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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Holografická anténa / Holographic antenna

Klečka, Tomáš January 2011 (has links)
This master’s thesis deals with principle of microwave holography, methods of microwave hologram recording and analyzes some types of holographic antennas from structural and functional point of view. It also includes simulations of selected holographic antennas and their modi?cations, applies optimization on three types of antennas. Finally it reviews measured results of three costructed antennas.
192

Koherencí řízený holografický mikroskop ve výzkumu životního cyklu buňky / Coherence-controlled holographic microscope in cell's life cycle research

Křížová, Aneta January 2012 (has links)
The goal of this diploma thesis was using of a coherence-controlled holographic microscope in cell’s life research. A brief history of interference microscopy and it’s applications in biology is described. Also other microscopy techniques routinely used for transparent objects imaging are mentioned and the biology of cell’s life cycle briefly explained. Characteristics describing the shape of a cell were proposed and tested with respect to identification of particular phases of its life cycle. The method of dynamic phase differences was modified in order to distinguish the internal motion of cell’s mass from the movement of the whole cell. Selected characteristics were used to evaluate observations carried out with the holographic microscope and the possibilities of their further applications were depicted. In conclusion, obtained findings were summarized and modifications of microscope construction as well as data-processing software were suggested.
193

Optická pinzeta pro koherencí řízený holografický mikroskop / Optical tweezers for coherence-controlled holographic microscope

Straka, Branislav January 2013 (has links)
In the master's thesis, there has been described and explained the principle of operation of the second generation coherence controlled holographic microscope (CCHM2) designed at the Brno University of Technology. There has also been listed theoretical description of the operation of the optical trap, together with the calculation of the forces acting on it, ways of measuring the stiffness of the optical trap and the principle of~creating a time-shared optical traps. The optical tweezers forming a separate module connectable to CCHM2 was designed. Simulation and optimization of parameters of the optical system, mechanical design, manufacturing documentation, current source to power the laser diode which allows to control the diode output power by the controller card connected to the PC was designed. The galvano-optics mirror angle is controlled by the PC card too. The optical tweezer has been designed, manufactured and tested in conjunction with the CCHM2.
194

Automatizované procedury pro Koherencí řízený holografický mikroskop / Automated Procedures for Coherence Controlled Holographic Microscope

Dostál, Zbyněk January 2016 (has links)
Coherence-Controlled Holographic Microscope (CCHM) and a Fluorescence Holographic Microscope (FHM) were developed particularly for quantitative phase imaging and measurement of live cell dynamics, which used to be a subject of digital holographic microscopy (DHM). CCHM and FHM in low-coherence mode extend capabilities of DHM in the study of living cells. However, this advantage following from the use of low coherence is accompanied by increased sensitivity of the system to its correct alignment. Therefore, the introduction of an automatic self-correcting system is inevitable. Accordingly, in the thesis, the theory of a suitable control system is derived and the design of an automated alignment system for both microscopes is proposed and experimentally proved. The holographic signal was identified as a significant variable for guiding the alignment procedures. On this basis the original basic realignment algorithms were proposed, which encompasses the processes for initial and advanced alignment as well as for long-term maintenance of the microscope aligned state. Automated procedures were implemented in both microscopes unique set of robotic mechanisms designed and built within the frame of the thesis work. All of the procedures described in the thesis were in real experimentally proved at real microscopes in the experimental biophotonics laboratory. In addition, the control software, which contains the needed automated procedures, was developed for FHM.
195

Dual-Axis Acousto-Optic/Electro-Optic Deflectors in Lithium Niobate for Full-Parallax Holographic Video Displays

Adams, Mitchell Robert 30 July 2021 (has links)
A major limitation of acousto-optic (AO) leaky-mode modulator based holographic displays is their inability to present full-parallax. We propose that full-parallax capabilities can be bestowed on these displays by integrating an electro-optic (EO) phased array into the architecture. We validated this concept by rendering computational models and by fabricating and testing a basic two-axis AO/EO deflector prototype in lithium niobate. This was, to our knowledge, the first instantiation of an integrated, hybrid AO/EO deflector. The prototype had a 6° deflection range along the AO-axis, and a 3° deflection range along the EO-axis. A series of models provide us with a clear path forward for optimizing this deflector. They suggest that an AO/EO modulator with an EO deflection range of 24.5° and that requires less than 7.5 V can be fabricated within the limitations of standard photolithography.
196

Koherencí řízený holografický mikroskop nové generace / New Generation of a Coherence-Controlled Holographic Microscope

Slabý, Tomáš January 2015 (has links)
This doctoral thesis deals with design of a new generation of coherence-controlled holographic microscope (CCHM). The microscope is based on off-axis holographic configuration using diffraction grating and allows the use of temporally and spatially incoherent illumination. In the theoretical section a new optical configuration of the microscope is proposed and conditions for different parameters of the microscope and its optical components are derived. The influence of different sources of noise on phase detection sensitivity is studied. In the next section design of experimental setup is described and automatable adjustment procedure is proposed. Last section describes experimental verification of the most important optical parameters of the experimental setup. When compared to previous generation of CCHM, the newly proposed configuration uses infinity-corrected objectives and common microscope condensers, allows more space for the specimens, eliminates the limitation of spectral transmittance and significantly simplifies the adjustment procedure so that automation of this procedure is possible.
197

Visions of Couture : Designing an Interactive System for Fashion

Gradellini, Gianmarco January 2023 (has links)
Visions of Couture is a project that explores the relationship between high fashion and technology. The aim of this work was to incorporate interactivity in a context, namely fashion, that has always been a pioneer in research and innovation but where interactive artefacts have so far had quite a marginal role. After collecting insights through literature review and interviews, the project focused on creating a system for fashion showrooms that would permit users and clients to interact with holographic projections of the models through gestures. This system allows for a slower and more attentive interaction, in contrast with the frenzy of the fashion show, letting the users linger on the looks they are interested in and possibly overcoming the space and time limitations that fashion showrooms usually have. The result of this project is a system composed of a holographic projection mesh and a wearable bracelet to recognise gestures. The bracelet contains an Arduino Nano 33 BLE that has been trained through Machine Learning to recognise the selected gestures and communicates with Processing to play the right videos. The project suggests a way to use holography as a mean for a shared and embodied mixed reality experience and a path for designing comfortable gesture interactions that are intuitive and coherent with the context. Crucial to this project were the concepts of embodiment, corporality, shared mixed reality and intuitive gestures.
198

(Not) Drawing The Line: Technology Reexamined

Liguori, Elizabeth Angela 07 June 2017 (has links)
(Not) Drawing The Line: Technology Re-examined is the culmination of interdisciplinary research exploring the nature of materiality and process in the fields of art, science, and technology. Exploration and experimentation in these diverse disciplines have helped to illuminate many of the ideas and concepts that have guided the overall research process. These explorations have also honed the ability to critically examine how technology is perceived and represented, post-internet.   This document illustrates the processes involved in the conception and creation of a body of work manifested through visual and technological problem solving, investigative research of materials and technologies, and the fundamental concerns of art, technology, form and pattern. These empirical areas of research are punctuated by literary texts on the philosophy of art and technology that have informed many of the visual comparisons represented. This body of evidence is an exploration of the idea that the evolution of technological developments can often be attributed to the creation of art through the heuristic experimentation and visual explorations of the artist. / Master of Fine Arts
199

An Exploration of Visual Sensations: The Use of Depth Perception to Create Pre-Architectural Forms

Rushton, Nan Michelle 10 January 2006 (has links)
This exploration is one artist's view of visual reasoning through the study of depth perception. The experiment searched for pre-architectural forms through an investigation of geometric rectangular shapes and planar figures in anticipation of finding architectural volumes, that is, three-dimensional objects. I used three parameters to observe: the expected or planned, the anticipated, and the unforeseen. The pre-architectural sketching style used the disciplines of painting, sculpture, graphic arts, color theory, optics, and photography to formulate an architectural language. First, as artist (painter), I selected the medium of light as the brushstroke, color as the pigment, and photographic film plane as the canvas to capture image abstractions. Second, I used one-point perspective as the viewer's line of sight. Finally, I employed a series of shape abstractions to form a succession of transparent sections that composed the subject matter. This experiment sought to analyze visual perception by capturing the spatial depth of images, that is, a reproduction of something sculptural in likeness. The challenge was to reintegrate the abstracted Rectangular Shapes and Planar Figures. In order to achieve this physical abstraction, I created a modified camera obscura. This exploration produced clearly defined images-as-products that were interpreted as pre-architectural forms, which allowed me to translate color abstractions into architectural form studies, or models-as-products. Thus, the experiment created architectural volumes using light and color in order to draw points, lines, planes, and spatial depth. / Master of Architecture
200

Wellenlängenmultiplexing mit thermisch fixierten Volumenphasenhologrammen in photorefraktiven Lithiumniobat-Kristallen / Wavelength Division Multiplexing with Thermally Fixed Volume Phase Holograms in Photorefractive Lithium Niobate Crystals

Breer, Stefan 08 September 2000 (has links)
Wavelength division multiplexing (WDM) is essential for further enhancement of the transmission capacities of optical telecommunication systems. Key devices in WDM networks are multiplexing/demultiplexing components, which enable the combination/separation of several carrier waves with different wavelengths for the purpose of simultaneous transmission through one optical fibre. These components can be realized using Bragg diffraction from volume holographic gratings. Especially reflection holograms provide a pronounced wavelength selectivity which makes them attractive for free-space WDM applications. Holograms can be stored permanently in photorefractive lithium niobate crystals by the method of Thermal Fixing. Heating of the crystal during or after the recording process and subsequent development by homogeneous illumination at room temperature create nonvolatile holograms. The recording and development processes of Thermal Fixing in iron- and copper-doped lithium niobate crystals were investigated. Macroscopic Gaussian-shaped intensity patterns were used to analyse the origin of the fixing mechanism. Spatially resolved absorption measurements were performed to determine the concentration profiles of electron traps (Fe II/III) and protons. Results of computer simulations were compared with experimental results, which showed that protons can be found to work as compensators during hologram recording at temperatures around 180 degree C. Nevertheless thermal fixing without protons was possible, another compensation mechanism stood in. The obtained refractive-index changes were due to the electro-optic effect, other contributions could be neglected. With this detailed knowledge about thermal fixing, a two-channel demultiplexing unit was built by superposition of two thermally fixed reflection holograms in an iron-doped lithium niobate crystal. For this purpose a special two-beam interference setup with precisely adjustable writing angles was arranged in a vacuum chamber to eliminate thermally induced phase disturbances of the holographic recording procedure. Continuous development of the holograms by incoherent light was necessary. In the dark, the enhanced dark conductivity of the crystal used gave rise to a hologram degradation within about one day. Large diffraction efficiencies were attained (intensity losses between 2.3 and 5.2 dB only) uilizing crystals with high-quality polished surfaces. The crosstalk supression of the realized demultiplexer was > 25 dB, which is comparable with the performance of other multiplexing techniques like fibre Bragg gratings or arrayed-waveguide gratings. The low polarization dependence of the demultiplexer can be improved by superposition of two holograms for each channel.

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