The Compact Linear Collider (CUC) is a proposed electron-positron collider with a centre- of-mass energy of 0.5 to 5 TeV, optimised for a nominal centre-of-mass energy of 3 TeV, at high luminosities exceeding 1034 cm-2s-J. The high beam charges in the CUC beams make classical techniques for measuring the transverse beam size such as optical transition radiation (OTR) screens or wire scanners very difficult, which necessitates the use of non-invasive beam- size monitors. The laser-wire is a system that meets these requirements; it uses inverse Compton scattering to determine transverse beam-sizes by scanning a laser beam across the electron beam. This thesis describes how such a laser-wire system was installed and operated at PETRA-III at DESY, which uses an automated mirror to scan a Q-switched laser pulse across the electron beam and is developed from the system previously operated at PETRA-II. The measurements of key performance parameters are described and used in determining the emittance of the PETRA-III beam. The thesis includes a detailed investigation of the laser .' system as well as the collision measurements. Furthermore, simulations were carried out to design a similar system for the proposed transfer line of the CUC Drive-Beam and the necessary baseline characteristics of such a system are described.

This Ph.D. work is dedicated to advancements in burst-mode laser technology and their applications in MHz-rate high-speed gas-phase environments. A comprehensive computational model for simulating experimental burst-mode systems is discussed. Direct comparison of the modeled results to the output of a constructed nanosecond (ns) burst-mode laser shows agreement within a factor of 2 for output energy, the temporal domain skews positively in an appropriate manner, and the spectral domain correctly remains unchanged. The modeled output of a femtosecond (fs) burst-mode laser displays near perfect agreement with its hardware, generating only a 1.7% deviation for output energy, an 11% deviation in spectral bandwidth, and a temporal profile that correctly remains unchanged. The experimental ns to fs burst-mode lasers systems used to compare with the aforementioned model are described in detail and demonstrated for use in measurements of temperature, species, and velocity at high repetition rates. In the ns regime, a compact-footprint (0.18 m2 ) flashlamp-pumped, burst-mode Nd:YAGbased master-oscillator power-amplifier (MOPA) laser is developed with a fundamental 1064 nm output of over 14 J per burst. This portable laser system uses a directly modulated diode laser seed source to generate 10 ms duration arbitrary sequences of 500 kHz doublet or MHz singlet pulses for flow-field velocity or species measurements, respectively. In the fs regime, a flashlamp-pumped burst-mode laser system with high peak power and a broad spectral bandwidth of >10 nm is constructed without the use of nonlinear compression techniques. A mode-locked, 1064.6 nm fundamental-wavelength broadband master oscillator, a fiber amplifier/pulse stretcher, and four Nd:glass power amplifiers are used to generate a sequence of high-repetition-rate, transform-limited 234 fs pulses over a 1 ms burst duration at a 0.1 Hz burst repetition rate. The generated peak powers are 1.24 GW at 100 kHz and 500 MW at 1 MHz with M2∼1.5. An adaptation of the fs burst-mode laser is used for femtosecond laser electronic excitation tagging (FLEET) of nitrogen for tracking the velocity field in high-speed flows at kilohertz– megahertz (kHz–MHz) repetition rates without the use of added tracers. The fs burst-mode laser is used to produce 500 pulses per burst with pulses having a temporal separation as short as 1 µs, an energy of 120 µJ, and a duration of 274 fs. This enables 2 orders of magnitude higher measurement bandwidth over conventional kHz-rate FLEET velocimetry. 15 The fs burst-mode system was further improved to include a picosecond (ps) leg for hybrid fs/ps rotational coherent anti-Stokes Raman scattering (RCARS) at MHz rates. Using a common fs oscillator, the system simultaneously generates time synchronized 1061 nm, 274 fs and 1064 nm, 15.5 ps pulses with peak powers of 350 MW and 2.5 MW, respectively. The system is demonstrated for two-beam fs/ps RCARS in N2 at 1 MHz with a signal-to-noise ratio of 176 at room temperature. This repetition rate is an order of magnitude higher than previous CARS using burst-mode ps laser systems and two to three orders of magnitude faster than previous continuously pulsed fs or fs/ps laser systems. As a continuation of the above advances in fs regime, a regenerative fs burst-mode laser is discussed in detail with motivations, design layouts, and cavity physics laid out. Preliminary construction of the system with a ns seed source is underway to assess the detailed system design and evaluate the potential for optical damage due to Kerr lensing or other nonlinear effects. This system and other potential follow-on research topics are discussed.

M.Ing. (Electrical and Electronic Engineering) / This dissertation deals with the mapping of an unknown environment. Mapping of an environment can be accomplished by asking the question “What is in my world?” whilst moving through the environment. Once the objects occupying the ‘world’ have been discovered, the locations of these objects are stored somewhere (for example on paper), so that the environment can be navigated at a later stage. In the context of robots, a map provides the robot with a certain degree of “intelligence”. Several different types of applications are available for robots with “intelligence”; ranging from mining applications, to search and rescue situations, to surveillance applications and recognisance applications. The research hypothesis posed by this dissertation is as follows: Produce a human readable map for an unknown defined structured environment using a single laser range finder (LRF). The focus was on mapping environments resembling mine tunnels. In mine tunnel environments sensors, such as wheel odometers, can fail. This failure makes it advantageous to be able to create a map of the environment with the data obtained solely from the LRF. For this dissertation, the following restrictions were placed on the environment being mapped. It had to be structured (i.e. the environment could be described by simple geometric primitives such as lines); it had to be static (the only entity allowed to move in the environment was the LRF to obtain data); and the environment had to be defined (i.e. have a starting and ending point). During the course of this Masters research, it was discovered that in order to create a human readable map, one has to determine the accurate localisation of the sensor in the environment whilst mapping. The described scenario is a typical problem in mapping and is referred to as the ‘simultaneous localisation and mapping (SLAM) problem’. This dissertation shows results when mapping was done with – and without – accurate localisation. The final approach used to create the human readable map consisted of determining scan matched odometry (based on a feature matching and ICP algorithm). The scan matched odometry is incorporated into a grid-based SLAM technique that utilises a particle filter to accurately determine the position of the sensor in the environment, in order to create a human readable map of the environment. The algorithm used (as described) was able to close loops (i.e. the mapping algorithm was able to handle the sensor returning to its starting point) and it produced satisfactory results for the types of environments as required by the scope of this dissertation.

Indoor horticulture offers a promising solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available lighting is suboptimal, therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. Lasers are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Besides, laser beams can be tailored to match the absorption profiles of different plants. We have developed a prototype laser growth chamber and demonstrate that laser-grown plants can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteomic data show that the singlewavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture. Furthermore, stomatal movement partly determines the plant productivity and stress management. Abscisic acid (ABA) induces stomatal closure by promoting net K+-efflux from guard cells through outwardrectifying K+ (K+ out) channels to regulate plant water homeostasis. Here, we show that the Arabidopsis thaliana guard cell outward-rectifying K+ (ATGORK) channel is a direct target for ABA in the regulation of stomatal aperture and hence gas exchange and transpiration. Addition of (±)-ABA, but not the biologically inactive (−)-isomer, increases K+ out channel activity in Vicia faba guard cell protoplast. A similar ABA-modulated K+ channel conductance was observed when ATGORK was heterologously expressed in human embryonic kidney 293 (HEK-293) cells. Alignment of ATGORK with known PYR/PYL/RCARs ABA receptors revealed that ATGORK harbors amino acid residues that are similar to those at the latchlike region of the ABA-binding sites. In ATGORK, the double mutations K559A and Y562A at the predicted ABA-interacting site impaired ABA-dependent channel activation and reduced the affinity for ABA in vitro.

The means of communication in oceanic environments is currently dominated by sonar. Although it is reliable for long-distance transmission, the vision of internet of underwater things (IoUT) requires an alternate means for high-data-rate transmission. It is also envisaged that a networked underwater and above-water objects, such as sensor nodes, and autonomous underwater vehicles will benefit seafloor exploration. The use of laser-based optical communication is poised to realize this dream while working hand-in-hand with acoustic and radio-frequency technologies from the littoral zone to deep blue sea. While blue and green lasers are typically utilized depending on the optical properties of the water, laser-based white light is attractive in a number of aspects. In this thesis, we proposed and realized the use of white light to model the channel and to provide the immediate decision for the preferred system configuration, which is critical for developing reliable communication links, particularly, in the presence of turbulence, which makes the alignment of underwater wireless optical communication (UWOC) links challenging. Temperature and salinity changes are among factors that change the refraction index, giving rise to beam wander. This thesis explores the dependence of underwater turbulence on the wavelength. After comparing the performance of red, green, and blue lasers, an ultra-fast comprehensive method that utilizes a white-light source that can produce a wide range of wavelengths is implemented. Experimental results show an 80%-decrease in the scintillation index as the wavelength is increased from 480 to 680 nm in weak turbulence caused by a 0.02-℃/cm temperature gradient with a 40-ppt salt concentration, which emulates conditions found in the Red Sea. The effect of turbulence on the bit error ratio (BER) is also investigated experimentally. Temperature gradients increased the BER especially for shorter wavelengths. The results along long-transmission distances were verified using Monte Carlo simulations. The correlation matrix between wavelengths was studied, which is important for designing multiple-input multiple-output systems. The results obtained show that as the difference in the wavelengths increases, the correlation decreases. Based on the interplay among scintillations, scattering, absorption, and the correlation between different wavelengths, it is possible to design a more reliable UWOC link.

Orientador: Edson Moschim / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-10T09:27:29Z (GMT). No. of bitstreams: 1 Muramoto_WillianSadaiti_M.pdf: 2409655 bytes, checksum: 095d332f24becfd479ff86a233ffcc95 (MD5) Previous issue date: 2007 / Resumo: Este trabalho apresenta um estudo e simulações de um enlace atmosférico para comunicações ópticas e como os diversos fatores intrínsecos ao enlace podem influenciar na qualidade do sinal. O uso de um canal atmosférico para a propagação de um sinal óptico é chamado de FSO, Óptica do Espaço Livre, que é uma alternativa barata para enlaces de curto alcance, devido aos baixos custos no seu desenvolvimento, instalação e manutenção. A principal contribuição deste trabalho esta na reunião dos modelos matemáticos que caracterizam o enlace óptico atmosférico / Abstract: This is a study and simulation on free space optical communication analyzing many factors that can influence the transmitted signal quality. The use of an atmospheric channel to propagate optical signal is called FSO, Free Space Optics, and it is a cheap alternative for low length paths, because the low cost in it development, installation and maintenance. The mainly contribution for this work are in group many characteristic equations for atmospheric optical links / Mestrado / Engenharia de Computação / Mestre em Engenharia Elétrica

<p>This study is focused on the prediction of residual stresses and microstructure development of steel and aluminum alloys during laser-based manufacturing processes by means of multi-physics numerical modeling.</p> <p>A finite element model is developed to predict solid-state phase transformation, material hardness, and residual stresses produced during laser-based manufacturing processes such as laser hardening and laser additive manufacturing processes based on the predicted temperature and geometry from a free-surface tracking laser deposition model. The solid-state phase transformational model considers heating, cooling, and multiple laser track heating and cooling as well as multiple layer tempering effects. The residual stress model is applied to the laser hardening of 4140 steel and to laser direct deposition of H13 tool steel and includes the effects of thermal strain and solid-state phase transformational strain based on the resultant phase distributions. Predicted results, including material hardness and residual stresses, are validated with measured values.</p> <p>Two dendrite growth predictive models are also developed to simulate microsegregation and dendrite growth during laser-based manufacturing processes that involve melting and solidification of multicomponent alloys such as laser welding and laser-based additive manufacturing processes. The first model uses the Phase Field method to predict dendrite growth and microsegregation in 2D and 3D. It is validated against simple 2D and 3D cases of single dendrite growth as well as 2D and 3D cases of multiple dendrite growth. It is then applied to laser welding of aluminum alloy Al 6061 and used to predict microstructure within a small domain. </p> The second model uses a novel technique by combining the Cellular Automata method and the Phase Field method to accurately predict solidification on a larger scale with the intent of modeling dendrite growth. The greater computational efficiency of the this model allows for the simulation of entire weld pools in 2D. The model is validated against an analytical model and results in the literature.

Continuous welding is one of the prominent techniques used in producing seamless piping used in many applications such as the mining and the oil and gas industries. Weld defects cause significant loss of time and money in the piping production industry. Therefore, there is a need for effective online weld defects detection systems. A laser-based weld defects detection (LBWDD) system has been developed by the industrial partner. However, the current LBWDD system can only detect some geometrically based weld defects, but not material inhomogeneity such as voids, impurities, inclusions, etc. The main objective of this study is to assess the predictability of a thermal imaging-based weld defects detection system (TIBWDD) using an IR camera that can be integrated with the current LBWDD system. The aim of the integrated detection system is to be able to detect a wider range of weld defects. A test rig has been designed and used to carry out a set of emissivity (ε) calculation experiments considering three different materials – Aluminum 5154 (Al), Stainless Steel 304L (SS), and Low Carbon Steel A131 (LCS) with two surface finishes 0.25 μm (FM) and 2.5 μm (RM), which are relevant to pipe welding operations. Al showed least change in ε varying from 0.162 to 0.172 for FM samples and from 0.225 to 0.250 for RM samples from 50°C to 550°C. LCS showed highest change in ε varying from 0.257 – 0.918 for FM samples and from 0.292 to 0.948 for RM samples. SS showed a consistent increase in ε for both FM and RM samples. Experimental and numerical analysis have been carried out mimicking two sets of possible weld defects investigating defect size, Dh, and distance between effect and sample surface, δ. Results showed that the δ based defects that are located within 3 mm can be detected by the IR camera. Defects with Dh = 1. 5 mm can be detected by the IR camera with and without glass wool. Laser welding simulations using 2D and 3D Gaussian heat source models have been carried out to assess the predictability of a set of possible weld defects. The heat source models have been validated using experimental data. Three sets of defects were considered representing material-based inhomogeneity, step and inclined misalignment defects. For material-based inhomogeneity in thin plates all defects located at 1.25 mm from the surface are found detectable as ΔT (temperature difference obtained on surface) > ΔTmin (detectability limit of TIBWDD system). For inhomogeneity defects in thick plates, except defects of 2.5 mm in square size all other defects were found detectable as ΔT > ΔTmin. All step misalignment defects were detected for thin and thick plates. In the case of inclined misalignment defects, for thin plates, the misalignment error in the thin plate had to be at least 0.275 mm to be detected. In the case of thick plates, the misalignment error had be at least 0.375 mm to be detected. Overall, results of the present study confirm that thermal imaging can be successfully used in detecting material-based and geometry-based weld defects. / Thesis / Master of Applied Science (MASc)

<p dir="ltr">From transonic to hypersonic regimes, the characterization of high-speed flow dynamics is critical for the development, testing, and improvement of launch and reentry vehicles, boost-glide vehicles, and thermal protection systems. The design of this technology often relies on computational/empirical models for predictions which make quantitative thermodynamic measurements crucial for numerical validation. Laser diagnostic techniques facilitate non-intrusive, <i>in situ</i> measurements of fluid dynamic properties as well as visualization of flows, shocks, and boundary layer interactions. However, many diagnostics rely on seeding the flow with foreign materials to make measurements, such as the application of particle image velocimetry (PIV), Doppler global velocimetry (DGV), and planar laser-induced fluorescence (PLIF). Molecular filtered Rayleigh scattering (FRS) diagnostics are attractive for flow characterization due to the fact that pressure, temperature, density and velocity measurements can be made directly from air or N₂ molecules without the need for seeding materials. The development of the burst-mode laser (BML) has enabled high-energy pulses generated at the rates necessary to resolve phenomena such as instabilities in boundary-layers and shock-wave evolution using Rayleigh scattering methods. The goal of this dissertation is to advance molecular burst-mode FRS for quantitative, high resolution, multi-parameter measurements. For fixed-wavelength FRS measurements, the spectral characteristics of a BML system were investigated and improved by integrating an etalon for spectral-gating. For multi-parameter measurements, two strategies for wavelength-agility, the ability to quickly switch between two or more laser wavelengths, of the BML were explored: frequency-scanning and frequency-shifting. The frequency-scanning FRS (FS-FRS) technique measurement rate was increased to 1 kHz and demonstrated for 1-ms pressure, temperature, and radial velocity measurements in an underexpanded jet flow. Building upon this, an acousto-optic modulator-based method was implemented to generate frequency-shifted pulses. The rapid frequency-shifting increased the effective FRS multi-parameter measurement rate to 25 kHz and planar pressure, temperature, and radial velocity measurements were captured in an overexpanded jet flow. Finally, design tools for the laser configuration of wavelength-agile FRS were developed for the optimization of relative absolute measurement errors.</p>

Os Medidores de Distância por Triangulação a Laser são sistemas optoeletrônicos destinados à medição de pequenas distâncias ou deslocamentos, sem contato físico direto. Estes equipamentos possuem um grande campo de aplicações industriais. Este trabalho descreve as diversas configurações que este equipamento pode se apresentar, discutindo suas vantagens relativas. São estudadas também as suas partes e os componentes mais indicados. O projeto detalhado de um medidor usando sensor tipo CCD, e apresentado. Algumas aplicações industriais deste modelo são relatadas e diversos métodos e sugestões de uso são apresentadas, com base nas experiências realizadas pelo autor. / Laser Triangulation Rangefinders are non-contact, optoelectronic devices for measurement of small displacements or distances. These devices offer a broad range of industrial applications. This work explains common configurations, parts and main components, comparing their advantages. A detailed project on a CCD based Laser Rangefinder is presented. Some industrial applications for that project are related, discussing practical aspects based on authors experience. Some potential applications are also suggested.