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 58 for “"Phase Retrieval"”.
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Compressive phase retrieval
… intensities. This is unfortunate since the phase can reveal important information about the object. When the light is partially coherent, a complete description of the phase requires knowledge about the statistical correlations for each pair of points in space. Recovery of the correlation …
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Fast Phase Retrieval: A Robust and Efficient Multidimensional Phase Retrieval Algorithm
We present the first phase retrieval algorithm with a set of deterministic recovery guarantees. We show that for a class of objects known as "Schwarz Objects", the algorithm is guaranteed to reconstruct the object given only the magnitudes of its discrete Fourier transform. We present numerical …
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Phase Retrieval Under a Generative Prior
The phase retrieval problem, arising from X-ray crystallography and medical imaging, asks to recover a signal given intensity-only measurements. When the number of measurements is less than the dimensionality of the signal, solving the problem requires additional assumptions, or priors, on its …
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Phase Retrieval of Sparse Signals from Magnitude Information
The ability to recover the phase information of a signal of interest from a measurement process plays an important role in many practical applications. When only the Fourier transform magnitude of the signal is recorded, recovering the complete signal from these nonlinear measurements turns into a …
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The Phase Retrieval Algorithm as a Dynamical System
… we need to know both its modulus and its phase. The problem of reconstructing an object from only its Fourier modulus, or equivalently, the retrieving of an object’s Fourier phase, not surprisingly, is known as the phase retrieval problem. This problem belongs to a branch of mathematics …
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Algorithms and Theory for Robust PCA and Phase Retrieval
… <p>The second part of the thesis studies the phase retrieval problem, which requires recovering an unknown vector from only its magnitude measurements. Differently from the first part, we solve this problem directly via optimizing nonconvex objectives. As the nonconvex objective is often …
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Stable Phase Retrieval Using Low-Redundancy Frames of Polynomials
… the magnitudes of linear functionals while the phase information of these functionals is unavailable. Examples of these type of measurements occur in optics, quantum mechanics, speech recognition, and x-ray crystallography. The main topic of this thesis is the recovery of the phase information …
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DEVELOPMENT OF PHASE RETRIEVAL TECHNIQUES IN DISPLACEMENT AND DISPLACEMENT DERIVATIVES MEASUREMENT
… based fringe analysis technique are proposed for phase derivatives determination. A derivative based simplified phase tracker model is proposed for phase demodulation from a single fringe pattern. In time-average speckle interferometry, novel amplitude varied refreshing reference frame technique …
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Gyrotron mode converter mirror shaping based on phase retrieval from intensity measurements
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.
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Computational optical imaging: Applications in synthetic aperture imaging, phase retrieval, and digital holography
… will investigate the resolution enhancement of phase objects such as transparent biological cells. One key challenge is how to measure phase experimentally. Standard interferometric techniques have the drawback of being sensitive to environmental vibrations and temperature fluctuations, and they …
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Optimization Techniques for Phase Retrieval Based on Single-Crystal X-Ray Diffraction Data
… triplets is proposed for initially setting the phases of structure factors that compose a Karle-Hauptman matrix. Initialization in this manner is motivated by a proof of the relation between invariants and the Karle-Hauptman matrix determinant generated from a phase set. Phase initialization by …
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Double Alternating Minimization (DAM) for Phase Retrieval in the Presence of Poisson Noise and Pixelation
… can only read intensity information, and thus phase information of wavefronts is lost. Phase retrieval algorithms are used to estimate the lost phase and reconstruct an accurate effective pupil function, where the squared modulus of its Fourier transform is detected by a camera. However, …
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Deep Learning and Phase Retrieval for Chemical Holographic Imaging: System Inverse Modeling and Sample Property Prediction
… CHIS provides additional information with phase-sensitive measurements based on the DFIR imaging technique. Different forward modeling strategies are discussed, such as forward models for layered homogeneous samples and spherical heterogeneous samples. Potential inverse models for CHIS are …
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Scalar Scattering Theory and Physics-inspired Optimization for Computational Imaging
… imaging, focusing on the critical problems of phase retrieval and optical scattering—essential for accurately extracting physical information from photons. It aims to enhance the understanding and computational efficiency of existing models by addressing the fundamental challenges encountered …
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Optical imaging with machine learning for the automated characterization of micro- and nanoscale devices
… with standard optimization algorithm(s). Two phase retrieval techniques are compared: diffraction phase microscopy (DPM) and transport of intensity (TIE). TIE is modified for low intensity and zero intensity images. Modified TIE is optimized for theoretical analysis of Gaussian mode phase …
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From bits to information : learning meets compressive sensing
… to supervised learning, compressive sensing, and phase retrieval is presented in this thesis. We introduce a set of common techniques that allow us, in those three settings, to represent high dimensional data using the order statistics of linear and non linear measurements. We introduce new …
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Optimisation of Phase-Only Computer-Generated Holograms
… displays is constrained by the need to compute phase-only holograms compatible with current spatial light modulators (SLMs), which are not yet capable of displaying fully complex holograms but can only modulate either phase or amplitude, among which phase modulation is usually preferred. A …
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Sampling in Computational Cameras
… or video quality. Next we consider coherent phase retrieval. We first study the Fisher information and the Cram ́er-Rao lower bound on the mean squared error of coherent signal estimation from the squared modulus of its linear transform. Then we demonstrate two coding strategies to achieve …
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