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 162 for “"wavefront"”.
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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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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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Measuring Corneal Topography Using Wavefront Analysis Technique
… a corneal topographer based on a Hartmann-Shack wavefront sensor for measuring corneal elevation over a spherical surface, is presented in this thesis. The performed tests of the topography system showed a high accuracy and reproducibility of the measurements on spherical as well as on toric test …
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Development of a new Infrared Pyramid Wavefront Sensor
… for astronomical observations is sensing the wavefront at near-infrared wavelengths, where many bright stars are found, which can be used as guide stars and have no visible counterparts. A pyramid wavefront sensor was chosen due to its advantages over the Shack-Hartmann sensor. It is expected …
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Wavefront Engineering and Computational Sensing with Acoustic Metamaterials
<p>Acoustic metamaterials are a family of engineered materials that can be designed to possess flexible acoustic properties. They are composed of subwavelength periodic structures that can be homogenized as effective materials within the designed frequency bands. Acoustic wave controlling devices …
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3-dimensional surface imaging using Active Wavefront Sampling
A novel 3D surface imaging technique using Active Wavefront Sampling (AWS) is presented. In this technique, the optical wavefront traversing a lens is sampled at two or more off-axis locations and the resulting motion of each target feature is measured. This target feature image motion can be used …
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Distance estimation through wavefront curvature in cellular systems
Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.
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Recovery from transient faults in wavefront processor arrays
A transient fault in an array of processing elements results in an inconsistent or incorrect state in the processing element. If the erroneous information has already propagated before detection occurs, then the neighboring processing elements can also be in an incorrect state. Restarting the …
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Wavefront Healing and Tomographic Resolution of Mantle Plumes
… as an artifact. This is caused by different wavefront healing effects between P waves and S waves in thermal plume models. The bulk sound speed structure remains poorly resolved when P-wave and S-wave measurements are at different periods with similar wavelength. The differences in wave …
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Prototyping Blue Phase Wavefront Correctors for Astronomical Adaptive Optics
… applied with a root mean square of the wavefront of 76.05 radians across a 1 cm x 1 cm area at an applied field of 14.3 V/μm. This is a milestone achievement for blue phases in the first ever demonstration of them being used for astronomical adaptive optics. Moreover, these devices were …
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Wavefront modelling and sensing for advanced gravitational wave detectors
The Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) directly detected gravitational waves for the first time on the 14th of September 2015. In 2017 the detection of gravitational waves from a binary neutron star merger was subsequently followed up by observations by optical and …
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Active wavefront correction in laser interferometric gravitational wave detectors
… parts of the interferometer, result in critical wavefront deformations which will cripple the performance of the instrument. Discussed is a method of active wavefront correction via direct thermal actuation on optical elements of the interferometer; or, "thermally adaptive optics". A simple …
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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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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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Tomographic Reconstruction of Wavefront Aberrations using Multiple Laser Guide Stars
… class) telescopes (ELT). Modal decomposition of wavefront phase using Zernike 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 …
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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 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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Adding Personalized Wavefront Correction to a Scleral Lens After Lens Manufacture
PURPOSE: To date, wavefront-guided scleral lenses have relied on the full-surface method (FSM) of manufacture, which requires the wavefront correction to be integrated into the design of a traditional scleral lens prior to lens manufacture. A novel patch-cutting method (PCM) of manufacture would …
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Algorithms for the application of Hartmann-Shack wavefront sensors in ophthalmology
… algorithms for applications of Hartmann-Shack wavefront sensors in ophthalmology. Two compact systems were built to do measurements of the entire optical system of the human eye. Automatic pre-correction modules were integrated to compensate a sphere of -11.25 dpt to 3.25 dpt and an astigmatism …
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