Date of Award

3-2008

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Electrical and Computer Engineering

First Advisor

Jason D. Schmidt, PhD

Abstract

Using a device to act as a surrogate for atmospheric turbulence in a laboratory is necessary to build and test optical systems for imaging, lidar, laser weapons, and laser communications. Liquid-crystal spatial light modulators (LC SLMs) and segmented micro-electro-mechanical-system (MEMS) deformable mirrors (DMs) are commonly used devices for altering wavefronts in order to simulate a portion of atmospheric turbulence. The best location of these devices was theoretically analyzed to obtain the broadest possible range of atmospheric conditions. It was found that two phase screens should be placed at the beginning of the optical path to achieve maximum turbulence strength for an incident plane wave. It was also revealed that a layered model for atmospheric turbulence strength can be represented by the atmospheric coherence diameter that a single segmented wavefront control device can produce. The limitations of pixelation effects on a segmented wavefront control device were investigated theoretically. The results of this analysis were then confirmed in simulation. It was found that while LC SLMs with high bandwidth have almost no adverse effects from pixelation, segmented MEMS DMs have limitations as a result of the number of mirror segments on a DM. The performance capabilities of several available commercial devices are better understood as a result of this research.

AFIT Designator

AFIT-GEO-ENG-08-02

DTIC Accession Number

ADA482906

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