A low-cost 3-D laser imaging system

This paper presents the design and development of a low cost three-dimensional laser imaging system for scanning suitable surfaces. A generic, low cost, off-the-shelf laser range finder is used to obtain the primary one dimensional distance measurement. The range finder’s laser beam is reflected by a twin-axis mirror assembly driven by stepper motors providing the system with two angular degrees of freedom, allowing 3-D measurements to be determined. A camera and image processing techniques are used to determine the measured 1-D range value from the generic range-finding device. A computer program then uses the obtained data to create a 3-D point cloud. An algorithm is then used to construct a 3-D wire frame mesh representing the scanned surface. The system has an angular resolution of 1.8° and the results obtained demonstrate the system to have an accuracy of approximately ± 2cm at a scanning distance of 1.0m.

Resource use by the Eastern Grey Kangaroo and the Black Wallaby in a managed remnant woodland community

This work studies the interactions and relationships that exist between Eastern Grey Kangaroos and Black Wallabies in their utilisation of spatial and trophic resources in a managed remnant woodland community. The thesis provides a closer understanding of the way in which these species impact upon their habitats. The Coranderrk Reserve, near Healesville in eastern Victoria, Australia was the study site. A floristic analysis of the communities of the study site was conducted. This consisted of plant biomass measurements, estimates of plant abundance and cover determination. Faecal pellets from Eastern Grey Kangaroos and Black Wallabies were collected from ten vegetation communities during three different plant productivity periods. The spatial and temporal distribution of the animals was identified by analysing the frequency of occurrence of faecal pellets in the various communities. The use of faecal pellet density as a measure of habitat utilisation was examined. Eastern Grey Kangaroos utilised communities which were characterised by the presence of a dense grassy statum. Black Wallabies were able to utilise all of the communities of the study site regardless of their floristic composition. A reference herbarium of the leaf epidermis of 233 possible forage plant species was accumulated. These epidermal specimens were prepared for Confocal Scanning Laser Microscopy. The information gained was enhanced and stored digitally. Diagnostic information critical for the identification of plant epidermal fragments was assembled into a computer database. This was used to assist in the recognition of unknown epidermal fragments in macropodid faeces. These epidermal plant recognition techniques enabled a list of the contents of Eastern Grey Kangaroo and Black Wallaby faeces during the sampling periods in the individual communities, to be accumulated. Eastern Grey Kangaroos utilised forage which consisted largely of grass and their diets were similar regardless of their feeding sites or the time of the year. Black Wallaby diets were heterogenous with wide variations over space and time observed. The implications of these findings for current wildlife management practices were considered. Black Wallaby and Eastern Grey Kangaroo herbivory have significant impacts on ecosystem integrity. Management strategies should seek to establish ecologically sustainable populations of both species in remnant woodlands where conservation values are important.

The application of Cd Se/ZnS quantum dots and confocal laser scanning microscopy for three-dimensional imaging of nanfibrous structures

This paper reports a fast, accurate, and non-destructive three-dimensional imaging approach based on using quantum dots and confocal laser scanning microscopy to get three-dimensional images of internal pore structure of the nanofibrous materials. A practical method of making the fiber fluorescent using quantum dots was applied before three-dimensional imaging by confocal laser scanning microscopy. Fibrous scaffolds with different porosity parameters produced by electrospinning and their three-dimensional pore structure was evaluated by this approach. Furthermore, the introduced approach can be used to measure the pore interconnectivity of the scaffold

High-temperature laser-scanning confocal microscopy as a tool to study the interface instability during unsteady-state solidification of low-carbon steel

Solidification microstructure is a defining link between production techniques and the mechanical properties of metals and in particular steel. Due to the difficulty of conducting solidification studies at high temperature, knowledge of the development of solidification microstructure in steel is scarce. In this study, a laser-scanning confocal microscopy (LSCM) has been used to observe in situ and in real-time the planar to cellular to dendritic transition of the progressing solid/liquid interface in low carbon steel. Because the in situ observations in the laser-scanning confocal microscopy are restricted to the surface, the effect of sample thickness on surface observations was determined. Moreover, the effect of cooling rate and alloy composition on the planar to cellular interface transition was investigated. In the low-alloyed, low-carbon steel studied, the cooling rate does not seem to have an effect on the spacing of the cellular microstructure. However, in the presence of copper and manganese, the cell spacing decreased at higher cooling rates. Higher concentrations of copper in steel resulted on an increased cell spacing at the same cooling rates.

Confocal laser scanning microscopy elucidation of the micromorphology of the leaf cuticle and analysis of its chemical composition

Electron microscopy techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been invaluable tools for the study of the micromorphology of plant cuticles. However, for electron microscopy, the preparation techniques required may invariably introduce artefacts in cuticle preservation. Further, there are a limited number of methods available for quantifying the image data obtained through electron microscopy. Therefore, in this study, optical microscopy techniques were coupled with staining procedures and, along with SEM were used to qualitatively and quantitatively assess the ultrastructure of plant leaf cuticles. Leaf cryosections of Triticum aestivum (wheat), Zea mays (maize), and Lupinus angustifolius (lupin) were stained with either fat-soluble azo stain Sudan IV or fluorescent, diarylmethane Auramine O and were observed under confocal laser scanning microscope (CLSM). For all the plant species tested, the cuticle on the leaf surfaces could be clearly resolved in many cases into cuticular proper (CP), external cuticular layer (ECL), and internal cuticular layer (ICL). Novel image data analysis procedures for quantifying the epicuticular wax micromorphology were developed, and epicuticular waxes of L. angustifolius were described here for the first time. Together, application of a multifaceted approach involving the use of a range of techniques to study the plant cuticle has led to a better understanding of cuticular structure and provides new insights into leaf surface architecture.

Laser-induced site-selective silver seeding on polyimide for electroless copper plating

Ag particles were generated on Ag+-doped polyimide film by laser direct writing, followed by selective copper deposition using the metallic silver particles as seeds. Laser irradiation caused in situ reduction and agglomeration of silver on the polyimide film. The copper lines were less uniform and compact with higher scanning velocity and the width of the deposited copper line could reach 25 mu m. Equations of the relationship between scanning velocity and connectivity of the deposited copper patterns have been derived. The process was characterised by AFM, XPS, SEM, and semiconductor characterisation system.

Local laser heat treatment in dual-phase steels

This research deals with processes leading to local strengthening effects in hot-rolled dual-phase (DP) steels. For this purpose, a method was investigated to achieve local strengthening, namely, local laser heat treatment (LHT). DP sheet steels were globally and homogenously deformed with different degrees of prestrains by cold rolling and subsequently locally heat treated by laser. Following this treatment with selected parameters, the microstructure of the surface and cross section of the heat-treated area as well as the mechanical properties were evaluated by light optical microscopy (LOM), scanning electron microscopy (SEM), as well as transmission electron microscopy (TEM), hardness measurement, and tensile testing. It can be stated that with partial heat treatment, local high strengthening can be produced. At lower heat treating temperatures, this effect could be attributed to bake hardening (BH). Increasing the prestrain as well as temperature results in improving the local properties. With increased heat treating temperature, the initial microstructure near the surface is affected. Partial strengthening of DP steels by laser can open up new fields of application for locally using the strengthening effect to only influence relevant areas of interest, thus providing the potential for saving energy and designed the component's behavior.

Effects of multiple laser shock processing (LSP) impacts on mechanical properties and wear behaviors of AISI 8620 steel

The aim of this paper was to address the effects of multiple laser shock processing (LSP) impacts with different pulse energy on mechanical properties and wear behaviors of AISI 8620 steel. Wear analyses were conducted by means of calculation of volume loss and scanning electron microscope (SEM) of the wear surface. Surface profiles, roughness and micro-hardness were measured. The micro-structures in the surface layer of the untreated and LSPed samples (treated by multiple LSP impacts) were investigated by using transmission electron microscopy (TEM) observations. Experimental results and analyses indicated that multiple LSP impacts can remarkably improve the wear resistance of AISI 8620 steel, and the wear mechanism of multiple LSP impacts on AISI 8620 steel was also entirely revealed. The wear process of the unpolished sample subjected to multiple LSP impacts can be described as follows: the wear rate was big at the beginning of sliding dry wear, but then decreased after the micro-indention in the sample surface was polished to the disappear. This phenomenon can be attributed to the fact that multiple LSP impacts generate many micro-indents in the sample surface.

Comparative study of the microstructures and mechanical properties of direct laser fabricated and arc-melted AlxCoCrFeNi high entropy alloys

High entropy alloys (HEA) are a relatively new metal alloy system that have promising potential in high temperature applications. These multi-component alloys are typically produced by arc-melting, requiring several remelts to achieve chemical homogeneity. Direct laser fabrication (DLF) is a rapid prototyping technique, which produces complex components from alloy powder by selectively melting micron-sized powder in successive layers. However, studies of the fabrication of complex alloys from simple elemental powder blends are sparse. In this study, DLF was employed to fabricate bulk samples of three alloys based on the AlxCoCrFeNi HEA system, where x was 0.3, 0.6 and 0.85M fraction of Al. This produced FCC, FCC/BCC and BCC crystal structures, respectively. Corresponding alloys were also produced by arc-melting, and all microstructures were characterised and compared longitudinal and transverse to the build/solidification direction by x-ray diffraction, glow discharge optical emission spectroscopy and scanning electron microscopy (EDX and EBSD). Strong similarities were observed between the single phase FCC and BCC alloys produced by both techniques, however the FCC/BCC structures differed significantly. This has been attributed to a difference in the solidification rate and thermal gradient in the melt pool between the two different techniques. Room temperature compression testing showed very similar mechanical behaviour and properties for the two different processing routes. DLF was concluded to be a successful technique to manufacture bulk HEA[U+05F3]s.

A survey on mechanisms and critical parameters on solidification of selective laser melting during fabrication of Ti-6Al-4V prosthetic acetabular cup

Additive Manufacturing (AM) includes a range of approaches that correlate with computer aided design (CAD) and manufacturing by fabrication via precise layers and is a promising method for the production of medical tools. In this study, different aspects and mechanisms of solidification for curved surfaces based on equilibrium at curved interfaces, Monge patch, interfacial and Gibbs energy will be discussed. Also, the effect of capillarity, geometry, substrate temperature, cooling rate and scanning parameters in the solidification of a prosthetic acetabular cup (PAC) using selective laser melting (SLM) is analysed. The contributions of this work are analysing solidification and effective factors in this process to produce parts with a higher quality and mechanical properties such as strength, strain, porosity, relative density and hardness. Results indicate that due to the surface to volume (S/V) ratio, and the increasing effect of the radius on Monge patch, thermal stresses and surface forces are more prevalent on outer surfaces. Moreover, solidification and mechanical properties are related to capillarity, geometry, substrate temperature, cooling rate, scanning power and speed. The results also indicate the interaction of solute diffusion and heat transfer with interatomic forces in large S/V ratio and at small scales tend to improve solidification.

Tool wear and surface integrity analysis of machined heat treated selective laser melted Ti-6Al-4V

In this study, the tool wear and surface integrity during machining of wrought and Selective LaserMelted (SLM) titanium alloy (after heat treatment) are studied. Face turning trails were carried out onboth the materials at different cutting speeds of 60,120 and 180 m/min. Cutting tools and machinedspecimens collected are characterized using scanning electron microscope, surface profiler and opticalmicroscope to study the tool wear, machined surface quality and machining induced microstructuralalterations. It was found that high cutting speeds lead to rapid tool wear during machining of SLMTi-6Al-4V materials. Rapid tool wear observed at high cutting speeds in machining SLM Ti-6Al-4Vresulted in damaging the surface integrity by 1) Deposition of chip/work material on the machinedsurface giving rise to higher surface roughness and 2) Increasing the depth of plastic deformationon the machined sub surface.