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 18 of 18 for “"Wavefront Sensing"”.
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Wavefront sensing in the human eye
Fortschritte in der chirurgischen Technik zur Korrektur von refraktionsbedingten Sehfehlern haben es ermöglicht, dass heute die Form der Hornhautvorderfläche auch ortsaufgelöst geändert werden kann. Die Refraktionsmessungen am menschlichen Auge beschränkten sich allerdings auf die Messung von …
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High Space -Bandwidth Wavefront Sensing by Sampling and Spatial Multiplexing
The SFS is a breakthrough concept in wavefront sensor design. It is, to our knowledge, the first high-accuracy, high-resolution, vibration-insensitive, one-shot wavefront sensor. It achieves high accuracy by using a phase-shift shearing interferometric approach in detecting wavefront phase …
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Adaptive wavefront correction in two-photon microscopy using Coherence-Gated Wavefront Sensing
… improved by using adaptive optics, i.e. wavefront correction based on coherence-gated wavefront sensing (CGWS). The advantage of using CGWS relies on the fact that the wavefront distortions are sensed by backscattered instead of fluorescent light. Thus, neither photodamage nor …
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Novel Adaptive Optics Concepts : Wavefront Sensing with Sodium Laer Guide Stars at Extemely Large Telescopes and Simultaneous Differential Imaging
Durch den Einsatz Adaptiver Optik (AO) besitzt die astronomische Gemeinschaft seit fast 15 Jahren ein Werkzeug um mit modernen Großteleskopen beugungsbegrenzte Abbildungsqualität zu erreichen. Im Hinblick auf geplante Riesenteleskope wie das "Overwhelming Large Telescope" (OWL) der Europäischen …
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Design, implementation and control of a sparse aperture imaging satellite
… procedures encompassing the nature of coherent wavefront sensing, control and combining as well as various systems engineering aspects to achieve cost effectiveness, are developed. To demonstrate a complete spacecraft in a 1-g environment, the ARGOS system is mounted on a frictionless …
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Reconstruction Of A Univariate Discrete Function From The Magnitude Of Its Fourier Transform
… This problem occurs in electron microscopy and wavefront sensing. Another problem which occurs in astronomy and crystallography is to reconstruct $f$ when only $|F|$ and some constraints on $f$, e.g., $f \geq 0$, are available. In this paper we study the latter problem in a context where $f$ is …
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A Solid-State Phase Camera for Advanced Gravitational Wave Detectors
<p>I present a novel way of wavefront sensing using a commercially available, continuouswavetime-of- ight camera with QVGA-resolution. This CMOS phase camera is capable of sensing externally modulated light sources with frequencies up to 100 MHz. The high-spatial-resolution of the sensor, combined …
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Adaptive Wavefront Estimation Algorithms for High-Contrast Imaging of Exoplanets
… Creating a DZ requires the use of focal plane wavefront sensing and control techniques, which estimates the electric field of the starlight in the focal plane of the telescope using a camera and then informs the deformable mirrors (DMs) located upstream of the coronagraph to null these electric …
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Phasing of Ground-based Optical Arrays for Space Applications
… including optical communication, active sensing, laser propulsion, and the removal of space debris. However, large monolithic optics required to obtain high directivity are costly and difficult to slew at the rates required to track an object in low earth orbit (LEO). Coherent combination …
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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.
… monocular viewing conditions produced similar wavefront error dynamics. The AO system has a dual wavefront sensing channel. The extra sensing channel permits direct measurement of the eye¿s aberrations independent of the deformable mirror. Dynamic correction of aberrations during steady-state …
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Simulation and testing of wavefront reconstruction algorithms for the deformable mirror (DeMi) cubesat
… needs. Specifically, we develop and demonstrate wavefront sensing approaches suitable for demonstrating and characterizing a MEMS DM on a small satellite platform.
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Sensorless Wavefront Correction Algorithms for Free-Space Optical Communications
… along such links usually 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 …
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Adaptive optics stimulated emission depletion microscope for thick sample imaging
… 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 resolution beyond diffraction barrier. The developed STED microscope achieved the resolution of …
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Accelerating Embedded HOWFSC Algorithms
… processors. Direct imaging requires precise wavefront control to acquire the 1010 contrast necessary to reveal a dim, Earth-like exoplanet. This precise level of control is only possible if high-order wavefront sensing and control (HOWFSC) algorithms are executed with enough speed to offset …
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Embedded Computing for Wavefront Control on Future Space Telescopes
… We survey the current landscape of high-order wavefront sensing and control (HOWFSC) algorithms for a future mission like HWO. We parameterize the compute requirements of multiple algorithms through analyses of computational patterns, benchmarks, and problem scaling. In parallel, we assess the …
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Mode Matching sensing in Frequency Dependent Squeezing Source for Advanced Virgo plus
… this degradation mechanism requires a dedicated wavefront sensing technique. In fact, the simpler approach based on studying the resonance peak of the cavity is not enough. This method can only estimate the total amount of the optical loss generated by the mismatch, but it cannot characterise the …
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The Adaptive Optics Lucky Imager: combining adaptive optics and lucky imaging
… the adaptive optics system and a new type of wavefront sensor, the non-linear curvature wavefront sensor (nlCWFS), being used within the instrument. The development of the nlCWFS has been the focus of my work, bringing the technique from a theoretical concept to physical realisation at the WHT …
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Detector Improvements and Optimization to Advance Gravitational-wave Astronomy
… I worked to develop and test a high-resolution wavefront sensor that employs a time-of-flight sensor. By achieving phase-locking between the demodulation signal for the time-of-flight sensor and the incident modulated laser beam, this camera is capable of sensing higher-order mode distortions of …