Sökning: "Laser"

Visar resultat 1 - 5 av 1850 avhandlingar innehållade ordet Laser.

1. 1. Pulsed laser ablation studied using digital holography

   Författare :Eynas Amer; Bill O’Neill; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Experimental Mechanics; Experimentell mekanik;

   Sammanfattning : Pulsed digital holographic interferometry has been used to study the plume and the shock wave generated in the laser ablation process on different targets under atmospheric air pressure. A pulsed Nd-YAG laser system (pulse duration 12 ns) has been used both for ablating the material (wavelength 1064 nm) and for measurement (wavelength 532 nm). LÄS MER

3. 2. Laser Sheet Imaging and Image Analysis for Combustion Research

   Författare :Rafeef Abu-Gharbieh; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; non-linear diffusion filtering; optically dense sprays; curve evolution propagation; image sequence analysis; laser induced fluorescence; geodesic paths; level sets; LIF; optical density; spray characterization; flame propagation; laser; particle image velocimetry; spectroscopy; combustion engines; spray diagnostics; Mie scattering; flame fronts; laser attenuation; tracking; combustion diagnostics; curve matching; combustion; laser sheet imaging; PIV; time resolved imaging; segmentation;

   Sammanfattning : This Thesis presents techniques that aim at exploiting the potential of image analysis and processing in order to solve problems of data reduction, interpolation, quantification, and interpretation within the field of experimental laser imaging of combustion processes. Combustion is the most important source of energy for power generation, heating, and transportation in the world today and its strong dominance is projected to continue in the foreseeable future. LÄS MER

4. 3. Novel Technologies for Mode-Locking of Solid-State Lasers

   Författare :Niels Meiser; Valdas Pasiskevicius; Steinmeyer Günter; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; laser; mode-locked laser; pulsed laser; quantum dot; carbon nanotube; nonlinear optics; saturable absorber; Kerr-lens mode-locking; ultra-fast laser; picosecond laser; pulsed laser; semiconductor saturable absorber;

   Sammanfattning : The subject of this thesis is the investigation of novel technologies for mode-locking of diode-pumped, solid-state lasers. Novel saturable absorbers are used: quantum dots (QDs) and carbon nanotubes (CNTs), which both are low-dimensional nano-formations. In addition, mode-locking by cascaded nonlinearities is explored. LÄS MER

5. 4. Laser cutting and piercing: Experimental and theoretical investigation

   Författare :Jetro Pocorni; Alexander F. H. Kaplan; John Powell; Jan Frostevarg; William O'Neill; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Laser cutting; laser piercing; efficiency; fibre laser; CO2 laser; high speed imaging; Produktionsutveckling; Manufacturing Systems Engineering; Maskinteknik;

   Sammanfattning : This thesis concerns experimental investigations of laser cutting and piercing, with theoretical and practical discussions of the results. The thesis is made up of an introduction to laser cutting and six scientific Papers. LÄS MER

7. 5. Laser welding : energy redistribution and weld geometry

   Författare :Conny Lampa; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Material Mechanics; Materialmekanik;

   Sammanfattning : Over the past few years laser welding has developed into a process which has a wide range of application over a number of industries. Industrial growth in this area has been stimulated by improvements in production rates and quality but technologically the process is still not fully understood. LÄS MER