Investigation of Aero-Optical Wavefront Measurements using Laser-Induced Breakdown Sparks

Doctoral Dissertation

Abstract

This dissertation focuses on the problem of improving wavefront measurements that use the light from a laser-induced breakdown (LIB) spark as the light source. The contextual motivation involves the development of instruments for in-flight measurement aero-optical flow that is self-contained and non-intrusive. Previous studies have shown that wavefronts measured with the light from an LIB spark have dominant low-order Zernike components, specifically defocus, vertical astigmatism, and horizontal coma, that are not characteristic of aberrations on wavefronts passing through flows of interest such as a boundary layer. This research explores different models of LIB sparks to determine if the amplitudes of these Zernike aberrations can be predicted based on variations in spark attributes such as length and position that arise in spark to spark ignitions. Principal component analysis of experimentally obtained spark wavefronts revealed that the first principal component consists primarily of defocus and that next several principal components are combinations astigmatism, coma, and trefoil, all of which are predicted to arise from displacements of simple point source models. Investigation into more complicated models revealed that the light captured from wavefront sensors predominantly come from the surface of the spark.

Attributes

Attribute NameValues
Author Minh Nguyen
Contributor Eric J. Jumper, Research Director
Contributor Stanislav Gordeyev, Committee Member
Contributor R. Mark Rennie, Research Director
Contributor Joe Fernando, Committee Member
Degree Level Doctoral Dissertation
Degree Discipline Aerospace and Mechanical Engineering
Degree Name Doctor of Philosophy
Banner Code
  • PHD-AME

Defense Date
  • 2019-12-19

Submission Date 2020-04-02
Record Visibility Public
Content License
  • All rights reserved

Departments and Units
Catalog Record

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