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The excellent pseudoelasticity, shape memory and biocompatibility of Nitinol have made it a leading candidate for applications in various fields, including aerospace, micro-electronics and medical devices. Challenges associated with laser processing need to be resolved before its full potential in practical applications can be realized. The current thesis details the effects of pulsed Nd:YAG laser processing on Ni-rich (Ni-49.2. at.% Ti) Nitinol. First, the mechanical, pseudoelastic and cyclic loading properties for varying process parameters have been compared to those of the base metal. Process parameters were shown to greatly influence the mechanical performance. This was due to local yielding occurring within the processed material during tensile straining. In addition, laser processed samples showed higher permanent residual strain and exhibited a slightly higher efficiency for energy storage during the initial 5 cycles compared to base material. Fracture surfaces of base material revealed ductile dimpled surfaces while welded specimens exhibited both brittle (low peak power) and ductile (high peak power) failure modes. DSC analyses conducted on the processed metal revealed additional high temperature transformation peaks. These peaks were attributed to the local phase conversion induced by laser processing. Further corroboration was made with room temperature XRD analysis, showing only austenite in the base metal and added martensite peaks in the melted metal. Temperature controlled TEM observations confirmed high temperature transformation peaks to be associated with processed metal. Furthermore, TEM analysis aided in identifying the submicron second phase particles observed in fracture surfaces as Ti2Ni. Finally, local phase conversion was correlated to change in local chemical composition. Preferential vaporization of nickel was determined to cause the change in Ni/Ti ratio. This in turn explained the altered mechanical performance and presence of the Ti-rich intermetallic (Ti2Ni). Consequently, a novel method using a high power density energy source to alter transformation temperature of shape memory alloys (SMA’s) was developed. Results were used to successfully demonstrate a novel technology that can embed additional memories in Nitinol and other SMA’s. Possessing the ability to control local transformation temperatures and as a result the shape memory effect of SMA’s promises to enhance their functionality while enabling new applications to be realized.

Two synthesis pathways were employed throughout this work to create a variety of unique carbon materials. The first of these routes involves the photo-dissociation of liquids by direct irradiation with ultrashort laser pulses; while the second entails the bombardment of polycrystalline chemical layers by a pulsed laser induced carbon plasma. The pulsed laser irradiation (PLI) of liquid benzene (C6H6) was found to result in the formation of amorphous carbon nanoparticles consisting of clusters of sp2-bonded aromatic rings bridged by sp hybridized polyyne functionalities. In a complimentary experiment, liquid toluene (C6H5CH3) was irradiated under similar conditions leading to the synthesis of a series of free floating methyl capped polyynes, with chain lengths ranging from C10 – C20. The synthesis of polyynes is an active and cutting edge topic in material science and chemistry. In a more complex experiment, solutions of ferrocene and benzene were irradiated by fs-laser pulses resulting in highly ordered mesoscale structures exhibiting four unique geometries; ribbons, loops, tubes, and hollow spherical shells. After a purification process, the higher order structures were destroyed and replaced with nanoparticles consisting of three distinct species including; pure iron, and two phases in which part of the ferrocene molecule was bound to either carbon or iron/carbon complexes. This material is extremely interesting because it exhibits properties similar to that of an electret and is also ferromagnetic over a large temperature range. In the final liquid phase laser irradiation experiment, a new hybrid deposition technique was originated and used to coat stainless steel electrodes with disordered mesoporous nanocrystalline graphite. This method involves the laser induced breakdown of benzene and the subsequent electrodeposition of the resulting carbon ions. Another focus in this work involved the synthesis of a special class of polymer-like carbon nanomaterials using a new method that augments traditional pulsed laser deposition. This technique involves the plasma processing of frozen materials with a pulsed laser initiated graphitic plasma. We call this technique "pulsed laser induced plasma processing" or "PLIPP". Various thin film compositions were created by processing alkane and alkene ices. Finally, in a slight departure from the previous experiments, the effects of carbon ion bombardment on water ice were examined in an effort to understand certain astrophysical processes.

The need for custom footwear among the consumers is growing every day. Serious research is being undertaken with regards to the fit and comfort of the footwear. The integration of scanning systems in the footwear and orthotic industries have played a significant role in generating 3D digital representation of the foot for automated measurements from which a custom footwear or an orthosis is manufactured. The cost of such systems is considerably high for many manufacturers due to their expensive components, complex processing algorithms and difficult calibration techniques. This thesis presents a fast and robust calibration technique for a low-cost 3D laser scanner. The calibration technique is based on determining the mathematical relationship that relates the image coordinates to the real world coordinates. The relationship is determined by mapping the known real world coordinates of a reference object to its corresponding image coordinates by multivariate polynomial regression. With the developed mathematical relationship, 3D data points can be obtained from the 2D images of any object placed in the scanner. An image processing script is developed to detect the 2D image points of the laser profile in a series of scan images from 8 cameras. The detected 2D image points are reconstructed into 3D data points based on the mathematical model developed by the calibration process. Following that, the output model is achieved by triangulating the 3D data points as a mesh model with vertices and normals. The data is exported as a computer aided design (CAD) software readable format for viewing and measuring. This method proves to be less complex and the scanner was able to generate 3D models with an accuracy of +/-0.05 cm. The 3D data points from the output model were compared against a reference model scanned by an industrial grade scanner to verify and validate the result. The devised methodology for calibrating the 3D laser scanner can be employed to obtain accurate and reliable 3D data of the foot shape and it has been successfully tested with several participants.

This thesis is concerned with sensitivity alterations of Fiber Bragg Grating (FBG), sensors through additive coatings produced by a combined Laser-Assisted Maskless Micro-deposition (LAMM) and electroless plating process. The coatings can also protect the brittle FBG used in harsh environments. The thesis encompasses design, fabrication procedures, modeling and comparison of experimental and modeling results to gain insight into the advantages and short-comings of the approach. Starting with the opto-mechanical modeling, a program is written in MAPLE to analyze the effect of different on-fiber metallic materials and coating thicknesses on the sensitivity of FBGs to temperature and axial force. On the basis of the proper material and thickness, the sensitivity of FBG at different thermal and loading strains are predicted. The optimal theoretical data suggests that if the thickness of the Ni layer is 30–50 μm, maximum temperature sensitivity is achieved. Some experiments are proposed to test the feasibility of the coated FBG sensors. LAMM is used to coat bare FBGs with a 1-2 μm thick conductive silver layer followed by the electroless nickel plating process to increase layer thickness to a desired level ranging from 1 to 80 μm. Our analytical and experimental results suggest that the temperature sensitivity of the coated FBG with 1 μm Ag and 33 μm Ni is increased almost twice compared to a bare FBG with sensitivity of 0.011±0.001 nm/°C. On the contrary, the force sensitivity is decreased; however, this sensitivity reduction is less than values reported in the literature.

Lasergestützte Mikromanipulation an der Kanincheneizelle im Rahmen von Kerntransferexperimenten Bohn, Dirk Aus der Ambulatorischen und Geburtshilflichen Tierklinik der Veterinärmedizinischen Fakultät der Universität Leipzig und dem Institut für Tierzucht und Tierhaltung mit Tierklinik der Landwirtschaftlichen Fakultät der Martin-Luther-Universität Halle-Wittenberg Juni, 2001 120 S., 199 Lit., 38 Tab., 20 Abb.; Anhang 15 S.: 8 Abb., 15 Tab. Mit der vorliegenden Arbeit sollten erstmalig die Methoden der Laser-vermittelten, berührungsfreien Öffnung der Zona pellucida (Laser-Zona-Drilling, LZD) und der funktionellen Deaktivierung der Vorkerne als einfachere und die Entwicklungsfähigkeit behandelter Zellen weniger beeinträchtigende Methoden im Vergleich zu herkömmlichen mechanischen Methoden des Kerntransfers experimentell bearbeitet werden. Für den Einsatz des Lasers sind grundlegende Kenntnisse über die Wirkungsweise der fokussierten Laserstrahlen am Zielobjekt der Mikromanipulation, den Kanincheneizellen, notwendig. Deshalb wurden zunächst sehr umfangreiche Untersuchungen zum Einfluß steigender Einwirkzeiten des Lasers bei Verwendung drei verschiedener Objektive an und in befruchteten Eizellen in vitro und in vivo durchgeführt. Hierfür kamen 863 Eizellen in 11 verschiedenen Methoden (M) zum Einsatz. Mit den Methoden 1-3 (231 Eizellen) wurde der Einfluß der Objektive beim LZD in vitro untersucht. In den Methoden 4 und 5 kam der Embryotransfer nach LZD zur Anwendung (202 Embryonen). Die Methoden 6-8 (202 Eizellen) wurden zum Einfluß der drei Objektive bei der direkten Laserfokus-vermittelten Manipulation der lichtmikroskopisch sichtbaren Vorkerne in vitro durchgeführt. Bei den Methoden 9-11 (228 Eizellen) wurde der Laserfokus (gleiches Objektiv) in seiner Lage zu den Vorkernen verändert (defokussiert), um zur Wirkungsweise der fokussierten Laserstrahlen in der Eizelle Aussagen zu ermöglichen. Auf der Grundlage dieser Ergebnisse wurden 3 Kerntransfergruppen (G) nach definierter Methodik gebildet, wobei zur Vergleichbarkeit die Parameter der Lasereinstellung (maximale Pulsfrequenz und Energie) von den methodischen Untersuchungen übernommen wurden. Die Empfängereizellen (Vorkerne) der ersten beiden Gruppen (G1: 117; G2: 129) wurden einheitlich mit 10 Sekunden manipuliert. Der Unterschied bestand in der Blastomeren-gewinnung (G1: nach LZD; G2: enzymatisch). Die Empfängereizellen der Gruppe 3 (134) wurden lediglich mit 2 Sekunden manipuliert (enzymatische Blastomerengewinnung) fusioniert. Nachdem die Kerntransferembryonen der Gruppe 3 in vitro die beste Entwicklungsfähigkeit zeigten, wurden 112 so erstellte Kerntransferprodukte auf 8 pseudogravide Ammentiere übertragen. Bei den Untersuchungen zum LZD (M1-M3) und zur direkten Vorkernbearbeitung (M6- M8) zeigte sich eine Abhängigkeit vom verwendeten Objektiv dahingehend, daß die Verwendung des Achroplan den größten und des Neofluar den geringsten depressiven Einfluß auf die Entwicklungsfähigkeit behandelter Eizellen hat. Das Ultrafluar-Objektiv ist dem Neofluar-Objektiv sehr ähnlich. Mit Hilfe des Embryotransfers (202 Embryonen) nach LZD (M4 u. M5) konnte die Entwicklungspotenz dieser Embryonen in vivo (45 Nachkommen) gezeigt werden, wobei die Geburtsrate der übertragenen 2-Zeller (27,55 %) (M5) den 1-Zellern (17,31 %) (M4) signifikant überlegen ist. Mit den Methoden 9-11 wurde nachgewiesen, daß im Strahlkegel, in unmittelbarer Nähe zum Laserfokus, die depressive Beeinflussung vergleichbar zur direkten Vorkernmanipulation ist. Der mit steigender Einwirkzeit kontinuierlich sinkenden Entwicklungsfähigkeit bei Laserfokuspositionierung unter der Zelle (M10) steht eine mit kurzen Einwirkzeiten bessere, jedoch mit steigender Einwirkzeit sprunghaft schlechter werdende Entwicklungsfähigkeit bei Laserfokuspositionierung neben den Vorkernen in der Zelle (M11) gegenüber. Bei den Kerntransferexperimenten konnten die Totalausfälle durch Verzicht auf die mechanische Entkernung mit der damit verbundenen Verringerung der Anzahl an Empfängereizellen vermieden werden (nahezu identisches Ausgangsmaterial). Da kein Zytoplasma abgesaugt wurde, bestand ein hoher Anpressdruck auf die sich berührenden Fusionsmembranen von Oozyte und Blastomere, wodurch sich die sehr hohen Fusionsraten im Einzelschritt (G1: 75,2 %; G2: 86,8 %; G3: 97,7 %) erklären lassen. Die signifikant geringere Fusionsrate der Gruppe 1 ist wie die signifikant geringere Teilungsrate (G1:73,9 % versus G2: 92,0 % bzw. G3: 95,2%) auf die Blastomerengewinnung nach LZD zurückzuführen. Die Entwicklungsfähigkeit der Kerntransferembryonen in vitro der Gruppen 1 und 2 ist mit 3,1 % (G1) bzw. 1,9 % (G2) zum 32-Zeller als maximal erreichtes Entwicklungsstadium sehr schlecht. Nach Verringerung der Lasereinwirkzeit auf 2 Sekunden (G3) konnten die Kerntransferembryonen, als erster Erfolg der neuen Methode, mit 40,0 % in vitro das Morulastadium erreichen. Allerdings blieb nach Transfer so erstellter 112 Kerntransferembryonen auf pseudogravide Ammentiere die Geburt von Jungtieren aus. Durch die Verringerung der Pulsfrequenz und Laserenergie in Verbindung mit der gezielten Bearbeitung des gesamten Raumes der Vorkerne sollte eine vollständige Deaktivierung der Vorkerne bei größtmöglicher Schonung des Zytoplasmas möglich sein. Nach Ermittlung dieser Parameter sollten sie zur Entkernung von Metaphase-II-Oozyten verwendet werden. / Laser-microbeam-delivered micromanipulation during nuclear transfer experiments in rabbit oocytes Bohn, Dirk From the Large Animal Clinic for Theriogenology and Ambulatory Services Faculty of Veterinary Medicine, University of Leipzig and the Institute of Animal Breeding and Husbandry with Veterinary Clinic of the Martin-Luther-University, Halle-Wittenberg June, 2001 120 p., 199 ref., 38 tab., 20 fig.; Annex 15 p.: 8 fig., 15 tab. The object of this work was to establish the first time the methods of Laser-microbeam-delivered non-touched opening of the Zona pellucida (known as Laser-Zona-Drilling, LZD) and the functional enucleation of the pronucleus. This methods are efficient and provide a good developmental capability of manipulated cells in comparison to previous used mechanical nuclear transfer methods. The basis for utilising Laser is to know about the effects of the focused laser-microbeam on targeted micromanipulated rabbit oocytes. Therefore, we next analysed in a number of in vivo and in vitro studies the time-dependent influence of laser in three different objectives of the device on or in fertilised oocytes. For this purpose about 863 oocytes in eleven different methods were used. In groups 1-3 (containing 231 oocytes) it was measured in vitro the influence of the objective during LZD, whereas in group 4 and 5 embryo transfer (202 embryos) after LZD was undertaken. In further in vitro studies (group 6-8, 202 oocytes), we were interested on the effects of three objectives on light-microscopic visible pronuclei which were directly manipulated with the laser-focus. Lastly, to follow the different application modus of the laser-focus (groups 9-11, 228 oocytes) the position of the laser-microbeam to the oocytes pronuclei was changed. Based up on these results three defined nuclear transfer groups (G) were built to compare the data of the first methodological validation with unchanged laser parameters (pulse repetition rate, laser energy). Recipient oocytes (pronuclei) of the first two groups (G1: 117; G2: 129) were manipulated with same time-duration of 10 seconds. The difference between both groups were in the isolation of blastomeres which was performed after LZD (G1) or enzymatic (G2). Recipient oocytes of group 3 (134) were merely treated with time-duration of 2 seconds and fused with enzymatic dissociated blastomeres. The nuclear transferred embryos in group 3 have shown the best developmental capability.

Thesis (PhDApSc(MineralsandMaterials)--University of South Australia, 2004.

Master of Engineering / Turbulent propagating premixed flames are encountered in spark ignition engines, gas turbines, industrial burners, as well as in vented gas explosions. In all these applications, the flame fronts interact with complex solid boundaries which not only distort the flame structure but directly affect the propagation rate in ways that are not yet fully understood. This thesis aims to provide both a quantitative and qualitative understanding of the link between overpressure, flame front wrinkling and turbulence levels generated in the propagating medium. This is an issue of importance for the provision of improved sub-models for the burning rates of premixed flames. An experimental chamber was constructed where controlled premixed flames were ignited from rest to propagate past solid obstacles and/or baffle plates strategically positioned in the chamber. Laser Doppler Anemometry was used to measure the velocity field and turbulence fields while pressure transducers were used to obtain pressure-time traces. In addition to this Laser-Induced Fluorescence of the Hydroxyl radical is was to image the flame front as it consumes the unburnt fuel captured in the re-circulation zone behind the main obstruction. The thesis reports on the effects of various parameters such as the inclusion of grids and obstructions, blockage ratio, and repeated obstacles to explore possible correlations between the pressure and the flow-fields. Pressure, velocity and LIF images were correlated and analysed to prove the significance of grid location and number on overall turbulence intensity. Corresponding flow field parameters such as flame front wrinkling, peak overpressure and RMS all combine to conclusively demonstrate their interaction and influence to turbulence intensity. By progressively positioning more grids further downstream, consequent rises in the flow field parameters and the establishment of positive trends indicates the overall significance of kernel development and flow disturbances in relation to turbulence generation.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.