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 20 for “"Adaptive optics (AO)"”.
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Assembly and proving of a wave front sensing confocal Scanning Laser Ophthalmoscope
… is not as high as expected. By the use of adaptive optics (AO) resolution can be dramatically increased. Implementing a wave front sensor into a conventional confocal Scanning Laser Ophthalmoscope (cSLO), therefore, is the first step to set up a compact adaptive-optical cSLO. In this work a …
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Technologies for Astronomical Wide-Field Adaptive Optics
Adaptive Optics (AO) can greatly enhance the resolution of astronomical images, achieving close to diffraction-limited performance in the near infrared; however there are a number of areas where significant improvements can be made, one of them being the very limited field of view that current AO …
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Tomographic Reconstruction of Wavefront Aberrations using Multiple Laser Guide Stars
… polynomials is a widely used technique in adaptive optics (AO) research. However, this approach breaks down with the large number of degrees of freedom required by ELTs.This research proposes the use of an alternative basis, the disk harmonic functions, to overcome the disadvantages of the …
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Exploring retinal changes in Dementia and Multiple Sclerosis
… laser scanning ophthalmoscopy imaging (UWFI), adaptive optics (AO) and widefield perimetry combined with recently developed image analysis methods and algorithms. <br/><br/><br/>In this thesis I present evidences that there are detectable changes on different eye imaging modalities that …
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The nucleus of Centaurus A
… merger-induced star formation in detail. Using Naos-Conica and SINFONI at the ESO Very Large Telescope (VLT), we obtained adaptive optics (AO) assisted data at unprecedented spatial resolution. We demonstrate that thorough kinematical modelling of AO data is feasible and leads to an accurate …
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The Deformable Mirror Demonstration Mission (DeMi) On-Orbit Analysis
… (MEMS) deformable mirror (DM) and a closed-loop adaptive optics (AO) system in space. DeMi launched to the International Space Station (ISS) on the NG-13 Cygnus resupply mission on February 15, 2020 and was deployed from the ISS into a 51° inclination, 423 km average altitude low-Earth orbit on …
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Adaptive Mode Control in Few-Mode and Highly Multimode Fibers
… modes as well as their superpositions through adaptive optics (AO). Specifically, in the case of step-index FMFs, a phase-only spatial light modulator (SLM) is employed to manipulate the light at the fiber input end, driven by the feedback signal provided by the correlation between the charge …
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Adaptive optics, aberration dynamics and accomodation control. An investigation of the properties of ocular aberrations, and their role in accomodation control.
… of ocular aberrations; and the application of an adaptive optics (AO) system to investigate the effect of the manipulation of aberrations on the accommodation control. The binocular SH sensor consists of one laser source and one camera to reduce system cost and complexity. Six participants took …
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Design of the tip-tilt mirror for the adaptive optics system of amateur telescopes, and optimum placement of actuators
The recent development of the Adaptive Optics (AO) system for ground based telescopes has enabled astronomers to improve the quality of images distorted by atmospheric turbulence. The main objective of the present work is to design a tip-tilt AO system for telescopes used by amateur astronomers. …
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Low-Cost Spatial Light Modulator for Applications in Free-Space Optical Communication
… (SLMs) are core components deployed for Adaptive Optics (AO) to compensate for atmospheric distortions. AO is an enabling technology for Free-Space Optical Communication, whose performance is severely degraded by the atmosphere. This thesis proposes two low-cost AO strategies: (1) …
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Development of Multi-modal and Super-resolved Retinal Imaging Systems
… close to the fovea without the use of adaptive optics (AO), which require bulky and expensive components that limit the potential for widespread clinical use. </p><p>In this dissertation, techniques for extending the diagnostic capability of SLO and OCT systems are developed. These …
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Simulation and testing of wavefront reconstruction algorithms for the deformable mirror (DeMi) cubesat
… performance necessary for high-contrast imaging, adaptive optics (AO) techniques in space are needed. High actuator count deformable mirrors (DMs) used in an AO system enable the required contrasts across sufficient fields of view, but typically have high size, weight, and power requirements, and …
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Point Spread Function Reconstruction for the Adaptive Optics System ALFA and its Application to Photometry
The ALFA adaptive optics (AO) system, operated by the Max-Planck-Institut für Astronomie at the Calar Alto Observatory, has been available as a standard facility instrument for some years now. As with other AO systems, however, the scientific use of observations with this instrument is complicated …
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Graph Theory and Dynamic Programming Framework for Automated Segmentation of Ophthalmic Imaging Biomarkers
… such as optical coherence tomography (OCT) and adaptive optics (AO) have facilitated in vivo visualization of the eye at the cellular scale, the massive influx of data generated by these systems is often too large to be fully analyzed by ophthalmic experts without extensive time or resources. …
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On-Orbit Pointing Risk Mitigation for the Agile MicroSat (AMS) CubeSat Laser Guidestar Payload
… low Earth orbit reference for high-angle rate adaptive optics (AO). During the science phase of the mission, it will establish a space-to-ground link with an AO-equipped ground station. Due to budget constraints and size, weight, and power (SWaP) limitations, the AMS Beacon was designed without …
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Sensorless Wavefront Correction Algorithms for Free-Space Optical Communications
… necessitate active wavefront correction via adaptive optics (AO). Conventional AO algorithms rely on direct wavefront sensing, an approach that is high in cost and SWaP and usually degrades in strong atmospheric scintillation. Sensing methods that are more tolerant to scintillation have been …
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Adaptive optics stimulated emission depletion microscope for thick sample imaging
… nanoscopic resolution. In order to achieve that, adaptive optics (AO) has been employed for correcting the aberrations, using the indirect wavefront sensing approach. This thesis presents a custom built 3D STED microscope with the AO correction and the resulting images of thick samples with …
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Adaptive Optics for Stellar Interferometry
… from seeing will need the consideration of adaptive optics (AO). Accordingly, this dissertation will first examine the problem that seeing causes in stellar interferometers. The application of Adaptive Optics in Stellar Interferometry will then consider these results to achieve the final …
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Adaptive Control of Waveguide Modes in Two-Mode Fibers
… a two-mode fiber (TMF). Our method is based on adaptive optics (AO), where one utilizes proper feedback signals to shape the wavefront of the input beam in order to achieve the desired LP mode composition. In the first part of this thesis, we demonstrate the feasibility of AO-based mode control …
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Beyond the speckles: New horizons in high-contrast imaging for exoplanet science
Direct imaging of exoplanets offers a uniquely powerful way of characterizing planetary atmospheres, surface conditions, and potential biological markers beyond our solar system. However, the extreme contrast and small angular separations involved present significant observational challenges that …