Sökning: "beam"
Visar resultat 21 - 25 av 1397 avhandlingar innehållade ordet beam.
21. Direct Nanoprototyping of Functional Materials via Focused Electron Beam
Sammanfattning : During recent years the demand for nanoscale materials with tailor-made functional properties as bulk species, is continuously and progressively rising for such fields as e.g. micro- and nano-electronics, plasmonics, spintronics, bio-technology, bio-sensing and life sciences. LÄS MER
22. Applications of Ion Beam Methods in Silicide/Si and Silicide/GaAs Nanometre Structures
Sammanfattning : Ion beam methods are used to analyse material (Ion Beam Analysis, IBA) and to modify the target (Ion Beam Modification of Materials, IBMM). In this thesis, ion beams have been used in various IBA techniques to investigate the surface nanometre structures, and also in an ion beam synthesis (IBS) technique to form thin films and to modify material properties. LÄS MER
23. Propagation of some coherent and partially coherent laser beams
Sammanfattning : In this thesis, we investigate the propagation of some coherent and partially coherent laser beams, including a dark hollow beam (DHB), an elliptical Gaussian beam (EGB), a flat-topped beam and a twisted anisotropic Gaussian Schell-model (TAGSM) beam, through a paraxial optical system or a turbulent atmosphere. Several theoretical models are proposed to describe a DHB of circular or non-circular symmetry. LÄS MER
24. Nematic Liquid Crystal Spatial Light Modulators for Laser Beam Steering
Sammanfattning : Laser beam control is important in many applications. Phase modulating spatial light modulators (SLMs) can be used to electronically alter the phase distribution of an optical wave-front and thus change the direction and shape of a laser beam. LÄS MER
25. Location-aided Beam Alignment and Handover in Millimeter-wave Networks
Sammanfattning : Ever-increasing data rate demands in mobile networks and the spectrum scarcity at the microwave bands have resulted in the exploration of millimeter-wave (mmWave) frequencies for the next generation of wireless networks. While mmWave frequencies offer large bandwidth, communication at these frequencies is not straightforward due to the challenging propagation characteristics. LÄS MER