Techniques for fast, 3D, quantitative microscopy are of great interest in many fields. In this context, in-line digital holography has significant potential due to its relatively simple setup (lensless imaging), its three-dimensional character and its temporal resolution. The goal of this thesis is to improve existing hologram reconstruction techniques by employing an "inverse problems" approach. For applications of objects with parametric shapes, a greedy algorithm has been previously proposed which solves the (inherently ill-posed) inversion problem of reconstruction by maximizing the likelihood between a model of holographic patterns and the measured data. The first contribution of this thesis is to reduce the computational costs of this algorithm using a multi-resolution approach (FAST algorithm). For the second contribution, a "matching pursuit" type of pattern recognition approach is proposed for hologram reconstruction of volumes containing parametric objects, or non-parametric objects of a few shape classes. This method finds the closest set of diffraction patterns to the measured data using a diffraction pattern dictionary. The size of the dictionary is reduced by employing a truncated singular value decomposition to obtain a low cost algorithm. The third contribution of this thesis was carried out in collaboration with the laboratory of fluid mechanics and acoustics of Lyon (LMFA). The greedy algorithm is used in a real application: the reconstruction and tracking of free-falling, evaporating, ether droplets. In all the proposed methods, special attention has been paid to improvement of the accuracy of reconstruction as well as to reducing the computational costs and the number of parameters to be tuned by the user (so that the proposed algorithms are used with little or no supervision). A Matlab® toolbox (accessible on-line) has been developed as part of this thesis

In dieser Arbeit wird die digital-holographisch-interferometrische Zwei-Wellenlängen-Formerfassung sehr schnell bewegter Objekte behandelt und dafür unter Nutzung einer Ultrakurzpuls-Laserquelle mit der digitalen Einzelimpuls-Mehr-Wellenlängen-Holographie ein neuartigen Ansatz der digital-holographischen Aufnahme und Auswertung entwickelt. Mit der Entwicklung spezieller Methoden zur Formung der spektralen Signatur einer Ultrakurzpuls-Laserquelle hoher Leistungsdichte wurde zum ersten Mal die Voraussetzung für eine Zwei-Wellenlängen-Formerfassung hochdynamischer Objekte geschaffen. Die intrinsisch kurze Belichtungszeit unter einer Pikosekunde macht das Verfahren absolut stabil gegenüber Umwelteinflüssen. Für die simultane Aufnahme werden die spektral verschiedenen Hologramme mit einem eigens entwickelten Prinzip der Polarisationskodierung räumlich getrennt und zum ersten Mal mit zwei synchron laufenden Kameras gespeichert. Mit den in der digital-holographischen Einzelimpuls-Mehr-Wellenlängen-Interferometrie zusammengefassten numerischen Routinen zur Rekonstruktion und Phasenauswertung wird eine Zwei-Wellenlängen-Formerfassung mit mehreren Kameras möglich. In Anwendung des neuartigen Verfahrens an verschiedenen dynamischen Mikrosystemen konnte eine Genauigkeit von einem Zwanzigstel der erzeugten synthetischen Wellenlänge, bei der Auswertung der spektralen Differenzphase an Objekten in Reflexion erreicht werden. In einer digital-holographischen Hochgeschwindigkeitsformerfassung in Transmission wurden erstmals Bildfolgefrequenz von mehr als 0,4 kHz erreicht und der interferometrische Eindeutigkeitsbereich auf mehr als das 60-fache der optischen Wellenlänge ausgedehnt. Es wurden die Voraussetzungen für eine digitale Vier-Wellenlängen-Holographie geschaffen. Zukünftig wird eine Formerfassung mit einer Genauigkeit von 10nm über einen eindeutigen interferometrischen Bereich einiger 10 μm und die Untersuchungen von Prozessen auf einer Pikosekunden-Zeitskala möglich sein. / This work deals with the digital holographic interferometric two-wavelength contouring of very fast moving objects and develops with the digital single pulse multiwavelength holography a novel approach of digital holographic recording and analysis, using an ultrashort pulse laser source. The development of several methods to shape the spektral signature of an high power ultrashort pulse laser source provides the precondition for a two-wavelength contouring of highly dynamic objects for the first time. The intrinsically short exposure time shorter than a picosecond makes the system stable regarding external impacts. For the simultaneous recording the spektral different holograms are spatially separated in novel interferometric setups by the especially developed principle of polarization encoding and stored with two synchronized cameras for the first time. The digital holographic single pulse multi-wavelength interferometry combines the numeric routines of reconstruction and phase evaluation that make a two-wavelength contouring possible using more than one camera. The novel approach is successfully demonstrated on several dynamic microsystems. Evaluating the spectral phase difference for objects in reflection an accuracy of 2 μm, which corresponds to the twentieth of the realized synthetic wavelength, could be achieved. In a digital holographic high speed contouring in transmission a frame rate higher than 0,4 kHz was achieved for the first time and the interferometric range of unambiguity was extended larger than sixty times the optical wavelength. Furthermore, the developed digital holographic single pulse multi-wavelength interferometry is not limited to the evaluation of two wavelength. The principles of the method allow to perform digital four-wavelength holography. Future a contouring with an accuracy of 10nm over the unambiguous interferometric range of several 10 μm and the investigation of processes on a picosecond time scale will be possible.

No description available.

The multimedia watermarking techniques are evolved very quickly in the last years with the increase in the use of internet. The evolution of the internet makes the copyright issues very important and many different approaches are appeared to protect the digital content. On the other hand, holography is the method to store the 3-D information of an object but it is very applicable to use as a watermark because of the nature of the holographic data. The 3-D object can be reconstructed from the hologram even if the hologram is cropped or occluded. However, watermarking of an image with a hologram is a very novel approach and there are only a few works in the literature which are not very robust against the attacks like filtering or compression. In this thesis, we propose to embed the phase of the hologram to an image using quantization index modulation (QIM). QIM is utilized to make the watermarking scheme blind and degrade the host image as low as possible. The robustness of the proposed technique is also tested against several attacks such as filtering, compression, etc. The evaluated performance of this system is compared with the existing methods in the literature which uses either holograms or logos as the secret mark. Furthermore, the characteristics of the holograms are investigated and the findings about the hologram compression are reported in this work.

Lithium niobate (LiNbO3) and KTiOPO4 (KTP) are ferroelectric crystals of considerable interest in different fields of optics and optoelectronics. Due to its large values of the nonlinear optical, electro-optic (EO), piezoelectric and acousto-optical coefficients, LiNbO3 is widely used for laser frequency conversion using the quasiphase matching (QPM) approach where the sign of nonlinearity has been periodically modulated by electric field poling (EFP). In the microwave and telecommunication field LiNbO3 is used for surface acoustic devices and integrated optical modulators. KTP and its isomorphs, on the other hand, exhibit slightly lower nonlinear coefficients but have much higher photorefractive damage thresholds, so that it is mainly used in the fabrication of QPM devices for both UV, IR and visible light generation and in high power applications. This thesis focus on different key issues: (1) accurate characterization of specific optical properties of LiNbO3, which are of interest in nonlinear and EO applications; (2) in-situ visualization and characterization of domain reversal by EFP in LiNbO3 and KTP crystals for a through understanding of the ferroelectric domain switching; (3) fabrication of periodic surface structures at sub-micron scale in LiNbO for photonic applications. An interferometric method is used for accurate measurement of ordinary and extraordinary refractive indices in uniaxial crystals, which is of great interest in the proper design of QPM crystals. A digital holography (DH) based method is presented here for 2D characterization of the EO properties of LiNbO , which is considerably interesting in the applications where the proper design of the EO device requires a spatially resolved information about the EO behaviour and the existing pointwise techniques are not sufficient. A DH method for novel in-situ monitoring of domain reversal by EFP in both LiNbO3 and KTP, is also presented here. The technqiue could be used as a tool for high fidelity periodic domain engineering but also provides information about domain kinetics, internal field and crystals defects. 3 3 3 Finally this thesis presents novel results concerning nanoscale periodic surface structuring of congruent LiNbO3. Holographic lithography (HL) is used for sub-micron period resist patterning and electric overpoling for surface domain reversal. Surface structures are obtained by selective etching. Moiré effect is also used in the HL to fabricate complicated structures with multiple periods. The depth compatibility with waveguide implementation allows foreseeing possible applications of these structures for Bragg gratings or innovative photonic crystal devices, exploiting the additional nonlinear and EO properties typical of LiNbO3. / QC 20100824

This work builds up on the greatest minds of Cambridge Holography: Adrian Cable, Edward Buckley, Jonathan Freeman, and Christoph Bay. Cable and Buckley, developed an OSPR algorithm which was the first to provide high-quality real-time hologram generation using general-purpose hardware while Freeman designed a method to correct arbitrary aberrations. As ingenious as the method was, the calculations were extensively lengthy. Addressing this issue, a variant of OSPR suited for correcting spatially-varying aberration is presented. The algorithm combines the approaches of Cable, Buckley and Freeman to provide real-time hologram generation while incorporating various corrections (aberration, distortion, and pixel shape envelope). A high-performance implementation on a mid-range GPU achieved hologram generation up to 12 fps. Following topic studied is an adaptive optical correction. This work attempts to construct a set of methods, forming an automated testbed for holographic projectors. Each model, after exiting the production line is placed on such testbed, having all of its imperfections characterized. Once calibrated, each model is able to display highest-quality image throughout its life-span. An application of this work to industry was carried in collaboration with Dr Phillip Hands (University of Edinburgh) and LumeJET. Three demonstrators are constructed intending for a cost-effective system for holographic lithography. They are characterized using the developed testbed. Using the supersampled Adaptive OSPR algorithm, the diffraction limit was surpassed 2.75 times allowing to increase the patterning area. This combines approaches of Cable, Buckley, Freeman and Bay to achieve a wide field-of-view and high pixel-count replay field using off-the-shelf components. This thesis is finished describing the work on 3D holography carried with Penteract28. It is shown that the 2D hologram in the presence of spatially-varying aberrations is mathematically equivalent to a 3D hologram. The same implementation of the algorithm can be used to provide real-time 3D hologram generation.

This master’s thesis develops a novel method of digital holography, from recent studies known as Fresnel Incoherent Correlation Holography (FINCH). The method enables the reconstruction of the correlation records of three-dimensional objects, captured under quasi-monochromatic, incoherent illumination. The experimental system is based on an action of a Spatial Light Modulator, driven by computer generated holograms to create mutually correlated beams. Both optical and digital parts of the experiment can be carried out using procedures of classical holography, diffractive optics and digital holography. As an important theoretical result of the master’s thesis, a new computational model was proposed, which allows to describe the experiment completely with respect to its two basic phases. The proposed model allows to understood the method intuitively and can be used additionally for analysis and interpretation of the imaging parameters and the system optimalization. The theoretical part of the master’s thesis also presents a detailed description of the correlation imaging based on an appropriate reconstruction process. Computational models were developed for both monochromatic and quasi-monochromatic illumination. In experimental part, all theoretical results were verified. The imaging parameters were examined using standard resolution target tests and appropriate biological samples. As an original experimental result, spiral modification of the system resulting in a vortex imaging was proposed and realized. Here, a selective edge enhancement of three-dimensional objects is possible, resulting in a significant extension of possible applications of the method.

La réalisation de fonctions de filtrage complexes nécessite une parfaite maîtrise du processus de dépôt ainsi qu’un contrôle précis et en temps réel de l’épaisseur optique des couches déposées. Au cours de ma thèse, consacrée au développement de nouvelles modalités de contrôle optique in situ, je me suis particulièrement intéressé à deux sujets différents, à savoir : - D’une part, la détermination de la dépendance spectrale des constantes optiques (indice de réfraction et coefficient d’extinction) de matériaux diélectriques. Un moyen possible pour effectuer cette détermination consiste à utiliser un système de contrôle optique large bande afin d’enregistrer les spectres de transmission de l’empilement au fur et à mesure de sa formation. En effet, l’évolution temporelle, à chaque longueur d’onde, de ces spectres de transmission contient des informations quantitatives liées aux constantes optiques que nous souhaitons déterminer. - D’autre part, la mesure en temps réel du coefficient de réflexion (r) d’un empilement, en amplitude et en phase, lors de son dépôt. En effet, les méthodes de contrôles optiques en intensité présentent des limitations que la connaissance de l’information de phase devrait permettre de contourner. Cette mesure est réalisée par interférométrie holographique digitale à faible cohérence sur un substrat éclairé par sa face arrière et dont la face avant est équipée d’un masque annulaire. Ceci donne accès aux information de phase et d’amplitude recherchées tout en s’affranchissant des vibrations générées par le fonctionnement de la machine de dépôt ainsi que du mouvement de rotation à 120 tours par minute qu’effectue le porte-substrat. / The realization of complex filtering functions requires a perfect mastering of the deposition process as well as an accurate real time monitoring of the optical thickness of the deposited layers. During my PhD thesis, devoted to the development of new methods of in situ optical monitoring, I was particularly interested in two different subjects, namely:- On the one hand, the determination of the spectral dependence of optical constants (refractive index and extinction coefficient) of dielectric materials. A possible way to achieve this determination consist in using a broadband optical monitoring system in order to record the transmission spectra, in real time, of the stack during its formation. Indeed, the temporal evolution, at each wavelength, of these transmission spectra provide quantitative information related to the optical constants that we wish to determine.- On the other hand, the real time measurement of the reflection coefficient (r) of a stack, in amplitude and phase, during its deposition. Indeed, the optical monitoring methods based on intensity proprieties present some limitations that the knowledge of phase information should overcome. This measurement is performed by low coherence digital holographic interferometry on a substrate illuminated by its rear face and whose front face is equipped with an annular mask. This gives access to desired phase and amplitude information while avoiding the parasitic influence of the substrate motions induced by the vibrations of the deposition machine, and the rotation of the substrate holder at 120 rounds per minute.

Le développement de techniques de microscopie quantitatives tridimensionnelles et résolues en temps est fondamental dans de nombreux domaines. Dans ce cadre, l’holographie numérique en ligne recèle un fort potentiel, en raison de sa relative simplicité de mise en œuvre (imagerie sans lentille), de son caractère tridimensionnel et de sa résolution temporelle. Le but de cette thèse est l’amélioration des algorithmes de reconstruction des hologrammes par une approche « problèmes inverses ». Dans le cadre de la reconstruction d’objets paramétriques, des travaux antérieurs ont permis de proposer un algorithme glouton permettant de résoudre le problème inverse de reconstruction (intrinsèquement mal posé) par une maximisation de la vraisemblance entre un modèle de formation d’hologramme et les données. Une première contribution de ce travail de thèse a été de réduire le temps de calcul de cet algorithme en utilisant une approche multi-résolution (algorithme FAST). Dans une deuxième contribution, une approche reconnaissance de forme de type « matching pursuit » est utilisée pour la reconstruction d’objets quelconques en recherchant les éléments d’un dictionnaire les plus proches des figures de diffraction composant l’hologramme. La réduction des dimensions du dictionnaire est proposée en utilisant une décomposition en valeurs singulières tronquée. La troisième contribution de cette thèse a été réalisée en collaboration avec le LMFA. L’algorithme glouton a été utilisé sur un cas réel : la reconstruction et le suivi de gouttelettes d’éther évaporantes en chute libre. Dans tous ces développements une attention particulière a été portée sur la précision des reconstructions, sur la réduction du nombre de paramètres à régler par l’utilisateur (algorithmes peu ou non supervisés). Une boîte à outils Matlab® (en ligne) a été développée dans le cadre de cette thèse / Techniques for fast, 3D, quantitative microscopy are of great interest in many fields. In this context, in-line digital holography has significant potential due to its relatively simple setup (lensless imaging), its three-dimensional character and its temporal resolution. The goal of this thesis is to improve existing hologram reconstruction techniques by employing an “inverse problems” approach. For applications of objects with parametric shapes, a greedy algorithm has been previously proposed which solves the (inherently ill-posed) inversion problem of reconstruction by maximizing the likelihood between a model of holographic patterns and the measured data. The first contribution of this thesis is to reduce the computational costs of this algorithm using a multi-resolution approach (FAST algorithm). For the second contribution, a “matching pursuit” type of pattern recognition approach is proposed for hologram reconstruction of volumes containing parametric objects, or non-parametric objects of a few shape classes. This method finds the closest set of diffraction patterns to the measured data using a diffraction pattern dictionary. The size of the dictionary is reduced by employing a truncated singular value decomposition to obtain a low cost algorithm. The third contribution of this thesis was carried out in collaboration with the laboratory of fluid mechanics and acoustics of Lyon (LMFA). The greedy algorithm is used in a real application: the reconstruction and tracking of free-falling, evaporating, ether droplets. In all the proposed methods, special attention has been paid to improvement of the accuracy of reconstruction as well as to reducing the computational costs and the number of parameters to be tuned by the user (so that the proposed algorithms are used with little or no supervision). A Matlab® toolbox (accessible on-line) has been developed as part of this thesis

Dizertační práce je uceleným shrnutím výsledků dosažených v průběhu doktorského studia. V úvodní části práce je představena motivace, odborné a technické zázemí a grantová podpora realizovaného výzkumu. Popsány jsou také dosažené výsledky a jejich význam pro skupinu Experimentální biofotoniky, Ústavu fyzikálního inženýrství, Vysokého učení technického v Brně. Vědecká část práce je rozdělena do dvou hlavních bloků, které se postupně zabývají návrhem nových zobrazovacích koncepcí a technickou modifikací stávajících zobrazovacích systému v praktických aplikacích. Dosažené vědecké výsledky podporují vývoj v oblastech korelační a spirální mikroskopie s prostorovou modulací světla. V části zabývající se návrhem nových zobrazovacích koncepcí je provedena studie korelačního zobrazení v podmínkách proměnné časové a prostorové koherence. Následně jsou zkoumány možnosti praktického využití vírových a nedifrakčních svazků v oblastech korelační, holografické a optické mikroskopie. Interference vírových svazků a samozobrazení nedifrakčních svazků je postupně využito k dosažení 3D zobrazení s hranovým kontrastem a rotující bodovou rozptylovou funkcí. Pokročilé zobrazovací metody jsou úspěšně zavedeny optickou cestou ale i digitální modifikací holografických záznamů. Výsledky teoretických modelů a numerických simulací jsou doprovázeny praktickým vyhodnocením navržených zobrazovacích principů. V technicky zaměřené části jsou navrženy nové způsoby zavedení prostorové modulace světla, které umožňují rozšíření zorného pole v experimentech korelačního zobrazení a dosažení achromatizace při zobrazení pomocí programovatelných difraktivních prvků. Rozšíření zorného pole v korelačních experimentech umožňuje přizpůsobovací optický systém vložený do standardní zobrazovací sestavy. Achromatizace difraktivního zobrazení je zajištěna použitím speciálně navrženého refraktivního korektoru. V navazující části je navržena nová metoda krokování fáze, která pracuje s dvojlomností kapalných krystalů využívaných v systémech pro prostorovou modulaci světla. Použití metody je experimentálně demonstrováno v polarizačně modifikovaném Mirau interferometru. Získané technické zkušenosti jsou využity v praktickém návrhu a realizaci multimodálního zobrazovacího systému s prostorovou modulací světla.