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.
Results
Showing 1 to 20 of 124 for “"high contrast"”.
-
Pyrrolopyrrole-Based Materials for High-Contrast Electrochromics
… (DHPPs) are synthetically simple and highly tailorable chromophores that can be decorated with diverse functionalities that readily manipulate optoelectronic properties useful for a variety of applications. However, a thorough understanding of how these functionalities influence …
-
High-Contrast Observations with an Integral Field Spectrograph
… companion discovery which takes advantage of the high-precision relative astrometry enabled by a pupil plane reticle grid. This tool, in combination with the spectrophotometric capability of the integral field spectrograph, reveal that the A5V star Alcor has a heretofore unknown M-dwarf companion. …
-
High Contrast Imaging: Exoplanet and Low Stellar Mass Populations
… at wider sepa- rations. Sophisticated high-contrast techniques are applied to the sample in order to remove the stellar point-spread function and to open up sensitivity to planetary mass companions down to 5′′ separations. This enables sensitivity to 0.5 − 13 MJ planets at physical …
-
Adaptive Wavefront Estimation Algorithms for High-Contrast Imaging of Exoplanets
… be able to suppress the starlight to achieve a “contrast” of 10−10 in the image. This is typically achieved using a coronagraph, which blocks the light from the star while allowing the light from the planet to pass through. However, some starlight that leaks through the coronagraph needs to be …
-
High contrast interferometry and finite temperature coherence of Bose-Einstein condensates
… involving BEC interferometry. When subject to high cloud aspect ratios, BECs become elongated and exhibited phase fluctuations, which can have a dramatic affect on the performance of matter-wave interferometers. A brief overview of the history and basic theory of Bose-Einstein condensates is …
-
Surface-emitting lasers for communications: novel metal-cavity microlasers and high-contrast-grating tunable VCSELs
… sources. Surface-emitting tunable lasers for high-speed, long-haul communication are investigated. Novel laser designs using micro-electro-mechanical system controlled high-contrast gratings as tunable mirrors are presented. Rigorous, accurate, and efficient electromagnetic models for …
-
Theory and simulation of subwavelength high contrast gratings and their applications in vertical-cavity surface-emitting laser devices
… can be attained by these structures including high reflectivity or low reflectivity with broad and narrow spectral responses. In the course of this thesis the physical basis for this phenomenon will be presented as well as a mathematical derivation. After discussion of the mechanics of the …
-
Increased Proton Energies - Above the ~ 60 MeV Empirical Barrier, from High-Contrast High-Intensity Short-Pulse Laser-Interactions with Micro-Cone Targets
Ultra-high intensity lasers enable the investigation of extreme states of matter and the study of high energy density physics in the laboratory, as well as the creation of various intense radiation sources, i.e. electrons, X-rays, and ions. Of particular interest to this dissertation is the …
-
Wide Viewing Angle Liquid Crystal Displays
… applied to the designs of wide viewing angle and high transmittance liquid crystal displays. First, a design of wide viewing angle liquid crystal displays utilizing crossed linear polarizers is proposed. The designed multi-domain vertical-alignment liquid crystal display predicts superb contrast …
-
Coronagraphic data post-processing using projections on instrumental modes
High contrast astronomy has yielded the direct observations of over a dozen exoplanets and a multitude of brown dwarfs and circumstellar disks. Despite advances in coronagraphy and wavefront control, high contrast observations are still plagued by residual wavefront aberrations. Post-processing …
-
Information theoretic design of breast sonography
… discriminability except for one case involving high-contrast lesions. This study explores an adaptive, iterative Wiener filter that includes a lesion segmentation algorithm to improve discriminability for high-contrast lesions. Predicted performance is compared with that measured from trained …
-
Ray-based Physical Optics for the Design of Astronomical Observatories
… designed to image faint stellar companions at high contrast using specialized pupil-plane and image-plane masks. When imaging Earth-like exoplanets at small angular separations, coronagraphs are limited by telescope stability and polarization aberrations. The state of the art handles the …
-
Relationship of Ruffed Grouse Home Range Size and Movement to Landscape Characteristics in Southwestern Virginia
… increased, and decreased as the amount of high contrast edge in the landscape increased. The distance between seasonal home range centers increased as Shannon's diversity index and the average distance between patches of similar cover types increased, and decreased as the amount of high …
-
Simulation and testing of wavefront reconstruction algorithms for the deformable mirror (DeMi) cubesat
… by their host stars by a factor of 10₁₀, meaning high-contrast imaging is required to see them. Coronagraphs are typically used to block the starlight to achieve high contrast, but atmospheric, thermal, and mechanical aberrations can cause spurious speckles of starlight to contaminate the image. …
-
Phase derivative microscopy of biological cells and tissues
… and gradient field microscopy (GFM), generates high contrast images of transparent specimens. These methods utilize spatial light modulation at the Fourier plane of a bright field microscope to optically obtain the derivatives of the phase and increase the contrast of the final image. The …
-
Applications of Layer-by-Layer Films in Electrochromic Devices and Bending Actuators
… work done to improve the switching speed and contrast performance of electrochromic devices. Layer-by-Layer (LbL) assembly was used to deposit thin electrochromic films of materials ranging from organic, inorganic, conducting polymers, etc. The focus was on developing new materials with high …
-
An on-Line Image Pre-Processing Camera System for Pattern Recognition
… been developed which is capable of recognizing high contrast two-dimensional visual patterns and which is insensitive to the translation, rotation, and size of a pattern. The unique characteristics of the system are its speed, its low cost and the fact that it is completely self-contained. The …
-
Fabrication of Novel Three-Dimensional Photonic Crystals Using Multi-Beam Interference Lithography
… Band gap studies on structures that possess both high band gap and high contrast are performed. The optical setup for a diamond structure utilizing two right-angled prisms is discussed and promising experimental results are presented.
-
Electromagnetic Inverse Scattering Problems for Strong Scatterers
… scatterers, especially metallic objects and high-contrast dielectric objects. These theories advance the solutions of nonlinear inverse problems, which are useful for practical problems. Applications requiring a full nonlinear solution include medical and geophysical settings.
-
Portal Imaging Using a CSI (TL) Scintillator Coupled to a Cooled CCD Camera
<p>The purpose of this research was to design a high performance digital portal imaging <br />system, using a transparent x-ray scintillator coupled to a cooled CCD camera. Theoretical <br />analysis using Monte Carlo simulation was performed to calculate the QDE, SNR and DQE of <br />the system. A …
Page 1 of 7