Holographic representation: Hologram plane vs. object plane

Digital holography allows the recording, storage and subsequent reconstruction of both amplitude and phase of the light field scattered by an object. This is accomplished by recording interference patterns that preserve the properties of the original object field essential for 3D visualization, the so-called holograms. Digital holography refers to the acquisition of holograms with a digital sensor, typically a CCD or a CMOS camera, and to the reconstruction of the 3D object field using numerical methods. In the current work, the different representations of digital holographic information in the hologram and in the object planes are studied. The coding performance of the different complex field representations, notably Amplitude-Phase and Real-Imaginary, in both the hologram plane and the object plane, is assessed using both computer generated and experimental holograms. The HEVC intra main coding profile is used for the compression of the different representations in both planes, either for experimental holograms or computer generated holograms. The HEVC intra compression in the object plane outperforms encoding in the hologram plane. Furthermore, encoding computer generated holograms in the object plane has a larger benefit than the same encoding over the experimental holograms. This difference was expected, since experimental holograms are affected by a larger negative influence of speckle noise, resulting in a loss of compression efficiency. This work emphasizes the possibility of holographic coding on the object plane, instead of the common encoding in the hologram plane approach. Moreover, this possibility allows direct visualization of the Object Plane Amplitude in a regular 2D display without any transformation methods. The complementary phase information can easily be used to render 3D features such as depth map, multi-view or even holographic interference patterns for further 3D visualization depending on the display technology.info:eu-repo/semantics/publishedVersio

A study of digital holographic filter generation

Problems associated with digital computer generation of holograms are discussed along with a criteria for producing optimum digital holograms. This criteria revolves around amplitude resolution and spatial frequency limitations induced by the computer and plotter process

OAM multiple transmission using uniform circular arrays: numerical modeling and experimental verification with two digital television signals

In this work we present the outcomes of a radio-frequency OAM transmission between two antenna arrays performed in a real-world context. The analysis is supplemented by deep simulative investigations able to provide both a preliminary overview of the experimental scenario and a posteriori validation of the achieved results. As a first step, the far-field OAM communication link is tested at various frequencies and the corresponding link budget is studied by means of an angular scan generated by the rotation of the receiving system. Then, on the same site, two digital television signals encoded as OAM modes ($\ell$=1 and $\ell$=-1) are simultaneously transmitted at a common frequency of 198.5 MHz with good mode insulation.Comment: 16 pages, 14 figure

Volumetric velocimetry for fluid flows

In recent years, several techniques have been introduced that are capable of extracting 3D three-component velocity fields in fluid flows. Fast-paced developments in both hardware and processing algorithms have generated a diverse set of methods, with a growing range of applications in flow diagnostics. This has been further enriched by the increasingly marked trend of hybridization, in which the differences between techniques are fading. In this review, we carry out a survey of the prominent methods, including optical techniques and approaches based on medical imaging. An overview of each is given with an example of an application from the literature, while focusing on their respective strengths and challenges. A framework for the evaluation of velocimetry performance in terms of dynamic spatial range is discussed, along with technological trends and emerging strategies to exploit 3D data. While critical challenges still exist, these observations highlight how volumetric techniques are transforming experimental fluid mechanics, and that the possibilities they offer have just begun to be explored.SD was partially supported under Grant No. DPI2016-79401-R funded by the Spanish State Research Agency (SRA) and the European Regional Development Fund (ERDF). FC was partially supported by the U.S. National Science Foundation (Chemical, Bioengineering, Environmental, and Transport Systems, Grant No. 1453538)

New advances in high-resolution optical microscopy

La microscopio ía tiene como nalidad observar muestras que no pueden distinguirse a simple vista por el ojo humano dado que el tamaño de ellas es menor que su l mite de resoluci on. Un microscopio produce una imagen ampliada de la muestra a analizar. Debido a que la microscopía es un instrumento b asico para la ciencia de la vida y de los materiales, en esta Tesis se desarrolla un estudio exhaustivo de la microscopía óptica. Los microscopios opticos se pueden con gurar de diferentes formas para producir im agenes con diferentes caracter sticas. El microscopio de campo amplio, el m as simple de todos, presenta algunas limitaciones que debe ser superadas para obtener im agenes de mayor calidad. Entre estas limitaciones encontramos: el barrido axial mec anico para proporcionar toda la informaci on de la estructura de la muestra, la presencia de aberraci ón esf érica debido a los desajustes del í ndice de refracci ón entre el medio de inmersi on del objetivo, el cubreobjetos y la muestra, la limitaci ón de la resoluci ón espacial impuesta por la difracci ón y la incapacidad de obtener im ágenes cuantitativas de fase. Tales limitaciones se analizan en esta Tesis y se proponen algunas soluciones con el fi n de proporcionar mejores im ágenes micros ópicas. En particular, nosotros hemos obtenido: (1) un r ápido barrido axial de muestras gruesas, en tiempo real y sin ning ún movimiento mecánico, (2) un microscopio invariante a la aberraci ón esf érica, (3) im agenes con alta resoluci on lateral y seccionado optico y (4) im agenes cuantitativas de fase precisas y sin deteriorar el l mite de resoluci on. Todos estos resultados se han demostrado tanto te oricamente como experimentalmente.Microscopy is the science which aim is to view objects that can not be distinguished with the naked eye because the size of those objects are not within its resolution range. A microscope produces an enlarged image of a sample under research. Since microscopy is an essential tool for live and material sciences, this Thesis is devoted to study thoroughly optical microscopy. Optical microscopes can be performed in di erent ways to provide resulting images with di erent features. The simplest optical microscope is the wide eld microscope. However it presents some limitations that needs to be overcome to obtain high-quality images. Among these limitations we nd: axial mechanical scanning to provide the whole structure of a sample, the presence of spherical aberration due to the refractive-index mismatches between the immersion medium of the microscope objective, the coverglass and the specimen, the limitation of spatial resolution imposed by di raction and the inability of obtaining quantitative phase images. Such limitations are analyzed in this Thesis and some solutions are proposed in order to provide better microscopic images. In particular, we have achieved: (1) a fast-axial scanning of thick samples in real time and without any mechanical movement, (2) an SA-invariant imaging system, (3) images with high lateral resolution and optical sectioning and (4) accurate quantitative phase images and without deteriorating the resolution limit imposed by di raction. All these ndings have been veri ed both theoretically and experimentall

Holography and Optical Filtering

Holography and optical filtering techniques for structural analysis, material tests, and astronomical observation - conferenc

A cybernetic approach to prediction with an outline of an adaptive optical computer

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Since the pioneering work of Kolmogoroff and Wiener the use of computing devices to solve problems concerned with - the prediction of future states of a time series has stimulated a large amount of research. Despite all this, however the results have been disappointing. If significant progress were to be made in this field it would lead not only to the possibility of forecasting economic events, the weather, earthquakes, epidemics, and so on, but also -to the possibility of simulating these system. Approaches involving the programming of a computer to carry out this task run into the difficulty of defining the variables involved in a precise enough manner, whereas using the computer -to investigate all the past events of that time series requires a large processing time and an enormous memory store. This thesis examines an approach to this problem which involves the use of a device for processing information in a parallel manner. The system envisaged consists of a holographic recognition device controlled by a digital computer -a combination of analogue and digital techniques. The principle of this device is that developed by Gabor and others, and allows the system to learn to predict the future of a time series. The system learns to predict the future of a time series by using a past length of time series as a training set. Using this training set it attempts to predict the next values of the time series, which can then be compared with the actual time series. The system, then, attempts to optimize its prediction by minimizing the error between the predicted and actual values

Modeling and detection for holographic data storage

Master'sMASTER OF ENGINEERIN

Augmented Reality and Its Application

Augmented Reality (AR) is a discipline that includes the interactive experience of a real-world environment, in which real-world objects and elements are enhanced using computer perceptual information. It has many potential applications in education, medicine, and engineering, among other fields. This book explores these potential uses, presenting case studies and investigations of AR for vocational training, emergency response, interior design, architecture, and much more