The conventional methods for diagnosing pathological conditions of the tympanic membrane (TM) and other abnormalities require measuring its motion while responding to acoustic excitation. Current methodologies for characterizing the motion of the TM are usually limited to either average acoustic estimates (admittance or reflectance) or single-point mobility measurements, neither of which is sufficient to characterize the detailed mechanical response of the TM to sound. Furthermore, while acoustic and single-point measurements are useful for the diagnosis of some middle ear disorders, they are not useful in others. Measurements of the motion of the entire TM surface can provide more information than these other techniques and may be superior for the diagnosis of pathology. In this Thesis, the development of an optoelectronic holographic otoscope (OEHO) system for characterization of nanometer scale motions in TMs is presented. The OEHO system can provide full-field-of-view information of the sound-induced displacements of the entire surface of the TM at video rates, allowing rapid quantitative analysis of the mechanical response of normal or pathological TMs. Preliminary measurements of TM motion in cadaveric animals helped constrain the optical design parameters for the OEHO, including the following: image contrast, resolution, depth of field (DOF), laser power, working distance between the interferometer and TM, magnification, and field of view (FOV). Specialized imaging software was used in selecting and synthesizing the various components. Several prototypes were constructed and characterized. The present configuration has a resolution of 57.0 line pairs/mm, DOF of 5 mm, FOV of 10 ´ 10 mm2, and a 473 nm laser with illumination power of 15 mW. The OEHO system includes a computer controlled digital camera, a fiber optic subsystem for transmission and modulation of laser light, and an optomechanical system for illumination and observation of the TM. The OEHO system is capable of operating in two modes. A 'time-averaged' mode, processed at video rates, was used to characterize the frequency dependence of TM displacements as tone frequency was swept from 500 Hz to 25 kHz. A 'double-exposure' mode was used at selected frequencies to measure, in full-field-of-view, displacements of the TM surface with nanometer resolution. The OEHO system has been designed, fabricated, and evaluated, and is currently being evaluated in a medical-research environment to address basic science questions regarding TM function. Representative time-averaged holographic and stroboscopic interferometry results in post-mortem and live samples are herein shown, and the potential utilization discussed.

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.

No description available.

In this thesis, applications of Holography in the context of Condensed Matter Physics and in particular hydrodynamics, will be studied. Holog- raphy or gauge/gravity duality has been an enormously useful tool in studying strongly-coupled Field Theories with particular success in their low-frequency and large-wavelength fluctuation regime, i.e the hydrody- namical regime. Here, following a phenomenological approach, gravita- tional systems, simple enough to be properly examined, will be studied in order to derive as much information as possible about their dual theories, given that their exact form is not accessible in this way. After a review of the most important elements of standard Condensed Matter Theory, the gauge/gravity duality itself will be presented, along with some of its most important achievements. Having established the framework of this work, the main results of this thesis will be presented. Initially the sound channel of the theory dual to the anti-de Sitter Reissner–Nordstro ̈m black hole space-time will be studied, at finite temperature and finite chemical potential. Hydrodynamical properties of the boundary theory will be of major interest. Following that, focus will be shifted towards another grav- itational system, namely the Electron Star. There, the shear channel of the dual theory will be mainly examined. The goal will be, as before, to extract information about the hydrodynamical properties of the boundary theory.

This work presents recent progress in the area of organic photorefractive polymer composites. These materials have been previously shown to be a suitable medium for dynamic holographic displays, with multiple colors and single frame writing times on the order of seconds. However, these materials still require large electric fields and high intensity lasers to function effectively. Recent advancements in improving these areas are discussed, including a review of the history and state-of-the-art in photorefractive polymer composites.The addition of electron traps via low loading of the electron-transporting molecule Alq3 is shown to dramatically improve the diffraction efficiency and reduce the required field. The grating formation also proceeds faster by more than one order of magnitude, leading to an increase in sensitivity by a factor of 3. The dynamics of these materials also show evidence of competing gratings indicative of bipolar charge transport and trapping.The addition of an amorphous polycarbonate (APC) buffer layer is reported to have a similar effect on the steady-state diffraction efficiency, and the further doping with a fullerene derivative (PCBM) allows a 3x increase in the efficiency in the reflection geometry, which is normally poor due to the small grating spacing. These composites reveal the fundamental limits of the reflection geometry, based on the physics of high frequency gratings. A reversal in the direction and increase in the magnitude of the two-beam coupling energy transfer is also observed.The use of interdigitated coplanar electrodes, instead of the standard uniform electrodes in a parallel-plate geometry, is shown to result in large diffraction efficiency with symmetric writing beams due to the increased projection field. The efficiency is similar to that achieved in the standard samples with large slant angles and much better than those geometries typically used in applications, with the benefit that the writing beams do not have to be slanted with respect to the sample normal. Different electrode widths are examined and the trade-offs discussed. This device makes beam injection simpler and allows one to bring the benefits of highly slanted geometries, common to small area setups, to the large-area applications.

The polarization dependent diffraction efficiency and imaging properties of high numerical aperture (N.A.) holographic optical elements (HOEs) were investigated to determine the suitability of these elements for magneto-optic data storage head applications. Two-wave first-order coupled wave theory was combined with a local planar grating model to determine the s and p-polarization diffraction efficiency characteristics of these HOEs. Experimental results for 0.55 N.A. focusing HOEs fabricated in silver halide photographic emulsions and dichromated gelatin films demonstrated that the p-to-s-polarization diffraction efficiency ratio at the Bragg angle corresponded with theoretical results to within 5%. Diffraction based wave propagation theory and a geometrical ray trace model were used to evaluate the imaging performance of these elements. Results from the diffraction based wave propagation model showed that the HOEs imaging performance had very minimal polarization dependence. The ray trace model indicated precise alignment and good wavelength stability are needed to achieve diffraction limited performance.

In 1993, 't Hooft (1999 Nobel Prize winner in physics) proposed that quantum gravity requires that the information in a three dimensional world can be stored on a two dimensional manifold much like a hologram. This is known as the holographic principle, and since then this idea has changed the direction of researches in quantum gravity. A concrete realization of this idea in string theory was first discovered in 1997 by Maldacena in his famous anti de-Sitter/Conformal Field Theory\footnote{AdS/CFT for short. AdS stands for anti de-Sitter, and CFT is the acronym for Conformal Field Theory.} correspondence conjecture. The AdS/CFT correspondence states that some string theories on a certain manifold that contains AdS space, in some limits, are dual to a CFT living on the boundary of this manifold. Despite the rapid progress in studying the AdS/CFT, this proposal is still away from practical applications. Some of the reasons are the fact that the AdS (anti-de Sitter) spacetime is not likely the spacetime where we are living nowadays and the existence of extra dimensions (as one of the ingredients in string theory) is still under question. The Kerr/CFT correspondence which was proposed in 2008 by Strominger et al appears to be a more ``down to earth'' duality, compared to the AdS/CFT correspondence. Originally, this new correspondence states that the physics of extremal Kerr black holes which are rotating by the maximal angular velocity can be described by a two dimensional CFT living on the near horizon. In this thesis, after reviewing some concepts in Kerr/CFT correspondence, I present some of my research results which extend and support the correspondence for non-extremal rotating black holes. I discuss the extension of the Kerr/CFT correspondence for the rotating black holes in string theory, namely Kerr-Sen black holes, and the Kerr/CFT analysis for vector field perturbations near the horizon of Kerr black holes. It is recently conjectured that a generic non-extremal Kerr black hole could be holographically dual to a hidden conformal field theory in two dimensions. Furthermore, it is known that there are two CFT duals (pictures) to describe the charged rotating black holes which correspond to angular momentum $J$ and electric charge $Q$ of the black hole. Furthermore these two pictures can be incorporated by the CFT duals (general picture) that are generated by $SL(2,\mathbb{Z})$ modular group. The general conformal structure can be revealed by looking at a charged scalar wave equation with some appropriate values of frequency and charge. In this regard, we consider the wave equation of a charged massless scalar field in the background of Kerr-Sen black hole and show in the ``near region", the wave equation can be reproduced by the squared Casimir operator of a local $SL(2,\mathbb{R})_L \times SL(2,\mathbb{R})_R$ hidden conformal symmetry. We can find the exact agreement between macroscopic and microscopic physical quantities like entropy and absorption cross section of scalars for Kerr-Sen black hole. We then find an extension of the vector fields that in turn yields an extended local family of $SL(2,\mathbb{R})_L \times SL(2,\mathbb{R})_R$ hidden conformal symmetries, parameterized by one parameter. For some special values of the parameter, we find a copy of $SL(2,\mathbb{R})$ hidden conformal algebra for the charged Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole in the strong deflection limit. The generic non-extremal Kerr-Newman black holes are holographically dual to hidden conformal field theories in two different pictures. The two pictures can be merged together to the CFT duals in the general picture that are generated by $SL(2,\mathbb{Z})$ modular group. We find some extensions of the conformal symmetry generators that yield an extended local family of $SL(2,\mathbb{R})_L \times SL(2,\mathbb{R})_R$ hidden conformal symmetries for the Kerr-Newman black holes, parameterized by one deformation parameter. The family of deformed hidden conformal symmetry for Kerr-Newman black holes also provides a set of deformed hidden conformal generators for the charged Reissner-Nordstrom black holes. The set of deformed hidden conformal generators reduce to the hidden $SL(2,\mathbb{R})$ conformal generators for the Reissner-Nordstrom black hole for specific value of deformation parameter. We also find agreement between the macroscopic and microscopic entropy and absorption cross section of scalars for the Kerr-Newman black hole by considering the appropriate temperatures and central charges for the deformed CFTs. Also in this thesis, we derive an appropriate boundary action for the vector fields near the horizon of near extremal Kerr black hole. We then use the obtained boundary action to calculate the two-point function for the vector fields in Kerr/CFT correspondence. In performing this analysis we borrow a formula proposed in AdS/CFT, namely the equality between the bulk and boundary theories partition functions. We show the gauge-independent part of the two-point function is in agreement with what is expected from CFT.

The work embodied in this thesis describes software techniques developed to analyse digital inline holograms of suspended particle fields, particularly in aquatic environ- ments. The primary motivation behind this work has been development of tech- niques to extract useable information from individual holograms within holovideos, producing focused silhouettes of recorded plankton and other particulates with min- imal user intervention. Two automated focusing algorithms are developed and presented in this work, both of which obtain comparable results for holograms of sparse plankton populations. The first approach is based on rectangular regions of interest (ROIs), which are aligned to (x, y) dimensions, and localise particles within the two-dimensional recon- structed planes obtained from holovideo frames. Due to poor immunity to particle merging when applied to denser particle fields, a second approach was developed using arbitrary polygons with which to localise particle positions in reconstructed planes. This new approach offers a greater immunity to the merging of particles lying in close proximity in the (x, y) dimensions of the hologram, and allows better particle localisation for high density particle holograms. Both ROI and polygon based particle localisation are explored to identify strengths and weaknesses, and complete automated scanning procedures developed in both cases. Examples are provided of typical output from automated scanning algorithms when applied to a number of sample holograms, and areas of weakness highlighted for future work.

Digital holography (DH) has a variety of applications on measuring the 3D position of different kinds of particles, including the droplets created in drop breakups, seeding particles for flow velocity measurements, characterizations of the behavior of the microorganisms, etc. A particle detection method is required to extract the 3D information encoded in the interference patterns of the holograms, which is desired to be accurate and fast. As the accuracy of the particle detection method improves, the time efficiency of the method decreases. In this study, an optimization process is developed based on an existing method to shorten the processing time. The optimization process includes reducing the complexity of the method and introducing the parallel processing algorithm that can be implemented on cluster machines. The existing particle detection method is separated into several steps and analyzed. The most time consuming step, refining the threshold to separate overlapping particles, is the focus of complexity reduction optimization. A Python code is developed, based on object oriented programming, to implement the optimization. Message Passing Interface (MPI) is applied for parallel processing with a 24-core remote workstation. The optimized Python code is compared with the existing Matlab code in both time consumption and accuracy aspects with synthetic holograms. It is found that the optimization process is able to reduce the time consumption by about four times with an acceptable sacrifice in accuracy. Finally, a DIH system with the optimized method, is applied to characterize different kinds of solid particles. One is noted that the previous studies focus on measuring artificial particles or droplets which are both spherical particles, while most natural solid particles usually have irregular shapes. Equivalent diameter, circularity and aspect ratio are introduced to quantify the dimension and morphology of the irregular shapes. The statistics of the parameters are generated to characterize different kinds of the particles. The accuracy of the characterization of the particles are verified with the observation of the microscopic images of the particles, which can further prove the improvement of the optimized method for particle detection.

A finalidade deste trabalho é aplicar a técnica de holografia em cristais fotorrefrativos para o estudo de propriedades mecânicas de microdispositivos, garantindo ainda a obtenção de uma geometria de arranjo holográfico simples e compacto. Foram feitas a análise de vibração e a análise de deformação de microdispositivos por meio da interferometria de média temporal e de dupla exposição, respectivamente. Como fontes de luz, foram utilizados diodos laser emitindo em 660nm, e um He-Ne laser emitindo em 632,8nm. Como meio fotorrefrativo de registro holográfico foi utilizado o cristal Bi12TiO20, (BTO) da família das selenitas. Foi proposto um arranjo óptico de holografia de reflexão do tipo Denisiuk, e a este arranjo foi adicionado um conjunto de lentes objetiva e ocular para formar uma configuração de microscópio composto, com o objetivo de obterem-se imagens holográficas de objetos de dimensões microscópicas. A gravação e a reconstrução do holograma se deram simultaneamente, devido à associação do cristal fotorrefrativo a uma câmera CMOS. Desta maneira, a observação dos hologramas foi feita em tempo real. Foram feitas, inicialmente, imagens de dupla exposição de piezorresistores MEMS (microelectromechanical systems), de geometria reduzida (2,96 x 0,6 mm2), e de dispositivos CMUT (Capacitive Micromachined Ultrasonic Transducers) com 640m de diâmetro. Através desta técnica foi possível medir deslocamentos de 0,33m a 4,3m. Foram obtidos também interferogramas de média temporal de cerâmicas e transdutores piezoelétricos, porém, iluminando apenas pequenas regiões destes objetos. Estas imagens mostraram qualidade razoável, indicando que é possível aplicar a técnica de interferometria em média temporal para objetos com amplitude de vibração entre 0,12m e 1,7m. Para investigar as potencialidades microscópicas foram feitas imagens de padrões de teste de resolução, onde foi possível visualizar estruturas com geometrias entre 2mm e 20m. / The aim of this work is to apply photorefractive crystals holography technique for the study of mechanical properties of micro-devices; it ensures obtaining a simple and compact geometry of holographic setup. Vibration and deformation analyses of micro-devices were performed using time average and double exposure interferometry, respectively. As light sources, it was used diode lasers emitting at 660nm, and He-Ne laser emitting at 632.8nm. As photorefractive holographic recording medium was used Bi12TiO20 (BTO) crystal, family of selenites. An optical setup of Denisiuk-type reflection holography was proposed, and this setup was added a set of objective and eyepiece lenses to form a compound microscope configuration, in order to obtain holographic images of objects with microscopic dimensions. Recording and reconstruction of the hologram occurred simultaneously, due to the combination of the photorefractive crystal to a CMOS camera. Thus, holograms observation occurs in real time. It was initially performed double exposure images of MEMS (microelectromechanical systems) piezoresistors, with reduced geometry (2.96 x 0.6 mm2), and CMUT (capacitive micromachined ultrasonic transducers) devices with 640m diameter. By this technique was possible measure displacements of 0.33m to 4.3m. Time average interferograms of Ceramics and piezoelectric transducers were also obtained, however, it illuminating only small regions of these objects. These images showed reasonable quality, indicating that it is possible apply the time average technique for objects with vibration amplitude between 0.12m e 1.7m. In order to investigate the microscopic potentialities images of resolution test chart were done, where it was possible to visualize structures with geometries between 20 m and 2mm.