In this thesis, we build upon the work of Plate by advancing the theory and utility of Holographic Reduced Representations (HRRs). HRRs are a type of linear, associative memory developed by Plate and are an implementation of Hinton’s reduced representations. HRRs and HRR-like representations have been used to model human memory, to model understanding analogies, and to model the semantics of natural language. However, in previous research, HRRs are restricted to storing and retrieving vectors of random numbers, limiting both the ability of HRRs to model human performance in detail, and the potential applications of HRRs. We delve into the theory of HRRs and develop techniques to store and retrieve images, or other kinds of structured data, in an HRR. We also investigate square matrix representations as an alternative to HRRs, and use iterative training algorithms to improve HRR performance. This work provides a foundation for cognitive modellers and computer scientists to explore new applications of HRRs. / Thesis (Master, Computing) -- Queen's University, 2010-08-10 12:50:04.004

This thesis introduces normal factor graphs under a new semantics, namely, the exterior function semantics. Initially, this work was motivated by two distinct lines of research. One line is ``holographic algorithms,'' a powerful approach introduced by Valiant for solving various counting problems in computer science; the other is ``normal graphs,'' an elegant framework proposed by Forney for representing codes defined on graphs. The nonrestrictive normality constraint enables the notion of holographic transformations for normal factor graphs. We establish a theorem, called the generalized Holant theorem, which relates a normal factor graph to its holographic transformation. We show that the generalized Holant theorem on one hand underlies the principle of holographic algorithms, and on the other reduces to a general duality theorem for normal factor graphs, a special case of which was first proved by Forney. As an application beyond Forney's duality, we show that the normal factor graphs duality facilitates the approximation of the partition function for the two-dimensional nearest-neighbor Potts model. In the course of our development, we formalize a new semantics for normal factor graphs, which highlights various linear algebraic properties that enables the use of normal factor graphs as a linear algebraic tool. Indeed, we demonstrate the ability of normal factor graphs to encode several concepts from linear algebra and present normal factor graphs as a generalization of ``trace diagrams.'' We illustrate, with examples, the workings of this framework and how several identities from linear algebra may be obtained using a simple graphical manipulation procedure called ``vertex merging/splitting.'' We also discuss translation association schemes with the aid of normal factor graphs, which we believe provides a simple approach to understanding the subject. Further, under the new semantics, normal factor graphs provide a probabilistic model that unifies several graphical models such as factor graphs, convolutional factor graphs, and cumulative distribution networks.

The performance of communication and storage systems can be improved if the data being sent or stored has certain patterns and structure. In particular, some benefit if the frequency of the symbols is balanced. This includes magnetic and optical data storage devices, as well as future holographic storage systems. Significant research has been done to develop techniques and algorithms to adapt the data (in a reversible manner) to these systems. The goal has been to restructure the data to improve performance while keeping the complexity as low as possible. In this thesis, we consider balancing binary sequences and present its application in holographic storage systems. An overview is given of different approaches, as well as a survey of previous balancing methods. We show that common compression algorithms can be used for this purpose both alone and combined with other balancing algorithms. Simplified models are analyzed using information theory to determine the extent of the compression in this context. Simulation results using standard data are presented as well as theoretical analysis for the performance of the combination of compression with other balancing algorithms. / Graduate

The aim of this project was to develop a passive optical compensating arrangement that would allow the formation and continued stability of interference patterns over a long timescale and also to investigate optical wave scattering in thick gratings at extreme angles of scattering. A novel passive arrangement based on a Sagnac interferometer is described that produces interference patterns more stable than those produced by a conventional arrangement. An analysis of the arrangement is presented that shows it to be an order of magnitude more stable than an equivalent conventional approach. The excellent fringe stability allowed holographic gratings with small periods (~ 0.5 μm) to be written in photorefractive lithium niobate with low intensity writing fields (~mW/cm2) produced by a He:Ne laser, despite long grating fabrication times (~ 1000 s). This was possible because the optical arrangement compensated for phase shifts introduced by translational and rotational mirror motion caused by environmental perturbations. It was shown that the rapid introduction of a phase shift in one of the writing fields can change the direction of energy flow in the two-wave mixing process. It was found that the improvement in stability of the modified Sagnac arrangement over a conventional interferometer decreased when the crossing angle was increased and that the point about which the mirrors are rotated greatly affects the stability of the arrangement. For a crossing angle of 12 degrees, the modified Sagnac arrangement is more than twice as stable when the mirrors are rotated about their midpoints, rather than their endpoints. Investigations into scattering in the extremely asymmetrical scattering (EAS) geometry were undertaken by scattering light from a 532nm Nd:YAG laser off gratings written in photorefractive barium titanate and lithium niobate. Despite the difficulties posed by background noise, there was very good agreement between the observed scattered field and that predicted by a previously established theoretical model. Thus, this work represents the first experimental observation of EAS in the optical part of the spectrum.

Colloidal particles are small particles ranging in size from nanometres to micrometres suspended in a fluid. Amongst many scientific and biological applications, they have been used to model crystallisation, vitrification, and particle interactions along with the use of colloidal model systems for the study of the fundamental nature of the fluid-crystal and fluid-glass phase transitions. It has been shown that colloidal particles can be trapped and manipulated using strongly-focused light beams known as optical tweezers, and this has paved the way for research into the area of micromanipulation using optical trapping. Holographic elements can replace multiple lenses in creating large numbers of optical tweezers and this is known as holographic optical trapping (HOT). A computer generated hologram can be designed to create large structured light fields, consisting of multiple foci, to enable trapping of multiple particles in arbitrary configurations. The overall aim of this project was to design, develop and test the suitability of a simple, inexpensive optical trapping arrangement suitable for multiple optical trapping. To achieve this, a theoretically-exact expression for the wavefront of a single point source was implemented in the coding scheme, allowing for the fast creation of multiple point sources suitable for holographic optical trapping experiments. Compensation for the spherical aberration present in the focusing optics was implemented into the coding scheme. Kodalith photographic film was chosen as the holographic recording medium for its high contrast and availability. The film has proven to be a successful medium, when used to record photographically-reduced images of high-quality printouts of the computed diffraction pattern, as it was able to successfully reproduce complex light fields. It is believed that this will be the first time that this film has been implemented for optical trapping purposes. The main limitations concerning the performance of the holograms recorded on Kodalith were the phase nonuniformities caused by unevenness in the film thickness which resulted in a failure to separately resolve light traps separated by less than about 5 (Mu)m. Index matching of the film between sheets of flat glass helped to compensate for these limitations. Holographic optical trapping was successfully observed using a variety of different initial beam powers, holographic aperture settings and light field configurations. Trapping experiments on of two types of particles (PMMA and polystyrene) were successfully conducted, with as little as ~ 150 (Mu)W per trap being required for multiple polystyrene trapping. However, particles were weakly trapped and were easily dislodged at these powers, and a higher power per trap of around 1 mW is preferred. The use of a relatively low numerical aperture (NA) 50 mm SLR lens for focusing the holographic optical traps was successful, proving that optical trapping can be conducted without the use of high NA microscope-objective lenses commonly used in other set ups. Holographic trapping of colloidal particles was successfully conducted at RMIT University for the first time proving the validity of the coding scheme, the recording method and the trapping arrangement.

The premise of this thesis is that the ???concrete holographic image???, a laser transmission hologram which has an object or a hologram of an object as its subject, has unique spatial and temporal properties which can suggest a plurality of tenses to a viewer. There is a lack of comprehensive analysis of the holographic representational system within art related theoretical and critical writing and a tendency to analyse individual works only in terms of generalities which apply to the concepts surrounding the holographic medium. While these form an important background for art image production, in some cases corresponding to artists works, the existing written material on the subject is inadequate as a model from which to draw the all important temporal conclusions. To date the critical reception of holograms has made no mention of acuity, the size of the viewing frustum, the depth of the image and scant mention of interference phenomena which are the intrinsic factors which I believe precipitate temporal illusions. Therefore this thesis examines the concrete holographic image in great detail on its own terms, firstly through theories of the basic image forming phenomena of interference and diffraction and secondly through the techniques of production as they have been adapted for the making of my art works. The extent of the metaphorical and allegorical potential of the spatial and temporal properties of the concrete holographic image are put to the ultimate test in a commission for St Brigid???s Church, Coogee. The Shrine of the Sacred Heart commission for St Brigid???s requires a concrete holographic image to facilitate devotion to the Sacred Heart. The Sacred Heart is not a physical thing but a complex, evolving spiritual entity with a realist pictorial history.

Thesis (M.Sc.) - University of Queensland, 2004. / Includes bibliography.

Holographic sensors are photonic layered structures contained in analyte sensitive lms that upon illumination produce monochromatic reflections (λ). The present work reports the fabrication of oxygen and ammonia sensors in Nafi on membranes and hydrocarbon and volatile organic compound sensors in poly(dimethylsiloxane) (PDMS) films. A holographic recording technique was developed to suit these materials consisting of the in situ formation of nanoparticles of 18nm average diameter and their subsequent ordered ablation with a 300mJ laser. The wavelength of the monochromatic reflections depends principally on the refractive index of the resulting layers (n) and the separation between them (Λ). Changes in these parameters are generated by the analyte-sensor interactions and their magnitude can be correlated to the analyte concentration. The strength of these interactions is determined by the thermodynamic properties of the analytes, such as the cohesive energy density (δ^2), and this, was coupled with a photonic model for the prediction of the holographic response. After exposure to different concentrations of the analytes, the kinetics of the responses were determined and the lowest detection limits (LDL) established as follows: Hydrocarbons in PDMS holograms 1% (v/v) in 3s for a range of concentrations from 0-100%; ammonia in Nafi on holograms 0.16% in 100s in the 0-12.5% range; the LDL for oxygen sensing could not be determined although the response was recorded down to 12.5% and up to 100% in 100s. Holographic sensors show competitive responses comparable to commercially available gas sensors for biomedical diagnostics and industrial process monitoring because of their facile fabrication and their shared sensing platform allowing multiplexing.

Dentre dos procedimentos geradores de perfil óptico encontra-se a microscopia holográfica digital. Esta ferramenta interferométrica surgiu da ideia inicial proposta por D. Gabor sobre holografia, a qual permite mediante o registro da interferência de campos ópticos coerentes, guardar e extrair informações de imagens. A microscopia holográfica digital permite a análise de objetos com resoluções transversais semelhantes às obtidas por microscopia óptica, e ainda, possui a vantagem pela natureza da holografia de permitir realizar análises através do acesso a valores quantitativos de fase. Apresentam-se neste trabalho os conceitos básicos da holografia digital e da microscopia holográfica digital, com o objetivo, de introduzir o desenvolvimento de uma metodologia para a implementação da microscopia holográfica digital por reflexão para o controle dimensional de objetos e determinação da rugosidade superficial de amostras de aço. Os hologramas são obtidos mediante uma instalação óptica, que consiste em um interferômetro de Michelson por reflexão com o uso de uma lente objetiva de microscópio e uma câmera CCD sem lente. Para a reconstrução das imagens de contraste de fase são utilizadas técnicas numéricas que capacitam à microscopia holográfica digital para a supressão do termo de ordem zero, controle da resolução de pixel, desmodulação da fase óptica, determinação dos mapas de intensidades e fase, filtragem e compensação de aberrações dos hologramas obtidos. As reconstruções numéricas dos feixes objeto e referência são realizadas utilizando o método de dupla propagação. Foi desenvolvido um algoritmo que apresenta a imagem de contraste de fase com base num critério de distância a partir de um único holograma. Desta forma o programa utilizado permite a realização de medições quantitativas das dimensões dos objetos e da rugosidade superficial de amostras de aço, assim como, a representação em 3D da imagem de fase reconstruída com resultados validados através de um perfilômetro óptico 3D sem contacto modelo CCI-MP. / Among the procedures generating optical profile is the digital holographic microscopy. This interferometric tool arose from the initial idea proposed by D. Gabor on holography, which allows by recording the interference of coherent optical fields, save and extract information from images. Digital holographic microscopy allows the analysis of objects with transversal resolutions similar to those obtained by optical microscopy, and also has the advantage of the nature of holography to allow to perform analyzes through the access to quantitative phase values. This paper presents the basic concepts of digital holography and digital holographic microscopy, with the objective of introducing the development of a methodology for the implementation of digital holographic microscopy by reflection for the dimensional control of objects and determination of surface roughness of samples of steel. The holograms are obtained by means of an optical installation consisting of a Michelson interferometer by reflection using an objective microscope lens and a lensless CCD camera. For the reconstruction of phase contrast images, numerical techniques are used that enable digital holographic microscopy to suppress the zero-order term, control pixel resolution, optical phase demodulation, determination of intensity and phase maps, filtering and compensation of aberrations of the obtained holograms. Numerical reconstructions of the object and reference beams are performed using the double propagation method. An algorithm has been developed that presents the phase contrast image based on a distance criterion from a single hologram. In this way the program used allows the realization of quantitative measurements of the object dimensions and the surface roughness of steel samples, as well as the 3D representation of the reconstructed phase image with results validated through a 3D contactless optical profilometer model CCI- MP.

Orientador: Lucila Helena Deliesposte Cescato / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-07T11:04:51Z (GMT). No. of bitstreams: 1 Quinonez_FabiolaAzanha_M.pdf: 3774661 bytes, checksum: 43303e872404bf21c83ed4ea86d8befe (MD5) Previous issue date: 2006 / Resumo: Nesta tese foi utilizado um programa baseado em elementos finitos para projetar cristais fotônicos bidimensionais, assim como foram desenvolvidos processos de litografia holográfica para gravação destas estruturas fotônicas em filmes de carbono amorfo hidrogenado, depositados sobre substratos de vidro. O projeto dos parâmetros geométricos das estruturas que apresentam um gap fotônico, numa dada região de interesse do espectro óptico, foi feito através do cálculo dos diagramas de bandas das estruturas, levando-se em consideração as dimensões e formas que possam ser fabricadas utilizando a técnica de litografia holográfica. Para gravação dos cristais fotônicos bidimensionais, com simetrias cúbica e hexagonal, foi utilizada a técnica de superposições sucessivas de padrões, gerados pela interferência de duas ondas planas (exposições holográficas), associadas à litografia do filme de carbono por plasma reativo (RIE ¿ Reactive Ion Etching) / Abstract: In this thesis, we employed a software based on finite element method to design two-dimensional photonic crystals, as well as we developed a holographic lithography process to record these photonic structures in amorphous carbon films, coated on glass substrates. In order to present a photonic band gap in a desired region of the optical spectrum, the geometrical parameters of the structures were defined by analyzing the calculated band diagram of the structures. Such definition takes into account the dimensions and forms of the structures that can be fabricated using techniques of holographic lithography. To record the two-dimensional photonic crystals, with cubic and hexagonal symmetries, we used the technique of successive superimposition of fringe patterns. The patterns were generated by the interference of two plane waves (holographic exposures), associated to the lithography of the carbon film by reactive ion etching / Mestrado / Propriedades òticas e Espectroscopia da Matéria Condensada ; Outras Inter. da Mat. Com Rad. e Part / Mestre em Física