Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 26 for “"Scanning Speed"”.
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3-D Printing, Characterizing and Evaluating the Mechanical Properties of 316L Stainless Steel Materials with Gradient Microstructure
… the processing parameters (hatch spacing, scanning speed, and laser power and scanning speed) of the Selective Laser Melting (SLM). The Materials with Graded Microstructure (MGMs) are characterized by optical and scanning electron microscopy (SEM). Image processing framework is utilized to …
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A study on laser engraving process parameters and performance characteristics for wood base materials
… the effects of using input parameters such as scanning speed, burning time and laser height towards the output results which were identified as surface roughness, depth of engraving and Head Affected Zone (HAZ). A second order equation by Response Surface Method (RSM) was used to get the …
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Investigation of selective optical properties of Si/SiO2 nanostructures generated by pulsed laser ablation as-deposited and post-treated
… power, repetition rate, pulse duration, and scanning speed were changed to vary the structural and compositional properties of synthesized nanofibrous thin films. Transmission and specular reflection measurements along with material characterization techniques, Raman, FTIR XPS, and XRD were …
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Development of high-speed two-photon microscopy for biological and medical applications
… practical limitation of TPM is its slow imaging speed (0.3 1 frames/s). We designed high-speed two-photon microscopes (HSTPMs) whose imaging speed is more than 10 times faster than traditional TPM, while their imaging depths, image contrast are comparable to those of TPM. The first high speed …
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Thermocapillary Convection During Laser Surface Heating (Surface Tension)
… recirculating velocity is much higher than the scanning speed. A perturbation solution is therefore sought for the three-dimensional case. The basic solution corresponds to the stationary axisymmetric case. The scanning case is obtained by perturbing the basic solution with the scanning speed. …
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Wideband and fast THz spectrometer using dual-frequency-comb on CMOS
… scheme does not only improve the scanning speed by 20 x, but also reduces the overall energy consumption to 90 mJ/point with 1 Hz bandwidth (or 0.5 s integration time). With its channelized 100-GHz scanning range and sub-kHz specificity, wide range of molecules can be detected. In …
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Near-field scanning optical microscopy with laser trapping
… understanding of particle-trapped near-field scanning optical microscopy. This technique is unique in that it relies on the collection of scattered evanescent waves from a sample with a laser-trapped particle. In comparison with the other forms of near-field scanning optical microscopy with a …
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Modified chalcogenide glasses for optical device applications
… 1.47 dB/cm are 0.36 µJ pulse energy and 50 µm/s scanning speed. The observation of spectral broadening in these waveguides indicates that they may have applications for nonlinear optical devices. Fs laser written waveguides in transition metal doped GLS could lead to broadband active optical …
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Strain sensor using fiber bragg grating interrogation
… usage of OSA are very costly, bulky and has slow scanning speed. Therefore, research is conducted to design and construct a fully portable, low-cost and low-powered interrogator which is specifically designed to read FBGs within the C-band. An optical strain sensor utilizing reflected light of FBG …
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Quantitative phase imaging : a study from 2D to 3D
… device (DMD) was used to provide the angle scanning illumination, which significantly boosts the angle scanning speed to the magnitude of kHz. However, this angle scanning method suffers from the diffraction noise caused by the binary grating pattern, which significantly deteriorates the …
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Computational control of laser systems for micro-machining
… frequency, PRF, number of pulses, N, and scanning speed, U. Output dimensions measured included equivalent voxel diameter as well as microchannel width, depth and surface roughness. A 3D microfabrication system was developed using the Nd:YV04 laser (2.5 W, 1.064 pm, 80 ns) to fabricate …
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Photoelectrochemical imaging of gold nanoparticles by light-activated electrochemistry
… compared to the conventional methods like scanning electrochemical microscopy, that employ a mechanically moving tip with predefined geometry, limited scanning speeds and intricate positioning. Whereas, the LAE-based technique developed in this thesis takes advantage of a high-speed light …
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Laser Powder Bed Fusion Additive Manufacturing of Fe-based Shape Memory Alloys for Biomedical Applications
… LPBF process parameters—including laser power, scanning speed on microstructural evolution, phase constitution, corrosion behaviour, and fatigue performance. The relationship between process-induced microstructure and accelerated degradation rates in simulated physiological conditions is …
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An Experimental Study Of Atomic Scale Friction And Adhesion For 2d And Layered Materials: The Effects Of Interfacial Contact, Compliance, And Commensurability
… will decrease logarithmically with increasing scanning speed. This phenomenon is attributed to a depletion of bonds across the tip/sample interface due to the faster sliding speed. Thirdly, sample deposition methods modify the frictional behavior of MoS2 monolayers, as the stronger adhesion …
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Nanosecond Pulsed Laser Processing of Metals and Welding of Metal-Glass Nanocomposites
… of 532nm or 1064 nm. The laser fluence and scanning speed are important parameters to control the results. <br/> The first part of thesis is on the laser generation of microstructures on metal surfaces. Copper (Cu) and titanium (Ti) have been studied. According to the reflectivity of metals, …
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Real-time characterization of transient dynamics in thulium-doped mode-locked fiber laser
… methods, which are limited to the scanning speed of the spectrometer and the electronic speed of photodetector and digitizer, so that the details of the non-repetitive events can be buried. In recent years, a technique called dispersive Fourier transform (DFT) has been developed and …
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Predicting microstructural heterogeneities in the laser powder bed fusion of γ′ strengthened nickel-base superalloys
… that no proportional correlation between the scanning speed, ν, and the induced cooling rate, $\dot T$, can be anticipated, as it is conventionally assumed in the 3D printing of metals. This coupling scheme delivered compelling insights into the development of various microstructural …
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Thermoelectric Energy Harvesting in Harsh Environments and Laser Additive Manufacturing for Thermoelectric and Electromagnetic Materials
… analysis of process parameters such as laser scanning speed and power input. The results provided insights into temperature distribution, powder bed shrinkage, and molten pool dynamics, advancing the understanding and optimization of thermoelectric device fabrication using additive …
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TOMOGRAPHIC IMAGE RECONSTRUCTION: IMPLEMENTATION, OPTIMIZATION AND COMPARISON IN DIGITAL BREAST TOMOSYNTHESIS
… current tomosynthesis systems include a longer scanning time than a conventional digital X-ray modality and a low spatial resolution due to the movement of the single X-ray source. Dr.Otto Zhou's group proposed the concept of stationary digital breast tomosynthesis (s-DBT) using a Carbon …
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A MOBILE XRF SCANNER FOR A REAL-TIME ELEMENTAL IMAGING OF PAINTED ARTWORKS
… with several sophisticated imaging techniques. Scanning MA-XRF technique provides information on pigment materials and their distribution over the painted surface in non-invasive manner. Further, it provides information on conservation state of artworks and also their authenticity can be …
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