This research focused on three main objectives: (1) quantify coarse aggregate morphological characteristics using an improved FTI (Fourier Transform Interferometry) image analysis system, (2) evaluate the effects of morphological characteristics of coarse aggregates of various mineral compositions on the mechanical performances of stone matrix asphalt (SMA) mixtures constituted; (3) investigate the relationship between the uncompacted void content of coarse aggregates and morphological characteristics. To achieve the first research objective, a Fourier Transform Interferometry (FTI) system was adopted to capture three-dimensional high-resolution images of aggregates. Based on these digital images, the FTI system uses the two-dimensional Fast Fourier Transform (FFT2) method to rapidly measure aggregate morphological characteristics, including sphericity, flatness ratio, elongation ratio, angularity, and surface texture. The computed shape characteristics of all aggregates were in good agreement with manual measurement results, demonstrating the accuracy and reliability of this image analysis system. For the second objective, a series of simple performance laboratory tests were performed on eight types of SMA mixtures with different morphological characteristics. Test included wheel-track loading, dynamic modulus, flow number, and beam fatigue. The wheel tracking test included asphalt pavement analyzer (APA) and Model mobile load simulator (MMLS). In the APA test, samples included eight types of SMA mixtures that consisted of aggregates of 22 fractions. In the MMLS test, six types of SMA mixture samples that consist of coarse aggregate of 15 fractions were tested. Regression analyses were then conducted between weighted mean morphological characteristics and performance parameters. The fatigue performance parameters include |E*|sin φ, where |E*| is complex modulus obtained from dynamic modulus test, the number of loading cycles to failure, and the seismic modulus difference. The rutting performance parameters include |E*|/sin φ, flow number, flow number slope, rut depth and creep slope. For the third objective, different coarse aggregate fractions from different quarries in Virginia were analyzed using the improved FTI system. Regression analyses were performed to investigate the correlation between morphological characteristics and uncompacted void content of coarse aggregates at the size ranges of 4.75-9.5mm and 9.5-12.5 mm, respectively. Aggregate morphological characteristics were found to play an important role in the mechanical performance of stone matrix asphalt mixture and the uncompacted air void content of the coarse aggregates. Both the experimental results and simulation results demonstrated that using more of equi-dimensional, less flaky and elongated coarse aggregates with angular and rougher-textured aggregates is favorable to the mechanical performances of SMA mixtures. Recommended values for each morphological characteristic are provided. / Ph. D. / Asphalt concrete pavement is used in roads around the world. Keeping this pavement in working condition requires routine maintenance, which can be costly. Therefore, a key problem in civil engineering is the design of resilient asphalt concrete that requires less maintenance. This dissertation experimentally investigates the relationship between the composition of asphalt concrete and its performance. To determine the relationship, several samples of asphalt concrete were collected. Aggregates from these samples were then scanned, and software was used to determine the properties of these aggregates. These asphalt concrete samples were then experimentally tested to determine their mechanical properties. A relationship was then established between the software-determined properties of the aggregates and the mechanical properties of the asphalt concrete samples.

<p dir="ltr">Accurately locating a radio-frequency (RF) emitter is imperative in the defense sector, and passive direction finding systems are intriguing due to relatively low cost. This approach involves using the time difference between a signal’s impact at equispaced antennas to determine the location of the emitter, a particular challenge for wideband waveforms operating near the noise floor. Microwave photonic systems have been demonstrated for passive direction finding. These techniques possessed drawbacks, such as reliance on the incoming signal’s bandwidth, dependence on laser power, or the inability to recover an angle from wideband pulses. This thesis presents a novel approach to passive direction finding by translating the methods of spectral interferometry from the optical domain to RF. Spectral interferometry involves interfering a time-delayed reference pulse with a “signal” pulse that has passed through an unknown system. By removing the spectral phase of the reference pulse from the resulting interferogram, the spectral phase of the uncharacterized system is recovered. This enables direction-finding for many waveforms, including the wideband low peak power chirps frequently used in radar. Incorporating an analog optical delay line into both a hard-wired RF interferometer and a two-element antenna array demonstrated spectral interferometric processing of chirped signals with up to 1 GHz instantaneous bandwidth. The technique extracted accurate delays and angles to within 2$\degree$ throughout testing. This approach only requires the imposed delay be longer than the autocorrelation of the bandwidth limited pulses. With additional backend processing, this method could simultaneously determine the angle and classify the incoming signal.</p>

In vorliegender Arbeit werden Aufbau und Charakterisierung des beidseitig antastenden Interferometers vorgestellt, mit dem die absolute Länge prismatischer Körper ohne Anschub an eine Referenzplatte gemessen werden kann, was Verformungen durch Wechselwirkungen von Endmaßen mit angeschobenen Platten verhindern kann. Die Messunsicherheit im Vergleich zum Prototypen konnte aufgrund eines verbesserten Temperaturmesssystems, eines temperaturstabilisierten Vakuumkessels, Optiken mit besserer Ebenheit und Kameras größerer Auflösung deutlich reduziert werden. Das entwickelte Justageverfahren mit Autokollimationsscan und die Korrektur von Wellenfrontaberrationen tragen ebenso zu einer reduzierten Messunsicherheit bei, wie der durch optimale Ausrichtung der keilförmigen Strahlteilerplatten reduzierte Einfluss von Störinterferenzen. Vergleichsmessungen eines Stahl- und eines Filterglasendmaßes mit einseitig antastenden Interferometern zeigten mit Differenzen im Bereich von 0,4 bis 2,6 nm im Rahmen der Unsicherheiten konsistente Probenlängen, was die gute Eignung des beidseitig antastenden Interferometers für absolute Längenmessungen zeigt. Vergleichsmessungen an Silizium ergaben für die beidseitig antastend gemessenen Längen gegenüber im einseitig antastenden Interferometer gemessenen Längen deutlich geringere Werte und eine reproduzierbare Differenz zwischen den mit 532 und 633 nm gemessenen Längen von etwa 4 nm. Diese Effekte sind vermutlich auf die sich beim beidseitig antastenden Verfahren deutlich stärker auswirkenden Material- und Oberflächeneigenschaften zurückzuführen. Das volle Potential des beidseitig antastenden Interferometers entfaltet sich aufgrund des großen Messunsicherheitsbeitrages der Rauheit und des Phasensprungs bei der Reflexion vor allem bei der Messung von Längenänderungen, wie der thermischen Ausdehnung oder der Langzeitstabilität verschiedener Materialien, für die die Effekte der Rauheit und des Phasensprungs eine vernachlässigbare Rolle spielen. / The present thesis adresses the setup and characterization of PTB´s double-ended interferometer, which allows for absolute length measurement of prismatic bodies without the need for wringing to a platen, which prevents deformation caused by their interaction. In comparison with PTB´s prototype, the measurement uncertainty has been substantially reduced due to an improved temperature measurement system, a temperature stabilized vacuum chamber, optics of better flatness and cameras with higher resolution. Further reduction of the measurement uncertainty has been achieved by the developed adjustment procedure including an autocollimation scanning and a correction of the influence of wavefront aberrations. Multiple configurations of orientation of the beamsplitter plate wedges were tested to minimize the influence of parasitic interferences. Comparison measurements against single-ended interferometers on a steel and a filter glas gauge block resulted in deviations of the measured length in the range of 0.4 to 2.6 nm, which is in good agreement with measurement uncertainties. This proves the capability of absolute length measurement of the double-ended interferometer. Comparison measurements on silicon gauge blocks resulted in significantly shorter lengths than those measured in single-ended interferometers with a reproducible length difference of 4 nm for the different used wavelengths of 532 and 633nm. Those effects are presumably based on material and surface characteristics which seem to have a much stronger impact on the measured length when the sample is not wrung to a platen. Due to the large contribution of the roughness and the phase change on reflection to the measurement uncertainty, the full potential of the double ended interferometer will unfold for measurements on lengths changes, like measurement of the thermal expansion or long term stability of different materials, for which the influence of the roughness and phase change on reflection can be neglected.

Es wird ein "off-axis" Aufbau zur digitalholographischen Mikroskopie in Durchlicht- und Auflichtanordnung vorgestellt, der gleichzeitig hoch aufgelöste "full-field" Amplituden- und quantitative Phasenkontrastmikroskopie ermöglicht. Dabei werden verschiedene Algorithmen zur numerischen Rekonstruktion der komplexen Objektwelle bzgl. ihrer Eignung für die mikroskopische Anordnung miteinander verglichen. Durch Kombination eines beugungsfreien räumlichen Phasenschiebeverfahrens, das die Rekonstruktion ohne "Twin-Image" und nullte Beugungsordnung ermöglicht, und der Auswertung des Fresnel-Kirchhoff''schen Beugungsintegrals mit der Faltungsmethode werden die besten Ergebnisse erzielt. Die gleichzeitige Rekonstruktion der Amplitude und der Phase der Objektwelle aus einem einzigen Hologramm erfordert die mathematische Beschreibung der räumlichen Phasenverteilung in der Hologrammebene. Zur Bestimmung der Modellparameter wurde ein effizienter Algorithmus entwickelt und hinsichtlich seiner Genauigkeit getestet. Darüber hinaus wurde der Zusammenhang zwischen axialer Probenposition und dem Rekonstruktionsabstand, dessen Kenntnis zur quantitativen Auswertung und für eine rein numerische Fokussierung notwendig ist, hergeleitet. Anhand von Untersuchungen an technischen Objekten werden die laterale Auflösung und die Phasenauflösung des Systems quantifiziert und weitere experimentelle Parameter optimiert. Transparente biologische Proben, wie lebende Zellen, werden in Durchlichtanordnung analysiert. Dabei ist zur Bestimmung der Zelldicke die Kenntnis der Brechungsindizes von Zelle und Medium erforderlich. Hierfür wird ein experimentelles Verfahren vorgestellt, das die Abschätzung des integralen Brechungsindexes von Einzelzellen anhand ihrer rekonstruierten räumlichen Phasenverteilung ermöglicht. Exemplarisch wird Zelldifferenzierung aufgrund morphologischer Eigenschaften nachgewiesen und es werden Ergebnisse dynamischer Untersuchungen an lebenden Zellen gezeigt und diskutiert. / An off-axis setup for digital holographic microscopy in incident and transmission light arrangement for simultaneous high resolution full field amplitude and quantitative phase contrast microscopy is presented. Different kinds of algorithms for numerical reconstruction of the complex object wave are compared concerning their applicability to the microscopy arrangement. By combining a non-diffractive spatial phase shifting algorithm that performs reconstruction without the disturbing terms twin image and zero order with the numerical evaluation of the Fresnel-Kirchhoff diffraction integral by a convolution method we achieve best results. The simultaneous reconstruction of the object wave''s amplitude and phase from a single hologram requires a mathematical model of the spatial phase distribution within the hologram plane. An efficient numerical algorithm has been developed for determining the model''s parameters automatically and tested concerning its accuracy. Furthermore, the relation between the axial position of the object and the distance of reconstruction which is required for the quantitative evaluation of the reconstructed images and the application of a pure numerical focus is derived. Technical objects were used to quantify the lateral resolution and the phase resolution of the system and to optimize several parameters of the setup. Biological probes such as living cells are analyzed in transmission light arrangement. As a result the knowledge of the refractive index of the medium and the cell is required to derive the cell''s thickness from the reconstructed phase. Thus a special experimental method for the approximation of the integral refractive index of single cells from the reconstructed phase has been developed. Finally results of cell differentiation by morphological varieties as well as results of stimulated dynamic morphological changes are presented and discussed.

Die einzigartige (bio)-chemische Spezifität der mittleren Infrarotmikroskopie birgt ein enormes Potential für eine breite Palette biomedizinischer und industrieller Anwendungen. Eine wesentliche Einschränkung ergibt sich jedoch durch die unzureichenden Detektionsmöglichkeiten in diesem Wellenlängenbereich, da derzeitige Mittelinfrarot-Detektoren meist durch geringere Leistungsfähigkeit bei deutlich höheren Anschaffungskosten gekennzeichnet sind. Dementsprechend verlagern neuentwickelte Technologien mitunter die Detektion in den sichtbaren Spektralbereich, in dem eine weitaus bessere, Silizium-basierte Kameratechnologie verfügbar ist. Ein solches Verfahren, das im Mittelpunkt dieser Arbeit steht, ist die Quantenbildgebung mit undetektiereten Photonen, welche sich zunehmend als leistungsfähiges Werkzeug für Infrarot-Bildgebung entwickelt. Der optische Aufbau basiert auf nichtlinearer Interferometrie bei der räumlich verschränkte, nicht-entartete Photonenpaare die Entkopplung der Analyse- und Detektionswellenlängen ermöglicht. Entsprechend wird die Bildgebung im mittleren Infrarotbereich durch die Detektion von Nahinfrarotlicht mit einer handelsüblichen CMOS-Kamera realisiert. In dieser Arbeit wird die beschriebene Methode auf die Mikroskopie übertragen, wodurch Abbildungen biologischer Gewebeproben im mittleren Infrarotbereich mit einer Auflösung von geringer als 10 Mikrometer angefertigt werden können. Darüber hinaus werden zwei Abbildungsregime untersucht, die auf den komplementären Impuls- und Positionskorrelationen der Photonenpaare basieren. Weiterführende Möglichkeiten der Kombination von Quanten-Bildgebung mit unentdeckten Photonen und FTIR-Spektroskopie zum Zwecke der räumlich-spektral kontinuierlichen Datenerfassung werden besprochen. Die vorgestellten Ergebnisse stellen die Entwicklungsfähigkeit der Quantenbildgebung mit unentdeckten Photonen unter Beweis und demonstrieren ihr Potential für praxisnahe Anwendungen in der Biomedizin und der Industrie. / The unique (bio)-chemical specificity of mid-infrared (IR) microscopy holds tremendous promise for a wide range of biomedical and industrial applications. Significant limitation, however, arises from poor detection capabilities in this wavelengths range, with current mid-IR detection technology often marrying inferior technical capabilities with prohibitive costs. Accordingly, emerging approaches shift detection into the visible regime, where vastly superior silicon-based camera technology is available. One such technique, and the one that is in the center of this thesis is quantum imaging with undetected photons (QIUP), which has recently emerged as a new powerful imaging tool. The optical layout is based on nonlinear interferometry, where spatially entangled non-degenerate photon pairs enable the decoupling of the sensing and detection wavelengths, facilitating mid-IR wide-field imaging through the detection of near-IR light with an off-the-shelf CMOS camera. Additionally, the method is expanded towards microscopy, attaining sub-10 μm resolution, demonstrating our technique is fit for purpose, acquiring microscopic images of biological tissue samples in the mid-IR. Additionally, two imaging regimes are explored, based on the complementary momentum and position correlations. A comparison between the two regimes is presented and some limitations of the technique are discussed. Further efforts of combining QIUP with Fourier Transform IR spectroscopy for spatio-spectral continuous data acquisition are reviewed. The presented results demonstrate the achieved progress towards advancing QIUP to enable real-world biomedical as well as industrial imaging applications.

As advances in thin films are made there is a parallel requirement to develop equipment capable of measuring their properties accurately and consistently. In addition there is a need to understand the parameters that are measured. Typical DPI measurements allow both the refractive index (related to density) and the thickness of the adsorbed layer to be calculated with relatively few assumptions, to a very high precision in real time. This thesis presents the research undertaken to develop multiple path length dual polarisation interferometry (MPL-DPI) and absorption enhanced dual polarisation interferometry (AE-DPI). In addition research is presented that can be used to improve the interpretation of the measured parameters for inhomogeneous films and uniaxial films. The new Interferometric technique MPL-DPI allows the thickness and refractive index of in situ and ex-situ coated ultra-thin films to be measured. The procedures and the mathematics required to calculate the properties of films have been described and the technique verified. The technique was demonstrated using films of PMMA, where good agreement was found with complementary techniques. Furthermore, some key features of MPL-DPI were demonstrated using the measurements of interfacially grafted acrylic acid. The absorption enhanced DPI uses the attenuation of the light within the waveguide, due to the light absorbing properties of a film on its surface. As the composition of a film changed, it was shown that the refractive index and extinction coefficients could be used to separate the mass of the components of the film that absorbed light, from the components of the film that did not. With the use of a semi-uniaxial model, the extra data from the attenuation in two polarisations was used to fit the extraordinary and ordinary extinction coefficients. The extraordinary and ordinary extinction coefficients were used to demonstrate that molecular orientation could be implied. The influence that an inhomogeneous film has on the measured thickness, refractive index and extinction coefficient fitted by homogeneous models were investigated. Formulas are presented to explain the thickness, refractive index and extinction coefficient of the measured film. A formula for the total mass per unit area that uses the refractive index was created to account for films that contain molecules of different refractive index increments (dn/dc's). To separate the mass of the individual molecular species from the total mass per unit area, formulas that use the extinction coefficient were derived so molecules that absorb light could be separated from those that do not. The mass calculated from the refractive index and the mass calculated from the extinction coefficient were also examined for uniaxial films. For uniaxial films both measures of the adsorbed mass were found to be relatively accurate and benefited from a partial cancellation of errors. The accuracy of the measurements made by dual polarisation interferometry technology is systematically examined throughout this thesis. Improvements in the calibration routines are suggested and a procedure for the identification and reduction of errors in the phase and contrast is demonstrated.

The two main themes in this thesis are the implementation of interference methods with optically trapped particles for measurements of position and optical phase (optical interferometric metrology) and the optical manipulation of nanoparticles for studies in the assembly of nanostructures, nanoscale heating and nonlinear optics (nanophotonics). The first part of the thesis (chapter 1, 2) provides an introductory overview to optical trapping and describes the basic experimental instrument used in the thesis respectively. The second part of the thesis (chapters 3 to 5) investigates the use of optical interferometric patterns of the diffracting light fields from optically trapped microparticles for three types of measurements: calibrating particle positions in an optical trap, determining the stiffness of an optical trap and measuring the change in phase or coherence of a given light field. The third part of the thesis (chapters 6 to 8) studies the interactions between optical traps and nanoparticles in three separate experiments: the optical manipulation of dielectric enhanced semiconductor nanoparticles, heating of optically trapped gold nanoparticles and collective optical response from an ensemble of optically trapped dielectric nanoparticles.

Mergers are known to be essential in the formation of large scale structures and to have a significant role in the history of galaxy formation and evolution. Besides a morphological transformation, mergers induce important bursts of star formation. These starburst are characterised by high Star Formation Efficiencies (SFEs) and Specific Star Formation Rates, i.e., high Star Formation Rates (SFR) per unit of gas mass and high SFR per unit of stellar mass, respectively, compared to spiral galaxies. At all redshifts, starburst galaxies are outliers of the sequence of star-forming galaxies defined by spiral galaxies. We have investigated the origin of the starburst-mode of star formation, in three local interacting systems: Arp 245, Arp 105 and NGC7252. We combined high-resolution JVLA observations of the 21-cm line, tracing the Hi diffuse gas, with UV GALEX observations, tracing the young star-forming regions. We probe the local physical conditions of the Inter- Stellar Medium (ISM) for independent star-forming regions and explore the atomic-to-dense gas transformation in different environments. The SFR/H i ratio is found to be much higher in central regions, compared to outer regions, showing a higher dense gas fraction (or lower Hi gas fraction) in these regions. In the outer regions of the systems, i.e., the tidal tails, where the gas phase is mostly atomic, we find SFR/H i ratios higher than in standard Hi-dominated environments, i.e., outer discs of spiral galaxies and dwarf galaxies. Thus, our analysis reveals that the outer regions of mergers are characterised by high SFEs, compared to the standard mode of star formation. The observation of high dense gas fractions in interacting systems is consistent with the predictions of numerical simulations; it results from the increase of the gas turbulence during a merger. The merger is likely to affect the star-forming properties of the system at all spatial scales, from large scales, with a globally enhanced turbulence, to small scales, with possible modifications of the initial mass function. From a high-resolution numerical simulation of the major merger of two spiral galaxies, we analyse the effects of the galaxy interaction on the star forming properties of the ISM at the scale of star clusters. The increase of the gas turbulence is likely able to explain the formation of Super Star Clusters in the system. Our investigation of the SFR–H i relation in galaxy mergers will be complemented by highresolution Hi data for additional systems, and pushed to yet smaller spatial scales.

L'interférométrie à rétro-injection optique, également connu sous le nom de Self-Mixing, permet de concevoir des capteurs qui sont compacts, auto-alignés et sans contact. Dans ce phénomène, une partie du faisceau laser de retour réfléchi par la cible rentre dans la cavité active de laser et fait varier ses propriétés spectrales. La diode laser agit alors comme une source de lumière, un microinterféromètre ainsi qu'un détecteur de lumière. Dans cette thèse, un capteur de déplacement, basé sur la rétro-injection optique, a été optimisé de sorte que des mesures précises peuvent être obtenues en temps réel. Le capteur est robuste à la disparition des franges de self-mixing pour des vibrations harmoniques. Il est également capable de s'adapter à un changement dans le régime de feedback optique et peut donc extraire le déplacement dans les cas les plus répandus expérimentalement, à savoir un feedback faible puis modéré. L'utilisation de l'optique adaptative, sous la forme d'une lentille liquide, a également été démontrée pour ce capteur, ce qui nous a permis de maintenir le capteur dans un régime de feedback favorable. L'influence du speckle a également été réduite de telle sorte que le capteur mesure jusqu'à la gamme centimétrique pour des cibles non- oopératives. Une nouvelle technique est également présentée, elle permet de rendre le capteur insensible aux vibrations mécaniques parasites qui fausseraient la mesure pour des conditions industrielles. / Optical Feedback Interferometry, also known as Self-Mixing, results in compact, selfaligned and contact-less sensors. In this phenomenon, a portion of the laser beam is back reflected from the target and enters the active laser cavity to vary its spectral properties. The laser diode then simultaneously acts as a light source, a micro- nterferometer as well as a light detector. In this thesis, a self-mixing displacement sensor has been optimised so that precise measurement can be obtained in real-time. The sensor is robust to the disappearance of self-mixing fringes for harmonic vibrations. It is also able to auto-adapt itself to a change in the optical feedback regime and so can extract displacement from the weak as well as moderate feedback regime signals. The use of adaptive optics, in the form of a liquid lens, has also been demonstrated for this sensor, which has allowed us to maintain the sensor in a fringe-loss less regime. The influence of speckle has also been reduced so that the sensor can now measure up to the centimetric range for non-cooperative targets. A novel technique has also been presented that makes the sensor insensitive to parasitic mechanical vibrations that would falsify the measurement under industrial conditions.

Le but de ce mémoire est de valider la microscopie électro-optique Pockels comme méthode de mesure et de cartographie de champ électrique aux échelles micro et nanométriques. Une première partie est dédiée à la description de l’instrumentation d’imagerie mise en jeu. Nous développons ensuite son application en physique et biophysique. Une étude de couches minces monocristallines de 2-methyl-4-nitroaniline (MNA) a permis de sonder localement la variation de champ électrique appliqué, mais aussi d’étudier l’orientation des axes optiques de ce cristal dans l’espace. A l’échelle sub-longueur d’onde nous avons pu isoler la modulation électro-optique de la diffusion de lumière associée à une nanoparticule isolée de KTiOPO4 (KTP) d’une taille de 150nm. La dépendance polaire du signal Pockels sur la polarisation lumineuse incidente a permis de prédire l’orientation de la maille cristalline du KTP dans l’espace. De telles sondes de champs électriques nanométriques peuvent avoir de nombreuses applications en nano-photonique. Dans le cas d’entité biologiques comme des neurones, la propagation de l’information est assurée par celle d’un champ électrique dans les membranes plasmiques. Dans une première étape, nous nous sommes intéressés à l’étude de bicouches artificielles dopées par un colorant non-linéaire, le DI-8-ANEPPS. Un signal électro-optique Pockels y a été mesuré pour la première fois. La caractérisation de l’insertion du colorant dans la membrane a été aussi discutée. La grande sensibilité à la mesure d’un champ électrique assurée par l’interféromètre permet d’envisager des possibilités d’applications dans des cellules vivantes. Des expériences menées sur des cellules de type PC12 ont montré l’existence d’un signal optique qui est associé à la distribution spatiale du champ électrique. L’ensemble de ces travaux montrent que la microscopie électro-optique s’avère constituer un outil important pour la physique et biophysique. / The aim of this thesis is to validate the electro-optical Pockels microscopy as a powerful technique for electric field imaging at nano and micrometer scales. A first part of this manuscript is dedicated to the instrumental aspects of this new microscope modality. Then we discuss its application in physical and biophysical domains. We have investiguqted 2-methyl-4-nitroaniline(MNA) monocrystalline molecular thin films where the electric field distribution could be imaged, and crystal orientation retrieved. At sub-wavelength scale, we were able to isolate the electro-optical modulation of light scattered by isolated 150nm size KTiOP04 (KTP) nanoparticles. Using the angular dependency of the Pockels response to the polarization of light we could determine the a priori random, spatial orientation of the nanocrystal. Such electric-field nano-probe configuration could find its way in various applications. In the case of biological entities such as neurons, information is transmitted via an electric field signal, propagating through the plasmid membrane. We concentrated first on a model artificial membrane doped with the DI-8-ANEPPS nonlinear dye, evidencing for the first time a Pockels electro-optical response. A relatively high sensitivity to the electric field allows to envision interesting applications in living cells. Experiences performed with PC 12 cells have shown an optical response that reflects the electric field spatial distribution. This work demonstrates that the electro-optical microscopy is emerging as a new powerful tool for sub-wavelength investigation of electro-optical properties in physics and biology.