Modeling anisoplanatic effects from atmospheric turbulence across slanted optical paths in imagery

Date of Award

2016

Degree Name

M.S. in Electrical Engineering

Department

Department of Electrical and Computer Engineering

Advisor/Chair

Advisor: Russell C. Hardie

Abstract

When viewing objects over long distances, atmospheric turbulence introduces significant aberrations in imagery from optics with large apertures. We present a model for simulating turbulent effects in imagery using a technique similar to Bos and Roggemann's model [1]. This simulation will support efforts in developing innovative turbulence mitigation techniques and replacing expensive flight tests. The technique implements the commonly used split-step beam propagation method with phase screens optimally placed along the optical path. This method is used to supply a turbulence distorted point spread function (PSF) along the unique, optical path from the object to the camera aperture for each pixel of an image. The image is then distorted by scaling and summing each PSF with the appropriate surrounding area of the corresponding pixel for new pixel values. Very large phase screens have been integrated into the simulation to account for low spatial frequencies and wind speed in video. Additionally, a modified version of Schmidt's method [2] is implemented for estimating statistics for the individual phase screens in the model and for angle spectrum propagation through free space. The proposed model has the capability of simulating over horizontal or slanted paths using the Huffnagel Valley turbulence profile. For verification purposes, analysis of average simulated PSFs for short and long exposures and angle of arrival were compared to theoretical results. Further analysis of simulated error statistics were carried out against varying elevation in the atmosphere.

Keywords

Turbulence Simulation methods, Optical data processing, Aerial photography, Optics, Engineering, Electrical Engineering, Computer Science, Atmospheric Sciences, Atmospheric Turbulence, Numerical Simulation, Anisoplanatism, Turbulence in Imagery

Rights Statement

Copyright © 2016, author

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