PhD Dissertation Defense: Daniel A. Paulson

Monday, April 13, 2020
9:00 a.m.
Zoom - (Audio and video enabled) meeting link: https://umd.zoom.us/j/900029622
Maria Hoo
301 405 3681
mch@umd.edu

ANNOUNCEMENT:  Ph.D. Dissertation Defense

 

Name:  Daniel A. Paulson

 

Committee:
Prof. Christopher Davis, Chair/Advisor
Prof. Phillip Sprangle
Prof. Thomas M. Antonsen, Jr.
Prof. Julius Goldhar
Prof. Douglas C. Currie, Dean's Representative

 

Date/Time: Monday,  April 13, 2020 at 9:00 a.m.

 

Location:  Zoom - (Audio and video enabled) meeting link:  https://umd.zoom.us/j/900029622

 

Title:  Experimental Characterization of Atmospheric Turbulence Supported by Advanced Phase Screen Simulations

 

Abstract:  

Characterization of optical propagation through the low turbulent atmosphere has been a topic of scientific investigation for decades, and has important engineering applications in the fields of free space optical communications, remote sensing, and directed energy.  Traditional theories, starting with early radio science, have flowed down from the assumption of three dimensional statistical symmetry of so-called fully developed, isotropic turbulence.  More recent experimental results have demonstrated that anisotropy and irregular frequency domain characteristics are regularly observed near boundaries of the atmosphere, and similar findings have been reported in computational fluid dynamics literature.  We have used a multi-aperture transmissometer in field testing to characterize atmospheric transparency, refractive index structure functions, and turbulence anisotropy near atmospheric boundaries.  Additionally, we have fielded arrays of resistive temperature detector probes alongside optical propagation paths to provide direct measurements of temperature and refractive index statistics supporting optical turbulence observations.  We are backing up these experimental observations with a modified algorithm for modeling optical propagation through atmospheric turbulence. Our new phase screen approach utilizes a randomized spectral sampling algorithm to emulate the turbulence energy spectrum and improve modeling of low frequency fluctuations and improve convergence with theory.  We have used the new algorithm to investigate open theoretical topics, such as the behavior of beam statistics in the strong fluctuation regime as functions of anisotropy parameters, and energy spectrum power law behavior.  These results have been leveraged in order to develop new approaches for characterization of atmospheric optical turbulence.

 

Audience: Graduate  Faculty 

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