Hologramas podem ser produzidos utilizando-se técnicas tradicionais de holografia ou podem ser gerados também por computador, conhecidos como hologramas gerados por computador (HGCs). A maioria destes hologramas opera usando luz monocromática. Por outro lado, os hologramas podem também operar com luz branca. Estes elementos de luz branca são usados em diversas aplicações, como segurança, para verificar a autenticidade dos cartões de crédito e outros documentos, porque seus processos de fabricação são difíceis e caros de serem reproduzidos. Entretanto, os hologramas de luz branca convencionais operam baseados na reflexão da luz, e apresentam alguns efeitos indesejáveis, como distorções cromáticas, como o efeito rainbow. Neste trabalho foi proposto um elemento óptico difrativo de luz branca gerado por computador. O elemento é calculado baseado na técnica de halftoning e na coerência espacial parcial de uma fonte de luz branca estendida. Os elementos da fase são produzidos através de técnicas de fabricação bem estabelecidas de circuitos integrados, e as simulações óticas são apresentadas. Não há necessidade de métodos iterativos. Os resultados das reconstruções ópticas e simuladas deste elemento de luz branca são muito semelhantes e produzem imagens nítidas, não sendo observadas distorções cromáticas. O elemento de luz branca ainda não foi descrito na literatura, e algumas de suas aplicações podem ser um correlator óptico ou arte holográfica. Este trabalho foi realizado no laboratório de óptica do departamento da engenharia elétrica do EESC, e financiado por CAPES (Coordenadoria de Aperfeiçoamento de Pessoal de Nível Superior). / Holograms can be produced using traditional holography techniques or may be also generated by computer, which are known as CGHs(Computer-generated holograms). Most of these holograms operate using monochromatic light. On the other hand, holograms can also operate with white light. These white light holograms are used in several applications, such as security, to verify the autencity of credit cards end other documents, because their fabrication processes are dificult to reproduce and are expensive. However, convencional white light holograms operate based on reflection of light, and present some undesirable effects, like chromatic distortions, such as rainbow effect. In this work it was proposed a computer-generated phase optical difractive element designed to operate under white light illumination. The element is calculated based on the halftoning technique and in the partial spatial coherence of a white light extended source. Phase elements are manufactured using well-established integrated circuits fabrication techniques and optical simulations are shown. No iterative methods are necessary. Simulated and optical reconstructions results are very similar and produce good clear images, and no chromatic distortions are observed. The white light element was not yet described on literature, and some of its applications may be an optical correlator or holographic art. This work was carried at the laboratory of optics of the department of electrical engineering of the EESC, and supported by CAPES (Coordenadoria de Aperfeiçoamento dePessoal de Nível Superior).

This thesis details the design, construction and characterisation of an ultracold atoms system, developed in conjunction with a flexible optical trapping scheme which utilises a Liquid Crystal Spatial Light Modulator (LC SLM). The ultracold atoms system uses a hybrid trap formed of a quadrupole magnetic field and a focused far-detuned laser beam to form a Bose-Einstein Condensate of 2×105 87Rb atoms. Cold atoms confined in several arbitrary optical trapping geometries are created by overlaying the LC SLM trap on to the hybrid trap, where a simple feedback process using the atomic distribution as a metric is shown to be capable of compensating for optical aberrations. Two novel methods for creating flexible optical traps with the LC SLM are also detailed, the first of which is a multi-wavelength technique which allows several wavelengths of light to be smoothly shaped and applied to the atoms. The second method uses a computationally-efficient minimisation algorithm to create light patterns which are constrained in both amplitude and phase, where the extra phase constraint was shown to be crucial for controlling propagation effects of the LC SLM trapping beam.

Methods for analysis and optimization of volume holographic recording are presented for two main groups of applications. In the first group of applications (mainly storage systems), the designs and the techniques of volume holography are well known and the main optimization effort is finding the proper material to store the holograms. One of the results of this research is complete global optimization of dynamic range and sensitivity in two-center recording that is the best technique for persistent rewritable storage. For this purpose, a complete theoretical analysis as well as experimental demonstration is presented. Also, other effects and processes such as electron tunneling and recording at high temperature are considered for possible improvement of the dynamic range of the material. For the second group of applications (mainly holographic optical elements), the focus of this research is on analysis and optimization of the design of the volume holograms in contrast to material optimization. A new method (multi-grating method) is developed for the analysis of an arbitrary hologram that is based on the representation of the hologram as the superposition of several plane wave gratings. Based on this method, a new class of optical devices that integrates the functionalities of different optical elements into a simple volume hologram is introduced and analyzed. As a result, very compact, low cost, and easy to use devices such as portable spectrometers can be made with particular applications in biological and environmental sensing.

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.

Hologramas podem ser produzidos utilizando-se técnicas tradicionais de holografia ou podem ser gerados também por computador, conhecidos como hologramas gerados por computador (HGCs). A maioria destes hologramas opera usando luz monocromática. Por outro lado, os hologramas podem também operar com luz branca. Estes elementos de luz branca são usados em diversas aplicações, como segurança, para verificar a autenticidade dos cartões de crédito e outros documentos, porque seus processos de fabricação são difíceis e caros de serem reproduzidos. Entretanto, os hologramas de luz branca convencionais operam baseados na reflexão da luz, e apresentam alguns efeitos indesejáveis, como distorções cromáticas, como o efeito rainbow. Neste trabalho foi proposto um elemento óptico difrativo de luz branca gerado por computador. O elemento é calculado baseado na técnica de halftoning e na coerência espacial parcial de uma fonte de luz branca estendida. Os elementos da fase são produzidos através de técnicas de fabricação bem estabelecidas de circuitos integrados, e as simulações óticas são apresentadas. Não há necessidade de métodos iterativos. Os resultados das reconstruções ópticas e simuladas deste elemento de luz branca são muito semelhantes e produzem imagens nítidas, não sendo observadas distorções cromáticas. O elemento de luz branca ainda não foi descrito na literatura, e algumas de suas aplicações podem ser um correlator óptico ou arte holográfica. Este trabalho foi realizado no laboratório de óptica do departamento da engenharia elétrica do EESC, e financiado por CAPES (Coordenadoria de Aperfeiçoamento de Pessoal de Nível Superior). / Holograms can be produced using traditional holography techniques or may be also generated by computer, which are known as CGHs(Computer-generated holograms). Most of these holograms operate using monochromatic light. On the other hand, holograms can also operate with white light. These white light holograms are used in several applications, such as security, to verify the autencity of credit cards end other documents, because their fabrication processes are dificult to reproduce and are expensive. However, convencional white light holograms operate based on reflection of light, and present some undesirable effects, like chromatic distortions, such as rainbow effect. In this work it was proposed a computer-generated phase optical difractive element designed to operate under white light illumination. The element is calculated based on the halftoning technique and in the partial spatial coherence of a white light extended source. Phase elements are manufactured using well-established integrated circuits fabrication techniques and optical simulations are shown. No iterative methods are necessary. Simulated and optical reconstructions results are very similar and produce good clear images, and no chromatic distortions are observed. The white light element was not yet described on literature, and some of its applications may be an optical correlator or holographic art. This work was carried at the laboratory of optics of the department of electrical engineering of the EESC, and supported by CAPES (Coordenadoria de Aperfeiçoamento dePessoal de Nível Superior).

No description available.

La realidad mixta, unificación de la realidad virtual y la realidad aumentada, posee muchas expectativas debido a las grandes tendencias que han surgido desde su creación y la forma en que ha fusionado casi en su totalidad a nuestro mundo real con el mundo digital, con la proyección de objetos digitales que estimulan los sentidos, logrando obtener una percepción similar a los objetos del entorno real y llevando su uso a múltiples posibilidades. En la investigación se identificó la problemática que aborda la necesidad de profundizar sobre las propiedades de la realidad mixta y los objetivos a trazar para cubrir con dicha necesidad. Durante el proyecto se logró recolectar información y crear un catálogo sobre los distintos tipos de aplicaciones, dispositivos y soluciones tecnológicas implementadas referente a la tecnología. Se investigó acerca de la parte teórica de la realidad mixta en base a las distintas definiciones del autor seminal y de expertos en la materia, además de las definiciones sobre las tecnologías con funcionalidades similares. Además, se procesó la información obtenida, identificando los rubros de negocio en donde se desempeña la realidad Mixta. Finalmente, se logró crear una taxonomía de realidad mixta y un gráfico estadístico de la participación de cada rubro de negocio en el mercado, con el fin de poder tener un panorama claro de la adopción y el valor comercial de cada rubro en donde se ejerce dicha tecnología y que pueda ser utilizado como referencia para la creación de proyectos de tecnología. / Mixed reality, the union of virtual reality and augmented reality, has high expectations due to the biggest trends that have emerged since its inception and the way in which it has almost entirely merged the real world with the digital world with the projection of digital objects that stimulate the senses, achieving a perception similar to the objects in the real environment and taking their use to multiple possibilities. The research identified the problem that addresses the need to delve into the properties of mixed reality and the objectives to be set in order to meet this need. During the project, information was collected in order to create a catalog on the different types of applications, devices and technological solutions implemented regarding that technology. The theoretical part of mixed reality was researched based on the different definitions given by authors and experts in the field, in addition to the definitions of technologies with similar functionalities. Moreover, the information obtained was processed, identifying the business areas where the mixed reality operates. Finally, it was possible to create a mixed reality taxonomy and a statistical graph of the participation of each business area in the market, for the purpose of being able to have a clear overview of the adoption and commercial value of each area where said technology is used and that can be employed as a reference for the creation of future technology projects. / Tesis

No description available.

Recent developments in holographic recording of volume Bragg gratings (VBGs) in photo-thermo-refractive (PTR) glass have demonstrated their utility as components in high power laser systems for spectral narrowing, transverse mode control, beam combining, and pulse stretching/compression. VBG structures are capable of diffracting incident light into a single diffraction order with high efficiency given the Bragg condition is met. The Bragg condition depends on both the wavelength and angle of the incident light making VBGs useful for filtering and manipulating both the wavelength and angular spectrum of a source. This dissertation expands upon previous research in PTR VBGs by investigating multiplexed VBGs and their applications in laser systems. Multiplexing involves the integration of several VBGs into the same volume of PTR glass. This process enables the fabrication of splitting and combining elements which have been used for high power beam combining with significantly reduced complexity as compared to other combining schemes. Several configurations of multiplexed beam combiners were demonstrated for both spectral and coherent combining systems with high power results yielding a combined power of 420 W with 96% efficiency. Multiplexing was also used to produce unique phase structures within VBGs. This effect was exploited to create extremely narrowband spectral filters called moire Bragg gratings. The technical challenges of producing moire gratings in bulk glass have revealed new insights into the use of PTR glass as a recording medium and produced devices capable of narrowband filtering of only 15 pm in the near infrared. Experiments were performed using such devices as intra-cavity laser elements for longitudinal mode selection. Investigations have also been made into increasing the level of multiplexing possible within PTR glass. These explorations included scaling the number of beam combining channels, fabrication of integrated multi-notch filters, and generated several other potentially interesting devices for future research. The summation of this work indicates a promising future for multiplexed VBGs in PTR glass.

Augmented reality is poised to become the next dominant computing paradigm over the course of the next decade. With the three-dimensional graphics and interactive interfaces that augmented reality promises it will rival the very best science fiction novels. Users will want to have shared experiences in these rich augmented reality scenarios, but surely users will want to restrict who can see their content. It is currently unclear how users of such devices will authenticate one another. Traditional authentication protocols reliant on centralized authorities fall short when different systems with different authorities try to communicate and extra infrastructure means extra resource expenditure. Augmented reality content sharing will usually occur in face-to-face scenarios where it will be advantageous for both performance and usability reasons to keep communications and authentication localized. Looks Good To Me (LGTM) is an authentication protocol for augmented reality headsets that leverages the unique hardware and context provided with augmented reality headsets to solve an old problem in a more usable and more secure way. LGTM works over point to point wireless communications so users can authenticate one another in any circumstance and is designed with usability at its core, requiring users to perform only two actions: one to initiate and one to confirm. LGTM allows users to intuitively authenticate one another, using seemingly only each other's faces. Under the hood LGTM uses a combination of facial recognition and wireless localization to ensure secure and extremely simple authentication. / Master of Science