Spatial Heterodyne Imaging Using a Broadband Source

Date of Award

2018

Degree Name

M.S. in Electro-Optics

Department

Department of Electro-Optics

Advisor/Chair

Advisor: Paul McManamon

Abstract

Imaging through obscurants is a critical issue for lidars looking through clouds, or human tissue. Traditionally Spatial heterodyne imaging has been performed with a low-bandwidth laser source that exhibits good coherence length characteristics. One of the drawbacks of using a low-bandwidth source with long coherence length is that signal return from all objects within the coherence length of the source mix equally well on the camera imaging the system. Broadening the bandwidth of the source shortens the coherence length of the system. This thesis intends to show that through careful system design, spatial heterodyne imaging can be performed in the presence of a broadband source, allowing significantly improved imaging in the presence of obscurants such as clouds or human tissue. The method used will be phase modulating the source with a pseudo-random bit sequence and matching the optical path lengths of the signal and local oscillator branches of the system. By matching the path lengths for a pseudo-random coded source we can image objects at specific distances related to the modulation speed and code length, while isolating the power of signal return from objects at other distances as a factor of the autocorrelation coefficient of the code.

Keywords

Electrical Engineering, Engineering, Optics, Remote Sensing, Spatial Heterodyne Imaging, Digital Holography, Spatial Heterodyne, Lidar, Ladar, Pseudo-random bit sequence, pseudo-random code, pseudo random bit sequence, pseudo random code, PRBS, Phase Modulation, Laser Radar

Rights Statement

Copyright © 2018, author

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