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Bosch Thierry - One of the best experts on this subject based on the ideXlab platform.
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Lower detection limit of the Acousto-Optic Effect using Optical Feedback Interferometry
'Institute of Electrical and Electronics Engineers (IEEE)', 2020Co-Authors: Knudsen Einar, Perchoux Julien, Mazoyer Thierry, Jayat Francis, Tronche Clément, Bosch ThierryAbstract:International audienceMeasurement and 3D imaging of acoustic waves through the Acousto-Optic Effect has recently been demonstrated by means of Optical Feedback Interferometry (OFI). In this paper we study experimentally the lower limits of detection of an acoustic wave using an OFI sensor. We show that the OFI sensor exhibits a linear response to acoustic power variations, and we obtain a lower limit of detection of 83 dB rms for a planar acoustic wave at 3 kHz. We also determine the equivalent displacement, that is seen by the OFI sensor at this pressure level, to be 96 pm. A deeper understanding of the limits of the technology and the quantification of the Acousto-Optic Effect shall help improve the applications already created for the measurement of acoustic pressure waves using OFI
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Experimental Demonstration of the Impact of theFringe Shape in Sub-Lambda / 2 Sensing With OpticalFeedback Interferometry
'The Optical Society', 2020Co-Authors: Knudsen Einar, Perchoux Julien, Mazoyer Thierry, Jayat Francis, Tronche Clément, Imas José, Veng Mengkoung, Bosch ThierryAbstract:International audienceIt is established in the Optical Feedback Interferometry (OFI) theory that the shape of the interferometric fringe has an impact on the detector's response to very small displacement measurements. In this paper we validate-for the first time based on experimental results-this statement by comparing experiments to an established model implementation. Through these experiments we show that the amplitude of the signals induced by sub-lambda/2 optical path variations is linearly dependent on the slope of the underlying fringe. Thus, careful control of the phase allows us to maximize the detection amplitude of very small displacements by positioning the phase where the fringe slope is the steepest. These results are directly applicable to established OFI applications that measure sub-lambda/2 optical path variations, such as OFI vibrometers or acoustic imaging though the Acousto-Optic Effect
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Experimental Demonstration of the Impact of theFringe Shape in Sub-Lambda / 2 Sensing With OpticalFeedback Interferometry
'The Optical Society', 2020Co-Authors: Knudsen Einar, Perchoux Julien, Mazoyer Thierry, Jayat Francis, Tronche Clément, Imas José, Veng Mengkoung, Bosch ThierryAbstract:It is established in the Optical Feedback Interferometry (OFI) theory that the shape of the interferometric fringe has an impact on the detector's response to very small displacement measurements. In this paper we validate-for the first time based on experimental results-this statement by comparing experiments to an established model implementation. Through these experiments we show that the amplitude of the signals induced by sub-lambda/2 optical path variations is linearly dependent on the slope of the underlying fringe. Thus, careful control of the phase allows us to maximize the detection amplitude of very small displacements by positioning the phase where the fringe slope is the steepest. These results are directly applicable to established OFI applications that measure sub-lambda/2 optical path variations, such as OFI vibrometers or acoustic imaging though the Acousto-Optic Effect
Knudsen Einar - One of the best experts on this subject based on the ideXlab platform.
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Acquisition acoustique non intrusive basée sur interférométrie à réinjection optique
HAL CCSD, 2021Co-Authors: Knudsen EinarAbstract:National audienceOptical Feedback Interferometry (OFI) is a compact and versatile non-contact sensing scheme with numerous areas of application. It is used in displacement sensing including vibrometry , absolute distance measurements, velocimetry and flowmetry , to mention a few. OFI is compact, robust, self-aligned and above all, it's need for very few optical elements compared to classical interferometric devices makes it a low cost sensing scheme. Recent have made the technology capable of measuring displacements in the range of 120 pm which is a major improvement of the OFI sensing scheme. This approach requires additional optical elements, and the increase of system complexity makes this approach cumbersome as it approaches the number of elements used in commercial interferometers today.Nevertheless, the OFI sensing scheme gains importance in various sensing domains such as vibrometry or the very promising acoustic imaging through the Acousto-Optical Effect. Bertling et al and Urgiles et al created visual representations of sound waves in air using OFI. Their method is based on the sensing of the Acousto-Optic Effect, where acoustic pressure variations induce modulations of the refractive index of air. These minute modulations create small changes in the optical path between the laser and the target. The variations are far below a half laser wavelength and at the edge of the limitations of the technology in its classical compact form.OFI operates the following way: Coherent light from the laser is backscattered from a target and returns back into the laser cavity. The returning light is coherently mixed with the lasing field. The mixing induces perturbations in the laser wave phase and amplitude, the latest which can be measured by the laser's in-package photodiode. An analysis of the signal provides information about the target it is pointing on. In particular, if the target is moving, interferometric fringes corresponding to a displacement of half the wavelength lambda will be observed. By simply counting fringes we can record the target's movement along the beam axis.In this PhD we present a dedicated, repeatable and robust experiment showing the impact of the fringe shape on small signals. We demonstrate experimentally that the signal amplitude is linearly coupled to the slope of the fringe, a result not yet explicitly published in the OFI literature. Furthermore we model an OFI system measuring sub-lambda/2 optical path variations using Kliese et al’s algorithm. Finally, we show the algorithm's performance in simulating sub-lambda/2 optical path variations through accurately simulating the experimental results.Furthermore we will present a model for the conversion of measured acoustic pressure through the opto-acoustic Effect to an equivalent displacement. The model works by calculating the refractive index of air with a given set of atmospheric conditions that are monitored in the lab. The refractive index is then calculated inside an acoustic wave, before it is used to calculate the change in optical path for a photon. The model is based on Philip E. Ciddor’s equations for calculating the refractive index of air.We’ve constructed a dedicated experimental setup designed to create planar acoustic waves which are measured by the laser. Using this dedicated setup we will perform two experiments. First we test our model of converting acoustic pressure to distance. The model currently estimates a displacement that is 1.22x greater than the measurement.Through experiments we have shown that the OFI sensing scheme is capable of detecting acoustic waves down to 37 dBrms under the right conditions. This is a 46 dB rms-improvement on the earlier published results of 83dBrms. The experiments shows that the minimal detectable acoustic amplitude is different for the four acoustic frequencies tested.The second research topic is about measuring acoustic waves at a distance. A small reflective particle, an aerosol, is small enough to be completely entrained by an acoustic wave. Acting as a retro diffusing target, the aerosol (or aerosols) will reflect a sufficient amount of light for the OFI scheme to detect its movement. Thus we propose using Optical Feedback Interferometry as a high-precision, low cost acoustic detector to measure the movement of particles entrained by acoustic waves in air.In this PhD we present a demonstrator of the Acoustic LIDAR by Optical Feedback Interferometry. In principle we measure the oscillating velocity of a particle entrained by an acoustic wave. We will build a LIDAR application similar to that of Epsiline, using their optics to acquire a signal. The signal processing algorithms are based on the Weighted Moments method often applied in fluid measurements.First, we derive a model to estimate particle movement under acoustic entrainment. The model is derived from Newton's equations, taking acoustic pressure and atmospheric parameters as input. Then an expression is developed, to convert a measured velocity oscillation into an acoustic pressure. The model is validated experimentally using an intensity probe, a device measuring the particle velocity in an acoustic wave. Further on we propose a modification to the OFI Power Equation, adapting it to model a flux of particles with oscillating velocity.The acoustic model and modified OFI Power Equation is finally combined to create a simulation of an OFI system's behavior when measuring the velocity of a flux of aerosol being modulated by acoustic waves. The simulation is enriched to reflect upon the Gaussian shape of the laser beam, and the random behavior of particles in air.A signal processing algorithm is developed to acquire the acoustic signal that set the particle flux in motion. The algorithm will first be used to demodulate the synthetic acoustic signal issued by our simulation. Then it will be applied to real signals acquired in a dedicated experiment.We present two main experiments with different configurations. Firstly we will measure the frequency response of the acquisition scheme using short-range acoustic acquisitions. The frequency response of the particle flux and laser system is measured and compared to the model. Then we will present a long range experiment, where use the optical setup from Epsiline's OFI anemometer. In this setup a laser beam is focused at 11.5m from the laser, and acoustic signals are acquired.L'interférométrie à réinjection optique (OFI) est un système de détection sans contact compact et polyvalent avec de nombreux domaines d'application. Il est utilisé dans la détection de déplacement, y compris la vibrométrie, les mesures de distance absolue, la vélocimétrie et pour mesurer des flux. OFI est compact, robuste, auto-aligné et surtout, il nécessite très peu d'éléments optiques par rapport aux dispositifs interférométriques classiques, ce que rend le capteur un système de détection à faible coût. Récemment, la technologie est capable de mesurer des déplacements de l'ordre de 120 pm, ce qui est une amélioration majeure du capteur OFI. Cette approche nécessite des éléments optiques supplémentaires, et l'augmentation de la complexité du système rend cette approche lourde car elle se rapproche du nombre d'éléments utilisés dans les interféromètres commerciaux aujourd'hui.Néanmoins, le capteur OFI gagne en importance dans divers domaines de détection tels que la vibrométrie ou l'imagerie acoustique très prometteuse grâce à l'effet acousto-optique. Bertling et al et Urgiles et al ont créé des représentations visuelles des ondes sonores dans l'air à l'aide d'OFI. Leur méthode est basée sur la détection de l'effet acousto-optique, où les variations de pression acoustique induisent des modulations de l'indice de réfraction de l'air. Ces minuscules modulations créent de petits changements de chemin optique entre le laser et la cible. Les variations sont bien inférieures à une demi-longueur d'onde laser et à la limite des limites de la technologie sous sa forme compacte classique.OFI fonctionne de la manière suivante: La lumière cohérente du laser est rétrodiffusée à partir d'une cible et retourne dans la cavité laser. La lumière de retour est mélangée de manière cohérente avec le champ laser. Le mélange induit des perturbations dans la phase et l'amplitude de l'onde laser, la dernière qui peut être mesurée par la photodiode intégrée au laser. Une analyse du signal fournit des informations sur la cible sur laquelle il pointe. En particulier, si la cible est en mouvement, des franges interférométriques correspondant à un déplacement de la moitié de la longueur d'onde lambda seront observées. En comptant simplement les franges, nous pouvons enregistrer le mouvement de la cible le long de l'axe du faisceau.Dans cette thèse, nous présentons une expérience dédiée, répétable et robuste montrant l'impact de la forme de la frange sur les petits signaux. Nous démontrons expérimentalement que l'amplitude du signal est couplée linéairement à la pente de la frange, un résultat non encore publié explicitement dans la littérature OFI. De plus, nous modélisons un système OFI mesurant les variations de chemin optique sous-lambda / 2 en utilisant l’algorithme de Kliese et al. Enfin, nous montrons les performances de l'algorithme dans la simulation des variations de chemin optique sous-lambda / 2 en simulant avec précision les résultats expérimentaux.De plus, nous présenterons un modèle de conversion de la pression acoustique mesurée par effet opto-acoustique en un déplacement équivalent. Le modèle fonctionne en calculant l'indice de réfraction de l'air avec un ensemble donné de conditions atmosphériques surveillées en laboratoire. L'indice de réfraction est ensuite calculé à l'intérieur d'une onde acoustique, avant d'être utilisé pour calculer le changement de chemin optique d'un photon. Le modèle est basé sur les équations de Philip E. Ciddor pour le calcul de l’indice de réfraction de l’air.Nous avons construit une configuration expérimentale dédiée conçue pour créer des ondes acoustiques planes qui sont mesurées par le laser. En utilisant cette configuration dédiée, nous Effectuerons deux expériences. Nous testons d'abord notre modèle de conversion de la pression acoustique en distance. Le modèle estime actuellement un déplacement 1,22 fois supérieur à la mesure.Grâce à des expériences, nous avons montré que le capteur OFI est capable de détecter des ondes acoustiques jusqu'à 37 dBrms dans les bonnes conditions. Il s'agit d'une amélioration de 46 dB rms par rapport aux résultats publiés antérieurement de 83 dBrms. Les expériences montrent que l'amplitude acoustique minimale détectable est différente pour les quatre fréquences acoustiques testées.Le deuxième thème de recherche concerne la mesure des ondes acoustiques à distance. Une petite particule réfléchissante, un aérosol, est suffisamment petite pour être complètement entraînée par une onde acoustique. Agissant comme une cible rétro-diffusante, l'aérosol (ou les aérosols) réfléchira une quantité de lumière suffisante pour que le schéma OFI détecte son mouvement. Ainsi, nous proposons d'utiliser l'interférométrie à réinjection optique comme détecteur acoustique de haute précision et à faible coût pour mesurer le mouvement des particules entraînées par les ondes acoustiques dans l'air.Dans cette thèse, nous présentons un démonstrateur du LIDAR acoustique par interférométrie à réinjection optique. En principe, nous mesurons la vitesse d'oscillation d'une particule entraînée par une onde acoustique. Nous allons construire une application LIDAR similaire à celle d'Epsiline, en utilisant leurs optiques pour acquérir un signal. Les algorithmes de traitement du signal sont basés sur la méthode des moments pondérés souvent appliquée dans les mesures de fluides.Premièrement, nous dérivons un modèle pour estimer le mouvement des particules sous entraînement acoustique. Le modèle est dérivé des équations de Newton, prenant la pression acoustique et les paramètres atmosphériques en entrée. Ensuite, une expression est développée, pour convertir une oscillation de vitesse mesurée en une pression acoustique. Le modèle est validé expérimentalement à l'aide d'une sonde d'intensité, un appareil mesurant la vitesse des particules dans une onde acoustique. Plus loin, nous proposons une modification de l'équation de puissance OFI, en l'adaptant pour modéliser un flux de particules à vitesse oscillante.Le modèle acoustique et l'équation de puissance OFI modifiée sont finalement combinés pour créer une simulation du comportement d'un système OFI lors de la mesure de la vitesse d'un flux d'aérosol modulé par des ondes acoustiques. La simulation est enrichie pour réfléchir sur la forme gaussienne du faisceau laser et le comportement aléatoire des particules dans l'air
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Lower detection limit of the Acousto-Optic Effect using Optical Feedback Interferometry
'Institute of Electrical and Electronics Engineers (IEEE)', 2020Co-Authors: Knudsen Einar, Perchoux Julien, Mazoyer Thierry, Jayat Francis, Tronche Clément, Bosch ThierryAbstract:International audienceMeasurement and 3D imaging of acoustic waves through the Acousto-Optic Effect has recently been demonstrated by means of Optical Feedback Interferometry (OFI). In this paper we study experimentally the lower limits of detection of an acoustic wave using an OFI sensor. We show that the OFI sensor exhibits a linear response to acoustic power variations, and we obtain a lower limit of detection of 83 dB rms for a planar acoustic wave at 3 kHz. We also determine the equivalent displacement, that is seen by the OFI sensor at this pressure level, to be 96 pm. A deeper understanding of the limits of the technology and the quantification of the Acousto-Optic Effect shall help improve the applications already created for the measurement of acoustic pressure waves using OFI
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Experimental Demonstration of the Impact of theFringe Shape in Sub-Lambda / 2 Sensing With OpticalFeedback Interferometry
'The Optical Society', 2020Co-Authors: Knudsen Einar, Perchoux Julien, Mazoyer Thierry, Jayat Francis, Tronche Clément, Imas José, Veng Mengkoung, Bosch ThierryAbstract:International audienceIt is established in the Optical Feedback Interferometry (OFI) theory that the shape of the interferometric fringe has an impact on the detector's response to very small displacement measurements. In this paper we validate-for the first time based on experimental results-this statement by comparing experiments to an established model implementation. Through these experiments we show that the amplitude of the signals induced by sub-lambda/2 optical path variations is linearly dependent on the slope of the underlying fringe. Thus, careful control of the phase allows us to maximize the detection amplitude of very small displacements by positioning the phase where the fringe slope is the steepest. These results are directly applicable to established OFI applications that measure sub-lambda/2 optical path variations, such as OFI vibrometers or acoustic imaging though the Acousto-Optic Effect
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Experimental Demonstration of the Impact of theFringe Shape in Sub-Lambda / 2 Sensing With OpticalFeedback Interferometry
'The Optical Society', 2020Co-Authors: Knudsen Einar, Perchoux Julien, Mazoyer Thierry, Jayat Francis, Tronche Clément, Imas José, Veng Mengkoung, Bosch ThierryAbstract:It is established in the Optical Feedback Interferometry (OFI) theory that the shape of the interferometric fringe has an impact on the detector's response to very small displacement measurements. In this paper we validate-for the first time based on experimental results-this statement by comparing experiments to an established model implementation. Through these experiments we show that the amplitude of the signals induced by sub-lambda/2 optical path variations is linearly dependent on the slope of the underlying fringe. Thus, careful control of the phase allows us to maximize the detection amplitude of very small displacements by positioning the phase where the fringe slope is the steepest. These results are directly applicable to established OFI applications that measure sub-lambda/2 optical path variations, such as OFI vibrometers or acoustic imaging though the Acousto-Optic Effect
Carlindo Vitoriano - One of the best experts on this subject based on the ideXlab platform.
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acousto optic Effect in nematic liquid crystals experimental evidence of an elastic regime
Physical Review E, 2013Co-Authors: Carlindo VitorianoAbstract:We show that the experimental data for the action of ultrasonic waves on homeotropically aligned nematic-liquid-crystal cells reported by Kapustina, in Akust. Zh. 54, 900 (2008) [Acoust. Phys. 54, 778 (2008)] can be explained in the framework of the director-density coupling theory in the regime of low acoustic intensity. This result therefore provides support for the hypothesis that the interaction between sound and nematic liquid crystals is dominated by an elastic energy.
John C Schotland - One of the best experts on this subject based on the ideXlab platform.
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acousto optic Effect in random media
Physical Review E, 2017Co-Authors: Jeremy G Hoskins, John C SchotlandAbstract:: We consider the Acousto-Optic Effect in a random medium. We derive the radiative transport equations that describe the propagation of multiply scattered light in a medium whose dielectric permittivity is modulated by an acoustic wave. Using this result, we present an analysis of the sensitivity of an Acousto-Optic measurement to the presence of a small absorbing inhomogeneity.
Gianluca Piazza - One of the best experts on this subject based on the ideXlab platform.
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novel on chip rotation detection based on the acousto optic Effect in surface acoustic wave gyroscopes
Optics Express, 2018Co-Authors: Mohamed Mahmoud, Msi Khan, Ashraf Mahmoud, Tamal Mukherjee, James A. Bain, Gianluca PiazzaAbstract:An Acousto-Optic Gyroscope (AOG) consisting of a photonic integrated device embedded into two inherently matched piezoelectric surface acoustic wave (SAW) resonators sharing the same acoustic cavity is presented. This constitutes the first demonstration of a micromachined strain-based optomechanical gyroscope that uses the Effective index of the optical waveguide due to the Acousto-Optic Effect rather than conventional displacement sensing. The theoretical analysis comparing various photonic phase sensing techniques is presented and verified experimentally for the cases based on a Mach-Zehnder interferometer, as well as a racetrack resonator. This first prototype integrates acoustic and photonic components on the same lithium niobate on insulator (LNOI) substrate and constitutes the first proof of concept demonstration of the AOG. This approach enables the development of a new class of micromachined gyroscopes that combines the advantages of both conventional microscale vibrating gyroscopes and optical gyroscopes.
