161 |
Průtokové komůrky pro mikroskopii živých buněk / Flow-chambers for microscopy of living cellsČolláková, Jana January 2011 (has links)
The perfusion chamber for long term observing of live cells by the means the Coherence-Controlled Holographic Microscope (CCHM) was designed. CCHM was built and designed at the Laboratory of the optical microscopy at the Institute of Physical Engineering, Brno University of Technology. CCHM can quantitatively evaluate dynamical changes inside live cells thanks to the quantitative information about phase shift in each pixel of the image. In order to demonstrate advantages of CCHM experimentally, it is important to keep the live cells in the good conditions. This is made by adding the fresh cultivation medium for studied cells directly in the microscope. In contrast to the stationary chamber the perfusion chamber allows both the cultivation medium exchange and the application of biological reagents without the necessity of removing the chamber from the microscope. Therefore we can study the vital signs of cells before and after the application of reagents. An original perfusion system with accessories compatible with CCHM was designed. The design is based on the previously published perfusion system solutions that are referred to in this thesis. The flow characteristics and medium exchange process was discussed and a modification of the internal geometry, based on numerical simulations, was introduced. The applicability of this perfusion chamber has been proven for the CCHM and even for different types of microscopes. The reactions of tumor and epithelial cells during the change of the environment from the cultivation medium to the physiologically solution were studied.
|
162 |
Možnosti trojrozměrného zobrazování v transmisním holografickém mikroskopu / Possibilities of three-dimensional imaging in transmitted-light holographic microscopeSládková, Lucia January 2013 (has links)
Digital holographic microscopy (DHM) is noninvasive method for obtaining images even from samples with low contrast. Nowadays DHM design makes it possible to illuminate sample by broad light source, halogene lamp. Broad light source is displayed in the front focal plane of condensor in such way, that Köhler illumination is achieved. Each point of the source corresponds to a plane wave in image field of objective, which illuminates the whole field of view, but from different direction. Position of the point determines the direction of illumination. In this reason, the microscope enables so reconstruct not only intensity, but also phase of object wave. New designed and constructed interchangeable pinhole aperture modify broad light illumination by rotation around the optical axis. Aperture is placed eccentrically considering the optical axis of microscope. Incidence of light beam on a sample would be under defined angle. After the reconstruction of taken phase images from individual angles of illumination should be possible to obtain three-dimensional structure of the sample.
|
163 |
Pozorování vlivu vnějšího prostředí na živé buňky holografickým mikroskopem / Observation of external environment influence on living cells with holographic microscopeKovářová, Klára January 2015 (has links)
Subject of this master's thesis is the observation of influence of external environment on the living cells with the use of multimodal holographic microscope. The theoretical part is summarising the development of the holographic microscopy at IPE FME BUT. The theoretical part also describes multimodal holographic microscope, which allows non-invasive observing of living cells. The thesis also covers construction of the microscope, basic working instructions and the hologram processing method. The main subject of the thesis is the research on the topic of chemotaxis and osmotic processes in the cells. Experiments were designed for the purpose of this thesis to cover topics mentioned above. The experimental part of the thesis deals with cultivation of the cells, preparation of the sample and observation chambers and processing of the data. This part later focuses directly on the laboratory measurements. In all experiments, cells K2 (full name LW13K2) were observed.
|
164 |
HOLOGRAPHIC TOOLS IN INDUSTRIAL ROBOT PROGRAMMING : LIMITATIONS AND FUTURE DEVELOPMENTSWallin, Emelie, Hansen, Isabella January 2022 (has links)
Due to their programmability, robots have been used instead of traditional automation for a longtime within the industrial sector. However, programming robots is complex and time-consuming,where for example small errors can have major consequences both materially and for the peopleworking next to the robot. Trying to find simpler ways of programming industrial robots is thus ofhigh relevance. The latest technique for simplifying programming is to use either augmented realityor mixed reality, and today, several studies show that these techniques are possible. However, moreresearch on usability and limitations such tools have is necessary. This study investigates how ageneric holographic tool, which utilizes mixed reality, needs to be improved to be usable for robotprogramming in realistic industrial settings. In this study this is done by investigating limitationsof using a holographic tool and then discuss how these limitations can be reduced or eliminated.To find limitations, a prototype has been designed and developed. The prototype can visualize adigital copy of a physical robot, that can be moved into different positions which in turn createsprogram instructions. The prototype was tested at ABB Robotics with the collaborative single armYuMi robot, and with users that had different amount of experience with similar programmingtools. The results showed several possible limitations, mainly linked to potential safety risks andtechnical limitations. Additionally, some perceived physical impact was found. The most importantimprovement stated were the importance of an easy access to an emergency stop. Finally, theprototype developed during this study does not support all functionality that are included in theprogramming tools used today. Therefore, more studies need to be made to see if the result staysthe same.
|
165 |
Time-Averaged Holographic Interferometry, Applied to the Vibration Analysis of High Frequency Loud-Speaker Cones (Part B)Hartmann, Wolfgang Joachim 04 1900 (has links)
One of two project reports. Part A can be found at: http://hdl.handle.net/11375/17932 / Time-averaged holographic interferometry is applied to the study of the resonance mode structures of an electromagnetic and a piezoelectric high frequency loud-speaker. Vibrational amplitude measurements were made using the simple concept of the holo-diagram. The vibrational amplitude sensitivity range was from 0.1 µm to 0.9 µm, which is an ideal range since the speaker vibrational amplitudes were always below 0.8 µm. Application of the technique to non-destructive speaker quality testing and optimum speaker design is also discussed in the report. / Thesis / Master of Engineering (ME)
|
166 |
Programming and Optimisation of a Digital Holographic Microscope for the Study of Eye Tissue / Programmering och optimering av ett digitalt holografiskt mikroskop för studier av ögonvävnadDilhan, Lucie January 2018 (has links)
The objectives of the present project were to set up, optimise and characterise a digitalholographic microscopy (DHM) laboratory set-up designed for the study of eyetissue and to implement and optimise digital data processing and noise reductionroutines. This work is part of a collaborative project aiming to provide quantitativemethods for the in vitro and in vivo characterisation of human corneal transparency.The laboratory set-up is based on a commercial laboratory microscope with zoomfunction (a “macroscope”). In continuation of previous work, we completed and optimised,and extended a software for holographic signal processing and numericalpropagation of the wavefront.To characterise the set-up and quantify its performances for standard operationand in its DHM configuration, we compare the magnification and resolution to theoreticalvalues for a given set of parameters. We determined the magnification factorand the rotation angle between the object and camera planes. With a laser wavelengthof 532 nm, a x1 objective and a zoom setting of x2.9 (which corresponds to aplane sample wavefront), we measured a magnification of 1.68. With the same parameters,we measure a holographic resolution of about 11 m. The wavefront phasecould be determined with a precision of a fraction of the wavelength.We subsequently performed analysis of the relative contribution of coherent noiseand implemented and evaluated several noise reduction routines. While the impactof coherent noise remained visible in the amplitude image, interferometric precisionwas obtained for the phase of the wavefront and the set-up was considered qualifiedfor its intended use for corneal characterisation.A first test measurement was performed on primate cornea.Subsequent work will address the further quantitative characterisation of the setupfor the full set of parameters (objectives, zoom positions, wavelengths), test measurementson samples with known transmission and light scattering properties (e.g.solutions of PMMA beads) and the comparison of the results with the predictions ofa theoretical model, and measurements on animal and human tissue.
|
167 |
Improving the Design of Holographic ICT tools in e-Learning : A User-Centered ApproachTcykin, Konstantin January 2022 (has links)
Information and Communication Technology (ICT) nowadays is constantly evolving and drastically impacting different fields of human activity, such as higher education. University education, due to ICT, was able to move from the traditional teaching and learning practices to e-Learning. That is, delivering education to the learner regardless of place and time via leveraging technology, such as computer-mediated platforms, based on synchronous video conferencing. The next generation of computer-mediated communication tools is ready to facilitate synchronous holographic communication among users. However, such tools have not been designed specifically for the field of university education and have not been taken into consideration the design requirements and needs of users to be successfully integrated to the e-Learning model. Hence, this master’s thesis study explores the perceptions of higher education teachers and students about the potential use of holographic ICT tools in the context of e-Learning, as well as their desired characteristics in regard to the design of such tools. For this, an interpretive qualitative ethnographic research was conducted. Data was collected through passive observations and focus group discussions with purposively selected university teachers and students, and by leveraging the method of Thinking Aloud. The collected data was subjected to thematic analysis to conclude to seven themes, which represent the findings of this study. These research findings were discussed in relation to the research aim, research questions and the theoretical framework including the approach of User-Centered Design. The research findings showed that university teachers and students acknowledge the potential of the holographic ICT tools and have an interest to try them out in the context of e-Learning activities. The potential use of holographic ICT tools was described as improving the quality of communication between teachers and students when on distance; delivering education globally and making it more accessible; lifting the current technological limitations and enriching the e-Learning practices. Some concerns, though, in regard to the use of such tools were expressed in terms of complexity and disturbances. The research findings also showed the university teachers’ and students’ desired characteristics in regard to the design of such tools, which include interoperability with the other systems used in e-Learning activities; high quality of human and non-human holographic representations; and indicators in holographs of the participants’ status, along with additional interactive features. In addition, the university teachers and students suggested the holographic ICT tools to be designed as a pair of comfortable augmented reality (AR) glasses, which can be easy to control and can be connected to personal devices. Finally, it was suggested to include main tools of teaching and learning activities -such as whiteboard, screensharing, slides presentation-; and multiple modes that can be used depending on the users’ teaching and learning needs. Thus, the research outcome contributes theoretically to the research field of informatics by providing insights and new knowledge about the potential use of novel holographic ICT tools for e-Learning. The research outcome also contributes practically to designers, developers, technology companies, and other interested stakeholders as it shortens the knowledge gap regarding the design principles of holographic ICT tools and their use cases within the context of education, and provides suggestions regarding their design from a user-centered approach.
|
168 |
Local Phase Manipulation for Multi-Beam Interference Lithography for the Fabrication of Two and Three Dimensional Photonic Crystal TemplatesLutkenhaus, Jeffrey Ryan 12 1900 (has links)
In this work, we study the use of a spatial light modulator (SLM) for local manipulation of phase in interfering laser beams to fabricate photonic crystal templates with embedded, engineered defects. A SLM displaying geometric phase patterns was used as a digitally programmable phase mask to fabricate 4-fold and 6-fold symmetric photonic crystal templates. Through pixel-by-pixel phase engineering, digital control of the phases of one or more of the interfering beams was demonstrated, thus allowing change in the interference pattern. The phases of the generated beams were programmed at specific locations, resulting in defect structures in the fabricated photonic lattices such as missing lattice line defects, and single-motif lattice defects in dual-motif lattice background. The diffraction efficiency from the phase pattern was used to locally modify the filling fraction in holographically fabricated structures, resulting in defects with a different fill fraction than the bulk lattice. Through two steps of phase engineering, a spatially variant lattice defect with a 90° bend in a periodic bulk lattice was fabricated. Finally, by reducing the relative phase shift of the defect line and utilizing the different diffraction efficiency between the defect line and the background phase pattern, desired and functional defect lattices can be registered into the background lattice through direct imaging of the designed phase patterns.
|
169 |
Mutual interactions of femtosecond pulses and transient gratings in nonlinear optical spectroscopyNolte, Stefan 16 November 2018 (has links)
This work is dedicated to a comprehensive experimental study on the interaction of femtosecond laser pulses with the nonlinear optical medium lithium niobate. The nonlinear optical response in the nanosecond regime was already studied extensively with a variety of techniques, whereas femtosecond pulses were mainly used in transient absorption or transient grating experiments. Naturally, the temporal resolution of these measurements depends on the pulse duration, however, dynamics during the pulse excitation were barely investigated.
The motivation of this work is to widen the limits of femtosecond spectroscopy, not only to temporally resolve faster nonlinear optical processes, but further to show a sensitivity to other coupling mechanisms between the pulses and the material. Especially, the role of transient, dynamic holographic gratings is investigated with a careful determination of the pulse duration, bandwidth and frequency chirp. A basis of this work is established in the first part by studying the material response via light-induced absorption before focusing on the main topic, the pulse interaction with elementary (holographic) gratings, both self-induced and static, in the second part. By this detailed study, several features of femtosecond laser pulses, holographic gratings and the ultrafast material response can be revealed: (i) grating recording is feasible even with pulses of different frequencies, provided that their pulse duration is sufficiently short, (ii) grating based pulse coupling causes a pronounced energy transfer even in a common pump-probe setup for transient absorption measurements with (non-)degenerated frequencies, (iii) beyond expectation, oscillations in the phonon frequency range become apparent in different measurements. The presented results point towards appropriate future experiments to obtain a more consistent, microscopic model for the ultrafast response of the crystal, involving the interplay between photo-generated polarons, self-induced gratings, and phonons.
|
170 |
Alternative techniques for the production and manipulation of ultracold atomsBruce, Graham D. January 2012 (has links)
This Thesis contains details of the construction and characterisation of a compact apparatus for the cooling of ultracold atoms to quantum degeneracy, and their manipulation in flexible holographic optical traps. We have designed and built two iterations of this apparatus. The first version consists of a stainless steel single-cell vacuum chamber, in which we confine ⁸⁷Rb and ⁶Li or ⁷Li in a Magneto-Optical Trap. We characterise the alternative methods of pulsed atomic dispenser and Light Induced Atomic Desorption (LIAD) to rapidly vary the background pressure in the vacuum chamber with the view to enabling efficient evaporative cooling in the single chamber, loading MOTs of up to 10⁸ atoms using pulsed dispensers. The LIAD is found to be ineffective in loading large MOTs in this setup, while the pulsed dispensers method gradually increases the background pressure in the chamber over time. Based on the results of this first iteration, we designed and built a second single-chamber apparatus for cooling of ⁸⁷Rb to quantum degeneracy. The LIAD technique was used to successfully load MOTs containing 8x10⁷ atoms in this single pyrex cell with a rapidly-varying background pressure. The lifetime of an atomic cloud loaded from the MOT into a magnetic trap increased by a factor of 6 when LIAD was used. The holographic optical traps for cold atoms are generated using a Spatial Light Modulator, and we present our novel method for improving the quality of holographic light patterns to the point where they are suitable for trapping ultracold atoms using a feedback algorithm. As demonstrations of this new capability, we show power-law optical traps which provide an efficient, reversible route to Bose-Einstein Condensation and a dynamic ring trap for the investigation of superfluidity in cold atoms.
|
Page generated in 0.0682 seconds