d'améliorer les performances du capteur. Il a ainsi été permis de l'intégrer dans un système mécanique miniature avec une limite de résolution de 27,4 nm sur une étendue linéaire de 9 mm. En dupliquant ce principe, des mesures dans un plan ont été réalisées. Le deuxième capteur développé mesure des déplacements angulaires au moyen d'une sonde, contenant deux détecteurs et d'un miroir non structuré. Une modélisation a été réalisée et une bonne corrélation a été observée entre les résultats numériques et expérimentaux sur une étendue comprise entre -23,44 et +23,44 avec une limite de résolution optimale de 0,48xI0-3o. Enfin, après duplication de ce dernier principe, un inclinomètre bidimensionnel miniature a été réalisé.The request increasing of miniature mechanical and mechatronics systems requires the miniaturization of the components to have a function of actuation or ability to measure to these systems. Miniature sensors, privileging a ratio between the limit of resolution and the range of measurement of about a 10-5 to 10-6, are then elements impossible to circumvent. This Ph.D. presents the design and the realization of two optical fibers sens ors for measurement with high resolution in two dimensions of linear and angular displacements on great range using the same principle. After a bibliographical study relating to the optical sensors, a geometrical modelling of the measure of linear displacements on a great range by the use of two probes and a grating was carried out. First, an optical grating in aluminium alloy was obtained by High Precision Machining. Then, thanks to the micro fabrication of silicon, a second grating was carried out with the aim of improving the sensor performances. It was thus allowed to be integrated in a miniature mechanical system with a limit of resolution of 27.4 nm on a linear range of about 9 mm. By duplicating this principle, the measurements on a plane were carried out. The second sens or developed measures the angular displacements by means of a probe, containing two detectors and a mirror not structured. A model was made and a good correlation was observed between the numerical and experimental results on a range between -23.44 and +23.44 with an optimal limit of resolution of 0.48 x 10-30. Lastly, after duplication of this last principle, a miniature two-dimensional inclinometer was carried out.COMPIEGNE-BU (601592101) / SudocSudocFranceF