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Numerical Simulation Of Tomographic Reconstruction For The Study Of Turbulence Using Optical Wavefront Sensor Measurements
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Book Synopsis Numerical Simulation of Tomographic Reconstruction for the Study of Turbulence Using Optical Wavefront Sensor Measurements by : Robert L. Johnson
Download or read book Numerical Simulation of Tomographic Reconstruction for the Study of Turbulence Using Optical Wavefront Sensor Measurements written by Robert L. Johnson and published by . This book was released on 1993 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: The optical quality of a coherent beam passing through a turbulent flow layer can be severely degraded by phase errors. The principle goal of this research is to model the use of wavefront sensor measurements and computed tomography to reconstruct refractive index distributions of transparent objects for the study of turbulent flows. Tomography is the processing of measurements of one-dimensional line integrals through a two-dimensional function to reconstruct a two-dimensional estimate of the function. A least-squares wavefront phase reconstructor is modeled using Zernike polynomials and triangle functions as elementary functions for the reconstructor. Two tomographic reconstruction algorithms are implemented: (1) iterative reconstruction and (2) filtered back-projection. Through numerical simulation, the effects of undersampling and limited wavefront sensor resolution are studied. Distorted wavefront data are generated by performing line integrals through known objects with different numbers and ranges of view angle. Wavefront reconstruction is applied using varying resolution. Two tomographic reconstruction methods are employed and comparisons are made with the original known objects. Results show that a least-squares wavefront reconstructor using triangle functions provides better results. Increasing the number and range of view angles generally improves the quality of the tomographic reconstruction. Furthermore, iterative tomographic reconstruction techniques prove superior when limited data are available. Optical tomography, Computed tomography, Wavefront reconstruction, Flow visualization, Three-dimensional reconstruction.
Book Synopsis Numerical Simulation of Tomographic Reconstruction for the Study of Turbulence Using Optical Wavefront Sensor Measurements by : Robert L. Johnson (CAPT, USAF.)
Download or read book Numerical Simulation of Tomographic Reconstruction for the Study of Turbulence Using Optical Wavefront Sensor Measurements written by Robert L. Johnson (CAPT, USAF.) and published by . This book was released on 1993 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 1028 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Book Synopsis Masters Theses in the Pure and Applied Sciences by : Wade H. Shafer
Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 38 (thesis year 1993) a total of 13,787 thesis titles from 22 Canadian and 164 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 38 reports theses submitted in 1993, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.
Download or read book Optical Engineering written by and published by . This book was released on 1995 with total page 922 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publishes papers reporting on research and development in optical science and engineering and the practical applications of known optical science, engineering, and technology.
Book Synopsis 18th AIAA Aerospace Ground Testing Conference by :
Download or read book 18th AIAA Aerospace Ground Testing Conference written by and published by . This book was released on 1994 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Announcements & Index by :
Download or read book Government Reports Announcements & Index written by and published by . This book was released on 1996-02 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Annual Index by :
Download or read book Government Reports Annual Index written by and published by . This book was released on 1994 with total page 1754 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Journal of the Optical Society of America by :
Download or read book Journal of the Optical Society of America written by and published by . This book was released on 2004 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Principles of Adaptive Optics by : Robert K. Tyson
Download or read book Principles of Adaptive Optics written by Robert K. Tyson and published by CRC Press. This book was released on 2022-02-28 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Principles of Adaptive Optics describes the foundations, principles, and applications of adaptive optics (AO) and its enabling technologies. This leading textbook addresses the fundamentals of AO at the core of astronomy, high-energy lasers, biomedical imaging, and optical communications. Key Features: Numerous examples to explain and support the underlying principles Hundreds of new references to support the topics that are addressed End-of-chapter questions and exercises A complete system design example threaded through each chapter as new material is introduced
Book Synopsis 26th AIAA Plasmadynamics and Lasers Conference by :
Download or read book 26th AIAA Plasmadynamics and Lasers Conference written by and published by . This book was released on 1995 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Tomographic Reconstruction of Wavefront Aberrations Using Multiple Laser Guide Stars by :
Download or read book Tomographic Reconstruction of Wavefront Aberrations Using Multiple Laser Guide Stars written by and published by . This book was released on 2009 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tomographic reconstruction using multiple laser guide stars (MLGS) will be required by the next generation of extremely large (30 m 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 basis, the disk harmonic functions, to overcome the disadvantages of the Zernike basis at high spatial resolution. A method of fast, analytic, modal tomographic modeling is developed and used for fast calculation of reconstruction matrices used on-sky at the MMT telescope. The specific reconstruction techniques of ground layer adaptive optics and laser tomography adaptive optics using MLGS are presented along with the results of on-sky experiments at the MMT. In addition to developing a laser AO instrument for the MMT, these experiments provide a test bed for validating the reconstruction techniques that will be critical to the success of ELTs. An approach to using real-time wavefront sensor and deformable mirror telemetry from the MLGS system to estimate the vertical distribution of turbulence in the atmosphere is also presented.
Author :American Institute of Aeronautics and Astronautics. Technical Information Service Publisher : ISBN 13 : Total Pages :226 pages Book Rating :4.3/5 (91 download)
Book Synopsis The Finding Guide to AIAA Meeting Papers by : American Institute of Aeronautics and Astronautics. Technical Information Service
Download or read book The Finding Guide to AIAA Meeting Papers written by American Institute of Aeronautics and Astronautics. Technical Information Service and published by . This book was released on 1994 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atmospheric and Oceanic Optics written by and published by . This book was released on 2000 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Numerical Simulation of Optical Wave Propagation with Examples in MATLAB by : Jason Daniel Schmidt
Download or read book Numerical Simulation of Optical Wave Propagation with Examples in MATLAB written by Jason Daniel Schmidt and published by Society of Photo Optical. This book was released on 2010 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical Simulation of Optical Wave Propagation is solely dedicated to wave-optics simulations. The book discusses digital Fourier transforms (FT), FT-based operations, multiple methods of wave-optics simulations, sampling requirements, and simulations in atmospheric turbulence.
Book Synopsis Statistical Tomography for Scalar Turbulence Measurements Using Line of Sight Optical Techniques by : Pankaj Sharadchandra Kolhe
Download or read book Statistical Tomography for Scalar Turbulence Measurements Using Line of Sight Optical Techniques written by Pankaj Sharadchandra Kolhe and published by . This book was released on 2009 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence has been an intriguing subject for several decades with past studies focusing on understanding the transition to turbulence and characterizing turbulence using statistical tools. In present research rainbow schlieren deflectometry (RSD), a line of sight optical technique, is used and its high spatio-temporal resolution measurement capability is demonstrated through transitional hydrogen gas jet diffusion flame experiments wherein hitherto unknown secondary instability in flame surface is captured by employing 23 microseconds exposure time and 400 micro-meter/pixel resolution at 2000 Hz image sampling rate. Significant effects of buoyancy previously thought unimportant are identified and a conceptual view of transitional jet diffusion flames illustrating various instabilities is developed. The quantitative characterization of turbulent flow requires local scalar field statistics. However, RSD provides path integrated measurements that must be deconvoluted to obtain the local field statistics. For round turbulent jets, Abel inverse transform can be used to deconvolute time averaged local field quantities such as mean refractive index difference. Based on critical evaluation of four techniques two point formula, a semi-analytical approach, is recommended to evaluate the improper integral in Abel inverse transform with best accuracy and minimum error propagation. For deconvolution of second moment statistics (scalar fluctuation intensity) from path integrated measurements cross beam correlation (CBC) algorithm is presented and analyzed using noise free synthetic scalar turbulent data. CBC algorithm is found to yield accurate reconstruction only in fully developed turbulent flows and it required knowledge of statistics at inlet boundary that are generally unknown. To overcome limitations of CBC algorithm, a novel spectral analysis algorithm is developed and verified using synthetic scalar turbulent data. The algorithm provided local field statistics (mean and variance) at high accuracy using path integrated data in only one line of sight. Present implementation was limited to time averaged axisymmetric turbulent flow although its extension to asymmetric flow is feasible. Spectral analysis algorithm was applied for measurements in a turbulent helium jet with diameter, d = 2.96 mm at Reynolds number, Re = 3500 and Richardson's number, Ri =0.0000102335. Mean, variance, autocorrelation function, and power spectra of local scalar properties are presented to characterize the turbulent flow.
