17 research outputs found
Diffuse reflectance spectroscopy-enhanced drill for bone boundary detection
Intramedullary nailing is a routine orthopedic procedure used for treating fractures of femoral or tibial shafts. A critical part of this procedure involves the drilling of pilot holes in both ends of the bone for the placement of the screws that will secure the IM rod to sections of the fractured bone. This step introduces a risk of soft tissue damage because the drill bit, if not stopped in time, can transverse the bone-tissue boundary into the overlying muscle, causing unnecessary injury and prolonging healing time due to periosteum damage. In this respect, detecting the bone-tissue boundary before break-through can reduce the risks and complications associated with intramedullary nailing. Hence, in the present study, a two-wavelength diffuse reflectance spectroscopy technique was integrated into a surgical drill to optically detect bone-tissue boundary and automatically trigger the drill to stop. Furthermore, Monte-Carlo simulations were used to estimate the maximum distance from within the bone at which the bone-tissue boundary could be detected using DRS. The simulation results estimated that the detection distance, termed the âlook-ahead-distanceâ was âŒ1.5 mm for 1.3 mm source-detector fiber separation. Experimental measurements with 1.3 mm source-detector fiber separation showed that the look-ahead-distance was in the order of 250 ”m in experiments with set drill rate and in the range of 1 mm in experiments where the holes were drilled by hand. Despite this difference, the automated DRS enhanced drill successfully detected the approaching bone tissue boundary when tested on samples of bovine femur and muscle tissue
Six-beam homodyne laser Doppler vibrometry based on silicon photonics technology
This paper describes an integrated six-beam homodyne laser Doppler vibrometry (LDV) system based on a silicon-on-insulator (SOI) full platform technology, with on-chip photo-diodes and phase modulators. Electronics and optics are also implemented around the integrated photonic circuit (PIC) to enable a simultaneous six-beam measurement. Measurement of a propagating guided elastic wave in an aluminum plate (speed ââ 909 m/s @ 61.5 kHz) is demonstrated
Pluggable single-mode fiber-array-to-pic coupling using micro-lenses
Single-mode optical coupling between fiber and photonic integrated circuit (PIC) requires precision alignment and bonding, and significantly adds to the cost of photonic packaging. This article describes how a pair of micro-lens arrays-one on the Si-PIC and the other on the fiber-array-can be used to achieve fiber-to-PIC grating-coupling with an insertion-loss of 1.7 dB (i.e., a coupling efficiency of 68%) at 1300 nm, and a 1 dB alignment tolerance of +/- 30 mu m. Such relaxed tolerances allow for a "pluggable" connector to have a make-break insertion-loss reproducibility of 0.2 dB (one standard deviation)
Speckle mitigation in laser Doppler vibrometry based on a compact silicon photonics chip
A compact six-beam homodyne laser Doppler vibrometry (LDV) system is realized based on a silicon-on-insulator (SOI) photonic integrated circuit. We demonstrate a speckle mitigation method by averaging signals from the six channels
Non-invasive cardiovascular disease assessment with miniaturized multi-beam laser Doppler vibrometry
A miniaturized 2Ă6-beam laser Doppler vibrometry sensor for non-invasive detection of cardiovascular disease is demonstrated. The pulse wave velocity is retrieved from preliminary experiments both on phantoms and on human subjects
Death and the Societies of Late Antiquity
Ce volume bilingue, comprenant un ensemble de 28 contributions disponibles en français et en anglais (dans leur version longue ou abrĂ©gĂ©e), propose dâĂ©tablir un Ă©tat des lieux des rĂ©flexions, recherches et Ă©tudes conduites sur le fait funĂ©raire Ă lâĂ©poque tardo-antique au sein des provinces de lâEmpire romain et sur leurs rĂ©gions limitrophes, afin dâouvrir de nouvelles perspectives sur ses Ă©volutions possibles. Au cours des trois derniĂšres dĂ©cennies, les transformations considĂ©rables des mĂ©thodologies dĂ©ployĂ©es sur le terrain et en laboratoire ont permis un renouveau des questionnements sur les populations et les pratiques funĂ©raires de lâAntiquitĂ© tardive, pĂ©riode marquĂ©e par de multiples changements politiques, sociaux, dĂ©mographiques et culturels. Lâapparition de ce qui a Ă©tĂ© initialement dĂ©signĂ© comme une « Anthropologie de terrain », qui fut le dĂ©but de la dĂ©marche archĂ©othanatologique, puis le rĂ©cent dĂ©veloppement dâapproches collaboratives entre des domaines scientifiques divers (archĂ©othanatologie, biochimie et gĂ©ochimie, gĂ©nĂ©tique, histoire, Ă©pigraphie par exemple) ont Ă©tĂ© dĂ©cisives pour le renouvellement des problĂ©matiques dâĂ©tude : rĂ©vision dâanciens concepts comme apparition dâaxes dâanalyse inĂ©dits. Les recherches rassemblĂ©es dans cet ouvrage sont articulĂ©es autour de quatre grands thĂšmes : lâĂ©volution des pratiques funĂ©raires dans le temps, lâidentitĂ© sociale dans la mort, les ensembles funĂ©raires en transformation (organisation et topographie) et les territoires de lâempire (du cĆur aux marges). Ces Ă©tudes proposent un rĂ©examen et une rĂ©vision des donnĂ©es, tant anthropologiques quâarchĂ©ologiques ou historiques sur lâAntiquitĂ© tardive, et rĂ©vĂšlent, Ă cet Ă©gard, une mosaĂŻque de paysages politiques, sociaux et culturels singuliĂšrement riches et complexes. Elles accroissent nos connaissances sur le traitement des dĂ©funts, lâemplacement des aires funĂ©raires ou encore la structure des sĂ©pultures, en rĂ©vĂ©lant une diversitĂ© de pratiques, et permettent au final de relancer la rĂ©flexion sur la maniĂšre dont les sociĂ©tĂ©s tardo-antiques envisagent la mort et sur les Ă©lĂ©ments permettant dâidentifier et de dĂ©finir la diversitĂ© des groupes qui les composent. Elles dĂ©montrent ce faisant que nous pouvons vĂ©ritablement apprĂ©hender les structures culturelles et sociales des communautĂ©s anciennes et leurs potentielles transformations, Ă partir de lâĂ©tude des pratiques funĂ©raires.This bilingual volume proposes to draw up an assessment of the recent research conducted on funerary behavior during Late Antiquity in the provinces of the Roman Empire and on their borders, in order to open new perspectives on its possible developments. The considerable transformations of the methodologies have raised the need for a renewal of the questions on the funerary practices during Late Antiquity, a period marked by multiple political, social, demographic and cultural changes. The emergence field anthropology, which was the beginning of archaeothanatology, and then the recent development of collaborative approaches between various scientific fields (archaeothanatology, biochemistry and geochemistry, genetics, history, epigraphy, for example), have been decisive. The research collected in this book is structured around four main themes: Evolution of funerary practices over time; Social identity through death; Changing burial grounds (organisation and topography); Territories of the Empire (from the heart to the margins). These studies propose a review and a revision of the data, both anthropological and archaeological or historical on Late Antiquity, and reveal a mosaic of political, social, and cultural landscapes singularly rich and complex. In doing so, they demonstrate that we can truly understand the cultural and social structures of ancient communities and their potential transformations, based on the study of funerary practices
Design and characterisation of plasmonic nanoantennas for cooled infrared photodetection
Lâimagerie infrarouge refroidie est portĂ©e par une demande forte pour des applications dans les secteurs militaire, industriel et spatial. Les enjeux actuels de ce marchĂ© sont le fonctionnement Ă haute tempĂ©rature et la fonctionnalisation spectrale des dĂ©tecteurs.Ces enjeux peuvent ĂȘtre adressĂ©s grĂące Ă lâutilisation de rĂ©sonateurs optiques et leur facultĂ© Ă concentrer le champ Ă©lectromagnĂ©tique. Ce travail de thĂšse montre comment des rĂ©sonateurs plasmoniques peuvent ĂȘtre intĂ©grĂ©s dans la filiĂšre HgCdTe.La thĂ©orie temporelle des modes couplĂ©s a Ă©tĂ© utilisĂ©e, de maniĂšre analytique, pour optimiser Ă travers la condition de couplage critique, lâabsorption dans un rĂ©sonateur plasmonique chargĂ© par un semiconducteur. La conception dâune photodiode HgCdTe ultramince plasmonique est ensuite dĂ©taillĂ©e. Elle repose sur lâutilisation dâun mode optique rĂ©sultant du couplage entre un mode plasmon de surface et un mode gap plasmon de cavitĂ©The market for cooled infrared imaging technologies is growing fast due to a range of applications covering military, commercial and space. Current research for innovative systems focuses on high operating temperature and multispectral detectors.To achieve these aims, optical resonators can be used to concentrate electromagnetic fields in thin absorbing media. This thesis investigates the possibility of using plasmonic resonators for HgCdTe photodetection.Temporal coupled-mode theory is used to optimise analytically the absorption in a plasmonic resonator incorporating an absorbing semiconductor subject to the critical coupling condition. A design of a thin plasmonic HgCdTe diode is then described. This includes a hybrid plasmonic mode arising from the coupling between a surface plasmon and a cavity gap-plasmon mod
Conception et caractérisation de nanoantennes plasmoniques pour la photodétection infrarouge refroidie
The market for cooled infrared imaging technologies is growing fast due to a range of applications covering military, commercial and space. Current research for innovative systems focuses on high operating temperature and multispectral detectors.To achieve these aims, optical resonators can be used to concentrate electromagnetic fields in thin absorbing media. This thesis investigates the possibility of using plasmonic resonators for HgCdTe photodetection.Temporal coupled-mode theory is used to optimise analytically the absorption in a plasmonic resonator incorporating an absorbing semiconductor subject to the critical coupling condition. A design of a thin plasmonic HgCdTe diode is then described. This includes a hybrid plasmonic mode arising from the coupling between a surface plasmon and a cavity gap-plasmon modeLâimagerie infrarouge refroidie est portĂ©e par une demande forte pour des applications dans les secteurs militaire, industriel et spatial. Les enjeux actuels de ce marchĂ© sont le fonctionnement Ă haute tempĂ©rature et la fonctionnalisation spectrale des dĂ©tecteurs.Ces enjeux peuvent ĂȘtre adressĂ©s grĂące Ă lâutilisation de rĂ©sonateurs optiques et leur facultĂ© Ă concentrer le champ Ă©lectromagnĂ©tique. Ce travail de thĂšse montre comment des rĂ©sonateurs plasmoniques peuvent ĂȘtre intĂ©grĂ©s dans la filiĂšre HgCdTe.La thĂ©orie temporelle des modes couplĂ©s a Ă©tĂ© utilisĂ©e, de maniĂšre analytique, pour optimiser Ă travers la condition de couplage critique, lâabsorption dans un rĂ©sonateur plasmonique chargĂ© par un semiconducteur. La conception dâune photodiode HgCdTe ultramince plasmonique est ensuite dĂ©taillĂ©e. Elle repose sur lâutilisation dâun mode optique rĂ©sultant du couplage entre un mode plasmon de surface et un mode gap plasmon de cavit