Im Jahr 1991 wurde erstmals die Interferenz von Atomen experimentell nachgewiesen. Seitdem wird dieses Phänomen in vielen Bereichen der Grundlagenforschung angewendet, unter anderem zur Bestimmung von Naturkonstanten mit bisher unerreichter Genauigkeit oder für Tests des Äquivalenzprinzips. Grundsätzlich können auch geophysikalische Vermessungen des Schwerefeldes der Erde von dieser neuen Technik profitieren, allerdings waren Atominterferometrie-Experimente aufgrund ihrer Komplexität bisher nur in Laboren möglich. Erst kürzlich wurde mit der Entwicklung mobiler Atominterferometer begonnen, die nun die hochpräzise Messung von Rotationen, Gravitationsgradienten sowie der absoluten Schwerebeschleunigung außerhalb von Laboren ermöglichen. Im Rahmen dieser Arbeit wurde ein absolutes Gravimeter entwickelt, konstruiert und getestet. Es basiert auf Rb87-Atomen, die in einer Vakuumumgebung gefangen, gekühlt und senkrecht entgegen der Erdanziehung beschleunigt werden. Während des anschließenden freien Falls werden die atomaren Ensembles durch drei Raman Lichtpulse aufgespalten und rekombiniert. Die lokale Schwerebeschleunigung kann aus den resultierenden Interferenzmustern bestimmt werden, die abhängig von der Bewegung der Atome in einem Gravitationspotential sind. Wir haben den Wert der lokalen Schwerebeschleunigung, g, mit einer Auflösung von 1 : 10^10 bei einer Integrationszeit von 12 Stunden vermessen. Dies entspricht 2,2 * 10^-7 m/s^2/Sqrt(Hz). Mit dieser Genauigkeit konnten bereits zeitliche Veränderungen des lokalen Schwerefeldes registriert werden, hervorgerufen durch eine Vielzahl an Effekten wie Erd- und Ozeangezeiten oder atmosphärischen Variationen. In einem Vergleich unter ähnlichen Messbedingungen konnte unser Instrument die lokale Schwerebeschleunigung mit einer um fast eine Größenordnung höheren Genauigkeit bestimmen als ein herkömmliches Gravimeter. / Since 1991, matter wave interferometry has been used in many laboratories for a variety of fundamental physics experiments, e.g. measurement of the fine-structure and gravity constants or equivalence principle tests. This new technique is also ideally suited for high-accuracy geophysical gravity measurements. However, due to the complexity of these experiments they were so far confined to laboratory environments. Only in recent years efforts have been undertaken to develop mobile atom interferometers. These new sensors now open up the possibility to perform on-site high-precision measurements of rotations, gravity gradients as well as absolute accelerations. This work reports on the design, construction and first tests of an absolute gravimeter. It is based on interfering ensembles of laser cooled Rb87 atoms in a one meter high atomic fountain configuration. Local gravity is measured by applying three Raman light pulses while the atoms are in free fall, thereby splitting and recombining the atomic wave packets. The resulting interference fringes are sensitive to the movement of the atoms within a gravitational potential. We have measured the value of local gravity g at a resolution of one part in 10^10 at an integration time of 12 hours, or 2.2 * 10^-7 m/s^2/Sqrt(Hz). This was high enough to be sensitive to a number of time varying gravity effects like tides, ocean loading or changes in gravity caused by air pressure. In a comparison under similar measurement conditions, the instrument has surpassed the performance of conventional mobile gravimeters by almost one order of magnitude.

Das gravimetrische Atominterferometer (GAIN) ist ein transportables Atominterferometer welches spezifisch für hochpräzise Schweremessungen in der Geodäsie und Geophysik entwickelt wurde. Es basiert auf einer Rubidium Atomfontäne, stimulierten Ramanübergängen und einer 3-Puls Mach-Zehnder Interferometriesequenz. Die vorliegende Arbeit beschäftigt sich mit der Optimierung und Anwendung von GAIN als transportables Gravimeter für Absolutschweremessungen an geodätischen Observatorien welche über den aktuellen Stand der Technik hinaus gehen. Dabei wurden eine Absolutgenauigkiet von 29 nm/s^2, eine Langzeitstabilität von 0.4 nm/s^2 sowie eine Sensitivität von 82 nm/s^2 in einer Sekunde erreicht. Die gemessene Genauigkeit und Langzeitstabilität stellen, nach dem Wissen des Authors, die bis heute besten publizierten Werte für ein transportablen Atominterferometer dar und repräsentieren einen bedeutenden Fortschritt im Bereich der Gravimetrie. Um dies zu erreichen wurden umfangreiche Verbesserungen am Gerät umgesetzt und eine ausführliche Analyse der systematischen Messabweichungen durchgeführt. Unter anderem wurden ein System zur Kompensation von Corioliskräften und Ausrichtungsfehlern, ein verbessertes Schwingungsisolationssystem zur nachträglichen Korrektur von Umgebungsvibrationen und eine magnetische Abschirmung instrumenteller Streufelder implementiert. Darüber hinaus wurden insgesamt vier Messkampagnen in Berlin, sowie an den geodätischen Observatorien in Wettzell, Deutschland und Onsala, Schweden durchgeführt, um GAIN mit anderen hochmodernen Absolut- und Relativgravimetern zu vergleichen. Der direkte Vergleich zwischen GAIN und anderen Gravimetern stellt den prinzipbedingten Vorteil der Atominterferometrie durch die Kombination aus Absolutgenauigkeit, Stabilität und Langzeitbetrieb klar hervor. Dies wurde in der Arbeit durch die um einen Faktor 2-5 verbesserte Kalibrierung des Skalenfaktor von zwei supraleitenden Gravimetern demonstriert. / The gravimetric atom interferometer (GAIN) is a transportable setup which was specifically designed to perform high-precision gravity measurements at sites of interest for geodesy or geophysics. It is based on a Rb atomic fountain, stimulated Raman transitions and a three-pulse Mach-Zehnder atom interferometry sequence. The presented work is concerned with the optimization and application of GAIN as a transportable gravimeter in order to perform gravity measurements beyond the state-of-the-art. An absolute accuracy of 29 nm/s^2, long-term stability of 0.4 nm/s^2 and short-term noise level as low as 82 nm/s^2 in one second was achieved. The obtained long-term stability and accuracy values are, to the knowledge of the author, the best published performance of any transportable atom interferometer to date and represent a significant advancement in the field of gravimetry. A comprehensive analysis of the systematic error budget was performed to improve the accuracy and stability of the measured gravity value. Several setup improvements were implemented to this end, including Coriolis force and alignment control systems, an improved vibration isolator with post-correction and magnetic shielding which reduces spurious coupling due to stray fields. Measurement campaigns were conducted in Berlin and at geodetic observatories in Wettzell, Germany, and Onsala, Sweden, in order to compare GAIN to other state-of-the-art absolute and relative gravimeters. The direct comparison of GAIN to other absolute and relative gravimeters shows the general advantage of atom interferometers due to their unique combination of absolute accuracy, stability and robust architecture enabling continuous measurements. This was demonstrated during the presented campaigns by the improvement of the scale factor calibration of two superconducting gravimeters by a factor 2 to 5 using GAIN data.

Percutaneous needle placement, a minimally invasive procedure performed dozens of millions in the U.S. each year, relies on dedicated skill and long-term training due to difficult control of needle trajectory inside tissue and mental registration of images to locations inside the patient. Inaccurate needle placement may miss cancer tumors during diagnosis or eradicate healthy tissue during therapy. MRI provides ideal procedure guidance with the merit of excellent soft tissue contrast and volumetric imaging for high spatial resolution visualization of targets and surgical tool. However, manual insertion in the bore of an MRI scanner has awkward ergonomics due to difficult access to the patient, making both training and intervention even harder. To overcome the challenges related to MRI electromagnetic compatibility and mechanical constraints of the confined close-bore, a modular networked robotic system utilizing piezoelectric actuation for fully actuated prostate biopsy and brachytherapy is developed and evaluated with accuracy study. To enhance manipulation dexterity, two kinds of steerable continuum needle robots are developed. The asymmetric tip needle robot performs needle rotation and translation control to minimize tissue deformation, and increase steering dexterity to compensate placement error under continuous MRI guidance. The MRI-guided concentric tube robot is deployed to access delicate surgical sites that are traditionally inaccessible by straight and rigid surgical tools without relying on tissue reaction force. The master-slave teleoperation system with hybrid actuation is the first of its kind for prostate intervention with force feedback. The teleoperation controller provides the feel and functionality of manual needle insertion. Fabry- Perot interferometer based fiber optic force sensor is developed for the slave manipulator to measure needle insertion force and render proprioception feedback during teleoperation.

Les interféromètres stellaires sont des dispositifs à très haute résolution angulaire, permettant une étude approfondie de l’Univers. Cette thèse décrit la mise en place en laboratoire d’un interféromètre à somme de fréquences dédié à la détection de rayonnement infrarouge en bande L :ALOHA@3.39. Afin de pouvoir limiter le bruit généré par les rayonnements thermiques ambiants et de pouvoir bénéficier des technologies matures en terme de détection et de transport cohérents de la lumière collectée, ce système intègre sur chacune des voies interférométrique un processus non linéaire de somme de fréquence. Les rayonnements autour de 3.39 μm sont transposés autour de 810 nm via des cristaux de PPLN alimentés par une pompe unique à 1064 nm. Une première partie présente le contexte expérimental et théorique de la thèse. La deuxième partie concerne la conception, la réalisation et la caractérisation du banc ALOHA@3.39. La troisième partie présente les résultats expérimentaux obtenus en laboratoire. La mesure répétée du contraste en régime de fort flux permet de calibrer le contraste instrumental du montage. Les premières mesures en régime de comptage de photons montrent que nous sommes actuellement capables de détecter des franges d’interférence avec de hauts contrastes en ne disposant que de 100 Fw à l’entrée de chacune des voies. Enfin, nos investigations nous ont amené à la détection de franges d’interférences via le prototype ALOHA@3.39 à partir d’une source thermique, assimilable à un corps noir. Cette thèse conclue sur une estimation de la magnitude limite accessible, et sur l’utilisation de nouvelles technologies de PPLN. / Stellar interferometers are high angular resolution devices, allowing for detailed research of the Universe. This thesis describes the in-lab implementation of a sum frequency generation interferometer dedicated to the infrared detection in the L band : ALOHA@3.39. In the aim of limiting thermal noise due to the room radiation, and benefit mature detectors and fibered components, this device includes a sum frequency generation non-linear process on each of its arms. Stellar radiations around 3.39 μm are transposed to around 810 nm thanks to PPLN cristals powered by a single pump signal at 1064 nm. The first part presents our global experimental context and theoretical elements about this thesis. The second part deals with the conception, the implementation and characterisation of the test bench ALOHA@3.39. The third part tables in-lab experimental results. Repeated measurements of the fringe contrast on high flux regime allow to calibrate the instrumental contrast of the set-up. First measurements on photon counting regime show we are currently able to detect interference fringes with high contrast with only 100 fW at the input of each arm. Finally, our research led us to realise interference fringes detection via the ALOHA@3.39 prototype, observing a thermal source, considered as a black body. This thesis concludes on an estimation of the limiting reachable magnitude, and on the future use of new PPLN technologies.

Les effets non-linéaires dépendant essentiellement de l’intensité du champ électrique de l’onde et du guide, sont indispensables à la génération des régimes impulsionnels dans les lasers à fibre dopée. L’effet Kerr, qui se manifeste quel que soit l’énergie de propagation et de pompage, va engendrer le phénomène de l’auto modulation de phase (SPM) qui se traduira par un élargissement spectral. La SPM peut se voir aussi dans l’interaction entre les deux ondes qui se propagent le long des axes lents et rapides du guide (XPM). Dans un guide uniforme passif, cette auto modulation de phase en se conjuguant avec la dispersion chromatique du guide peut conduire à l’impulsion soliton, mais ce cadre doit être largement dépassé pour aborder la mise en forme d’impulsions dans un système dissipatif, tel qu’une cavité laser. Ce cadre élargi est celui du soliton dissipatif. Dans ce travail, nous avons passé en revue la fibre optique dopée en tant que milieu actif. Nous avons présenté le principe physique du blocage de modes, en introduisant l’absorbant saturable virtuel reposant sur l’évolution non linéaire de la polarisation (ENLP). Dans la partie expérimentale, on s’est penché plus particulièrement sur de nouvelles dynamiques à haute cadence (multi-GHz) d’un laser à fibre dopée, à modes bloqués. Avant de présenter et positionner notre travail, on s’est intéressé dans un premier temps à ce qui a été publié sur la génération des trains d’impulsions ultracourtes à haute cadence. Nous avons étudié chaque configuration, allant de la génération de régime harmonique à haute cadence par le blocage de modes habituel jusqu’aux techniques utilisant l’instabilité de modulation avec un filtrage interférométrique (µcavité, F.P, SFBG). En évaluant les opportunités de réalisation de chacune, nous avons été attirés par la configuration de Mao, publiée dans Sci. Reports, toute fibrée, qui sera le premier volet de notre contribution expérimentale. Effectivement, dans un premier temps nous avons repris les travaux de Mao et al. où le MZI est pris en série dans la cavité fondamentale. Dans le souci d’apporter plus de stabilité, nous avons proposé une autre configuration où le MZI est pris dans une boucle de recirculation qui permettra plus de filtrage des modes cavité en phase. Cette stabilité du régime impulsionnel, à haute cadence, a été observée en temps réel. / Non-linear effects, which depend essentially on the intensity of the electric field of the wave and the guide, are essential for the generation of pulse regimes in doped fiber lasers. The Kerr effect, which occurs regardless of the propagation and pumping energy, will generate the phenomenon of phase auto modulation (SPM), which will result in a spectral expansion. The SPM can also be seen in the interaction between the two waves that propagate along the slow and fast axes of the guide (XPM). In a passive uniform guide, this self-phase modulation in combination with the chromatic dispersion of the guide can lead to the soliton pulse, but this framework must be largely overcome to address pulse shaping in a dissipative system, such as a laser cavity. This extended framework is that of the dissipative soliton. In this work, we reviewed doped optical fiber as an active medium. We presented the physical principle of mode blocking, introducing the virtual saturable absorber based on the non-linear evolution of polarization (ENLP). In the experimental part, we focused more particularly on new high rate dynamics (multi-GHz) of a doped fiber laser with blocked modes. Before presenting and positioning our work, we first focused on what was published on the generation of ultra-short high speed pulse trains. We studied each configuration, ranging from the generation of high-rate harmonic regime by blocking the usual modes to techniques using modulation instability with interferometric filtering (µcavity, F.P, SFBG). In assessing the opportunities for each, we were attracted by the configuration of Mao, published in Sci. Reports, all fiber, which will be the first part of our experimental contribution. Indeed, initially we resumed the work of Mao et al. where the MZI is taken in series in the fundamental cavity. In order to provide more stability, we have proposed another configuration where the MZI is caught in a recirculation loop that will allow more filtering of the cavity modes in phase. This stability of the impulse regime, at high repetition rate, was observed in real time.

Este trabalho descreve a utilização de um software livre educacional do interferômetro de Mach-Zehnder (IMZ), em português, como instrumento motivador, ilustrativo, de fácil manuseio e compreensão, para ajudar no ensino e aprendizagem de Física. Salientamos que este software educacional foi desenvolvido através de um projeto coordenado pelas professoras Fernanda Ostermann e Flávia Rezende, do Instituto de Física da Universidade Federal do Rio Grande do Sul (UFRGS) e da Universidade Federal do Rio de Janeiro (UFRJ) e foi utilizado como principal instrumento para introduzir conceitos fundamentais de física quântica em uma disciplina do curso Mestrado Profissional de Ensino de Física. No entanto, podemos dizer que esta foi a primeira vez que o IMZ foi aplicado a uma turma de professores não ligados profissionalmente à UFRGS. Em acréscimo ao software, foram elaborados e remodelados como produtos educacionais, textos de apoio e guias experimentais que poderão ser usados tanto por professores, como por alunos do Ensino Médio. Fenômenos ondulatórios foi o assunto explorado e um de seus subtemas, a interferência da luz, foi bastante enfatizada. Colocamos à disposição dos professores um material didático de fácil interpretação, podendo, também, ser utilizado com alunos do Ensino Médio. O desenvolvimento desse material tem caráter estratégico para que sirva de base a futuras transposições de temas da física quântica, em particular, o fenômeno da dualidade onda-partícula, para este nível de ensino. Este material de apoio e o software compreendem um curso de quarenta horas, para um grupo de seis professores da rede estadual, mais especificamente para os professores que lecionam Física, nas escolas que representam a 6ª Coordenadoria Regional de Educação (6ª CRE), com o apoio da mesma. O curso aconteceu em 2006, na Escola Estadual de Ensino Médio “Ernesto Alves de Oliveira”, em Santa Cruz do Sul, RS. Embasado na Teoria de Aprendizagem Significativa de Ausubel, o material servirá, também, como base ou conhecimento prévio para futuras investidas em outros temas relacionados à física quântica. O conteúdo da teoria ondulatória da luz, trabalhado sobre o aparato do interferômetro virtual de Mach-Zehnder proporcionou a interação entre o conhecimento novo (física quântica e dualidade ondapartícula, desenvolvida sobre o interferômetro virtual de Mach-Zehnder no regime quântico) e o prévio (teoria ondulatória da luz desenvolvida sobre o interferômetro virtual de Mach- Zehnder clássico), possibilitando uma aprendizagem significativa e dando sentido às novas informações. No decorrer do curso, ao analisarmos o comportamento e as atitudes dos professores, pudemos perceber que este assunto não é trabalhado no Ensino Médio, e que eles apresentam dificuldades em relação aos conceitos fundamentais da teoria. Entretanto, parte do grupo mostrou interesse em obter novos conhecimentos, pois em todos os encontros havia questionamentos relacionando novos conceitos com os pré-existentes. Enfim, o software gerou visível entusiasmo com as novas possibilidades de aulas “práticas”, com a aprendizagem dos novos conceitos e também a proposta de se avaliar com a utilização de mapas conceituais, estratégia desenvolvida por Novak. / In this work it is shown how the utilization of a free educational software can be useful as a motivating and illustrative tool to help the teaching and understanding of fundamental concepts on quantum mechanics. Besides being available also in Portuguese, the virtual Mach-Zehnder Interferometer (MZI) is easy to handle. The software has been developed under a project coordinated by Professor Ostermann (UFRGS) and Professor Rezende (UFRJ) and has been used as a main tool to introduce students from Mestrado Profissional em Ensino de Física to fundamental concepts on quantum physics. Here, it is reported the first time the software was used in an environment that is not university. Concepts of quantum physics were discussed in a 40 hours course given to a group of six secondary level school teachers in 2006. They were teachers working under the 6ª Coordenadoria Regional de Educação (6ª CRE). The course took place in Santa Cruz do Sul (RS) at Escola Estadual de Ensino Médio “Ernesto Alves de Oliveira”. In order to help the students with the software itself and physical concepts that could help the understanding of the simulations results, supporting materials like helping texts and experimental guides were prepared based on Ausubel framework. We were also concerned about an educational product that could also be helpful to secondary level school students. The texts are available in an easy language and straightforward physics. Although the number of students were relatively small, the group was representative in the sense it reproduces the reality of public secondary schools in Brazil. Physics is not, in general, taught by people that are graduated in Licenciatura em Física and the ones that are, are in general, not very well prepared. It was clear that no one in the group had enough confidence “to touch” subjects related to quantum physics in classes having the excuse this is a very difficult topic to overcome. Using optical physics as basis and the virtual MZI, we could see some enthusiasm when the students realize it is possible, for example, to discuss some concepts related to wave-particle duality without unreachable mathematics.

<p>Optical coherence tomography is an imaging modality with an outstanding resolution. During the project, a time domain OCT system based on a Michelson fibre interferometer was implemented and put into operation. A super-luminescent diode with a centre wavelength of 1295nm and a bandwidth of 45nm was selected as light source and a linear variable delay line as reference. Basic tests were made on phantoms constructed of filter foils and on gel-like agar slices with optical properties similar to human tissue. It was shown that the achievable resolution was at least 36um and can be increased. The system can easily be enhanced to create two-dimensional images.</p> / <p>Optische Kohärenztomographie ist ein bildgebendes Verfahren mit einer hervorragenden räumlichen Auflösung. Im Laufe des Projekts wurde ein OCT-System basierend auf einem faseroptischen Michelson-Interferometer implementiert und in Betrieb genommen. Als Lichtquelle wurde eine Superlumineszenzdiode mit einer Mittenwellenlänge von 1295nm und einer Bandbreite von 45nm gewählt. Eine variable optische Verzögerungsleitung diente als Referenz. Erste Messungen an Filterfolien und gelähnlichen Agarphantomen, die die optischen Eigenschaften von menschlichem Gewebe nachbildeten, lieferten eine räumliche Auflösung von mindestens 36um. Durch die modulare Bauweise ist das System leicht für zweidimensionale Aufnahmen erweiterbar.</p>

Optical coherence tomography is an imaging modality with an outstanding resolution. During the project, a time domain OCT system based on a Michelson fibre interferometer was implemented and put into operation. A super-luminescent diode with a centre wavelength of 1295nm and a bandwidth of 45nm was selected as light source and a linear variable delay line as reference. Basic tests were made on phantoms constructed of filter foils and on gel-like agar slices with optical properties similar to human tissue. It was shown that the achievable resolution was at least 36um and can be increased. The system can easily be enhanced to create two-dimensional images. / Optische Kohärenztomographie ist ein bildgebendes Verfahren mit einer hervorragenden räumlichen Auflösung. Im Laufe des Projekts wurde ein OCT-System basierend auf einem faseroptischen Michelson-Interferometer implementiert und in Betrieb genommen. Als Lichtquelle wurde eine Superlumineszenzdiode mit einer Mittenwellenlänge von 1295nm und einer Bandbreite von 45nm gewählt. Eine variable optische Verzögerungsleitung diente als Referenz. Erste Messungen an Filterfolien und gelähnlichen Agarphantomen, die die optischen Eigenschaften von menschlichem Gewebe nachbildeten, lieferten eine räumliche Auflösung von mindestens 36um. Durch die modulare Bauweise ist das System leicht für zweidimensionale Aufnahmen erweiterbar.

In this thesis, we test some interactions involving surfaces processes at the nanometer scale. The experiments are conducted with a highly sensitive interferometric Atomic Force Microscope (AFM), achieving a resolution down to E-28m2/Hz for the measurement of deflection. Combined with original thermal noise analysis, this tool allows quantitative characterization of the mechanical response of micrometer and nanometer sized systems, such as microcantilevers or carbon nanotubes, on a large frequency range.The first part of my work deals with the viscoelasticity of the coating of AFM cantilevers. Evidenced by a 1/f thermal noise at low frequency, this phenomenon is present when a cantilever is coated with a metallic layer (gold, aluminium, platinium, etc...). Using the fluctuation dissipation theorem and Kramers Kronig relations, we extract the frequency dependance of this viscoelastic damping on a wide range of frequency (1Hz to 20kHz). We find a generic power law dependence in frequency for this dissipation process, with a small negative coefficient that depends on materials. The amplitude of this phenomenon is shown to be linear in the coating thickness, demonstrating that the damping mechanism takes its roots in the bulk of the metallic layer.The second part of my work tackles new experiments on the interaction of carbon nanotubes with flat surfaces. Using our AFM, we perform a true mechanical response measurement of the rigidity and dissipation of the contact between the nanotube and the surface, in a peeling configuration (the nanotube is partially absorbed to the substrate). The results of this protocol are in line with the dynamic stiffness deduced from the thermal noise analysis, showing an unexpected power law dependence in frequency for the contact stiffness. We suggest some possible physical origins to explain this behavior, such as an amorphous carbon layer around the nanotube.

This research work has been conducted to introduce a novel class of Fabry-Perot (FP) resonators : curved FP cavity based on coating-free Bragg mirrors of cylindrical shape, obtained by silicon micromachining. Another specificity is the rather large cavity lengths (L>200 µm) combined with high quality factor Q (up to 104), for the purpose of applications requiring cavity enhanced absorption spectroscopy, in which the product Q.L is a figure of merit. In this contest, the basic architecture has been modeled analytically to know the high order transverse modes supported by such cavities. Hence, the experimental conditions which lead to preferential excitation (or rejection) of these modes have been tested experimentally leading to the validation of our theoretical model and to a better understanding of the cavity behaviour. A second architecture, based on the curved FP together with a fiber rod lens has been developed for the purpose of providing stable designs. It was also modeled, fabricated and characterized leading to the expected performance improvements. On another side, a highlight on one of the potential applications that we identified for the curved cavities is presented by inserting the cavity into an electro-mechanical system. It consists of exciting and measuring tiny vibration through opto-mechanical coupling in a MEMS mechanical resonator embedding an FP cavity.Finally, as a complement to our study on resonators, we started exploring applications of optical interferometers based on similar micromachined silicon Bragg mirrors. For this purpose, an optical measurement microsystem was designed, fabricated and characterized ; it consists of an optical probe for surface profilometry in confined environments, based on an all-silicon Michelson interferometer