[pt] No presente trabalho, demonstramos o uso de fibras de cristais fotônicos (PCF) em diferentes configurações para sensoriamento. Investigamos o uso de fibras PCF com alta birrefringência para sensoriamento de pressão hidrostática e deformação, explorando a baixa dependência térmica. Onde a interferência entre os modos que se propagam em uma fibra birrefringente é analisada. Monitoramos o deslocamento do padrão de interferência do espectro de reflexão, com a variação da pressão ou deformação aplicada à fibra. Demonstramos uma técnica de criar cavidades Fabry-Perot dentro de uma fibra óptica, bem como uma técnica para controlar seu comprimento, e consequentemente, o período das franjas no padrão de interferência no espectro de reflexão. O interferômetro Fabry-Perot (FPI) investigado, possuí um altíssimo contraste nas franjas do padrão de interferência, acima dos 30 dB, sendo no momento, o recorde para o valor do contraste das franjas para FPI silica-ar. O dispositivo foi investigado quanto à resposta a deformação. Um robusto encapsulamento foi feito, possibilitando investigar a resposta do dispositivo à vibração externa. Um estudo da relação da sensibilidade com o comprimento do FPI é também investigado. Construímos um outro interferômetro a partir de um pedaço de fibra PCF e de duas regiões de colapso de suas micro-estruturas. Estas regiões permitem a excitação e recombinação dos modos da fibra. Um dos modos que participa da interferência, é o modo de casca da fibra PCF, o qual é sensível a mudança de índice de refração do meio. O dispositivo apresenta contraste acima dos 40 dB, e é investigado quanto à resposta as mudanças de índices de refração do meio externo em contato com a fibra. Com a mesma montagem, funcionalizamos um pedaço de 2,0 cm de PCF para monitoramento de respiração humana. A partir disso, desenvolvemos um dispositivo capaz de monitorar a respiração do ser humano. / [en] In this work, we have demonstrated the use of Photonic Crystal Fiber (PCF), in different configurations, for sensing applications. The high birefringence and low temperature dependence characteristics of the PCF were explored for sensing hydrostatic pressure and deformation in a reflection configuration. Sensing was based on the analysis of the interference patterns between the modes that propagate in the birefringent fiber under the variation of pressure and deformation applied to the fiber. We have also demonstrated a technique to manufacture a Fabry-Perot Interferometer (FPI) cavity within an optical fiber with control of the cavity length and thus the control of the period of the fringes in the interference pattern. The Fabry-Perot Interferometer investigated presented a very high fringe contrast, above 30 dB, and showed a record value of the contrast of the fringes for FPI silica-air. The FPI device integrated within the fiber was tested as a strain sensor and also as a device to monitor vibration. A study of the relative sensitivity of the length of the FPI was also investigated. Another interferometer was built from a piece of standard fiber and a PCF with two regions of collapsed microstructures. These regions allowed the excitation and recombination of the fiber modes. This device was tested as a refractive index sensor, presenting a fringe contrast above 40 dB. An application of this device was the development of a humid sensor to monitor human breathing.

High Spectral Resolution Lidar (HSRL) is a backscatter lidar technique that employs an optical/spectral filter to distinguish between particulate (Mie) and molecular (Rayleigh) backscattered light. By separating the two types of returns, higher accuracy measurements are possible that will enable improved climate models, air quality measurements, and climate forecasting. A spaceborne HSRL instrument can provide great impact in these areas by enabling near-continuous measurements across the Earth, however the optical filter technology has typically been too complex for reliable long-duration space flight due to the need for complicated and costly electro-optic feedback loops, extra alignment detectors, and additional laser sources. Furthermore, these complexities limit the filter from use in other applications. In this research, a high-performance, ultra-narrowband interferometric optical filter with a specific thermo-optical behavior has been designed and built. The interferometer has been designed such that it can be reliably adjusted/tuned by simply monitoring and adjusting the temperature. The greatly reduced operational complexity was made possible through high-accuracy thermal characterization of the interferometer materials, combined with detailed Structural-Thermal-Optical-Performance (STOP) modeling to capture the complicated interactions between the materials. The overall design process, fabrication procedures, and characterization of the optical filter are presented. / Doctor of Philosophy / LiDAR (an acronym for Light Detection and Ranging) is a technology that can be used to measure properties of the atmosphere. It is similar to radar, but uses much smaller light waves rather than larger radio waves, enabling more detailed information to be obtained. High Spectral Resolution Lidar (HSRL) is a lidar technique that uses a high precision optical filter to distinguish between light that scatters from particulates (such as dust, smoke, or fog) and light that scatters from molecules (such as oxygen, nitrogen, or carbon dioxide) in the atmosphere. By separating the two types of backscattered light, higher accuracy measurements are possible that will enable improvements in climate models, air quality measurements, and climate forecasting. A spaceborne HSRL instrument can provide great impact in these areas by enabling near-continuous measurements across the Earth; however, the optical filter technology has typically been too complex for reliable long-duration spaceflight due to the need for complicated and expensive additional hardware. In this research, a high-performance HSRL optical filter that can be reliably operated by simply monitoring and adjusting the temperature has been designed, built, and tested. The greatly-reduced operational complexity has been made possible through a new process that enables more accurate prediction of the complicated interactions between the materials of the optical filter. This process is based on a combination of high-accuracy characterization of the materials and detailed structural-thermal-optical-performance (STOP) modeling. The overall design process, fabrication procedures, and characterization of the optical filter are presented.

Este trabajo de tesis recoge las contribuciones aportadas en el campo de los sensores de fibra óptica en tres ámbitos de trabajo. Un sistema sensor de alta temperatura sin contacto con transductores de fibras ópticas de sílice se ha presentado. Dos topologías de "ojo abierto" y "ojo cerrado" y un algoritmo de decodificación "pirometría de banda dual" propuesto en este trabajo son las novedosas aportaciones presentadas. El sistema ha sido validado en laboratorio y en pruebas de campo de forma exitosa. Para sensores de temperatura con fibras dopadas con Erbio se ha demostrado que su máxima sensibilidad tiene lugar cuando la longitud utilizada es superior a la óptima exigida por el bombeo. Finalmente se ha modelado y validado en laboratorio una red de sensores acústicos basados en interferómetros Fabry-Perot de cavidad larga determinando a partir del modelo obtenido la fase mínima detectable y la visibilidad máxima del sistema. / The thesis collects contributions in the field of optic fibre sensors for three areas. A high temperature sensor system without contact based on silica optic fibre transducers has been submitted. Two topologies "open eye" and "closed eye" and a dual band pyrometer decoding algorithm are the submitted innovative contributions. The system has been validated successful in the laboratory and field tests so. Another contribution has been the demonstration that the maximum sensitivity for temperature sensors based on Er-doped fibres occurs when the used length is more than the optimum required by pumping. Finally a network of acoustic sensors based on Fabry-Perot fibre interferometers has been modelled and validated in the laboratory. The minimum detectable phase and maximum visibility of the system has been obtained from the proposed and validated model

The aim of this Master’s Degree thesis project is to design and develop point diffraction interferometer plates. In this project the PDI plates are re-designed, changing the design which was used in previous projects in Halmstad University. The transparency of PDI plates can be controlled by coating them with NiCr film. Firstly, four plates with coating of different thickness of NiCr were developed. The relationship between transmittance and the thickness of NiCr was established by testing these plates for transmittance and reflectance with the help of a laser and an optical power meter. The absorption coefficient of clear substrates and reflection of light is also taken into account to achieve the correct results. The parameters like the diameter of semi-transparent area around the pinholes and the size of pinholes is chosen after fully understanding its application. The lay-out and description of design is also included in the report.

No description available.

Fluid suspended biological particles (bioparticles) flowing through a non-uniform electric field are actuated by the induced dielectrophoretic (DEP) force, known to be dependent upon the bioparticles’ dielectric phenotypes. In this work: a 10-1000 kHz DEP actuation potential applied to a co-planar microelectrode array (MEA) induces a DEP force, altering passing bioparticle trajectories as monitored using: (1) an optical assay, in which the lateral bioparticle velocities are estimated from digital video; and (2) a capacitive cytometer, in which a 1.478 GHz capacitance sensor measures the MEA capacitance perturbations induced by passing bioparticles, which is sensitive to the bioparticles’ elevations. The experimentally observed and simulated lateral velocity profiles of actuated polystyrene microspheres (PSS) and viable and heat shocked Saccharomyces cerevisiae cells verify that the bioparticles’ dielectric phenotypes can be inferred from the resultant trajectories due to the balance between the DEP force and the viscous fluid drag force.

Fluid suspended biological particles (bioparticles) flowing through a non-uniform electric field are actuated by the induced dielectrophoretic (DEP) force, known to be dependent upon the bioparticles’ dielectric phenotypes. In this work: a 10-1000 kHz DEP actuation potential applied to a co-planar microelectrode array (MEA) induces a DEP force, altering passing bioparticle trajectories as monitored using: (1) an optical assay, in which the lateral bioparticle velocities are estimated from digital video; and (2) a capacitive cytometer, in which a 1.478 GHz capacitance sensor measures the MEA capacitance perturbations induced by passing bioparticles, which is sensitive to the bioparticles’ elevations. The experimentally observed and simulated lateral velocity profiles of actuated polystyrene microspheres (PSS) and viable and heat shocked Saccharomyces cerevisiae cells verify that the bioparticles’ dielectric phenotypes can be inferred from the resultant trajectories due to the balance between the DEP force and the viscous fluid drag force.

L'existence des ondes gravitationnelles (OG) est l'une des prédictions les plus intéressantes de la théorie de la Relativité Générale d'Einstein. La découverte expérimentale des OG serait donc un test important de la théorie elle-même et permettra d'ouvrir une nouvelle fenêtre d'observation en particulier dans les régions de l'Univers inaccessible à l'observation électromagnétique. Les détecteurs interférométriques, comme Virgo, sont les dispositifs les plus prometteurs pour la détection d’OG. Actuellement, leur sensibilité n'est pas encore suffisante pour avoir un taux d'observation de quelques événements/an. Un intense programme expérimental pour l’améliorer est en cours. Particulièrement, les prochaines générations de détecteurs d'OG, aux basses fréquences, seront limitées par l'effet de la pression de radiation (PR) sur les miroirs suspendus. Ce phénomène, pas encore observé expérimentalement, est l'objet d'un champ de recherche très actif. Mon travail ici présenté vise à la construction d'un détecteur pour l'étude des effets quantiques de la PR dans les détecteurs d’OG: QuRaG. Il sera constitué d'un interféromètre de Michelson suspendu dont chaque bras sera une cavité Fabry-Pérot de très haute finesse, dans laquelle seulement le miroir de fond sera suspendu et sensible au bruit quantique de la PR. Durant ma thèse j'ai participé activement au R&D de tous les sous-systèmes de QuRaG. Par conséquent, le travail que j'ai fait porte sur divers aspects du projet dont les problématiques appartiennent à différents domaines de la physique. Mon travail présenté ici démontre que QuRaG sera réalisable et qu’il observera le bruit de la PR dans la bande de fréquences attendue. / The existence of gravitational waves (GW) is one of the most interesting predictions of the theory of general relativity of Einstein. The experimental discovery of GW would be an important test of the theory itself. In addition, the detection of GW will open a new window of observation especially in those regions of the Universe inaccessible to electromagnetic observations. Interferometers, as Virgo are the most promising devices for the detection of GW. Currently, the sensitivity of these detectors is not yet sufficient to have a detection rate of few events/year. Therefore, an intense experimental program to improve the sensitivity is underway. Specifically, the sensitivity of the next generations of GW detectors, at low frequencies, will be limited by the effect of the radiation pressure (RP) on the suspended mirrors. This phenomenon not yet observed experimentally in the ground based GW detectors band, is currently the subject of a very active research field. My work presented here aims at building a detector for studying quantum effects of RP in GW detectors: the QuRaG experiment. It will consist of a suspended Michelson interferometer where each arm will be a high finesse Fabry-Pérot cavity, in which only the end mirror will be further suspended and then sensitive to the RP noise. During my PhD I have actively participated to the R&D of all QuRaG subsystems. Therefore, the work that I have done deals with various aspects of the project whose related problems belong to different domains of physics. My work described in this manuscript demonstrates that QuRaG is realizable and that it will be able to observe the RP noise in the expected frequency range.

The aim of this diploma thesis is to develop a linear positioning stage for Ultra High Vacuum (UHV) environment. Simple prototypes of the linear positioning stage were designed and incorporated as part of a multiaxis sample manipulator for a UHV Scanning Tunneling Microscopy / Atomic Force Microscopy (STM/AFM). Different types of position encoders and linear guideways are discussed. Implementation of the homodyne interferometer as an optimization tool for a slip-stick based linear stage is described. Scalar diffraction theory is used to model the diffraction grating optical position encoder behavior.

This thesis solves the impact of conventional compensation to the volumetric accuracy of the CNC machine. It is therefore a practical research work, where are in the theoretical introduction mentioned requirements for machine tools, the types of errors that can occur on three-axis kinematics, compensation for the control system Siemens Sinumerik 840D sl and devices by means of which are these compensation under the work formed and subsequently verified. In this work can be seen the measured values and graphs from each measurements, a detailed analysis of the results and drawing conclusions from these results.