Date of Award

9-5-2008

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Electrical and Computer Engineering

First Advisor

Juan Vasquez, PhD

Abstract

A self-referencing interferometer based closed-loop adaptive optics controller is developed which is designed to operate effectively under strong turbulence conditions. The aberrated optical field is modeled stochastically and then estimates of the state of the system are developed using a steady-state, fixed-gain Kalman filter. The phase of the optical field is considered the state of the system which is wrapped in a limited range of (-π, π]. This phase is unwrapped through the use of a least-squares reconstructor which has been modified to work effectively in the presence of branch points associated with strong turbulence. The conjugate of the optical phase is then applied to the system's deformable mirror in order to correct for the effects of atmospheric turbulence on the optical field. The advances developed in this research are in the application of a steady-state, fixed- gain Kalman filter to the input of an adaptive optic system, unwrapping the optical phases after the field estimation, and improving the phase unwrapping by varying the domain of the rotational phase component present in strong turbulence. The system developed in this research is shown in computer simulation to be improved over current designs by comparing performance plots of system Strehl ratios for systems utilizing the different designs.

AFIT Designator

AFIT-DEE-ENG-08-21

DTIC Accession Number

ADA486851

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