On this thesis work, design and construction of an up to date complete RF excitation system was intended. This excitation system is mainly based on highly efficient switching power generators and proper coupling of the power to the object plasma. This new excitation system design should answer the demands of today&#039 / s progressed CO2 lasers on various power ranges. Though it could be used by a large variety of applications including RF plasma and RF heating, on the first occasion in order to define design considerations, this system is to be exploited by RF excited fast flow and RF excited slab CO2 laser constructions.

Made available in DSpace on 2016-12-12T20:27:39Z (GMT). No. of bitstreams: 1 Renan Sebem.pdf: 14781648 bytes, checksum: 1c30002408823e0116831038c8c98e8c (MD5) Previous issue date: 2015-09-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work explores the potential and shows the implementation of the long period gratings as refractive index sensors. It is proposed a sensor design where the refractive index sensitivity is improved. The design includes the use of the sensor with simple and low cost interrogation. Several manufacturing parameters are investigated and the process is enhanced to meet the design specifications, and also to obtain repeatability in the process. New ideas were proposed to manufacture tilted gratings and to control the index modulation duty cycle in a practical way with inexpensive equipment. The inscription of the fiber sensor is made by CO2 laser, point to point, with a uniform index modulation. The gratings were interrogated by an optical spectrum analyzer and also by edge filter demodulation in the 1550 nm region through an electronic board, developed in this work with automatic normalization of the signal. Results show that the refractive index sensitivity is influenced by several design and manufacturing parameters of the fiber grating. Performed experiments show a considerable increase in the refractive index sensitivity of the grating. / Este trabalho explora o potencial e demonstra a implementação das redes de período longo em fibra como sensores de índice de refração. É proposto um projeto do sensor em que a sensibilidade ao índice de refração é aperfeiçoada. O projeto contempla a utilização do sensor com interrogação de maneira simples e de baixo custo. Diversos parâmetros de fabricação são investigados e o processo é aprimorado para atingir as especificações de projeto, e também a fim da obtenção de repetibilidade no processo. Novas ideias foram propostas para fabricação de redes inclinadas e para o controle do duty cycle da modulação de índice da rede de maneira prática com equipamentos de baixo custo. A fabricação do sensor em fibra é feita através de laser de CO2, ponto a ponto, e com modulação de índice uniforme. As redes foram interrogadas através de analisador de espectro óptico e também por demodulação de borda de filtro na região de 1550 nm através de uma placa eletrônica, desenvolvida neste trabalho com normalização automática do sinal. Resultados mostram que a sensibilidade ao índice de refração é influenciada por alguns parâmetros de projeto e fabricação da rede em fibra. Experimentos realizados mostraram um aumento considerável na sensibilidade da rede ao índice de refração.

Estudos têm mostrado que a dentina pode ser modificada pelo laser pulsado de CO2 tornando-a um substrato mais ácido-resistente. Este estudo in vitro se propôs a estabelecer parâmetros seguros e efetivos de um laser pulsado de CO2 com comprimento de onda 10,6 ?m e avaliou seu efeito sobre a morfologia superficial e a composição química, assim como sobre a redução da desmineralização da dentina radicular. Noventa e cinco superfícies radiculares humanas obtidas de quarenta e oito terceiros molares foram aleatoriamente divididas em 5 grupos (n=15 para o grupo de controle e n=20 para os grupos irradiados com laser): G1 - Nenhum tratamento (controle), G2 - 2,5 J/cm2, G3 - 4,0 J/cm2, G4 - 5,0 J/cm2 e G5 - 6,0 J/cm2. A temperatura intrapulpar foi mensurada por meio de análise termográfica com termômetro de radiação infravermelha, as modificações químicas, por meio de espectroscopia FT-Raman e as alterações morfológicas por meio de microscopia eletrônica de varredura. Após o tratamento da superfície, os espécimes foram submetidos a 7 dias de ciclagem de pH, permanecendo diariamente em soluções desmineralizadora e remineralizadora por 3 h e 21 h, respectivamente. Após o desafio ácido, os espécimes foram seccionados e a perda mineral foi determinada por meio do teste de microdureza Knoop (5 g, 5 seg) em profundidades pré-determinadas em relação à superfície de dentina radicular (20 ?m - 275 ?m). Para todos os grupos irradiados, as mudanças de temperatura intrapulpar mostraram-se abaixo de 0,9°C. A espectroscopia FT-Raman não evidenciou alterações químicas entre os espécimes não-irradiados e os irradiados com laser de CO2. Entretanto a análise em microscópio eletrônico de varredura indicou que as densidades de energia a partir de 4,0 J/cm2 foram suficientes para induzir mudanças morfológicas na dentina radicular. Adicionalmente, para as densidades de energia iguais ou superiores a 4,0 J/cm2, foram observados efeitos de redução da desmineralização da dentina radicular induzidos pela irradiação laser. Pode-se concluir que densidades de energia em torno de 4,0 a 6,0 J/cm2 podem ser aplicadas à dentina radicular, a fim de promover mudanças morfológicas e reduzir a reatividade ácida da mesma, sem comprometer a vitalidade pulpar. / Studies have shown that dentin can be modified by pulsed CO2 laser to form a more acid-resistant substrate. This in vitro research aimed to establish safe parameters of a pulsed study 10.6 ?m CO2 laser and evaluate its effect on chemical and morphological features in dentinal surface, as well as on the reduction of root dentin demineralization. Ninety five human root surfaces obtained from forty eight third molars were randomly divided in 5 groups (n=15 for control group and n=20 for laser groups): G1 - No treatment (control), G2 -2.5 J/cm2, G3 - 4.0 J/cm2, G4 - 5.0 J/cm2 and G5 - 6.0 J/cm2. Intrapulpal temperature was evaluated during dentin irradiation by an infrared thermometer, chemical modifications by FT-Raman spectroscopy, and morphological modifications by SEM. After the surface treatment, the specimens were submitted to a 7 days pH-cycling model, consisted of the daily immersion in demineralizing and remineralizing solutions for 3 h and 21 h, respectively. After the acid challenge, the specimens were sectioned and the mineral loss was determined by means of cross-sectional Knoop microhardness (5 g, 5 sec) at different depths from the dentin root surface (20 ?m - 275 ?m). For all irradiated groups, intrapulpal temperature changes were below 0.9°C. FT-Raman spectroscopy did not show chemical changes in the irradiated specimens. However, scanning electron microscopy images indicated that fluences as low as 4.0 J/cm2 were sufficient to induce morphological changes in root dentin. Additionally, for fluences reaching or exceeding 4.0 J/cm2, laser-induced inhibitory effects on root dentin demineralization were observed. It was thus concluded that the laser energy density in the range of 4.0 to 6.0 J/cm2 could be applied to dental root dentin in order to produce morphological changes and reduce the acid reactivity of dentin without compromising the pulp vitality.

Due to their inherent BW capacity, optical interconnect (OI) offers a means of replacement to BW limited copper as bottlenecks begin to appear within the various interconnect levels of electronics systems. Low-cost optically enabled printed circuit boards are a key milestone on many electronics roadmaps, e.g. iNEMI. Current OI solutions found in industry are based upon optical fibres and are capable of providing a suitable platform for inter-board applications especially on the backplane. However, to allow component assembly onto high BW interconnects, an integral requirement for intra-board applications, optically enabled printed circuit boards containing waveguides are essential. Major barriers to the deployment of optical printed circuit boards include the compatibility of the technique, the cost of acquiring OI and the optical power budget. The purpose of this PhD research programme is to explore suitable techniques to address these barriers, primarily by means of laser material processing using UV and IR source lasers namely 248 nm KrF Excimer, 355 nm UV Nd:YAG and 10.6 μm IR CO2. The use of these three main lasers, the trio of which dominates most PCB production assembly, provides underpinning drive for the deployment of this technology into the industry at a very low cost without the need for any additional system or system modification. It further provides trade-offs among the suitable candidates in terms of processing speed, cost and quality of waveguides that could be achieved. This thesis presents the context of the research and the underlying governing science, i.e. theoretical analysis, involving laser-matter interactions. Experimental investigation of thermal (or pyrolitic) and bond-breaking (or photolytic) nature of laser ablation was studied in relation to each of the chosen lasers with regression analysis used to explain the experimental results. Optimal parameters necessary for achieving minimum Heat Affected Zone (HAZ) and surface/wall roughness were explored, both of which are key to achieving low loss waveguides. While photochemical dominance - a function of wavelength and pulse duration - is desired in laser ablation of photopolymers, the author has been able to find out that photothermallyprocessed materials, for example at 10.6 μm, can also provide desirable waveguides. Although there are literature information detailing the effect of certain parameters such as fluence, pulse repetition rate, pulse duration and wavelength among others, in relation to the etch rate of different materials, the machining of new materials requires new data to be obtained. In fact various models are available to try to explain the laser-matter interaction in a mathematical way, but these cannot be taken universally as they are deficient to general applications. For this reason, experimental optimisation appears to be the logical way forward at this stage of the research and thus requiring material-system characterisation to be conducted for each case thereby forming an integral achievement of this research. In this work, laser ablation of a single-layer optical polymer (Truemode™) multimode waveguides were successfully demonstrated using the aforementioned chosen lasers, thus providing opportunities for rapid deployment of OI to the PCB manufacturing industry. Truemode™ was chosen as it provides a very low absorption loss value < 0.04 dB/cm at 850 nm datacom wavelength used for VSR interconnections - a key to optical power budget - and its compatibility with current PCB fabrication processes. A wet-Truemode™ formulation was used which required that optical polymer layer on an FR4 substrate be formed using spin coating and then UV-cured in a nitrogen oxygen-free chamber. Layer thickness, chiefly influenced by spinning speed and duration, was studied in order to meet the optical layer thickness requirement for multimode (typically > 9 μm) waveguides. Two alternative polymers, namely polysiloxane-based photopolymer (OE4140 and OE 4141) from Dow Corning and PMMA, were sparingly utilized at some point in the research, mainly during laser machining using UV Nd:YAG and CO2 lasers. While Excimer laser was widely considered for polymer waveguide due to its high quality potential, the successful fabrication at 10.6 μm IR and 355 nm UV wavelengths and at relatively low propagation loss at datacom wavelength of 850 nm (estimated to be < 1.5 dB/cm) were unprecedented. The author considered further reduction in the optical loss by looking at the effect of fluence, power, pulse repetition rate, speed and optical density on the achievable propagation but found no direct relationship between these parameters; it is therefore concluded that process optimisation is the best practice. In addition, a novel in-plane 45-degree coupling mirror fabrication using Excimer laser ablation was demonstrated for the first time, which was considered to be vital for communication between chips (or other suitable components) at board-level.

This diploma thesis is divided into two main parts. The first section is dedicated to the history and development of the laser technology. The second part describes all individual types of laser technology which are used in the industry nowadays. The next section follows with the research of various laser devices which serve mainly as a cutting tool. This knowledge gathered in the previous part was used to create the next part including the own conception of the machine. The second half of this diploma thesis deals with a research of software available at the market today. Eventually, after summarizing the characteristics of each software, the new concept and implementation of own software are made. In the final section, there are mentioned the possible extension and available upgrades. The reader should be able to create his/her own conception of the laser device and software after reading and understanding this paper.

This diploma thesis is divided into two main parts. The first section is dedicated to the history and development of the laser technology. The second part describes all individual types of laser technology which are used in the industry nowadays. The next section follows with the research of various laser devices which serve mainly as a cutting tool. This knowledge gathered in the previous part was used to create the next part including the own conception of the machine. The second half of this diploma thesis deals with a research of software available at the market today. Eventually, after summarizing the characteristics of each software, the new concept and implementation of own software are made. In the final section, there are mentioned the possible extension and available upgrades. The reader should be able to create his/her own conception of the laser device and software after reading and understanding this paper.

This thesis deals with the possibilities of cutting strong steel metal sheets by means of laser and problems rising from the incision, their technological investigation. The basic philosophy consists on the research of the interaction between laser bunch and material, depending on the position of focal poin and sequential results in spec. heat. It determines the main parametres of the incision (from the total quantities and matematical description) which have the biggest effect on the occurence of wide cut and perhaps even on the quality of products and consequential optimalization of these quantities.

This thesis deals with laser cutting of metal sheets from selected steel producers. The basics of laser technologies, especially in industrial use, are described in the introductory part. There the material requirements are described from the point of view of laser cutting. The comparison of materials from different steel producers is made from different angles in the practical part. The conclusion is dedicated to the evaluation of achieved results.

This diploma thesis deals with the development, disign and manufacturing inspection device that is able to detect the presence of components in the assembly of the plastic molding. Evaluation of information are indicated by the operator device and sent for further processing. Rechecked product will be marked with a uniquemark.

The quantum properties of matter waves, in particular quantum correlations and entanglement are an important frontier in atom optics with applications in quantum metrology and quantum information. In this thesis, we report the first observation of sub-Poissonian fluctuations in the magnetization of a spinor 87Rb condensate. The fluctuations in the magnetization are reduced up to 10 dB below the classical shot noise limit. This relative number squeezing is indicative of the predicted pair-correlations in a spinor condensate and lay the foundation for future experiments involving spin-squeezing and entanglement measurements. We have investigated the limits of the imaging techniques used in our lab, absorption and fluorescence imaging, and have developed the capability to measure atoms numbers with an uncertainly < 10 atoms. Condensates as small as ≈ 10 atoms were imaged and the measured fluctuations agree well with the theoretical predictions. Furthermore, we implement a reliable calibration method of our imaging system based on quantum projection noise measurements. We have resolved the individual lattice sites of a standing-wave potential created by a CO2 laser, which has a lattice spacing of 5.3 µm. Using microwaves, we site-selectively address and manipulate the condensate and therefore demonstrate the ability to perturb the lattice condensate of a local level. Interference between condensates in adjacent lattice sites and lattice sites separated by a lattice site are observed.