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 31 for “"beam shaping"”.
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Annular Beam Shaping And Optical Trepanning
… drilling is accomplished by focusing the laser beam to approximately the required diameter of the hole, exposing the material to one or a series of laser pulses at the same spot to melt and vaporize the material. Drilling by trepanning involves cutting a hole by rotating a laser beam with an …
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Development of switchable planar reflectors for beam shaping realization
… patch element configurations for the design of beam switchable planar reflectors. Moreover unit cells based on liquid crystal substrates were also designed for comparison between two reconfigurable planar reflector design techniques. 3Dimensional electromagnetic computer models of CST Microwave …
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Optical and acoustic beam shaping for imaging and manipulation
… the difficulty of producing complex ultrasonic beams. Hence it makes perfect sense to explore sound based on the research of optics. Differences between light and sound are mainly due to the nature variety of their mechanisms and different scale of their wavelength. Those difference makes either …
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Application of beam shaping in second-harmonic generation microscopy
… the focal field intensity profile through beam shaping can be useful in reducing imaging artifacts and improving quantitative image analysis. In this dissertation, two different beam shapes are explored in the context of SHG imaging. The first approach incorporates a reflective microscope …
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Integrated diffractive optical elements for terahertz beam shaping and polarization control /
… optical elements (DOEs) for efficient beam focusing, polarization control and enhanced transparency in the terahertz (THz) frequency range (0.1–1 THz). Utilizing semiconductor- and metal-based elements, the research introduces hybrid multi-phase Fresnel zone plate (H-MPZP) lenses with …
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Applications of Optical Manipulation for Low Cost Implementation, Beam Shaping and Biophysical Force Measurements
… hugely versatile due to the wide assortment of beam shaping techniques that can be employed.<br/><br/>The work in this thesis can be broadly divided into two main themes: that quantifying the optical trapping forces in shaped beams; and bringing control and simplification of complex systems to …
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SCRIBE: Subsurface volumetric integration of freeform micro-optical elements for advanced beam shaping and light routing
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2025-05-01
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Thermal Management, Beam Control,and Packaging Designs For High Power
… arrays, a new and simple optical element, the beam control prism, is invented. It provides the ability to accomplish beam shaping and beam tilting at the same time. Several low thermal resistance diode packaging designs using beam control prisms are proposed, studied and produced. Two pump …
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On the Role of Linear Processes in the Development and Evolution of Filaments in Air
… stagesof propagation at low intensities the beamdynamics are dominated by diffraction and dispersion. During filamentation, self-focusing resulting from the nonlinear Kerr effect is balanced by higher order nonlinearities such as plasma induced defocusing and absorption.This work examines the …
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Additive Lithography Fabrication And Integration Of Micro Optics
… and are used to transform an input optical beam into a desired beam profile or to couple the input beam into waveguides, fibers, or other optical systems or devices. Macroscopic optical elements are easily fabricated using grinding and polishing techniques, but few methods exist for …
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Novel endoscopes for microscopic assessment of airway clearance using micro-optical coherence tomography
… of 4 mm and a two-prism configuration providing beam splitting and sample beam shaping into an annular profile. Image quality of the probe allowed visualization of the periodic pattern of ciliary beating, measurement of airway surface liquid depth (ASL) and visualization of mucociliary transport. …
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Bangolaidžių integravimas į lydytą kvarcą panaudojant femtosekundinius šviesos impulsus /
… 320 fs pulses. It is shown that, by using slit beam shaping method, optimising laser pulse energy and focusing depth it is possible to suppress spherical abberations affecting the laser beam and form type I modifications with a symmetrical cross-section as well as single mode waveguides and …
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Hyperpolarized xenon-129 production and applications
… a new optical arrangement for a better beam shaping of fiber coupled lasers and the first external-cavity spectrum narrowing of a stack of laser diode arrays.</p><p>A new accumulation technique for the hyperpolarized xenon was developed and full recovery of polarization after a …
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Concentric Microresonators Design For Dispersion Engineering and Scalable Electron-Beam Lithography for Si and SiN Photonic Platforms
… fabrication side, a robust subtractive electron-beam lithography (EBL) process is established for the silicon-on-insulator (SOI) platform, enabling reliable pattern transfer from sub-50 nm to micrometer-scale structures. Using this process, corrugated Bragg gratings for optical filtering and …
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Development of a Robotic Positioning and Tracking System for a Research Laboratory
… to other moving instrument components such as beam shaping jaws and detectors. Several factors could lead to inaccurate positioning on a neutron or synchrotron diffractometer. It is therefore essential to validate the accuracy of positioning especially during experiments which require a high …
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Multidimensional fiber quantum light sources and their applications
… four-wave mixing processes through precise beam shaping of the pump spatial mode. Employing stimulated emission and spatio-spectral control of the seed beam, we carefully characterize the photon pairs created from few-mode polarization-maintaining fibers. We develop spatial-mode quantum …
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Opto-fluidic neural probes for optogenetic brain interrogation
… in recent years to achieve spatial resolution by beam shaping methods. However, these methods fundamentally lack the ability to focus light along the propagation axis of the beam, limiting the localization of excitation to only two dimensions. Further, the strength of excitation is highest closest …
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The Design and Optimisation of Quasioptical Telescopes
… used to determine the phase centre of the beam from lens antennas are described, and use is made of the same optimisation techniques as for the MBI and ALMA work. As the beams propagating in these systems can be analysed accurately using the paraxial approximation, Gaussian Beam Mode …
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