Estimation of astronomical images from the bispectrum of atmospherically distorted infrared data.

Persistent Link:
http://hdl.handle.net/10150/184939
Title:
Estimation of astronomical images from the bispectrum of atmospherically distorted infrared data.
Author:
Freeman, Jonathan Dennis.
Issue Date:
1989
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The uses of the bispectrum for recovering the images of one-dimensional infrared astronomical speckle data are examined in detail. An analytic model for the bispectral transfer function, the variance, and the covariance of the bispectrum are developed. The models are evaluated by Monte Carlo integration and the results are compared to sample estimates of the same quantities obtained from simulated data. For comparison, the same sample quantities are computed from observed data. The bispectrum is shown to be useful for determining estimates of the object phase. A recursive method which is used to obtain the object phase estimates is introduced. Since the bispectrum provides multiple estimates of each object phase, a number of methods for combining the multiple estimates are developed and compared. Many techniques have been proposed to determine the phase of images which have been atmospherically distorted. Among these techniques are the Knox-Thompson, and the Simple Shift-and-Add algorithms. These methods are compared to the bispectrum via an objective measure which is developed. Optimization techniques are used to great success. A model for the bispectrum of a binary star is developed and fit to the image bispectrum by the Levenberg-Marquardt algorithm for non-linear least squares. The ability of the algorithm to determine binary star parameters from the bispectrum is tested with both simulated and observed data. Since the bispectrum may not always be available, a method is developed which determines binary star parameters from the image Fourier transform. The full set of object phases and moduli are determined by use of the conjugate gradient and conjugate direction algorithms in the last section. Two starting points for each algorithm are employed. The first starting point uses the estimates of the object phases obtained from the recursive bispectrum technique. The second assumes no information is known about the object. The speed of convergence of each algorithm is analyzed and recommendations are made for future use.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Interferometry; Infrared astronomy
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Applied Mathematics; Graduate College
Degree Grantor:
University of Arizona

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleEstimation of astronomical images from the bispectrum of atmospherically distorted infrared data.en_US
dc.creatorFreeman, Jonathan Dennis.en_US
dc.contributor.authorFreeman, Jonathan Dennis.en_US
dc.date.issued1989en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe uses of the bispectrum for recovering the images of one-dimensional infrared astronomical speckle data are examined in detail. An analytic model for the bispectral transfer function, the variance, and the covariance of the bispectrum are developed. The models are evaluated by Monte Carlo integration and the results are compared to sample estimates of the same quantities obtained from simulated data. For comparison, the same sample quantities are computed from observed data. The bispectrum is shown to be useful for determining estimates of the object phase. A recursive method which is used to obtain the object phase estimates is introduced. Since the bispectrum provides multiple estimates of each object phase, a number of methods for combining the multiple estimates are developed and compared. Many techniques have been proposed to determine the phase of images which have been atmospherically distorted. Among these techniques are the Knox-Thompson, and the Simple Shift-and-Add algorithms. These methods are compared to the bispectrum via an objective measure which is developed. Optimization techniques are used to great success. A model for the bispectrum of a binary star is developed and fit to the image bispectrum by the Levenberg-Marquardt algorithm for non-linear least squares. The ability of the algorithm to determine binary star parameters from the bispectrum is tested with both simulated and observed data. Since the bispectrum may not always be available, a method is developed which determines binary star parameters from the image Fourier transform. The full set of object phases and moduli are determined by use of the conjugate gradient and conjugate direction algorithms in the last section. Two starting points for each algorithm are employed. The first starting point uses the estimates of the object phases obtained from the recursive bispectrum technique. The second assumes no information is known about the object. The speed of convergence of each algorithm is analyzed and recommendations are made for future use.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectInterferometryen_US
dc.subjectInfrared astronomyen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineApplied Mathematicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.identifier.proquest9014668en_US
dc.identifier.oclc703612298en_US
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