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Theoretical Study Of Beam Transformations By Volume Diffraction, Sergiy V. Mokhov
Theoretical Study Of Beam Transformations By Volume Diffraction, Sergiy V. Mokhov
Electronic Theses and Dissertations
Laser beams can be manipulated by volume diffractive elements in addition to conventional optical elements like mirrors, lenses, and beam splitters. Conventional optical elements can be described by applying the basic laws of reflection and refraction at the surfaces of the elements. Even diffraction by surface gratings utilizes relatively simple mathematics. This is to be contrasted with the volume diffraction, which requires coupled wave theory in the slowly varying envelope approximation (SVEA) to obtain accurate results. Efficient spatially distributed diffraction of laser beams is possible due to the high coherence of laser light, and it occurs at specific resonant Bragg …
Femtosecond Laser Written Volumetric Diffractive Optical Elements And Their Applications, Jiyeon Choi
Femtosecond Laser Written Volumetric Diffractive Optical Elements And Their Applications, Jiyeon Choi
Electronic Theses and Dissertations
Since the first demonstration of femtosecond laser written waveguides in 1996, femtosecond laser direct writing (FLDW) has been providing a versatile means to fabricate embedded 3-D microstructures in transparent materials. The key mechanisms are nonlinear absorption processes that occur when a laser beam is tightly focused into a material and the intensity of the focused beam reaches the range creating enough free electrons to induce structural modification. One of the most useful features that can be exploited in fabricating photonic structures is the refractive index change which results from the localized energy deposition. The laser processing system for FLDW can …
Ultrashort Laser Pulse Interaction With Photo-Thermo-Refractive Glass, Leo Siiman
Ultrashort Laser Pulse Interaction With Photo-Thermo-Refractive Glass, Leo Siiman
Electronic Theses and Dissertations
Photo-thermo-refractive (PTR) glass is an ideal photosensitive material for recording phase volume holograms. It is a homogeneous multi-component silicate glass that demonstrates all the advantages of optical glass: thermal stability, high laser damage threshold, and a wide transparency range. Moreover the ability to record phase patterns (i.e. spatial refractive index variations) into PTR glass has resulted in the fabrication of volume holograms with diffraction efficiency greater than 99%. The conventional method of recording a hologram in PTR glass relies on exposure to continuous-wave ultraviolet laser radiation. In this dissertation the interaction between infrared ultrashort laser pulses and PTR glass is …
Design And Optimization Of Nano-Optical Elements By Coupling Fabrication To Optical Behavior, Raymond Rumpf
Design And Optimization Of Nano-Optical Elements By Coupling Fabrication To Optical Behavior, Raymond Rumpf
Electronic Theses and Dissertations
Photonic crystals and nanophotonics have received a great deal of attention over the last decade, largely due to improved numerical modeling and advances in fabrication technologies. To this day, fabrication and optical behavior remain decoupled during the design phase and numerous assumptions are made about "perfect" geometry. As research moves from theory to real devices, predicting device behavior based on realistic geometry becomes critical. In this dissertation, a set of numerical tools was developed to model micro and nano fabrication processes. They were combined with equally capable tools to model optical performance of the simulated structures. Using these tools, it …
Predicting Surface Scatter Using A Linear Systems Formulation Of Non-Paraxial Scalar Diffraction, Andrey Krywonos
Predicting Surface Scatter Using A Linear Systems Formulation Of Non-Paraxial Scalar Diffraction, Andrey Krywonos
Electronic Theses and Dissertations
Scattering effects from rough surfaces are non-paraxial diffraction phenomena resulting from random phase variations in the reflected wavefront. The ability to predict these effects is important in a variety of applications including x-ray and EUV imaging, the design of stray light rejection systems, and reflection modeling for rendering realistic scenes and animations of physical objects in computer graphics. Rayleigh-Rice (small perturbation method) and Beckmann-Kirchoff (Kirchhoff approximation) theories are commonly used to predict surface scatter effects. In addition, Harvey and Shack developed a linear systems formulation of surface scatter phenomena in which the scattering behavior is characterized by a surface transfer …
A Diffraction Model For Prediction Of Radar Signal Attenuation By A Rocket Exhaust Plume, Douglas Harrison Sphar
A Diffraction Model For Prediction Of Radar Signal Attenuation By A Rocket Exhaust Plume, Douglas Harrison Sphar
Retrospective Theses and Dissertations
This report documents the development of a method of estimating the signal attenuation induced by a rocket exhaust plume. The method is applicable to the early system design phase of high energy solid propellant rockets that produce highly ionized exhaust plumes. The method is based on the premise that when a plume is highly ionized, observed signal levels can be explained by assuming the signal propagates around the plume. A simple diffraction at a straight edge model is developed and compared to measured data. The report also provides an overview of exhaust plume electromagnetics and surveys prediction techniques.
An Application Of Hamilton's Principle To Diffraction Of Light By Ultrasound, Daniel F. Waterhouse
An Application Of Hamilton's Principle To Diffraction Of Light By Ultrasound, Daniel F. Waterhouse
Retrospective Theses and Dissertations
A covariant form of Hamilton's Principle of Stationary Action is formulated and used to solve the general eiconal equation describing the wave function of light in a medium carrying ultrasound. Tensor notation is reviewed and the tensor form of Maxwell's equations is developed. Boundary equation that the field quantities must satisfy in order for the variation of Hamilton's action integral to be stationary are determined and used to form the generalized eiconal equation of geometrical optics. The rays are introduced and through a canonical transformation the eiconal for the diffracted medium is solved and plotted.